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If your office is anything like mine, there is never we showed as of salesman stopping in ready to sell the next great advancement in bonding systems. The most recent, seems to be the introduction of the self etching primers. These are known as sixth generation adhesives. I'm glad I don't have to recite the previous five. The advance in this newest generation is the combining of the etchant in the primer. In other words, the chemists have grafted the primer molecule onto the phosphoric acid molecule with the idea being that the hydrogen ions will be given out first acid etchant, thereby leaving the primer molecule alone as the byproduct. This eliminates many steps on the process and presumably the chances for errors as well. It sounds feeling, but does it work for bonding orthodontic brackets?

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In the January two thousand and one issue of the Journal of Clinical Orthodontics, Dr. Robert Miller published report entitled ¡°Laboratory and clinical evaluation of a self etching primer¡±. I was disappointed one I found out the laboratory part of this investigation was data provided by the manufacturer rather than independent testing. The laboratory data shows that the strength of the self etching primer should be at least as great as a traditional etching-priming bonding procedure. So with the laboratory data supported it is the time to demonstrate the clinical usefulness of the self etching primer.

Dr. Miller conducted the study, which place brackets on teeth using either the self etching primer or a conventional etching-priming technique. The self etching primer technique consisted of pumicing the teeth, swirling the self etching primer on each enamel surface for two to five seconds, thinning the primer with the burst of air, than placing brackets with conventional light cured resin.

In this study, the author use the ESPE Prompt L-Pop self etching primer, which is identical to the Unitek Transbond Plus. In the clinical test, 464 brackets were bonded with the conventional etching-priming technique and 514 brackets with the self etching primer. The author didn't specify how many patients the brackets were place than but my math tells me about 25 patients per group, The bracket failures were recorded for six months, and the two techniques were compared. The bracket retention rate was about 99 percents for both techniques. In other words, the self etching primer was just as effective in bonding orthodontic brackets as conventional technique. The retention rate of 99 percent is quite high, and makes me wonder whether this study was done unconsecutive patients or select group with ideal characteristics.

It seems clear that the self etching primer has great promise, elimination of the rinsing and drying step has the potential to reduce the chance for error in the bonding process. I look forward to a little more vigorous investigation of self etching primers, so I can decide whether the added cost is worth possible gains and efficiency. In the meantime, if you want further information about this sixth generation bonding agent now, you can refer the Dr. Miller's article in the January two thousand one issue of the Journal of Clinical Orthodontics.

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Last month in these tape serise I reviewed the new experimental technique for three-dimensional imaging in localization of objects within the craniofacial region. Part of that study involved a localization test which indicated dentists were only correct 15 percent of the time when judging whether the mandibular canal was buccal or lingual to a tooth root. Are we any better when judging the buccal or lingual position of an impacted maxillary canine? Carol Mason and Colleagues from Eastman Dental Institute in London, recently published a paper entitled ¡°The radiographic localization of impacted maxillary canines: a comparison of methods¡±. This paper appears in the February, 2001 issue of the European Journal of Orthodontics and examines the questions of how accurately we can locate an impacted maxillary canine from commonly taken x-ray films.

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The authors identify one hundred cases that had at least 1 impacted maxillary canine. In addition, these patients also had panoramic x-ray and a maxillary occlusal x-ray available, and had undergone surgery to verify the actual position of the impacted tooth. The canine location was determined by two radiographic methods using a panel of six practitioners. The practitioners varied in specialty training and experience.

The first radiographic technique was the parallax or image shift technique. This used vertical tube shift between a panoramic film and an maxillary occlusal film to localize the impacted tooth. The magnification technique was used with panoramic film only as the second technique for localization. The magnification technique uses the greater horizontal magnification of palatally placed objects to determine location. Well, how good were these two techniques and how did they compare to one another? Overall, there was no statistically significant difference between the two techniques. Both techniques located the palatal canines correctly almost 90 percent of the time. The buccal canines however were different story. The parallax, image shift technique located the buccal canines correctly almost half the time, but the image magnification technique was only rarely successful. Based on these results, the authors recommend initially using the panoramic film for location. If the palatal position cannot be confirm from the panoramic film, then additional views should be taken for localization. The overall success rate for localization was only about 75 percent when palatal and buccal impactions were combined. This indicates a place for new technology in localization of impacted maxillary canines. I think we can say that radiographic localization of impacted canines is some what better than the previous study of locating the mandibular canal, but we are still far from perfect.

To read more about this specific study, refer to the February, 2001 issue of the European Journal of Orthodontics.

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Occasionally I have a class II patient with skeletal mandibular deficiency, that can be treated very nice dental result with orthodontic treatment only. The esthetic outcome is not optimal though because of the convex profile and chin deficiency. An ideal solution may be to consider advancement genioplasty. When I suggested this option to such a patient, they may ask whether such a procedure stable long term. Much of data on genioplasty is from studies of patients also had mandibular advancement procedure.

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Recently, Dr. Talebzadeh and colleagues from university of California at San Francisco conducted a study to determine if advancement genioplasty is stable when done alone and to see how the stability compares to genioplasty done in conjunction with mandibular advancement surgery. The study is recently published in the journal, Oral surgery Oral medicine and Oral pathology in February 2001 issue.

The title of the article is "Long term hard and soft tissue relapse rate after genioplasty". The authors collected 20 patients when underwent genioplasty. 11 of these patients had genioplasty alone and 9 had genioplasty along with mandibular advancement surgery. Lateral cephalometric X-rays were taken before surgery, immediately after surgery and 12 month after surgery.

The X-rays were traced and measured for both hard and soft tissue movements. The average advancement of the chin was just under 10 mm for the group of genioplasty alone and almost 15 mm for the genioplasty with mandibular advancement. The average hard tissue relapse was less then 1 mm when measured at 12 month. There is no difference in the relapse rate between those patients with genioplasty alone and those with concurrent mandibular surgery.

In addition there is no difference in the relapse rate a genioplasty greater than 7 mm compared to those less than 7 mm. The soft tissue advancement was approximately 90 % of the hard tissue advancement right after surgery. 1 year later although the hard tissue was stable, the soft tissue was only about 75 % of the hard tissue change. This likely indicates soft tissue remodeling takes place following surgery.

This study supports the long-term stability of genioplasty procedure done with or without mandibular advancement surgery. The average relapse of hard tissue was very small and the other look at the raw data indicates significant variability. The significance of this study is limited by small sample size.

However I think when put in context of all the data we have this suggest that we can be comfortable in offering genioplasty procedures to our patients with confidence of they will have good long-term stability. For more details of this study refer to February, 2001 issue of the triple 'O'.

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Palatally impacted canines can be classified as either simple or complex. The majority of palatally impacted canines fall in the simple category. These canines are usually not very deeply imbedded in the palatal bone and the incisal edge is located near the CEJ of the adjacent lateral and central incisor. Often times, these teeth can be palpated in the palate and a small bump can be seen which helps in the diagnosis of their location.

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The complex palatal impaction is deeply imbedded within the palatal bone and is positioned very high apically near the middle to apical third of the adjacent roots of the central and lateral incisor. There is usually no bump in the palatal tissue indicating the location of the tooth. The best way to ascertain the exact location of the tooth is by taking appropriate periapical radiographs from two different angles and using the buccal object rule, which will precisely allow the surgeon to know whether the tooth is on the labial, palatal or midalveolar position. A panoramic radiograph will not give this information.

The timing of the surgical uncovery is different for the simple and complex palatal impactions. I prefer to uncover the simple palatal impactions at least 6 months prior to the orthodontist initiating treatment. Our experience has found that these teeth will erupt on their own after they have been uncovered and it will greatly simplify the orthodontic positioning of the teeth, with less trauma on the canine, and less trauma on the adjacent dentition.

On the other hand, the complex palatal impaction should be surgically uncovered only after appropriate appliances are in place, and space is being opened for positioning of the canine. Because of the deep location of the complex palatal impaction, it is imperative that a bracket and chain be attached to the tooth and orthodontic movement be initiated within a few weeks after the uncovering. Otherwise, the tissue will grow over these deeply imbedded teeth.

Surgical uncovering of the palatal impaction is different depending on whether it is a simple or complex impaction. The simple palatal impaction is by far the most common impaction encountered. To uncover a simple palatal impaction, a palatal flap is reflected usually from the second bicuspid up to the central incisor. Often times the tooth has a shell of bone completely covering it. This bone can be removed very easily with a curette or with small round burs?

Curetting the sack around the tooth will help delineate the periphery of the clinical crown. It is very important that complete bone removal be accomplished around the clinical crown of the tooth. However, do not expose the cementoenamal junction. Once complete bone removal is accomplished, the palatal flap is repositioned and the tooth can be palpated through the flap. A small scalloping incision is made over the tooth, so that when the flap is ultimately sutured the tooth can be seen through the fenestration in the flap. I will often take a photograph, either a slide or a polaroid photograph of the tooth for the orthodontist so they can see the exact orientation of the tooth. This will be helpful for the orthodontist. If the deciduous canine is present, it is extracted at the time of the surgery. The flap is sutured and a dressing can be placed on the clinical crown of the tooth to prevent any tissue overgrowth.

If the tooth is moderately imbedded in the palate, then there is some concern that the tissue may grow over it. Then a bracket can be bonded to the tooth, which will aid in retention of the dressing. The patient is seen in one week, and the dressing is removed. If it appears that the tissue is not going to grow over the tooth, then no replacement of the dressing is necessary. If there is some concern that the tissue may granulate over the tooth, then the dressing will be placed for one more week. Following the removal of the dressing the patient is instructed in brushing the visible portion of the tooth in keeping it plaque free. Usually the margins of the scalloped flap will be healed within 4 weeks, and the tooth will already have begun to erupt.

Our experience has shown that when simple palatal impacted teeth are uncovered before orthodontic treatment, they will erupt considerably. And most interestingly, tend to erupt distally and move away from the adjacent central and lateral incisors. When the orthodontist initiates treatment, these teeth are very easy to move into the edentulous site with minimal trauma on the anchorage teeth. Most importantly, there is no trauma on the adjacent teeth, since the canine has already erupted and moved away from the root of the central and lateral.

The complex palatal impaction should be uncovered after appliances are on the teeth, and the appropriate space is being opened for the canine. Fortunately, the complex palatal impaction occurs infrequently, because these teeth are very difficult to surgically uncover, keep uncovered, and orthodontically move into the appropriate position. An extensive palatal flap is needed to uncover these teeth. Oftentimes, the flap will need to go from the first molar around to the opposite central incisor crossing the midline. Since these teeth are deeply imbedded with in the palatal bone, they can be very difficult to find and bone removal is necessary, as stated previously. This needs to be done very slowly and judiciously, so the enamel of the tooth is not marred and the root surface is not exposed.

Once the appropriate bone removal is accomplished, the area is isolated with hemostatic agents, the tooth is etched, a bonding agent is placed on it, and then a bracket is bonded on the tooth. I like to verify the security of the bracket by getting a hold of it with the hemostat when trying to dislodge the bracket. This will also verify that the tooth is mobile and not ankylosis. A photograph is taken of the exact location and orientation of the tooth, which will assist the orthodontist in the appropriate mechanics for tooth movement. The palatal flap is repositioned and a fenestration is made through the flap exposing the bracket on the tooth. A gold chain is ligated to the bracket and the other end is ligated to the bracket on the lateral incisor or bicuspid adjacent to the edentulous area. The orthodontist can initiate tooth movement within a few weeks. Usually, with the complex palatal impaction, it is necessary for the orthodontist to fabricate a lingual arch, soldered to the maxillary first molar bands. A spring can solder to the mid portion of the palatal arch which will allow eruption in a posterior direction. This will avoid damage to the adjacent root surfaces of the central and lateral incisor. Once the tooth is erupted into the palate, and away from the central and lateral incisor, it can then be walked into the edentulous area with the appropriate elastics and other orthodontic means.

With proper diagnosis, proper surgical uncovering, and proper orthodontic mechanics, a palatally impacted canine can be orthodontically positioned in the ideal location. In my experience of uncovering these teeth, over a twenty-five year period of time, I have never found a palatally impacted canine in an adolescent to be ankylosed. As patients approach 35 years of age and older, there is a greater likelihood that a palatally impacted canines could become ankylosed. However, in adolescents, we have never found and ankylosed palatally impacted tooth. Most of the palatally impacted canines that are claimed to be ankylosed, are usually ones that were improperly uncovered and appropriate bone removal was not accomplished so that the tooth could not be orthodontically erupted.

The other problem is improper orthodontic mechanics. If the tooth is pre-uncovered it will erupt on its own to a point where it will be very easy to move. On the other hand, if the tooth is more deeply imbedded in the bone, it is important for the orthodontist to realize that the tooth has to be erupted into the palate first and then moved into the site. If the orthodontist simply attaches a wire or elastic to the teeth and makes a direct pull to the edentulous area, the tooth will be very very slow to move, and may not move at all. The reason being that the coronal portion will not resorb bone and if you are pulling the crown into the bone the process is going to be very slow or may not occur at all. So the direction of the mechanics is important in erupting these teeth, and of course the surgeon has to create the appropriate bone removal so that they can be erupted out of the bone. The pre-orthodontic uncovery technique has really facilitated movement of the palatally impacted canines by allowing these teeth to erupt on their own in the palate and away from the central and lateral incisor.

We found that, not only is the orthodontic movement easier, it puts less trauma on the adjacent teeth so there is less possibility for root resorption on the anchorage teeth. We also found that the bone around the lateral incisor is normal, and the bone around the impacted tooth is normal following the completion of orthodontic treatment because there is no trauma to the adjacent site. The other important factor for retention of these teeth is that the orthodontist appropriately finishes the case with a root torque. Often times, these teeth have been pulled out of the palate and have improper root alignment and the orthodontist needs to make the appropriate root torque to finish the case, which will enhance the post-treatment retention of the tooth.

I hope that you have found this information to be helpful in dealing with the simple and complex palatally impacted canines

Orthodontic In Vivo Bond Strength: Comparison with In Vitro Results

Pickett KL, Sadowsky PL, et al
Angle Orthod 2001;71:141-148

April 12, 2002
Dr. Hye Young Ryu

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Let me ask you a couple of questions about your bonding technique. First of all, what type of bonding material do you use to secure brackets to teeth? I think today, most orthodontist use some sort of light-cure bonding material in order to enhanced strength of the bond bracket. Question number 2. Why did you select that particular bonding material? Today there's many many products available on the market to bond bracket to teeth. So, why were you using the current product, if selected? I'm sure the answer that question was very significantly among clinicians.

Some of simply use what works? Others several recieve recommendations from colleagues about certain products and still others may have seen products demonstrated at regional or national meeting. You know probably the best way the select the bonding material is to read literature. We're all interested keeping brackets on the teeth or another words, to avoid debonding during orthodontics. So What depending upon the bond strength? All products are tested in the laboratory. It is possible to find out the in vitro or laboratory bond strength of any product in use today in orthodontics, but what is that values mean? Does the laboratory testing of bonding bracket really relate to its clinical use? Other bond strength reported in the literature, actually related to bonding strength, that exist intraorally. I've often wonder about those questions. I found the answers in the articles, published in April, 2001 issue of the Angle Orthodontist.

The title of that article is¡°Orthodontic In Vivo Bond Strength: Comparison with In Vitro Results¡±. This study was coauthers by Kevin. Pickett and Lioneal Sandowsky, from the department of orthodontics at the University of Alabama in Birmingham. Studies in the past have evaluated in vivo and in vitro bond strength, but different types of debonding mechanisms were used. The significants of this particular study is the same type of debonding tool was used in both situations. Even more importantly the debonding tool was compared to the standard universal instron testing machine, Which is reported in most in vitro or laboratory studies. Let me explain what I mean. In the laboratory, when brackets are placed on extracted teeth and debonded, a standard machine called a universal Instron testing apparatus is typically used to measure the amount of force takes to debracket a tooth. But this type of machine, can't be used intraorally. So accurate comparison of intraoral and laboratory debonding strength is not possible. In this study, the researcher develop the tool and used this tool both intraorally and extraorally. Photographs of the instrument are printed in the article. Distinct of this paper is that the researchers then compare this apparatus to the Instrun testing machine in the laboratory. But also use the same debonding device on patient that had undergone orthodontic treatment.

For the laboratory test, 60 extracted premolars were used, they were etched and brackets were bonded using a light cure composite. Then the brackets were debonded and in 30 of the brackets and Instron testing machine was used debracket and the other 30, and intraoral debonding device was applied. The amount of force necessary to debond bracket was comparable. In other words, the force necessary to debond using the Instron was 12 MPa, and for the intraoral debonding device it was 11 MPa. So that was only a small difference between these two in vitro or laboratory approaches. Then 8 patients who near the end of the orthodontic treatment had the premolar brackets debonded with this intraoral testing device. These patients who had the bracket in placed for nearly 2 years. None of these brackets had accidently become debonded during orthodontics. The intraoral testing devices was then used to debracket these teeth and the force was recorded. What do you think this researchers found? Do you think the force, necessary to debond bracket intraorally, was the same as the in vitro or laboratory test? Not even close. That average force necessary to debond brackets intraorally was about 5 MPs. This is less than half the force necessary to debond bracket in the laboratory, and this was using the same device. So what's my point? Well I guess my point is don't believe the laboratory test entirely. In this study, the amount of force necessary to debond bracket in the lab was over twices much as that necessary intraorally. I believe that manufacturers should give us accurate information.

But we, clinician ready need to have connections reading little to know is the in vivo or intraoral debond strength of the materials that we use. Only in that way can be actually and adequately choose the proper bonding material. Hopely in the future, these the debonding tools or something like it would be used to test other bonding materials and have a better idea of the true bond strength of whatever material briefly using intraorally. If you interested in reading this article, you find it in the April 2001 issue of the Angle Orthodontist.

Long-term stability of dental arch form in normal occlusion from 13 to 31 years of age

Henrikson J, Persson M, Thilander B

Eur J Orthod 2001;23:51-61

 April 19, 2002

Dr. Seon Mi Kim

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As orthodontists, we attempt to create the ideal arch form for an individual patient at age 13, and then expect it to remain stable from that time forward. We may indicate the patients that with the proper maintenance and use of retainers, our treatment results can be stable long-term. Some orthodontists also believe that treating patients to a single universal arch form is indicated, and strive to obtain that arch form in all patients.

We may be able to make some judgement on these beliefs if we were able to look at the arch form of a group of untreated class I patients at age 13 and then follow these patients into adulthood to look at arch form changes might occur. This is exactly what a group of researchers from Sweden recently did when they published their paper; Long-term Stability of Dental Arch Form in Normal Occlusion from 13 to 31 Years of Age. This paper was published in the February 2001 issue of the European Journal of Orthodontics.

These researchers found a group of 30 individuals that had dental casts from age 13 and were available for follow-up at age 31. All of these individuals had Class I normal occlusion at age 13. The dental casts from age 13 and age 31 were subjected to a standardized photographic technique and digitized for arch form analysis and measurements. The arch forms were quantified using conic sections to allow comparison.

Did the researchers find evidence for a single universal arch form in this population? The answer is NO. There were significant variation in arch form at age 13 and even greater arch form variation at age 31. If this much variation was noted in rather homogeneous Scandinavian sample, imagine the variation that is likely to be found in the more diverse population.

Did the arch form remain stable for individuals from age 13 to 31? The answer is again NO. The mandibular arch form tended to become more rounded with age and both the upper and lower intercanine widths were reduced. One interesting finding was that  the lower intermolar width increased in the males and decreased slightly in the females.

Did the arch form changes that were noticed correlate with increase in incisor irregularly? The answer in this case is YES. The lower arch form became more rounded and shortened in depth, and these changes were correlated with an increase in lower incisor crowding.

This is only a small amount of the information that is available in this paper. There is additional information about specific arch form changes and about the variation and arch form that was discovered. This additional information is available in the article published in the February 2001 issue of the European Journal of Orthodontics.

Based on the information that I've reviewed with you, I think it is safe to say that searching for universal arch form that is right for all people is unrealistic. We also should consider the changes in arch form over time that were discovered when we determine strategies for long-term orthodontic stability.

Integrating Esthetic Dentistry and Space Closure in Patients with Missing Maxillary Lateral Incisors

Rosa M, Zachrisson BU

J Clin Orthod 2001;35:221-234

                                                                     May 10, 2002

                                                                Dr. Hang Ik Jang

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 Now that we have predictable and esthetic dental implant restorations available. Is canine substitution treatment no longer popular option for missing maxillary lateral incisors? Can't esthetics of canine substitution treatment be improved by combining orthodontic treatment? But techniques can temporary esthetic dentistry. Dr. Rosa & Dr. Jachrisson recently published the paper in the April 2001 issue of the Journal of Clinical Orthodontics that emphasizes the positive aspects of canine substitution treatment and demonstrates how to esthetics can be improved to make the result virtually indistinguishable from a natural dentition.

 The article is an entitled, "Integrating esthetic dentistry and space closure in patients with missing maxillary lateral incisors." To get the most value from this article, you must see the clinical photographs included, but I will try to summarize for you how to authors deal with the common esthetic problems associated with canine substitution treatment.

The crown shape problem is handled by a combination of enamel recontouring and esthetic build-up with hybrid composites or porcelain veneers. It is suggested that the canine in the lateral position elapse slightly convex on the facial surface due to the thin enamel and risk of dentin exposure if recontouring is too aggressive.

The gingival alignment difficulties often result in gingival contours too high on the canines in the lateral position and too low on the premolar in the canine position. This can be corrected by extruding the canine in the lateral position and recontouring the crown along with intruding the premolar to raise the gingival contour and an building up the crown with composite or porcelain veneer.

The problematic yellow color of some canines can be corrected prior to composite build-up with modern vital bleaching procedures. The inadequate crown torque of the canine in the lateral position can be corrected by proper orthodontic positioning focusing on increasing the lingual root torque of this tooth. The combination of this techniques leaves some impressive treatment results as demonstrated in the photographs included in the article. The authors emphasize that this approach_treatment allows completion of treatment in the adolescent dentition, where implant treatment may require interim tooth replacement until facial growth is completes. Other advantages may be improved gingival health and lower cost as compare to implant treatment.

 I was very impressed with this article, I do a few a number of canine substitution treatment and I am anxious to clue some of this ideas to improve the esthetic results. The authors also address solutions to the functional problems involve the canine substitution, but I don't have time to review them here.

 
 Look up this article in the April 2001 Journal of Clinical Orthodontics and I believe that you too will be impressed with the esthetics with cases that I presented and I may change your belief that canine substitution is a second best esthetic option for the treatment of missing maxillary lateral incisors.

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Now that we have predictable and esthetic dental implant restorations available. is canine substitution treatment no longer popular option for missing maxillary lateral incisors? Can't esthetics of canine substitution treatment be improved by combining orthodontic treatment with techniques of contemporary esthetic dentistry? Dr. Rosa & Dr. Zachrisson recently published the paper in the April 2001 issue of the Journal of Clinical Orthodontics that emphasizes the positive aspects of canine substitution treatment and demonstrates how the esthetics can be improved to make the result virtually indistinguishable from a natural dentition.

The article is entitled, "Integrating esthetic dentistry and space closure in patients with missing maxillary lateral incisors." To get the most value from this article, you must see the clinical photographs included, but I will try to summarize for you how the authors deal with the common esthetic problems associated with canine substitution treatment.

The crown shape problem is handled by a combination of enamel recontouring and esthetic build-up with hybrid composites or porcelain veneers. It is suggested that the canine in the lateral position elapse slightly convex on the facial surface due to the thin enamel and risk of dentin exposure if recontouring is too aggressive.

The gingival alignment difficulties often result in gingival contours too high on the canines in the lateral position and too low on the premolar in the canine position. This can be corrected by extruding the canine in the lateral position and recontouring the crown along with intruding the premolar to raise the gingival contour and an building up the crown with composite or porcelain veneer.

The problematic yellow color of some canines can be corrected prior to composite build-up with modern vital bleaching procedures. The inadequate crown torque of the canine in the lateral position can be corrected by proper orthodontic positioning focusing on increasing the lingual root torque of this tooth. The combination of this techniques leaves some impressive treatment results as demonstrated in the photographs included in the article. The authors emphasize that this approach to treatment allows completion of treatment in the adolescent dentition, where implant treatment may require interim tooth replacement until facial growth is complete. Other advantages may be improved gingival health and lower cost as compared to implant treatment.

I was very impressed with this article. I do a fairy number of canine substitution treatment and I am anxious to include some of these ideas to improve the esthetic results. The authors also address solutions to the functional problems involved with the canine substitution, but I don't have time to review them here.

Look up this article in the April 2001 Journal of Clinical Orthodontics and I believe that you too will be impressed with the esthetics with cases that I presented and it may change your belief that canine substitution is a second best esthetic option for the treatment of missing maxillary lateral incisors.

SureSmile Technology in a Patient-Centered Orthodontic Practice

Sachdeva RCL

J Clin Orthod 2001;35:245-253

May 17, 2002

Dr. Ji Young Park

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I do almost all my bracket placement using an indirect bonding technique. I believe this allows me to position my brackets at the beginning to more accurately put the teeth where I want them at the end of treatment. Even though I use some might object measurement guidelines for positioning, it's still boils down the clinical experience to individualize the bracket setup for each case. It works well and I wouldn't give it up. But what if I could do a set up an each patient at the beginning of treatment so that I would have better information about where I want to place the brackets.

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I do almost all my bracket placement using an indirect bonding technique. I believe this allows me to position my brackets at the beginning to more accurately put the teeth where I want them at the end of treatment. Even though I use some objective measurement guidelines for positioning, it still boils down to clinical experience to individualize the bracket setup for each case. It works well and I wouldn't give it up. But what if I could do a set up an each patient at the beginning of treatment so that I would have better information about where I want to place the brackets?

To do so_ plaster would be very time consuming_ but what if I could do a virtual set up on a computer screen at the start of treatment_ that would allow me more precise bracket placement. This is exactly what can be done using the SureSmile system that has been developed. Dr. Sachdeva describes this system in an article in_ April 2001 issue of the journal of clinical orthodontics. Dr. Sachdeva is one of the principal developer_ of this system and certainly has a financial interest in a success. So the information should be interpreted with in this mind.

 To do so, plaster would be very time consuming. But what if I could do a virtual set up on a computer screen at the start of treatment? That would allow me more precise bracket placement. This is exactly what can be done using the SureSmile system that has been developed. Dr. Sachdeva describes this system in an article in the April 2001 issue of the Journal of Clinical Orthodontics. Dr. Sachdeva is one of the principal developers of this system and certainly has a financial interest in a success. So the information should be interpreted with this in mind.

The heart of this system is a handheld portable scanner that allows direct 3D scanning of the teeth. The system uses a small structural light system to take many 3D pictures of the teeth and then the computers stitches these many individual 3D pictures together to provide_ one image of the entire dentition. This scanner if it proves be as accurate as the author suggests_ is in itself remarkable achievement since this does not use any external references at all. But this system goes far beyond just providing 3D pictures of the teeth.

 The heart of this system is a handheld portable scanner that allows direct 3D scanning of the teeth. The system uses a small structural light system to take many 3D pictures of the teeth and then the computers stitches these many individual 3D pictures together to provide one image of the entire dentition. This scanner, if it proves to be as accurate as the author suggests, is in itself remarkable achievement since it does not use any external references at all. But this system goes far beyond just providing 3D pictures of the teeth.

These 3D scans are then divided into individual teeth and the teeth can be placed in their ideal posttreatment positions in what is essentially a virtual tooth set up. Virtual brackets are then placed on the teeth in the ideal position. This ideal bracket position is then transferred back to the original malocclusion. The ingenious thing is how this bracket position then gets to transfer_ to the patient. The computer model is used to generate an actual resin model of the patient's  malocclusion with the brackets in ideal position by a process called sterolithography. A custom indirect bonding tray is then made on this resin model. and actual orthodontic brackets put in the transfer tray for bonding. Its standard indirect bonding clinical procedure then transfers the ideal bracket position to the patient. The SureSmile system also has the ability to produce custom formed arch wires using robot technology to help achieve the desired arch form and tooth position. The whole idea is_ maximize the efficiency of what we already do_by being precise from the very beginning.

 These 3D scans are then divided into individual teeth and the teeth can be placed in their ideal posttreatment positions in what is essentially a virtual tooth set up. Virtual brackets are then placed on the teeth in the ideal position. This ideal bracket position is then transferred back to the original malocclusion. The ingenious thing is how this bracket position then gets transfer red to the patient. The computer model is used to generate an actual resin model of the patient's  malocclusion with the brackets in ideal position by a process called sterolithography. A custom indirect bonding tray is then made on this resin model, and actual orthodontic brackets put in the transfer tray for bonding. Its standard indirect bonding clinical procedure then transfers the ideal bracket position to the patient. The SureSmile system also has the ability to produce custom formed arch wires using robot technology to help achieve the desired arch form and tooth position. The whole idea is to maximize the efficiency of what we already do, by being precise from the very beginning.

There are still a lot of hurdles to overcome before this becomes standard practice. Right now to get a scan directly of the teeth and opaquing spray must apply to the teeth. The scanning time is so quite high and of course the cost must become reasonable to justify its routine use. The article by Dr. Sachdeva is called _SureSmile technology in a patient-centered orthodontic practice_. and it's found in the April 2001 issue of the journal of clinical orthodontics. The article has many illustrations that may help you better understand this technology which may one day change the way you practice.

 There are still a lot of hurdles to overcome before this becomes standard practice. Right now, to get a scan directly of the teeth, an opaquing spray must be applied to the teeth. The scanning time is still quite high, and of course the cost must become reasonable to justify its routine use. The article by Dr. Sachdeva is called "SureSmile technology in a patient-centered orthodontic practice". And it's found in the April 2001 issue of the Journal of Clinical Orthodontics. The article has many illustrations that may help you better understand this technology which may, one day, change the way you practice.

Predicting and preventing root resorption: Part II. Treatment factors

Sameshima GT, Sinclair PM

Am J Orthod Dentofacial Orthop 2001;119:511-515

May 31, 2002

Dr.  Jin-Myoung, Song

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In part II of the article that I previously reviewed on root resorption, the author's used the same sample of 868 patients treated by six different privately practicing orthodontists. The purpose of part II what to determine which treatment factors are most clearly identified with external root resorption that is detectible on periapical radiographs at the end of treatment. Periapical radiographs were used to evaluate the amount of root resorption and pre- and post-treatment lateral headfilms were used to determine the vertical and horizontal displacement of the maxillary incisors.

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 In part II of the article that I previously reviewed on root resorption, the authors used the same sample of 868 patients treated by six different privately practicing orthodontists. The purpose of part II what to determine which treatment factors are most clearly identified with external root resorption that is detectible on periapical radiographs at the end of treatment. Periapical radiographs were used to evaluate the amount of root resorption and pre- and post-treatment lateral headfilms were used to determine the vertical and horizontal displacement of the maxillary incisors.

The author's used four classifications to evaluate the relationship of extraction patterns to root resorption. This included non-extraction, 4 first premolar extraction, maxillary first premolars only, in other extractions such as second premolars and lower incisors. They found the patients who underwent 4 first premolar extraction therapy had greater resorption than patients who were treated with non extraction. Additionally, they noticed that patients with only upper premolar extraction had less resorption than patient with 4 first premolar extraction. This seem to contradict the other findings that overjet at the amount of horizontal apical displacement were significant predicted factors for root resorption. However, I think this finding should not be considered surprising because other study have shown that the most common cause of maxillary incisor root resorption that is significant is forcing the apices of the maxillary incisors into the palatal cortical plate of the maxilla.

 The authors used four classifications to evaluate the relationship of extraction patterns to root resorption. These included non-extraction, 4 first premolar extraction, maxillary first premolars only, and other extractions such as second premolars and lower incisors. They found that patients who underwent 4 first premolar extraction therapy had greater resorption than patients who were treated non-extraction. Additionally, they noted that patients with only upper premolar extractions had less resorption than patients with 4 first premolar extraction. This seemed to contradict the other findings that overjet at the amount of horizontal apical displacement were significant predictive factors for root resorption. However, I think this finding should not be considered surprising because other studies have shown that the most common cause of maxillary incisor root resorption that is significant is forcing the apices of the maxillary incisors into the palatal cortical plate of the maxilla.

For adult patients who have large class II anteroposterior skeletal discrepancies. It is critical to avoid retracting the mandible canines in order to reduced the amount of maxillary incisor retraction that is required and therefore we reduced likely-hood running the maxillary anterior roots into_cortical plate. Obviously, 4 first premolar extractions would retract them mandibular canine. Treating patients however, with maxillary premolar extraction only versus for premolar extraction would obviously help in this regard. It was interesting to know that non of the mechanical treatment variables evaluated in this study or significantly associated with apical root resorption. Slot size and archwire type were not found to be significant variables and use of elastics is also not associated with increased resorption. Probably, most interesting finding of this study was that the patient's from two of the six offices study show that much higher amount of root resorption than the other four offices. Unfortunately, the author did not describe any treatment differences between the offices that show greater resorption than the other.

 For adult patients who have large Class II anteroposterior skeletal discrepancies, it is critical to avoid retracting the mandibular canines in order to reduce the amount of maxillary incisor retraction that is required and therefore reduce the likelihood of running the maxillary anterior roots into the cortical plate. Obviously, 4 first premolar extractions would retract the mandibular canines. Treating patients, however, with maxillary premolar extraction only versus for premolar extraction would obviously help in this regard. It was interesting to know that none of the mechanical treatment variables evaluated in this study were significantly associated with apical root resorption. Slot size and archwire type were not found to be significant variables and the use of elastics is also not associated with increased resorption. Probably, the most interesting finding of this study was that the patient's from two of the six offices studied show much higher amount of root resorption than the other four offices. Unfortunately, the authors did not describe any treatment differences between the offices that showed greater resorption and the others.

_Bottom line of this two part of article is that cautions should_exercised in patients for whom_orthodontic plans to displace the maxillary incisor distally in patients with abnormally shaped roots. In for, premolar extraction cases, in adult patients and the patient who I have been in treatment for a longer than the usual period of time which was shown to be positively correlated with root resorption.

 The bottomline of this two part of article is that cautions should be exercised in patients for whom the orthodontic plans to displace the maxillary incisor distally in patients with abnormally-shaped roots. In four premolar extraction cases, in adult patients and the patients who have been in treatment for a longer the usual period of time which was shown to be positively correlated with root resorption.

I thought both part of this study were well done and my only disappointment was that the author did not use_ cephalometric radiographs that was taken to evaluate relationship between moving apices of_maxillary anterior teeth into the cortical plate and resorption. This was previously shown to be significant factor for resorption by J. Kelly and C. Phillips in_article published in the Angle Orthodontist in 1991. You can found this article in May 2001 issue of American Journal of Orthodontics & Dentofacial Orthopedics.

 I thought both parts of this study were well-done and my only disappointment was that the author did not use the cephalometric radiographs that were taken to evaluate relationship between moving apices of the maxillary anterior teeth into the cortical plate and resorption. This was previously shown to be a  significant factor for resorption by J. Kelly and C. Phillips in an article published in the Angle Orthodontist in 1991. You can find this article in May 2001 issue of American Journal of Orthodontics & Dentofacial Orthopedics.

Rapid curing of bonding composite with a xenon plasma arc light

Oesterle LJ, Newman SM, Shellhart WC:

Am J Orthod Dentofacial Orthop 2001;119:610-6

June 7, 2002

Dr. Seong Joon Park

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Many orthodontists today are bonding brackets with light cured adhesives. And reducing the amount of time required for light curing would be a big advantage to both the orthodontists and the patient. The amount of polymerization is a critical factor in determining the strength of composite resin and the degree of polymerization is directly related to the amount of total light energy that the resin absorbs with total light energy being the intensity of the light times the duration of the exposure. Greater total light energy generally results in increase fracture toughness and greater flexural strength of the resin and translates into greater bond strengths. Therefore the advantage of high intensity light is that the same amount of total light energy can be delivered to the composite in a much shorter period of time.

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Many orthodontists today are bonding brackets with light cured adhesives. And reducing the amount of time required for light curing would be a big advantage to both the orthodontists and the patient. The amount of polymerization is a critical factor in determining the strength of composite resin and the degree of polymerization is directly related to the amount of total light energy that the resin resorbs with total light energy being the intensity of the light times the duration of the exposure. Greater total light energy generally results in increase fracture toughness and greater flexural strength of the resin and translates into greater bond strengths. Therefore the advantage of high intensity light is that the same amount of total light energy can be delivered to the composite in a much shorter period of time.

I find these comments in the article titled "Rapid curing of bonding composite with a xenon plasma arc light" by Larry Oesterle et al, which appeared in the June 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. This article reported the results of study the purpose of which was to test the efficiency of a xenon plasma arc light versus a conventional tungsten-quartz halogen light in producing effective bond strengths for orthodontic brackets. Because light intensity can reduce the amount of curing time needed, it was thought that laser units could be used to bond orthodontic brackets. However laser units are relatively bulky and very expensive. Also in some states they are considered to be instruments for cutting or removing hard and soft tissues and therefore can only be used by licensed dentist. The xenon plasma arc light on the other hand is capable of producing light at the much greater intensity than that of the conventional tungsten-quartz halogen light and can be filtered to an ideal band with for bonding adhesives.

 I find these comments in an article titled "Rapid curing of bonding composite with a xenon plasma arc light" by Larry Oesterle et al, which appeared in the June 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. This article reported the results of study the purpose of which was to test the efficiency of a xenon plasma arc light versus a conventional tungsten-quartz halogen light in producing effective bond strengths for orthodontic brackets. Because light intensity can reduce the amount of curing time needed, it was thought that laser units could be used to bond orthodontic brackets. However, laser units are relatively bulky and very expensive. Also in some states, they are considered to be instruments for cutting or removing hard and soft tissues and therefore can only be used by licensed dentist. The xenon plasma arc light, on the other hand, is capable of producing light at the much greater intensity than that of the conventional tungsten-quartz halogen light and can be filtered to an ideal band with for bonding adhesives.

In this study the authors tested the bonding strength of brackets bonded to 240 bovine teeth using 3 different orthodontic bonding materials. They bonded these brackets with the traditional tungsten halogen quartz light for 40 seconds and the xenon plasma arc light for 3, 6 and 9 seconds. They then tested the brackets for shear bond strength. The bottom line is that the xenon plasma arc light exposure times of six to nine seconds produce shear bond strength equal to those produce with 40 seconds exposures with the conventional tungsten-quartz halogen curing light. Simply put because the xenon light tested was 4 times more intense than the conventional light, the exposure time could be reduce by the factor of 4. One of the concerns with using lasers or other high intensity lights is that the possibility of excess heat to the pulp. To avoid this possibility the authors suggest that the xenon light should be limited to short durations and multiple locations. That is for 9_seconds cure it would be best to cure _ 3_seconds at 3 different locations.

 In this study, the authors tested the bonding strength of brackets bonded to 240 bovine teeth using 3 different orthodontic bonding materials. They bonded these brackets with the traditional tungsten halogen quartz light for 40 seconds and the xenon plasma arc light for 3, 6 and 9 seconds. They then tested the brackets for shear bond strength. The bottom line is that the xenon plasma arc light exposure times of six to nine seconds produce shear bond strength equal to those produce with 40 seconds exposures with the conventional tungsten-quartz halogen curing light. Simply put because the xenon light tested was 4 times more intense than the conventional light, the exposure time could be reduced by the factor of 4. One of the concerns with using lasers or other high intensity lights is that the possibility of excess heat to the pulp. To avoid this possibility the authors suggest that the xenon light should be limited to short durations and multiple locations. That is for 9-second cure would be best to cure for 3-second at 3 different locations.

Based on this study it appears that xenon plasma arc light has the potential to significantly reduce bonding time without reducing adhesive bond strength. For more details on this study you can find this article in the June 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

 Based on this study it appears that xenon plasma arc light has the potential to significantly reduce bonding time without reducing adhesive bond strength. For more details on this study you can find this article in the June 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

A Comparative Study of Caucasian and Japanese Mandibular Clinical Arch Forms

Nojima K, McLaughlin RP, Isshiki Y, Sinclair PM

Angle Orthod 2001;71:195-200

June 14, 2002

Go Woon Kim

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What type of arch form do you use for your orthodontic patients? or let me be more specific, do you vary the arch form if the patient is of the Caucasian or the Asian descent? Furthermore, do you vary the arch form if the patient has Class I or Class II, or Class III malocclusion? Today, with the popularity of preformed flexible arch wires, the clinician has a wide variety of choices of the shapes, and sizes of arch forms. So my question is, how do you decide what you use on an individual patient. This information was clarified in an article that appeared in the June 2001 issue of the Angle Orthodontist.

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What type of arch form do you use for your orthodontic patients? or let me be more specific, do you vary the arch form if the patient is Caucasian or Asian descent? Furthermore, do you vary the arch form if the patient has Class I or Class II, or Class III malocclusion? Today, with the popularity of preformed flexible arch wires, the clinician has a wide variety of choices of the shapes, and sizes of arch forms. So my question is, how do you decide what you use on an individual patient. This information was clarified in an article that appeared in the June 2001 issue of the Angle Orthodontist.

The title of the article is ¡°A comparative study of Caucasian and Japanese mandibular clinical arch forms¡±. This study was coauthor by Kunihiko Nojima and Richard P. McLaughlin from the university of Southern California in Los Angeles. The purpose of their study was to clarify morphologic differences between Caucasian and Japanese mandibular arch forms in Class I, Class II, and Class III malocclusions by measuring their arch dimensions. In order to accomplish this objective the authors gathered pre- and post-treatment mandibular dental casts of 300 patients. Half of these were Japanese, and the other half were Caucasian. These were further broken down into even numbers of Class I, Class II, and Class III malocclusions. Then the authors identified the contact points between the teeth, and by connecting them, determined the patients arch form. Then by measuring width and depth of the arch forms the authors could determine if there were differences between the two ethnic groups and also between the types of malocclusions.

 The title of the article is ¡°A comparative study of Caucasian and Japanese mandibular clinical arch forms¡±. This study was coauthor by Kunihiko Nojima and McLaughlin from the university of Southern California in Los Angeles. The purpose of their study was to clarify morphologic differences between Caucasian and Japanese mandibular arch forms in Class I, Class II, and Class III malocclusions by measuring their arch dimensions. In order to accomplish this objective the authors gathered pre- and post-treatment mandibular dental casts of 300 patients. Half of these were Japanese, and the other half were Caucasian. These were further broken down into even numbers of Class I, Class II, and Class III malocclusions. Then the authors identified the contact points between the teeth, and by connecting them, determined the patients arch form. Then by measuring width and depth of the arch forms the authors could determine if there were differences between the two ethnic groups and also between the types of malocclusions.

Ok! What do you think they found, first of all, let's take arch forms in general between the two ethnic groups. The authors found that regardless of Angle classification, the Caucasian showed narrower arch forms than those of the Japanese, and they also had increased depth of their arch forms relative to the Japanese, so there is a difference.

Ok! What do you think they found, first of all, let's take arch forms in general between the two ethnic groups. The authors found that regardless of Angle classification, the Caucasian showed narrower arch forms than those of the Japanese, and they also had increased depth of their arch forms relative to the Japanese, so there is a difference.

Second question, Are there differences between the tooth groups with respect to the three different types of arch forms; taper, ovoid, or square, relative to Class I, Class II, and Class III malocclusions. When the authors looked at this aspect, they found no statistically significant difference between the two different ethnic groups within each arch form. So what does this mean to us practicing orthodontist? Well, I believe that this study reiterates what we have known really for a long time and that is, there is no single arch form unique to any Angle classification or any ethnic group. So that is the case, how do you determine the arch form for any particular patient.

 Second question, Are there differences between the tooth groups with respect to the three different types of arch forms; taper, ovoid, or square, relative to Class I, Class II, and Class III malocclusions. When the authors looked at this aspect, they found no statistically significant difference between the two different ethnic groups within each arch form. So what does this mean to us practicing orthodontist? Well, I believe that this study reiterates what we have known really for a long time and that is, there is no single arch form unique to any Angle classification or any ethnic group. So that is the case, how do you determine the arch form for any particular patient.

In the final sentence of their conclusion in this paper, the authors recommended that the orthodontist should determine each patient's arch form based upon the pretreatment mandibular dental model in order to achieve posttreatment esthetics and occlusal stability. In other words, we know that orthodontic alternation of arch form tends to regress toward the original arch form, so it doesn't make sense to identify some predetermined arch form that would apply for all patients. Using the patients pretreatment intercanine and intermolar width is the best way, I have been surely the arch form doesn't change after orthodontic treatment has been completed. If you are interested in reading this excellent study, you can find it the June 2001 issue of the Angle Orthodontist.

 In the final sentence of their conclusion in this paper, the authors recommended that the orthodontist should determine each patient's arch form based upon the pretreatment mandibular dental model in order to achieve posttreatment esthetics and occlusal stability. In other words, we know that orthodontic alternation of arch form tends to regress toward the original arch form, so it doesn't make sense to identify some predetermined arch form that would apply for all patients. Using the patients pretreatment intercanine and intermolar width is the best way, I have been surely the arch form doesn't change after orthodontic treatment has been completed. If you are interested in reading this excellent study, you can find it the June 2001 issue of the Angle Orthodontist.  

Orthodontic side-effects of mandibular advancement devices during treatment of snoring and sleep apnoea

Marie Marklund, Karl A. Franklin and Maurits Persson

European Journal of Orthodontics 2001;23:135-144

June 21, 2002

Dr. Eun-Hee Koh

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Consider the situation where you receive a patient referral from _ local hospital for construction of the mandibular advancement device for the treatment of snoring or mild sleep apnoea. Because you may not construct these devices regularly, you do a better of research and find out that these devices are really quite similar to the functional appliances. You use for correction of Class II problems in growing children. You also know that the functional appliances in children work by a combination of growth changes and tooth movement.

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Consider the situation where you receive a patient referral from the local hospital for construction of the mandibular advancement device for the treatment of snoring or mild sleep apnoea. Because you may not construct these devices regularly, you'd better search and find out that these devices are really quite similar to the functional appliances you use for correction of Class II problems in growing children. You also know that the functional appliances in children work by a combination of growth changes and tooth movement.

The question comes to mind as to whether you need to be concerned about possible unwanted tooth movement over time in this adult for whom you make the advancement device. Thus, long term use of the mandibular advancement device for treatment of sleep apnoea or snoring results in changes in tooth position or occlusion. Fortunately, a resent study from Sweden _ was published in the April 2001 issue of the European Journal of Orthodontics by Marie Marklund and Karl A.. Answer_ somebody_ has questions. The article is titled orthodontic side effects of mandibular advancement devices during treatment of snoring and sleep apnoea.

The question comes to mind as to whether you need to be concerned about possible unwanted tooth movement over time in this adult for whom you make the advancement device. Thus, long term use of the mandibular advancement device for treatment of sleep apnoea or snoring results in changes in tooth position or occlusion. Fortunately, a recent study from Sweden that was published in the April 2001 issue of the European Journal of Orthodontics by Marie Marklund and colleagnes answers somebody's has questions. The article is titled orthodontic side effects of mandibular advancement devices during treatment of snoring and sleep apnoea.

The authors retrospectively identified 155 consecutive patients who have received mandibular advancement devices. 75 were these identified who had used their devices for more than half the nights, had adequate plaster casts from before treatment and who were available for follow-up. And additional 17 patients had an appliance constructed but warrant able to tolerate wearing it, These were identified as _ control group. Tooth position and occlusal changes were measured from plaster casts and direct intraoral measurements.

The authors retrospectively identified 155 consecutive patients who have received mandibular advancement devices. Seventy five of these were these identified who had used their devices for more than half the nights, had adequate plaster casts from before treatment and who were available for follow-up. And additional 17 patients had an appliance constructed but weren't able to tolerate wearing it. These were identified as a control group. Tooth position and occlusal changes were measured from plaster casts and direct intraoral measurements.

Do you think these devices cause tooth movement in these adults? The answer is Yes. But in general, the changes were very small_ less than _ half millimeter on average. But, when the authors looked at the 25 % of the patient_ with the greatest changes, they found changes in overjet from about 1-3 mm that could be significant.

Do you think these devices cause tooth movement in these adults? The answer is Yes. But in general, the changes were very small, less than a half millimeter on average. But, when the authors looked at the 25 % of the patients with the greatest changes, they found changes in overjet from about 1-3 mm that could be significant.

The study groups contain patients with two types of appliances. One has _ hard acrylic appliances with clasps and the other has soft acrylic appliances with greater extensions. The authors found that the least dental changes have occurred in patient_ with soft acrylic appliances and advancement of less than 6 mm. So, when you make the advancement device for the patient referred to you from the local hospital, you may want to follow up with the patient on and on going phases to monitor the occlusion. You now know that most patients have little change in tooth position, as a result of wearing these type of device but, that a few can have more significant changes of 2 or 3 mm. You also may want to consider of soft acrylic devices with greater extensions and limit the advancement to less than 6_mm as possible.

The study groups contain patients with two types of appliances. One was a hard acrylic appliance with clasps and the other was soft acrylic appliance with greater extensions. The authors found that the least dental changes occurred in patients with soft acrylic appliances and advancement of less than 6 mm. So, when you make the advancement device for the patient referred to you from the local hospital, you may want to follow up with the patient on and on going phases to monitor the occlusion. You now know that most patients have little change in tooth position, as a result of wearing this type of device but, that a few can have more significant changes of 2 or 3 mm. You also may want to consider a soft acrylic device with greater extensions and limit the advancement to less than 6 mm as possible.

This article can be found in the April 2001 issue of the European Journal of Orthodontics and it contains pictures of the devices used in the study. The article also contains greater detail regarding the dental changes as were seen and further speculation about the reason some individuals exhibit the greater changes than others.

This article can be found in the April 2001 issue of the European Journal of Orthodontics and it contains pictures of the devices used in the study. The article also contains greater detail regarding the dental changes that were seen and further speculation about the reason some individuals exhibit the greater changes than others.

Dose Reduction by Direct-Digital Cephalometric Radiography  

Visser H, R dig T, et al

Angle Orthod 2001;71:159-163

June 28, 2002

Dr. Jin-Myoung Song

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Had you switched over to digital radiography yet? Or perhaps you practice in a part of your country where radiographic clefs are common. If so, has your radiographic clef switch to direct-digital radiography? You know digital photography and digital radiography are becoming very popular. Many orthodontists have switched to digital photographs and they are enjoying the savings in film and also the improved quality of the digital photography and what about digital radiography. Is it worth changing? What are the real benefits to the patient in terms of reduced radiation dosage? That last question was answered in the study that was published in the June 2001 issue of the Angle Orthodontist.

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Have you switched over to digital radiography yet? Or perhaps you practice in a part of your country where radiographic craft are common. If so, has your radiographic craft switch to direct-digital radiography? You know digital photography and digital radiography are becoming very popular. Many orthodontists have switched to digital photographs and they are enjoying the savings in film and also the improved quality of the digital photography and what about digital radiography. Is it worth changing? What are the real benefits to the patient in terms of reduced radiation dosage? That last question was answered in the study that was published in the June 2001 issue of the Angle Orthodontist.

If you're considering switching to digital radiography in the future, this article is important for you. The title of the article is ¡°Dose Reaction by Direct -Digital Cephalometric Radiography¡±. It's coauthored by Heiko Visser and Tina R dig from the university of G ttingen in Germany. The purpose of their paper was really rather straightforward and simple. The author_ wanted to determine the difference in radiation dosage between traditional film radiography and direct-digital radiography.

 If you're considering switching to digital radiography in the future, this article is important for you. The title of the article is ¡°Dose Reaction by Direct -Digital Cephalometric Radiography¡±. It's coauthored by Heiko Visser and Tina R dig from the university of G ttingen in Germany. The purpose of their paper was really rather straightforward and simple. The authors wanted to determine the difference in radiation dosage between traditional film radiography and direct-digital radiography.

In order to accomplish this task, the authors used a mannequin. The mannequin was placed in a cephalometric unit and both conventional film and digital radiographs work both with the Siemens unit. A setup 100 thermoluminescent detectors were placed on the surface and the inside the mannequin's head. These detectors measured the amount of radiation exposure that occured during the radiography.

 In order to accomplish this task, the authors used a mannequin. The mannequin was placed in a cephalometric unit and both conventional film and digital radiographs work both with the Siemens unit. A setup 100 thermoluminescent detectors were placed on the surface and the inside the mannequin's head. These detectors measured the amount of radiation exposure that occured during the radiography.

Ok! What do you think this author's account? What's the radiation difference between typical film cephalometric radiography and digital cephalometric radiography? The answer is one half. That's correct. There was 50 percent reduction in the radiation dosage using digital radiography. That's substantial. In the future, as dental consumers continue to be concerned about accumulative effects of radiation dosage, most of us will probably be switching to digital radiograph. Not only are digital images easier to handle using the computers for storage, but the benefits to the patients is high with the 50 percent reduction in radiation dosage. Anyway if you're interested in reviewing this article that measures the radiation dosage in both film and digital cephalometric radiographs, you will find it in the June 2001 issue of the Angle Orthodontist.

 Ok! What do you think this author's fount? What's the radiation difference between typical film cephalometric radiography and digital cephalometric radiography? The answer is one half. That's correct. There was 50 percent reduction in the radiation dosage using digital radiography. That's substantial. In the future, as dental consumers continue to be concerned about accumulative effects of radiation dosage, most of us will probably be switching to digital radiograph. Not only are digital images easier the handle using the computers for storage, but the benefits to the patients is high with the 50 percent reduction in radiation dosage. Anyway if you're interested in reviewing this article that measures the radiation dosage in both film and digital cephalometric radiographs, you will find it in the June 2001 issue of the Angle Orthodontist.

The Effect of Moisture and Blood Contamination on Bond Strength of a New Orthodontic Bonding Material

Hobson RS, Ledvinka J, Meechan JG
Am J Orthod Dentofacial Orthop 2001;120:54-57

July 5, 2002
Dr. Ji Young Park

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It has been pretty well established that the most effective bond strengths are achieved by bonding to clean, dry, etched enamel surface. However, there are conditions that sometimes make it difficult to obtain a clean, dry surface when bonding such as when bonding to second molars, or when bonding to surgically exposed canines. A new bonding resin namely Transbond MIP from Unitek is supposed to be hydrophilic and capable of achieving sufficient bond strength even if etched to enamel surfaces that have been contaminated with moisture. Is this in fact true? A study titled "The Effect of Moisture and Blood Contamination on Bond Strength of a New Orthodontic Bonding Material" by Ross Hobson et al, which appeared in the July 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics addressed this question.

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It has been pretty well established that the most effective bond strengths are achieved by bonding to clean, dry, etched enamel surface. However, there are conditions that sometimes make it difficult to obtain a clean, dry surface when bonding such as when bonding to second molars, or when bonding to surgically exposed canines. A new bonding resin namely Transbond MIP from Unitek is supposed to be hydrophilic and capable of achieving sufficient bond strength even if etched to enamel surfaces that have been contaminated with moisture. Is this in fact true? A study titled "The Effect of Moisture and Blood Contamination on Bond Strength of a New Orthodontic Bonding Material" by Ross Hobson et al, which appeared in the July 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics addressed this question.

In this study, the authors used 90 human premolars and divided them into 3 groups. All 3 groups were etched with 37% phosphoric acid for 30 seconds, and have brackets bonded to them using Transbond MIP primer and Transbond XT composite. In group 1, the enamel surface had no contamination, in group 2, the teeth were contaminated with water, and in group 3, the teeth were contaminated with fresh human blood. What do you expect happened when the 3 groups of teeth were then tested for shear bond strength? Did the teeth contaminated with blood and water have equal bond strength when compared to the dry teeth? Did either the water-contaminated or blood-contaminated teeth show higher bond strength?

In this study, the authors used 90 human premolars and divided them into 3 groups. All 3 groups were etched with 37% phosphoric acid for 30 seconds, and have brackets bonded to them using Transbond MIP primer and Transbond XT composite. In group 1, the enamel surface had no contamination, in group 2, the teeth were contaminated with water, and in group 3, the teeth were contaminated with fresh human blood. What do you expect happened when the 3 groups of teeth were then tested for shear bond strength? Did the teeth contaminated with blood and water have equal bond strength when compared to the dry teeth? Did either the water-contaminated or blood-contaminated teeth show higher bond strength?

Well, the bottom line of this study is that the group that had brackets bonded to a clean surface showed a significantly higher bond strength than the other 2 groups, and there was no significant difference in bond strength between the moist- and blood-contaminated teeth. The Transbond MIP primer therefore did not produce equal strength under contaminated conditions. However, I should point out that the mean bond strength for the moisture- and blood-contaminated groups which were approximately 12 MPa are significantly higher than the bond strength that is commonly accepted as clinically desirable, which is 8 MPa. I think it is therefore reasonable to conclude that while using Transbond MIP primer under contaminated conditions will reduce the bond strength that you usually get. It should produce a clinically acceptable bond strength under contaminated conditions, and therefore might be desirable for bonding such teeth, as second molars and affected canines that are hard to maintain in a clean, dry condition. You can find this article in the July 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Well, the bottom line of this study is that the group that had brackets bonded to a clean surface showed a significantly higher bond strength than the other 2 groups, and there was no significant difference in bond strength between the moist- and blood-contaminated teeth. The Transbond MIP primer therefore did not produce equal strength under contaminated conditions. However, I should point out that the mean bond strength for the moisture- and blood-contaminated groups which were approximately 12 MPa are significantly higher than the bond strength that is commonly accepted as clinically desirable, which is 8 MPa. I think it is therefore reasonable to conclude that while using Transbond MIP primer under contaminated conditions will reduce the bond strength that you usually get. It should produce a clinically acceptable bond strength under contaminated conditions, and therefore might be desirable for bonding such teeth, as second molars and impacted canines that are hard to maintain in a clean, dry condition. You can find this article in the July 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Enhancing wire-composite bond strength of bonded retainers with wire surface treatment

Oesterle LJ, Shellhart WC, Henderson S:
Am J Orthod Dentofacial Orthop 2001;119:625-31

July 12, 2002
Dr. Seong Joon Park

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Bonded lower 3 to 3 retainers are popular because they eliminate patient compliance as retention factor. They also provide stable retention in an area that is the lower incisors where relapse is most common. It's that _advantage of bonded 3 to 3 retainers is their potential for failure and any orthodontist who uses bonded lower 3 to 3 retainers is consistently looking for ways to improve their bond strength and rate of failure. If you wanted to improve the retention rate of the lower bonded 3 to 3 retainers, what would you do? Would you use a round stainless steel wire or a coaxial stranded twist wire? Would you place right angle bends at the ends of the wire? Would you use the metal primer or adhesion promoter like silane? Would you microetch or sandblast wire? In an article titled, "Enhancing wire-composite bond strength of bonded retainers with wire surface treatment" by Larry Oesterle et al, it's appeared June 2001 issue of the American Journal of Orthodontics and Dentofacial orthopedics.

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Bonded lower 3 to 3 retainers are popular because they eliminate patient compliance as retention factor. They also provide stable retention in an area that is the lower incisors where relapse is most common. It's disadvantage of bonded 3 to 3 retainers is their potential for failure and any orthodontist who uses bonded lower 3 to 3 retainers is consistently looking for ways to improve their bond strength and rate of failure. If you wanted to improve the retention rate of the lower bonded 3 to 3 retainer, what would you do? Would you use a round stainless steel wire or a coaxial stranded twist wire? Would you place right angle bends at the ends of the wire? Would you use the metal primer or adhesion promoter like silane? Would you microetch or sandblast wire? In an article titled, "Enhancing wire-composite bond strength of bonded retainers with wire surface treatment" by Larry Oesterle et al, which appeared June 2001 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

The authors use all the methods I've just described independently and in combination to determine the optimal method for enhancing the wire composite bond strength. Now that you know of the different things that were done in an attempt to enhance adhesion what do you think work best? In a finding that surprisingly it turns out that microetching or sandblasting the portions of a stainless steel wire embedded in composite resin significantly enhanced the strength of the wire composite bond. The stainless steel wire that was used in this study was .030 round wire. The use of retentive bends or silane or metal primer adhesion promoters on stainless steel wire embedded in composite resin, either separately or in combination, did not resist dislodgement to the same degree as microetching alone. Also microetching a straight stainless steel wire provided a greater wire composite strength than using a coaxial wire. While the bond strength of the coaxial wire samples were significantly greater than those of the control samples which had no treatment or the wires treated with silane in metal primer only, they were significantly lower than either microetching alone or microetching in combination with either of the bond enhancers. In what I far wasn't impressive finding it was shown that microetching increased the bond strength to more than 24 times that of the control wire with no surface treatment. In another finding that I thought so much surprising, it was shown that not only did retentive bends at the end of the wire fail to increase bonding strength but the actually weakened composite resin pad strength and resulted in lower dislodging forces than those of a straight microetched wire.

The authors use all the methods I've just described independently and in combination to determine the optimal method for enhancing the wire composite bond strength. Now that you know of the different things that were done in an attempt to enhance adhesion what do you think work best? In a finding that surprisingly it turns out that microetching or sandblasting the portions of a stainless steel wire embedded in composite resin significantly enhanced the strength of the wire composite bond. The stainless steel wire that was used in this study was .030 round wire. The use of retentive bends or silane or metal primer adhesion promoters on stainless steel wire embedded in composite resin, either separately or in combination, did not resist dislodgement to the same degree as microetching alone. Also microetching a straight stainless steel wire provided a greater wire composite strength than using a coaxial wire. While the bond strength of the coaxial wire samples were significantly greater than those of the control samples which had no treatment or the wires treated with silane in metal primer only, they were significantly lower than either microetching alone or microetching in combination with either of the bond enhancers. In what I thought  was impressive finding it was shown that microetching increased the bond strength to more than 24 times that of the control wire with no surface treatment. In another finding that I thought so much surprising, it was shown that not only did retentive bends at the end of the wire fail to increase bonding strength but the actually weakened composite resin pad strength and resulted in lower dislodging forces than those of a straight microetched wire.

The bottom line, it's that the most effective way of enhancing the wire composite bond is microetching. Retentive bends tend to weakened the composite resin pad and adhesion promoters have little positive effect. Simply put, it appears that a straight microetched stainless steel wire provides the strongest orthodontic retainer. You can find this article in the June 2001 issue of the American Journal of Orthodontics and Dentofacial orthopedics.

The bottom line, it's that the most effective way of enhancing the wire composite bond is microetching. Retentive bends tend to weakened the composite resin pad and adhesion promoters have little positive effect. Simply put, it appears that a straight microetched stainless steel wire provides the strongest orthodontic retainer. You can find this article in the June 2001 issue of the American Journal of Orthodontics and Dentofacial orthopedics.

Quality of Life in Adults With Repaired Complete Cleft Lip and Palate

Marcusson A, Akerlind I, Paulin G
Cleft Palate-Craniofacial Journal 2001;38:379-385

July 19, 2002
Dr. Eun-Hee Koh

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Treatment of Cleft lip and palate patients is a very challenging part of orthodontic practice. You may see the patients for the first time when they are only a few days old and not finish treatment until the late teenagers. After the cleft team has done all that they can to normalize the anatomy and function, what sort of quality of life does the patient have as an adult? There was an excellent research project done in Sweden that was reported in the July 2001 issue of the Cleft Palate-Craniofacial Journal.

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Treatment of cleft lip and palate patients is a very challenging part of orthodontic practice. You may see the patients for the first time when they are only a few days old and not finish treatment until the late teenagers. After the cleft team has done all that they can to normalize the anatomy and function, what sort of quality of life does the patient have as an adult? There was an excellent research project done in Sweden that was reported in the July 2001 issue of the Cleft Palate-Craniofacial Journal.

That looks at the issue, a quality of life in adult treated cleft patients. This research effort was led by Dr. Marcusson and was reported in an article entitled ¡°Quality of Life in Adults With Repaired Complete Cleft Lip and Palate.¡± As with many studies done in Scandinavia, this investigation was possible because of the excellent medical record keeping and the relatively stable population.

 That looks at the issue, a quality of life in adult treated cleft patients. This research effort was led by Dr. Marcusson and was reported in an article entitled ¡°Quality of Life in Adults With Repaired Complete Cleft Lip and Palate.¡± As with many studies done in Scandinavia, this investigation was possible because of the excellent medical record keeping and the relatively stable population.

From the records, the investigators identified 80 patients born between 1968 to 1977 with the diagnosis of complete unilateral or bilateral cleft lip and palate that have received treatment through the cleft team at the University Hospital at Link ping, Sweden. They contacted these patients by letter and 68 of the 80 participated in the follow-up, that is 85%. Remarkable! These 68 patients then underwent the dental examination and completed questionnaires related to demographics, generic quality of life, well-being and health-related quality of life. The health-related items for the cleft groups specifically addressed the impact of their cleft deformity on their lives. For comparison an age and gender matched control group was identified from the same general geographic area. I expected to see some fairly significant differences between the cleft group and the unaffected controls. I was surprised that the differences were much less than I expected.

 From the records, the investigators identified 80 patients born between 1968 and 1977 with the diagnosis of complete unilateral or bilateral cleft lip and palate that have received treatment through the cleft team at the University Hospital at Link ping, Sweden. They contacted these patients by letter and 68 of the 80 participated in the follow-up, that is 85%. Remarkable! These 68 patients then underwent the dental examination and completed questionnaires related to demographics, generic quality of life, well-being and health-related quality of life. The health-related items for the cleft groups specifically addressed the impact of their cleft deformity on their lives. For comparison, an age and gender matched control group was identified from the same general geographic area. I expected to see some fairly significant differences between the cleft group and the unaffected controls. I was surprised that the differences were much less than I expected.

That cleft group and control group did not differ with regards the age, sex whether or not they had children and siblings or whether they were married or not. That cleft group and general had less education, lived in a more rural area, and were more likely to be unemployed, it is not clear whether these differences are related to the cleft or to the fact that it was a more rural population. In the quality of life measures, both groups scored relatively high with the cleft group lower in life meaning, family life and personal economy. The biggest differences were seen in the health-related or cleft-related quality of life issues. The non-cleft group had few health-related issues, whereas the cleft group showed little impact of health-related issues on practical daily life, but more impact on social and global concerns.

 That cleft group and control group did not differ with regards to age, sex whether or not they had children or siblings or whether they were married or not. That cleft group and general had less education, lived in a more rural area, and were more likely to be unemployed, it is not clear whether these differences are related to the cleft or to the fact that it was a more rural population. In the quality of life measures, both groups scored relatively high with the cleft group lower in life meaning, family life and personal economy. The biggest differences were seen in the health-related or cleft-related quality of life issues. The non-cleft group had few health-related issues, whereas the cleft group showed little impact of health-related issues on practical daily life, but more impact on social and global concerns.

Overall, the study showed that the treated cleft group was well adjusted, and didn't have big quality of life issues related to practical daily life. They did still demonstrate, however, an effect of  their deformity on their perception of the social life and more global issues. I was greatly encouraged by this findings, I think it suggest_ that all the efforts put forth by the cleft teams around the country and around the world are helping to produce adult cleft patients that are well adjusted and generally have a very good quality of life. Details of the specific questionnaire results and further discussion of the interpretation of these results can be found in the July 2001 issue of the Cleft Palate-Craniofacial Journal.

 Overall, the study showed that the treated cleft group was well adjusted, and didn't have big quality of life issues related to practical daily life. They did still demonstrate, however, an effect of  their deformity on their perception of the social life and more global issues. I was greatly encouraged by these findings, I think it suggests that all the efforts put forth by the cleft teams around the country and around the world are helping to produce adult cleft patients that are well adjusted and generally have a very good quality of life. Details of the specific questionnaire results and further discussion of the interpretation of these results can be found in the July 2001 issue of the Cleft Palate-Craniofacial Journal.

Bracket Bond Strength with Transillumination of  a Light-Activated Orthodontic Adhesive

Oesterle J, Craig Shellhart W
Angle Orthod 2001;71:307-311

July 26, 2002
Dr. Jae-Nam Kim

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Let me _ by ask_ you a couple of questions about your bonding technique. First of all, do you use light-cured composite when you bond brackets to the teeth? I think today that most orthodontist_ tend to use light-cured composite because it does have greater shear bond strength. So few another many orthodontist_ who do use light-cured composite from which direction do you direct the light to cure the bracket. Do you place the light on the labial or on the lingual? If you cured the composite from the lingual approach which was called transillumination, it is effective as curing from the labial. If you cured from the lingual, do you have to expose to composite too longer period_ of illumination with the light. Those questions or answered in an article_ was published in the August 2001 issue of the Angle Orthodontist. The title of the article is "Bracket Bond Strength with Transillumination of a Light-Activated Orthodontic Adhesive". This study was coauthored by Larry Oesterle and Craig Shellhart from the orthodontic department of University of Colorado.

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Let me start by asking you a couple of questions about your bonding technique. First of all, do you use light-cured composite when you bond brackets to the teeth? I think today that most orthodontists tend to use light-cured composite because it does have greater shear bond strength. So if you are one of the many orthodontists who do use light-cured composite, from which direction do you direct the light to cure the bracket? Do you place the light on the labial or on the lingual? If you cure the composite from the lingual approach, which was called transillumination, is it effective as curing from the labial? If you cure from the lingual, do you have to expose the composite to longer periods of illumination with the light? Those questions were answered in an article that was published in the August 2001 issue of the Angle Orthodontist. The title of the article is "Bracket Bond Strength with Transillumination of a Light-Activated Orthodontic Adhesive". This study was coauthored by Larry Oesterle and Craig Shellhart from the Orthodontic Department of University of Colorado.

The purpose of their study was obvious in the title. They want_ to determine of their any differences between the cure of the light-cured composite when directing the illumination from either the labial or the lingual. In order to answer this question and gather_ the sample of 100 extracted teeth. These were then divided into ten subgroups of ten teeth each. By the way these were extracted maxillary incisors. Now basically two procedures were tested either traditional light illumination from the labial or light illumination from the lingual. But with lingual illuminaton different exposure times or also evaluated. Times of 20 seconds, 30 seconds, 40 seconds and finally 50 seconds were evaluated from the lingual. From the labial approach only 40 seconds were used with _ light being directed on the mesial for 20 and on the distal of the tooth for 20 seconds.

 The purpose of their study was obvious in the title. They wanted to determine if there were any differences between the cure of the light-cured composite when directing the illumination from either the labial or the lingual. In order to answer this question, they gathered the sample of 100 extracted teeth. These were then divided into ten subgroups of ten teeth each. By the way, these were extracted maxillary incisors. Now, basically two procedures were tested, either traditional light illumination from the labial or light illumination from the lingual. But with lingual illuminaton, different exposure times were also evaluated. Times of 20 seconds, 30 seconds, 40 seconds and finally 50 seconds were evaluated from the lingual. From the labial approach, only 40 seconds were used with the light being directed on the mesial for 20 and on the distal of the tooth for 20 seconds.

Ok! I hope all this time in seconds in everything has_ confused you. But basically this was very simple study design comparing labial and lingual transmission of light. But different length_ of light exposure that were tested on the lingual. What do you think happened? Is the shear-bond strength affected adversely by transillumination of a maxillary incisor from the lingual?

Fortunately, the answer of the question is No. With the 20_, 30_ and 40_ seconds lingual transillumination, there was some slightly differences between lingual and labial approach. But with the 50_ seconds exposure from the lingual the shear bond strength was almost the same as on the light was directed from the labial. So watch with you as the clinician remember from this study. it's very simple. First of all,  you can use transillumination with high confidence to cure your orthodontic brackets. But, just remember when you_ using lingual trans- illumination increased _ exposure time _ 25 seconds_ and based upon this study you were have bond strength that is equivalant to bracket _ from the labial approach. If you like to review the study, you can find it in the August 2001 issue of the Angle Orthodontist.  

 Ok! I hope all this time in seconds in everything hasn't confused you. But basically, this was very simple study design comparing labial and lingual transmission of light. But different lengths of light exposure that were tested on the lingual. What do you think happened? Is the shear-bond strength affected adversely by transillumination of a maxillary incisor from the lingual?

Fortunately, the answer of the question is No. With the 20-, 30- and 40- seconds lingual transillumination, there were some slight differences between lingual and labial approach. But with the 50- second exposure from the lingual, the shear bond strength was almost the same as on the light was directed from the labial. So, what should you, as the clinician, remember from this study? It's very simple. First of all,  you can use transillumination with high confidence to cure your orthodontic brackets. But, just remember when you're using lingual trans- illumination increase the exposure time to 50 seconds. And, based upon this study, you will have bond strength that is equivalant to bracket that are cured from the labial approach. If you like to review the study, you can find it in the August 2001 issue of the Angle Orthodontist.

Complications of the Mandibular Sagittal Split Ramus Osteotomy Associated With the Presence or Absence of Third Molars.

Mebra P. Castro V. Freitas RZ. Wolford LM
J Oral Maxillofac Surg 2001;59:854-858

August 2, 2002
Dr. Go-Woon Kim

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Have you ever been asked this question? Suppose your performing at consultation for a 21-year-old female. She has-Class¥± division I. malocclusion and no crowding in either arch. Her main problem? She has a retrognathic mandible. You and she, and her parents have-that the best treatment is routine, non extraction orthodontics at the sagittal osteotomy to advance the mandible. She agrees, her parents agree. You're all set to go. After you review her records, she noted that she had two impacted mandibular third molars. So at your consultation, you recommended she has the third molars removed before you begin orthodontics so that the site were healed adequately prior to the surgery for the routine. But then she asks you the big question. Why can't she have the third molars removed when the surgery is being performed? That's save some money? She will have to have anesthetic twice, and sparse pain in more betterly. She will only have to go through the process once. Make sense! What would your answer be? You know, in the past my tendency would've been discouraged remove all of third molars at the same time as the surgery. I would start that this could complicate the healing and could result in the potential risk for fracture of the mandible in the area of the extraction. But is that really true? What does the research show? Well, that question finally has an answer, and it can be found in a study that was published in the august, 2001 issue of the Journal of Oral and Maxillofacial Surgery.

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Have you ever been asked this question? Suppose your performing at consultation for a 21-year-old female. She has a Class¥± division 1. malocclusion and no crowding in either arch. Her main problem? She has a retrognathic mandible. You and she, and her parents have both decided that the best treatment is routine, non extraction orthodontics at the sagittal osteotomy to advance the mandible. She agrees, her parents agree. You're all set to go. After you review her records, you noted that she had two impacted mandibular third molars. So at your consultation, you recommended she had the third molars removed before you begin orthodontics so that the site were healed adequately prior to the surgery for the routine. But then she asks you the big question. Why can't she have the third molars removed when the surgery is being performed? That will save some money. She won't have to have anesthetic twice, and as far as pain and morbidity. She will only have to go through the process once. Make sense! What would your answer be? You know, in the past my tendency would've been discouraged removal of third molars at the same time as the surgery. I would start that this could complicate the healing and could result in the potential risk for fracture of the mandible in the area of the extraction. But is that really true? What does the research show? Well, that question finally has an answer, and it can be found in a study that was published in the august, 2001 issue of the Journal of Oral and Maxillofacial Surgery.

The title of the article is "Complications of the Mandibular Sagittal Split Ramus Osteotomy Associated With the Presence or Absence of Third Molars". The study was coauthored by Larry Wolford, a very well-known oral and maxillofacial surgeon from Baylor University and three others colleagues in the surgical department at the university. This was a retrospective study. It analized 500 sagittal split ramus osteotomies, but they were devided into two groups.

 The title of the article is "Complications of the Mandibular Sagittal Split Ramus Osteotomy Associated With the Presence or Absence of Third Molars". The study was coauthored by Larry Wolford, a very well-known oral and maxillofacial surgeon from Baylor University and three of his fellow colleagues in the surgical department at the university. This was a retrospective study. It analized 500 sagittal split ramus osteotomies, but they were devided into two groups.

  In half of the sample, the third molars were extracted at the time of the surgery. In the other half of the sample, either third molars were congenitally missing or they had been extracted 1 year prior to surgery. One simple question was asked. Is there higher incidence of fracture across the extraction site if third molars were removed at the same time as the surgery. And the answer of that question is no. Another was slight difference. First of all, the incidence of fracture in this 500 ramus osteotomies was very very low as you might expect. The overall incidence was about 2%. It was slightly higher in the group that had the third molars were extracted at the time of the surgery. But that incidence was still only 3%. In the sample were the teeth removed a year before the surgery, the incidence was 1%. Statistically, these were not significantly different. One other question was asked by the way. And that is "Was there any difference in the incidence of relapse in patients that had fractures?" And the answer of that question was also no. So what's the bottom line here? Well, based upon this study, there is no higher incidence of mandibular fracture if the third molars were removed at the same time as the jaw surgery. Now, there may be some surgeons who still recommend early extraction of third molars for other reasons. But apparently concern over fracture of the mandible during surgery is based upon this study definitely not an issue. So, now you have an answer for your 21-year-old female patient. She wants to know about extracting third molars at the same time of the surgery? I would say, why not? It would save all procedure and as long as it didn't increase the incidence of fracture, perhaps it's not a problem.

 In half of the sample, the third molars were extracted at the time of the surgery. In the other half of the sample, either third molars were congenitally missing or they had been extracted 1 year prior to surgery. One simple question was asked. Is there higher incidence of fracture across the extraction site if third molars were removed at the same time as the surgery. And the answer of that question is no. Now there was slight difference. First of all, the incidence of fracture in this 500 ramus osteotomies was very very low as you might expect. The overall incidence was about 2%. It was slightly higher in the group that had the third molars were extracted at the time of the surgery. But that incidence was still only 3%. In the sample were the teeth removed a year before the surgery, the incidence was 1%. Statistically, these were not significantly different. Another question was asked by the way. And that is "Was there any difference in the incidence of relapse in patients that had fractures?" And the answer of that question was also no. So what's the bottom line here? Well, based upon this study, there is no higher incidence of mandibular fracture if the third molars were removed at the same time as the jaw surgery. Now, there may be some surgeons who still recommend early extraction of third molars for other reasons. But apparently concern over fracture of the mandible during surgery is based upon this study definitely not an issue. So, now you have an answer for your 21-year-old female patient. She wants to know about extracting third molars at the same time of the surgery? I would say, why not? It would save up procedure and as long as it didn't increase the incidence of fracture, perhaps it's not a problem.

If you like to review this interesting study, you will find it in the August, 2001 issue of the Journal of Oral and Maxillofacial Surgery.

  If you like to review this interesting study, you will find it in the August, 2001 issue of the Journal of Oral and Maxillofacial Surgery.

Orthodontic Tooth Movement Enhances Bone Healing of Surgical Bony Defects in Rats

 Vardimon AD, Nemcovsky CE, Dre E
 J Periodontol 2001;72:858-864

September 6, 2002
Dr. Hang-Ik Jang

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You are planning orthodontic treatment for 45-year-old male. He has a Class I mildly crowded malocclusion. His treatment isn't complicated at all. He was simply require non-extraction orthodontic therapy to align the teeth. But here's the dilemma. The patient has several periodontal defects. One_in particular_is a 3-wall defect around the mandibular molar.

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You are planning orthodontic treatment for 45-year-old male. He has a Class I mildly crowded malocclusion. His treatment isn't complicated at all. He was simply require non-extraction orthodontic therapy to align the teeth. But here's the dilemma. The patient has several periodontal defects. One, in particular, is a 3-wall defect around the mandibular molar.

Now the periodontist is planning to use regenerative therapy with bone grafting and placement of a membrane in this site. Here is my question. Will orthodontic treatment soon after the bone graft be detrimental or will it enhance bone deposition in the graft site? The answer_that question can be found in the title of this next article ¡°Orthodontic Tooth Movement Enhances Bone Healing of Surgical Bony Defects in Rats.¡±

 Now the periodontist is planning to use regenerative therapy with bone grafting and placement of a membrane in this site. Here is my question. Will orthodontic treatment soon after the bone graft be detrimental or will it enhance bone deposition in the graft site? The answer of that question can be found in the title of this next article ¡°Orthodontic Tooth Movement Enhances Bone Healing to Surgical Bony Defects in Rats.¡±

This article was published in the July 2001 issue of the Journal of Periodontology. It was co-authored by Alexander D. Vardimon and two-research colleagues from the school of dentistry at Tel Aviv University in Israel. This was an experimental study using rats as the experimental model.

 This article was published in the July 2001 issue of the Journal of Periodontology. It was co-authored by Alexander Vardimon and two-research colleagues from the school of dentistry at Tel Aviv University in Israel. This was an experimental study using rats as the experimental model.

Initially the authors created bone defects mesial to the maxillary molar. In part of the animals, the defect was simply allowed to heal. In the other group, orthodontic force was placed immediately on the animals to move the tooth near the area of the defect.

 Initially the authors created bone defects mesial to the maxillary molar. In part of the animals, the defect was simply allowed to heal. In the other group, orthodontic force was placed immediately on the animals to move the tooth near the area of the defect.

You see what the author's testing was whether or not orthodontics could enhance the repair process in these areas of bony defect. The analysis of the information was confirmed histologically.

 You see what the author's testing was whether or not orthodontics could enhance the repair process in these areas of bony defect. The analysis of the information was confirmed histologically.

Ok, what do you think this author's found? Does tooth movement after creation of bony defect enhance the repair process in the alveolar bone? Well, the answer is obvious from the title. It's Yes. In fact, the repair process in the experimental animals was 6 times greater or faster than the repair process in the control animals where no orthodontics tooth movement was performed. This study suggests that orthodontic tooth movement is a very useful to all in repairing at a deficient site that's not inflammed.

 Ok, what do you think these authors found? Does tooth movement after creation of bony defect enhance the repair process in the alveolar bone? Well, the answer is obvious from the title. It's Yes. In fact, the repair process in the experimental animals was 6 times greater or faster than the repair process in the control animals where no orthodontic tooth movement was performed. This study suggests that orthodontic tooth movement is a very useful tool in repairing at a deficient site that's not inflammed.

I emphasized the latter statement. The authors are suggesting that this technique would not necessarily or favorably in an active periodontal site that was undergoing bone resorption. But the authors believed that tooth movement in an area where_bony graft had been placed or regenerative therapy was been applied would benefit significantly. That is, by moving the teeth it would enhance the regenerative therapy.

 I emphasized the latter statement. The authors are suggesting that this technique would not necessarily or favorably in an active periodontal site that was undergoing bone resorption. But the authors believed that tooth movement in an area where a bony graft had been placed or regenerative therapy was been applied would benefit significantly. That is, by moving the teeth it would enhance the regenerative therapy.

So, back to your patient. 45-year-old male who have a bone graft and regenerative treatment performed on the 3-wall defect. Based upon the result of this study, orthodontic tooth movement in this patient could only enhance the effect of the regenerative therapy by initiating bone deposition around the tooth which would encourage the healing process of bone around 3-wall defect.

 So, back to your patient. 45-year-old male who have a bone graft and regenerative treatment performed on the 3-wall defect. Based upon the result of this study, orthodontic tooth movement in this patient could only enhance the effect of the regenerative therapy by initiating bone deposition around the tooth which would encourage the healing process of bone around 3-wall defect.

If you interested in reviewing this article, the documents of the favorable affects of orthodontics in areas of bone defects, you will find it in the July, 2001 issue of the Journal of Periodontology.

 If you interested in reviewing this article, the documents of the favorable affects of orthodontics in areas of bone defects, you will find it in the July, 2001 issue of the Journal of Periodontology.

Teaching Patients How to Stop Bruxing Habit

Shulman J
J Am Dent Assoc 2001;132:1275-1277

September 18, 2002
Dr. Kwang-Taek, Ko

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It is generally accepted that patients with bruxing habits can experience significant wear to the dentition, temporal mandibular disorders, and other problems.  How do you treat patients who present to you with bruxing habits?  Most articles that Ive read on this subject talk about using splints to treat the various symptoms created by the bruxing habit.  Most treatment modalities treat symptoms under the assumption that the bruxing habit cannot be changed.  An article titled,  ¡°Teaching Patients How to Stop Bruxing Habits¡±,  by Jeremy Schulman, which appeared in the September 2001 issue of the Journal of the American Dental Association described a unique and very interesting approach to stopping bruxing habits.

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It is generally accepted that patients with bruxing habits can experience significant wear to the dentition, temporomandibular disorders, and other problems.  How do you treat patients who present to you with bruxing habits?  Most articles that Ive read on this subject talk about using splints to treat the various symptoms created by the bruxing habit.  Most treatment modalities treat symptoms under the assumption that the bruxing habit cannot be changed.  An article titled,  ¡°Teaching Patients How to Stop Bruxing Habits¡±,  by Jeremy Schulman, which appeared in the September 2001 issue of the Journal of the American Dental Association described a unique and very interesting approach to stopping bruxing habits.

First of all, Dr. Schulman points out that bruxing is indeed a habit, and as with other pernicious habits, treatment should be primarily aimed at eliminating the habit rather than treating symptoms.  He describes a treatment approach that is based on explaining to the patient the basis and deleterious effects of the bruxing habit, and constructing what he refers to as a biofeedback splint.  This is a flat splint that is highly polished, and serves simply as a reminder to the patient.  He strongly suggests that at no time should dentists even suggest that the splint is a guard or that it is going to make them stop bruxing.  The splint is simply a training aid to make patients aware of when they are bruxing and help them to stop the habit.  He advises patients that teeth normally touch only during chewing or swallowing and that opposing teeth rarely touch even during chewing because of the food between them.  He then advises the patient that any jaw posturing habits or tooth contact other than those involved in chewing or swallowing are parafunctional habits that need to be eliminated.  The contact between the teeth and the splint during swallowing has no effect on the plastic.  However, greater pressures such as those that occur with bruxing will produce marks on the splint that serve as valuable feedback to the patient in the morning.  Patients are seen one week after receiving their splints and any scratches or dents in the splint are removed and the splint is highly polished.  Dr. Schulman states that about 90% of his patients are symptom-free within three or four appointments.  

 First of all, Dr. Schulman points out that bruxing is indeed a habit, and as with other pernicious habits, treatment should be primarily aimed at eliminating the habit rather than treating symptoms.  He describes a treatment approach that is based on explaining to the patient the basis and deleterious effects of the bruxing habit, and constructing what he refers to as a biofeedback splint.  This is a flat splint that is highly polished, and serves simply as a reminder to the patient.  He strongly suggests that at no time should dentists even suggest that the splint is a guard or that it is going to make them stop bruxing.  The splint is simply a training aid to make patients aware of when they are bruxing and help them to stop the habit.  He advises patients that teeth normally touch only during chewing or swallowing and that opposing teeth rarely touch even during chewing because of the food between them.  He then advises the patient that any jaw posturing habits or tooth contact other than those involved in chewing or swallowing are parafunctional habits that need to be eliminated.  The contact between the teeth and the splint during swallowing has no effect on the plastic.  However, greater pressures such as those that occur with bruxing will produce marks on the splint that serve as valuable feedback to the patient in the morning.  Patients are seen one week after receiving their splints and any scratches or dents in the splint are removed and the splint is highly polished.  Dr. Schulman states that about 90% of his patients are symptom-free within three or four appointments.  

At first glance, I would tend to question this high rate of success with such a simple treatment.  However, a long time ago, I adopted a somewhat similar program to correct thumb-sucking habits, which has been extremely successful.  It involves no appliances other than a band-aid, which is placed around the patients thumb to act as a reminder rather than a physical barrier.  I even have the patients suck their thumb with the band-aid on to show them that they can and that it is not a deterrent but rather a reminder to let them know when they are actually sucking their thumb.  I believe the use of a reminder splint as suggested by Dr. Schulman serves the same purpose.  

 At first glance, I would tend to question this high rate of success with such a simple treatment.  However, a long time ago, I adopted a somewhat similar program to correct thumb-sucking habits, which has been extremely successful.  It involves no appliances other than a band-aid, which is placed around the patients thumb to act as a reminder rather than a physical barrier.  I even have the patients suck their thumb with the band-aid on to show them that they can and that it is not a deterrent but rather a reminder to let them know when they are actually sucking their thumb.  I believe the use of a reminder splint as suggested by Dr. Schulman serves the same purpose.  

This interesting article which appeared in the September 2001 issue of The Journal of the American Dental Association goes into more detail regarding the specifics of Dr. Schulman's program.  

 This interesting article which appeared in the September 2001 issue of The Journal of the American Dental Association goes into more detail regarding the specifics of Dr. Schulman's program.  

Oral Hygiene and Postoperative Pain After  Mandibular Third Molar Surgery

Penarrocha M, Sanchis JM, et al
Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:260-264

September 27, 2002
Dr. Seon-Mi Kim

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 Most orthodontists refer hundreds of patients every year for extraction of third molars. When the news is delivered that it is time for the third molars to come out, there is usually little enthusiasm from the patients because most of them associate  third molar removal with pain.  Since I am always  looking for ways to stimulate good oral hygiene in my patients and would also like the opportunity to deliver some positive message when telling patients it is time for third molar surgery. I was interested in reading a study that  looked at the association between the level of oral hygiene and pain after third molar surgery.

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This study was conducted at Valencia University in Spain and was recorded in the September 2001 issue of the Journal of Oral Surgery, Oral Medicine, and Oral Pathology. The research team was lead by Dr. Penarrocha and the paper entitled ¡°Oral Hygiene and Postoperative Pain After Third Molar Surgery¡±.

  In order to study the relationship between oral hygiene and postsurgical pain, the authors recruited 190 consecutive patients who presented to the out-patient clinic in Valencia University for the surgical removal of at least one impacted lower third molar. The oral hygiene before surgery was scored using the simplified oral hygiene index which assessed the level of stain, plaque, and calculus. After surgery, the patients recorded the pain level using a visual analogue scale, and also used of prescribed analgesics was monitered.

 The level of trismus and inflammation was also recorded during this post-treatment period. All of study patients were treated with the same clinical technique and received same postoperative care. To analyze the data and the researchers divided by the sample into three groups based on oral hygiene. These 3 groups ; good, average, and poor oral hygiene were compared to each other for the level of pain, inflammation, and trismus.

 So, would I be justified telling my patients that they should brush and floss better, so they will have less pain after third molar surgery?

  According to this study, the answer is YES.

  The poor oral hygiene group had significantly more pain after surgery as measured by the visual analogue scale and the use the analgesics. There was no difference found in the level of trismus and inflammation between the groups. This study does have some limitations. Although the sample consisted of 190 patients, only 10% were classified by the hygiene scores into the poor hygiene category. This means the poor hygiene group which showed the difference was only 19 patients. This poor hygiene group also consisted almost exclusively of males and perhaps there is a difference with pain tolerance between males and females, that could explain some of the difference. So, this study is not perfect and really is not designed to show a cause and effect relationship between poor hygiene and postoperative pain. But, it certainly does indicate an association worthy of further study.

 In the mean time, I now have an additional motivator for patients to improve their oral hygiene. I can tell them that patients with good oral hygiene tend to have less pain after third molar surgery.

  To read further details of this study from Spain, refer to the September 2001 issue of Triple O.

Orthodontic Space Closure without Contralateral Extraction through Mesial Movement of Lower Molars in Patients with Aplastic Lower Second Premolars

Zimmer B. Guitard Y.
J Orofac Orthod 2001;62:350-365        

October 4, 2002
Dr. Hye-young Ryu

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Mandibular second premolars are one of commonly congenitally missing teeth.

How do you treat patients with unilaterally missing mandibular second premolar.

It seems to me that situations like this there are basically two options, one option is to maintain the primary second molar with possibility of prosthetical implant replacement at a later time . The second is to extract primary second molar and closed extraction space from post area in patient who have normally aligned mandibular dentition.

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I believe that the most common reason that most orthodontist with avoid trying to close extraction space from post area is likely heard creating asymmetry or the need for the additional extractions in the mandibular arch. An article titled, ¡°Orthodontic Space Closure without Contralateral Extraction through Mesial Movement of Lower Molars in Patients with Aplastic Lower Second Premolars¡±, by Berned Zimmer and Yann Guitard, which appeared in September 2001 issue of the Journal of Orthofacial Orthopedics.

The article describe a procedure for protacting first and second molars without creating an anterior arch asymmetry. They do this without use extraoral anchorage or implants. The treatment result a 13 consecutively treated patient using their system of treatment mechanics of presented. Complete mesial space closure occured in 8 of 13 patients with the other 5 patients demonstrate minimal deviation from ideal. The procedure that the authors use was placing open coil between the mandibular first and second molars, using the second molars as anchorage to move the first molar mesially. After the first molar was brought in contact with mandibular first premolar class II elastics to use to bring the mandibular second molar mesially. Basically the mandibular second molar and the maxillary dentition were used as anchorage. Using this procedures, no distal forces that could cause arch asymmetry were placed on a mandibular anterior teeth. After complete closure of the first molar, Burstone lingual arch was placed in 9 patient to correct the rotation of the mandibular first molar that had occured during the mesial movement. Above it was not used in the 13 consecutively treated patient described in the article, the author suggest that additional anchorage could be obtain by placing a passive lingual arch extending from first premolar an aplastic side to the first molars and the contralateral side. Additional labial crown torque in anterior segment would also be advantageous. The average treatment time for the patient in this sample, which was consecutively treated, was 2 years and 7 months.

The authors also know that the mesial movement of mandibular first and second molars allow for an earlier eruption of the mandibular third molar which would keep the maxillary second molar from being unapposed.  

Treating unilaterally congenitally missing mandibular second premolars by moving mandibular first and second molars mesially has the advantage of eliminating need any surgical of prosthetic procedures in the future. Even though this form of treatment may result slightly longer treatment time, it is available option that should be presented to patients. The treatment procedures in this article are excellent example of the possible changes that can be achieved when proper treatment mechanics are used.

You can find this article in the September 2001 issue of the Journal of Orofacial Orthopedics.  

Treatment Timing for Rapid Maxillary Expansion

Baccetti T, Franchi L, et al.
Angle Orthod 2001;71:343-350

October 11, 2002
Dr. Seong-Chool Lee

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Suppose you are examining your young boy who is about 10 years of age. He is in a transitional dentition and has class I malocclusion with bilateral constriction of the maxilla. So the treatment plan is pretty straight forward. He will need palatal expansion because he has very little crowding. It will probably non extraction orthodontic therapy.

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Let me describe a situation and then ask you couple of questions. Suppose you examining a young boy who is about 10 years of age. He is in a transitional dentition and has class I malocclusion with bilateral constriction of the maxilla. So the treatment plan is pretty straight forward. He will need palatal expansion and because he has very little crowding. It will probably be non extraction orthodontic therapy.

 Now for my question. Would you expand now or wait expansion for the remaining permanent teeth erupting in order to combine all treatment in one stage at later time. I guess the fundamental question and asking is will it be better for the patient if the expansion is performed early or later relative to the patient's growth spurt. Those questions were addressed in the study published in the October 2001 issue of the Angle Orthodontist. The title of this article is the ¡°Treatment Timing for the Rapid Palatal Expansion¡±. This study is coauthored by Tiziano Baccetti and Lorenzo Franchi, University of Flonce in Italy.

 Now for my question. Would you expand now or wait and expand on the remaining permanent teeth erupting in order to combine all treatment in one stage at the later time. I guess the fundamental question and asking is will it be better for the patient if the expansion is performed early or late relative to the patient's growth spurt. Those questions were addressed in the study published in the October 2001 issue of the Angle Orthodontist. The title of the  article is ¡°Treatment Timing for Rapid Maxillary Expansion¡±. This study is coauthored by Tiziano Baccetti and Lorenzo Franchi, from the University of Flonce in Italy.

 The purpose of their study was to determine any long term differences if the palatal expansion performed early during the transitional dentition or late after all permanent teeth had erupted. The sample for this study consisted 40 subjects who had palatal expansion. He devided into two parts. Those individuals who had palatal expansion before their adolescent growth spurt around 11 years of age and those individuals who had palatal expansion performed after their adolescent growth spurt around 14 years of age.

 The purpose of their study was to determine any long term differences if  palatal expansion was performed early during the transitional dentition or later after all permanent teeth had erupted. The sample for this study consisted 40 subjects who had palatal expansion. It was devided into two parts. Those individuals who had palatal expansion before their adolescent growth spurt around 11 years of age and those individuals who had palatal expansion performed after their adolescent growth spurt around 14 years of age.

 The authors used posteroanterior radiographs to determine the amount of change not only in the dentition but primarily in the skeletal base of the maxilla and nasal passage. In addition to this sample 20 control subjects with similar poteroanterior radiographs were obtained from the Michigan Growth Center to determine what happens to the face during normal growth in development. The treated sample had posteroanterior radiographs taken before expansion and immediately after expansion and long term interval which was between 7 and 10 years after expansion.

 The authors used posteroanterior radiographs to determine the amount of change not only in the dentition but primarily in the skeletal base of the maxilla and the nasal passages. In addition to this sample 20 control subjects with similar poteroanterior radiographs were obtained from the Michigan Growth Center to determine what happens to the face during normal growth in development. The treated sample had posteroanterior radiographs taken before expansion, immediately after expansion and as a long term interval which was between 7 and 10 years after expansion.

 Now in evaluating the sample the authors measured specific structures on either side of the midline. On these radiographs they wanted to determine if not only skeleton but the dentition were stable after expansion. OK! I think you understand this study. Let me give you the results.

When the authors compared the short term change after early or late expansion. They found no significant difference other than significant increase in the lateral nasal width in the early treated group. In other words when palatal expansion was performed before the adolescent growth spurt the patients had greater effect on the nasal bone and maxilla compared to the late treated group. When the authors compared the long term changes between early and later expansion they found that the early treated group had more significant maintenance of expansion of the skeletal base both the width of maxilla and the width of cross lateral nasal structures and infra orbital width were maintained over the long term when the expansion performed earlier. When expansion performed later the major changes that were documented were in the dentition. In other words over the long term the width of the cross lateral maxilla was not that different than the controls indicating the expansion done after patients growth spurt was more dental expansion rather than the skeletal expansion long term.

 Now in evaluating the samples the authors measured specific structures on either side of the midline on these posteroanterior radiographs. They wanted to determine if not only skeleton but the dentition were stable after expansion. OK! I think you understand this study. Let me give you the results.

When the authors compared the short term changes after early or late expansion. They found no significant differences other than significant increase in the lateral nasal width in the early treated group. In other words when palatal expansion was performed before the adolescent growth spurt the patients had greater effect on the nasal base and maxilla compared to the late treated group. When the authors compared the long term changes between early and late expansion they found that the early treated group had more significant maintenance of expansion of the skeletal base both the width of maxilla and the width of cross lateral nasal structures and infra-orbital width were maintained over the long term when expansion was performed earlier. When expansion performed later the major changes that were documented long term were in the dentition. In other words over the long term the width of the cross lateral maxilla was not that different than the controls indicating the expansion done after a patient growth spurt was more of a dental expansion rather than a skeletal expansion long term.

What this suggests is that after orthodontic treatment during the stabilization and retention phase although the dental expansion was maintained the skeletal expansion was not maintained and tend to relapse.

 What this suggests is that after orthodontic treatment during the stabilization and retention phase although the dental expansion was maintained, skeletal expansion was not maintained and tend to relapse.

So what information do we gain from this study? Well the authors believe that patients treated before the pubertal growth peak exhibited significant and more effective long term changes that the skeletal level in both the maxillary and circum-maxillary structures. In addition they believe that when rapid maxillary expansion is performed after the pubertal growth spurt maxillary adaptations to expansion therapy shift from the skeletal to the dental alveolar level.

 So what information do we gain from this study? Well the authors believe that patients treated before the pubertal growth peak exhibited significant and more effective long term changes that the skeletal level in both the maxillary and circum-maxillary structures. In addition they believe that when rapid maxillary expansion is performed after the pubertal growth spurt maxillary adaptations to expansion therapy shift from the skeletal to the dental alveolar level.

If you interested in reading this study on the¡°Treatment Timing of the Rapid Maxillary Expansion¡±, you will find it in the October 2001 issue of the Angle Orthodontist.

 If you interested in reading this study on the treatment timing of the rapid maxillary expansion, you will find it in the October 2001 issue of the Angle Orthodontist.

Bacterial Colonization Associated with Fixed Orthodontic Appliances:
A Scanning Electron Microscopy Study

Sukontapatipark W, El-Agroudi MA, et al
Eur J Orthod 2001;23:475-84

October 18, 2002
Dr. Jeong-Soon Ahn

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When an orthodontic bracket is placed on a tooth, we all know that plaque accumulation can be a problem.  This plaque can lead to decalcification or caries if not control. Where does the plague can develop on a tooth with the bonded bracket? And how does that plaque mature? I can give you some information that helps answer these questions by reviewing with you an article in the October, 2001 European Journal of Orthodontics in title that the ¡°Bacterial Colonization Associated with Fixed Orthodontics Appliances: A Scanning Electron Microscopy Study¡±.

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This research was done in the departments of orthodontics and dental research at the University of Bergen in Norway. The idea of the mind of this project was to look at the plague accumulation around bonded orthodontic brackets under scanning electron microscopy (SEM) to describe morphology and accumulation of the developing plaque. SEM study stopped for the live patients electron microscopy, then the next best thing was the study premolars double plan protraction. The research was done eleven patients with tolerable eighteen premolar pairs to be extracted. Orthodontic bracket was bonded on the teeth in a conventional manner with Concise composite resin and effort made during the bonding procedure to remove excess resin before the material hardened. Of each pair of bracket, one with who I gave it the wire ligature and the other elastomeric ligature. Patients were then instructed to continue their normal oral hygiene habits. Six premolar pairs were extracted after 1 week, 6 pairs after 2 weeks and the remaining 6 pairs after 3 weeks following extraction. The tooth was examined under electron microscopy to determine the morphologic bacterial types and the site of plaque accumulation.

Where did you think the plaque mature more rapidly? The answer is that around each brackets and areas excess composite loaded and also ten micrometers shrinkage gap was seen between the teeth and the enamel surface. This excess composite of the gap of the enamel junction was the site of early plaque maturation. At 2 and 3 weeks mature plaques were already seen in this area, whereas the adjacent enamel surface showed only early plaque formation. The researchers didn't find any different in the types of plaque with wire of elastomeric ligation. But noted that there seemed to be some  greater amount of plaques with the elastomeric ligature.

The take-home message from this research is that the excess composite left around the bracket base is barley can produce plaque development because of the rough surface and shrinkage gap present at the enamel surface. Anything that you can do to minimize the excess composite will make it easier for your patient to control the plaque around there brackets. To read more about this excellent research project that look at the growth of plaque around orthodontic brackets, refer to October 2001 issue of European Journal of Orthodontics.

Asthma

Sollecito TP, Tino G
Oral Surg Oral Med Oral Pathol 2001;92:485-490

October 25, 2002
Dr. Jin-myoung Song

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What is the most common medical condition that presents in your child and adolescent orthodontic patients? For me, I think_asthma. I bet that you, too. See many patients that have a positive history of asthma and many that are taking regular medications to treat it. How much do you know about asthma in its contemporary treatment. There was an excellent review article that appeared in the Nobember 2001 issue of Oral Surgery Oral Medicine and Oral pathology that gave on Medical Management Update of Asthma. The article was written by two individuals in the University of Pennsylvania, Dr. Sollecito, who's the director of the oral medicine program,_Dr. Tino who is in the position in pulmonary medicine.

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What is the most common medical condition that presents in your child and adolescent orthodontic patients? For me, I think it's asthma. I bet that you, too. See many patients that have a positive history of asthma and many that are taking regular medications to treat it. How much do you know about asthma in its contemporary treatment. There was an excellent review article that appeared in the Nobember 2001 issue of Oral Surgery Oral Medicine and Oral pathology that gave an Medical Management Update of Asthma. The article was written by two individuals in the University of Pennsylvania, Dr. Sollecito, who's the director of the oral medicine program, and Dr. Tino who is in the position in pulmonary medicine.

Asthma is a disease that is characterized by reversible airway obstruction. The symptoms include coughing, wheezing, difficulty breathing and tightness in the chest, and there are many possible triggers of the disease and some of these include exercise, medications, chemical irritants, viral respiratory infection and even stress. The disease is variable and classified in 4 steps, ranging from step 1 which is mild_intermittent asthma to step 4 which is severe persistant asthma.

 Asthma is a disease that is characterized by reversible airway obstruction. The symptoms include coughing, wheezing, difficulty breathing and tightness in the chest. There are many possible triggers of the disease and some of these include exercise, medications, chemical irritants, viral respiratory infection and even stress. The disease is variable and it's classified in 4 steps, ranging from step 1 which is mild, intermittent asthma to step 4 which is severe persistant asthma.

The treatment is based on the classification and therefore the severity of the disease. One of those recent advance in the understanding of asthma is the central role that inflammation plays in the disease. Inflammation causes edema, mucous production and reduced ciliary actions. All of these can contribute-the air way obstruction. Also important factors of the disease in-branchial spasm that occurs in the smooth muscle of the airway branches. Since recognition of the importance of inflammation in the airway constriction. The treatment is focused on prevention of acute episodes by controlling the inflammation. Inhaled corticosteroids have become important in the management of the disease. These inhaled corticosteroids are used regularly not just during the acute episodes and help to prevent more severe asthma attacks. These medications have brand names like Beclovent, Intal and Aerobid. Other entire inflammatory agents have been discovered that worked by stabilizing mast cells or acting as leukotriene modifier. These medications have brand manes such as Accolate and Singulair. The bronchodialatars such as Albuterol are still very important to manage acute episodes by relaxing the smooth muscles in the airway. It is the albuterol inhaler that you still see people carry with them to help manage, and asthmatic episodes caused by exercise and chemical irritants.

 The treatment is based on the classification and therefore the severity of the disease. One of the more recent advances in the understanding of asthma is the central role that inflammation plays in the disease. Inflammation causes edema, mucous production and reduced ciliary actions. All which can contribute to the air way obstruction. Also importance in the disease is the branchial spasm that occurs in the smooth muscle of the airway branches. Since recognition of the importance of inflammation in the airway constriction. Treatment is focused on prevention of acute episodes by controlling the inflammation. Inhaled corticosteroids have become important in the management of the disease. These inhaled corticosteroids are used regularly not just during the acute episodes and help to prevent more severe asthma attacks. These medications have brand names like Beclovent, Intal and Aerobid. Other entire inflammatory agents have been discovered that worked by stabilizing mast cells or acting as leukotriene modifiers. These medications have brand names such as Accolate and Singulair. The bronchodialatars such as Albuterol are still very important to manage acute episodes by relaxing the smooth muscle in the airway. It is the albuterol inhaler that you still see people carry with them to help manage, and asthmatic episodes caused by exercise or chemical irritants.

In summary, the recognition that inflammation plays on important role in asthma that has less treatment to prevent inflammatory response. The most frequent treatment is used corticosteroid inhaler in regular basis. Other medications are being developed that also interfere with inflammatory response and these many become more important in the future. Proper management of asthma is a child can help to prevent the permanent airway of changes that can otherwise occur. I would encourage you to read entire article to get a better understanding of asthma and its management. It is well written and has a lot of additional useful information. The article is published in_ November 2001 issue of_triple O and would make it good reference of article for your personal files.

 In summary, the recognition that inflammation plays an important role in asthma  has let's treatment to prevent inflammatory response. The most frequent treatment is use of corticosteroid inhaler on regular basis. Other medications are being developed that also interfere with inflammatory response and these many become more important in the future. Proper management of asthma is a child can help to prevent the permanent airway changes that can otherwise occur. I would encourage you to read entire article to get a better understanding of asthma and its management. It is well written and has a lot of additional useful information. The article is published in the November 2001 issue of the triple O and would make it good reference of article for your personal files.

Effect of After-meal Sucrose-free Gum-chewing
on Clinical Caries.

Sz ke J, B n czy J, Proskin H.M.
J Dent Res 2001;80:1725-1729

November 15, 2002
Dr. Go-woon Kim

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How do you reduce white lesions or areas of decalcification in your orthodontic patients? In other words, do you recommend any other adjuncts to oral health other than simply brushing-teeth? We know that accumulation of the plaque between the gingival margin and the bracket in many adolescent patients can cause white lesion or areas of decalcifications during orthodontics. And let's face it! Many adolescent patients are simply not good every removing the plaque_is the anyway of reducing caries potential of dental plaque. Actually researchers know that the pH of dental plaque drops to a highly acidic level for a period of time following ingestion of food. This enhances the ability of dental plaque to demineralize teeth and therefore produce white lesions or caries. Researchers are also aware that chewing of gum increases the flow of saliva and saliva is a buffer which increases the pH of the plaque. So if you are following this one possibility would be to have individuals chew gum after a meal as long as the chewing gum were sweetened with a none sucrose material. If this will accomplished, would there be a reduction in the amount of caries or white lesions? That question was addressed in the study that was published in the August 2001 issue of the Journal of Dental Research.

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How do you reduce white lesions or areas of decalcification in your orthodontic patients? In other words, do you recommend any other adjuncts to oral health other than simply brushing the teeth? We know that accumulation of the plaque between the gingival margin and the bracket in many adolescent patients can cause white lesions or areas of decalcifications during orthodontics. And let's face it! Many adolescent patients are simply not good every removing the plaque. Is there any way of reducing caries potential of dental plaque. Actually researchers know that the pH of dental plaque drops to highly acidic level for a period of time following ingestion of food. This enhances the ability of plaque to demineralize teeth and therefore produce white lesions or caries. Researchers are also aware that chewing of gum increases the flow of saliva and saliva is a buffer which increases the pH of the plaque. So if you are following this one possibility would be to have individuals chew gum after a meal as long as the chewing gum were sweetened with a none sucrose material. If this will accomplished, would there be a reduction in the amount of caries or white lesions? That question was addressed in the study that was published in the August 2001 issue of the Journal of Dental Research.

The top of the article is ¡°Effect of After-meal Sucrose free Gum-chewing on Clinical Caries¡±. Since all orthodontists treat some adolescents who simply don't press their teeth very well. I thought this was an extremely interesting study that may have a potential for some of our orthodontic patients. The study was coauthor by Dr. Sz ke and two research colleagues in the University of Budapest in Hungary. The purpose of the study was to determine if chewing of a sorbitol containing chewing gum after meal would reduce dental caries and the white lesions. In order to accomplish this, these authors investigate upon -very large investigation.

 The top of the article is ¡°Effect of After-meal Sucrose free Gum-chewing on Clinical Caries¡±. Since all orthodontists treat some adolescents who simply don't brush their teeth very well. I thought this was an extremely interesting study that may have potential for some of our orthodontic patients. The study was coauthor by Dr. Sz ke and two research colleagues from the University of Budapest in Hungary. The purpose of the study was to determine if chewing of a sorbitol containing chewing gum after meals would reduce dental caries and  white lesions. In order to accomplish this, these authors involved upon a very large investigation.

The sample consisted nearly 600 volunteers from the 3rd, 4th and 5th grades of 6 public schools in Budapest Hungary. -The water supply in Budapest is none fluorided. But apparently most of the participants in the study used fluoridized tooth pastes, so all individuals were maintaining their teeth in the same manner. This sample population was divided into two subgroups. One group was asked to chew a sorbitol containing gum for 20 minutes after each of their 3 meals each day. Since two of the meals were given to the children at school they could be controlled. The other group received a no chewing gum. Now each of the subgroups were evaluated at the outset for the number of the decayed, missing and filled surfaces of their teeth. Then they were reevaluated at one year and then finally at two years to determine if these were any differences in the amount of new decay or white lesions. So basically you can see the what these authors wanted to determine was the patients chew gum to increase saliva flow after meals would this reduce the number of new caries lesions. At the answer of that question is yes most definitely. In fact the numbers were very convincing the chewing gum group exhibited a 40% reduction in incremental caries compared with a controlled group after 1 year and a 33% reduction after 2 years. If the data on white lesions were eliminated the reduction was 43% after one year and 38% after 2 years.

 The sample consisted nearly 600 volunteers from the 3rd, 4th and 5th grades of 6 public schools in Budapest Hungary. Now the water supply in Budapest is none fluorided. But apparently most of the participants in the study used fluoridized tooth pastes, so all individuals were maintaining their teeth in the same manner. This sample population was divided into two subgroups. One group was asked to chew a sorbitol containing gum for 20 minutes after each of their 3 meals each day. Since two of the meals were given to the children at school they could be controlled. The other group received no chewing gum. Now each of the subgroups were evaluated at the outset for the number of the decayed, missing and filled surfaces of their teeth. Then they were reevaluated at one year and then finally at two years to determine if there were any differences in the amount of new decay or white lesions. So basically you can see the what these authors wanted to determine was the patients chew gum to increase saliva flow after meals would this reduce the number of new caries lesions. At the answer of that question is `yes' most definitely. In fact the numbers were very convincing the chewing gum group exhibited a 40% reduction in incremental caries compared with a controlled group after 1 year and a 33% reduction after 2 years. If the data on white lesions were eliminated the reduction was 43% after one year and 38% after 2 years.

So there was no doubt in this study chewing of sorbitol containing gum after each meal apparently increased the saliva flow which buffer the acidic effect of the pH of the plaque and in this way reduced the caries potential in this children and adolescence. You know the interesting is that this research has been going on now for over 15 years-researchers in Europe have conformed the positive effects of chewing sucrose free gum on reducing dental caries.

 So there was no doubt in this study chewing of sorbitol containing gum after each meal apparently increased the saliva flow which buffer the acidic effect of the pH of the plaque and in this way reduced the caries potential in these children and adolescences. You know the interesting is that this research has been going on now for over 15 years. Researchers in Europe have conformed the positive effects of chewing sucrose free gum on reducing dental caries.

I think the makes a lot of sense if we go back to my original question which was how do you reduce white lesions in your orthodontic patients. One possible way is to have them chew sorbitol containing gum for 20 minutes after every meal. When we think about it, the patients has nothing to lose and everything to gain from considering this approach. Anyway if you would like to review the study for yourself, you will find it in the August 2001 issue of the Journal of the Dental Research.

 I think the makes a lot of sense if we go back to my original question which was how do you reduce white lesions in your orthodontic patients. One possible way is to have them chew sorbitol containing gum for 20 minutes after every meal. When we think about it, the patients has nothing to lose and everything to gain from considering this approach. Anyway if you would like to review the study for yourself, you will find it in the August 2001 issue of the Journal of the Dental Research.

Self-ligating Brackets and Treatment Efficiency

Nigel W.T. Harradine
Clinical Orthodontic Research 2001;4:220-227

November 22, 2002
Dr. Eun-Hee Koh

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Do you use self-ligating brackets? If you don't use them, I'm certain that you've heard about them. Self-ligating brackets have actually been around for a long time. The first self-ligating bracket was called the 'Russell Lock' bracket. It was actually described in the 1930s. Since that time, several different products have been proposed and tested. You've heard the names. They include Edgelok, the SPEED bracket, Activa, and lately the Damon SL bracket. If you've never tried these, you may be wondering¡®are they any more efficient, does the treatment occur any more rapidly?' You see the theories that were this metal clip covering the arch wire, the friction is reduced with the tooth slice along the wire. But is that really true? In vivo studies, in the laboratory indicate that at self-ligating bracket were produced less friction than using elastomeric ties overall conventional bracket. But is that really true? Well, I found the study in the November 2001 issue of Clinical Orthodontic Research the compared the Damon self ligating bracket with the conventional bracket in the treatment of thirty matched consecutively finished cases in one orthodontic practice.

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Do you use self-ligating brackets? If you don't use them, I'm certain that you've heard about. Self-ligating brackets have actually been around for a long time. The first self-ligating bracket was called the 'Russell Lock' bracket. It was actually described in the 1930s. Since that time, several different products have been proposed and tested. You've heard the names. They include Edgelok, the SPEED bracket, Activa, and lately the Damon SL bracket. If you've never tried these, you may be wondering¡°Are they any more efficient?¡±, ¡°Does the treatment occur any more rapidly?¡± You see the theories that was this metal clip covering the arch wire, the friction is reduced with the tooth slides along the wire. But is that really true? In vivo studies, in the laboratory indicate that at self-ligating bracket were produced less friction than using elastomeric ties overall conventional bracket. But is that really true? Well, I found the study in the November 2001 issue of Clinical Orthodontic Research the compared the Damon self ligating bracket with the conventional bracket in the treatment of thirty matched consecutively finished cases in one orthodontic practice.

Although there are problems with these types of studies, I thought the article was reasonably well done and should be reported on this tape. The title of the article is ¡°Self-ligating Brackets and Treatment Efficiency". It's authored by Nigel Harradine from Bristol England. The purpose of his study was to compare treatment efficiency in cases treated with the self-ligating bracket and with the conventional bracket. This study included two samples. The first, with the sample of thirty consecutively finished patients were treated with the Damon SL brackets. These individuals were matched with a set of thirty patients who have been treated with the conventional brackets by the same clinician. The match was based upon age, type of malocclusion, extraction or non-extraction, and finally the complexity of the malocclusion as measured by the PAR index. So the author attempted to make two samples as comparable as possible with this type of research design. Then, the author measured the time to place and remove arch wires. Number 2, the number of appointments for each group. And Number 3, the number of month required to treat each of the patients. The final treatment result in each group was measured with the PAR index.

Although there are problems with these types of studies, I thought the article was reasonably well done and should be reported on this tape. The title of the article is ¡°Self-ligating Brackets and Treatment Efficiency". It's authored by Nigel Harradine from Bristol England. The purpose of his study was to compare treatment efficiency in cases treated with the self-ligating bracket and with the conventional bracket. This study included two samples. The first, with the sample of thirty consecutively finished patients were treated with the Damon SL brackets. These individuals were matched with a set of thirty patients who have been treated with the conventional brackets by the same clinician. The match was based upon age, type of malocclusion, extraction or non-extraction, and finally the complexity of the malocclusion as measured by the PAR index. So the author attempted to make two samples as comparable as possible with this type of research design. Then, the author measured the time to place and remove arch wires. Number 2, the number of appointments for each group. And Number 3, the number of month required to treat each of the patients. The final treatment result in each group was measured with the PAR index.

Ok! So what are this author find. First of all, is there any difference in the amount of time it takes to place or remove an arch wire when you are using a self ligating bracket as compare to elastomeric tie or ligature? The answer is No. The author found the difference in time was insignificant clinically. Question number 2, was there any difference in the length of time to treat these patients? The answer to this question is Yes, based upon the author's calculations. An averaged_patients treated with the self-ligating brackets were completed in a four months shorter time_ than patients with conventional brackets. Obviously if patients were treated in less time, it required fewer patient visits which the author verified with the data. Last question, was there any difference in the PAR scores for the patients in either of the two groups at the end? The answered that question was No. Even though patients with self-ligating brackets were completed in the shorter period time, the PAR scores for both groups were nearly equivalent. In the article, the author commented that there were several problems that were associated with breakage, or technical problems with the self-ligating system.

Ok! So what are this author find. First of all, is there any difference in the amount of time it takes to place or remove an arch wire when you are using a self ligating bracket as compare to elastomeric tie or ligature? The answer is No. The author found the difference in time was insignificant clinically. Question number 2, was there any difference in the length of time to treat these patients? The answer to this question is Yes, based upon the author's calculations. An averaged the patients treated with the self-ligating brackets were completed in a four months shorter time interval than patients with conventional brackets. Obviously if patients were treated in less time, it required fewer patient visits which the author verified with the data. Last question, was there any difference in the PAR scores for the patients in either of the two groups at the end? The answered that question was No. Even though patients with self-ligating brackets were completed in the shorter period time, the PAR scores for both groups were nearly equivalent. In the article, the author commented that there were several problems that were associated with breakage, or technical problems with the self-ligating system.

But, the author did comment that newer types of designs of these brackets have eliminated most of those problems. So, in conclusion this article has shown that self-ligating brackets can reduce the time it takes to treat the patient. Now, unfortunately this type of research has many many problems. First of all, this was a retrospective study. These patients were_treated at the same time. I am certain there are many many questions in your mind regarding the reliability of the study. But it is an attempt to determine any differences between these two types of brackets. If you_interested in reading this study, you will find it in the November 2001 issue of Clinical Orthodontic Research.

But, the author did comment that newer types of designs of these brackets have eliminated most of those problems. So, in conclusion this article has shown that self-ligating brackets can reduce the time it takes to treat a patient. Now, unfortunately this type of research has many many problems. First of all, this was a retrospective study. These patients were not treated at the same time. I am certain there are many many questions in your mind regarding the reliability of the study. But it is an attempt to determine any differences between these two types of brackets. If you're interested in reading this study, you will find it in the November 2001 issue of Clinical Orthodontic Research.

Evaluation of Nonrinse Conditioning Solution and a Compomer as an Alternative Method of Bonding Orthodontic Bracket

Bishara SE, Laffoon JF, et al
Angle Orthod 2001;71:461-465

November 29, 2002
Dr. Ji-Young Park

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Have you used the new nonrinse conditioning materials when you're bonding brackets to teeth? If you haven't used this new material, you've probably at least heard about it. Traditionally when we've bonded brackets to teeth in the past, we placed etchant, typically 37% phosphoric acid, allowed to set for 30 seconds, rinsed it away, placed the sealant and then bonded the bracket with a light cured composite, and this technique works very well. The debond rates with most materials placed in this manner were relatively low. In_attempt to simplify the bonding procedure, manufactures have recently produced products known as nonrinse conditioners. These materials that etched the surface of the tooth_do not require rinsing with water, and they also don't require a separate sealant painted over that area. These materials etch and seal at the same time followed by placement of a light cured composite, but are these as effective? That question was addressed in the study that was published in the December 2001 issue of the Angle Orthodontist.

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Have you used the new nonrinse conditioning materials when you're bonding brackets to teeth? If you haven't used this new material, you've probably at least heard about it. Traditionally when we've bonded brackets to teeth in the past, we placed etchant, typically 37% phosphoric acid, allowed to set for 30 seconds, rinsed it away, placed the sealant and then bonded the bracket with a light cured composite, and this technique works very well. The debond rates with most materials placed in this manner are relatively low. In an attempt to simplify the bonding procedure, manufactures have recently produced products known as nonrinse conditioners. These materials that etch the surface of the tooth but do not require rinsing with water, and they also don't require a separate sealant painted over that area. These materials etch and seal at the same time follow by placement of a light cured composite. But are these as effective? That question was addressed in the study that was published in the December 2001 issue of the Angle Orthodontist.

The title of the article is ¡°Evaluation of Nonrinse Conditioning Solution and a Compomer as an Alternative Method of Bonding Orthodontic Bracket¡±. This study was coauthor by Samir E. Bishara and three colleagues from the Department of Orthodontics at the University of Iowa in Iowa City. The purpose of the study was to compare conventional 3 step bracket placement and the new 2 step bracket placement using the nonrinse conditioner. In order to accomplish this experiment, the authors gathered forty freshly extracted human molars. After storing in the liquid solution, the teeth were pumiced and the labial surface was prepared for bracket placement. Two different types of preparation were performed. With 20 of the teeth, the typical 3 step bracketing procedure was used, that is etching with phosphoric acid, rinsing with water, drying with air, placement of sealant and then bonding the bracket with a light cured composite. For the other 20 molars in the sample, a nonrinse conditioner was placed first, then a compomer was used as the bracket bonding medium, it was also light cured. Now the compomer is a hybrid material that contains both resin and glass ionomer. Then each of the brackets were subjected to a shear force to determine the force necessary to debracket the tooth. This was recorded and then was compared for the two groups.

 The title of the article is ¡°Evaluation of Nonrinse Conditioning Solution and a Compomer as an Alternative Method of Bonding Orthodontic Bracket¡±. This study was coauthor by Samir Bishara and three colleagues from the Department of Orthodontics at the University of Iowa in Iowa City. The purpose of this study was to compare conventional 3 step bracket placement and the new 2 step bracket placement using the nonrinse conditioner. In order to accomplish this experiment, the authors gathered forty freshly extracted human molars. After storing in the liquid solution, the teeth were pumiced and the labial surface was prepared for bracket placement. Two different types of preparation were performed. With 20 of the teeth, the typical 3 step bracketing procedure was used, that is etching with phosphoric acid, rinsing with water, drying with air, placement of sealant and then bonding the bracket with a light cured composite. For the other 20 molars in this sample, a nonrinse conditioner was placed first, then a compomer was used as the bracket bonding medium, it was also light cured. Now the compomer is a hybrid material that contains both resin and glass ionomer. Then each of the brackets were subjected to a shear force to determine the force necessary to debracket the tooth. This was recorded and then was compared for the two groups.

Ok, I think you got the idea of what the experiment was all about. The question is ¡°Is there any difference in the bond strength with a nonrinsing conditioner_used along with a compomer compared to the typical type of bonding technique?¡±and the answer is ¡°yes¡±most definitely. The shear bond strength using the nonrinse conditioner and the compomer was about one tenth the bond strength compared to using the 3 steps typical method with a light cured composite. The difference was therefore highly significant. No question about it. So the conclusion of this study is that the nonrinse conditioner and the compomer don't make a good combination when bonding brackets to teeth. The debond rates were very high with this technique. Now, of course, there are other composites that could be used with this nonrinse conditioner but these were not tested in this study. The author has recommended that other combinations of composite and nonrinse conditioner should be tested to give the clinician an adequate appraisal of the effectiveness of these new materials. So if you're interested in reading this study that evaluated nonrinse conditioners along with a compomer as an alternative method of bonding, you can find it in the December 2001 issue of the Angle Orthodontist.

 Ok, I think you got the idea of what the experiment was all about. The question is ¡°Is there any difference in the bond strength when a nonrinsing conditioner is used along with a compomer compare to the typical type of bonding technique?¡±and the answer is ¡°yes¡±most definitely. The shear bond strength using the nonrinse conditioner and the compomer was about one tenth the bond strength compared to using the 3 steps typical method with a light cured composite. The difference was therefore highly significant. No question about it. So the conclusion of this study is that the nonrinse conditioner and the compomer don't make a good combination when bonding brackets to teeth. The debond rates were very high with this technique. Now, of course, there are other composites that could be used with this nonrinse conditioner but these were not tested in this study. The authors recommended that other combinations of composite and nonrinse conditioner should be tested to give the clinician an adequate appraisal of the effectiveness of these new materials. So if you're interested in reading this study that evaluated nonrinse conditioners along with a compomer as an alternative method of bonding, you can find it in the December 2001 issue of the Angle Orthodontist.

Radiographic Stereophotogrammetric Evaluation of Intersegmental Stability After Mandibular Sagittal Split Osteotomy and Rigid Fixation

Wall G, Rosenquist B
J Oral Maxillofac Surg 2001;59:1427-35.

December 6, 2002
Dr. Seong-Joon Park

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Have you ever been asked this question? You're treating a 25 year-old female.  She has Class II division 1 malocclusion with no crowding in either dental arch. Her original overjet was 10§®, so your plan was grind the teeth and then have a surgeon perform of mandibular advancement with_sagittal split osteotomy. Now the surgeon that will be performing the orthognathic surgical procedures routinely uses rigid internal fixation. At her last visit, the patient asked you an interesting question. She wanted to know whether or not rigid fixation was truly rigid, could changes or relapse still occur even though the fragments are fixed with bicortical screws. In other words, is there still a movement across the osteotomy sites? What would your answer me? Or let me give you some information that should help you answer that type of question for your patients. I found details in an article that was published in the December 2001 issue of the Journal of Oral & Maxillofacial Surgery.

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 Have you ever been asked this question? You're treating a 25 year-old female.  She has Class II division 1 malocclusion with no crowding in either dental arch. Her original overjet was 10§®, so your plan was aligned the teeth and then have the surgeon perform a mandibular advancement with the sagittal split osteotomy. Now the surgeon that will be performing the orthognathic surgical procedures routinely uses rigid internal fixation. At her last visit, the patient asked you an interesting question. She wanted to know whether or not rigid fixation was truly rigid, could change or relapse still occur even though the fragments were fixed with bicortical screws. In other words, is there still movement across the osteotomy sites? What would your answer be? Let me give you some information that should help you answer that type of question for your patients. I found details in an article that was published in the December 2001 issue of the Journal of Oral & Maxillofacial Surgery.

Since rigid internal fixation is routinely used today following sagittal split osteotomy. I believe this is important information for any clinician who's involved in treating these types of patients. The title of the article is radiographic stereogramic evaluation of intersegmental stability after sagittal split osteotomy with rigid fixation. This study is coauthored by Gert Wall and Bo Rosenquist from the University of Lone in Sweden. The purpose of their paper was to determine if rigid fixation is truly rigid or not. In order to accomplish this evaluation, the authors prospectively identify the sample of 10 patients. Who would be undergoing sagittal split osteotomy at the University of Lone in Sweden. All patients also had orthodontic treatment. Prior to the surgery, small metallic markers were placed in both rami, and in the body of the mandible. Three were placed in each region so that the position of both rami and the body of mandible could be seen on radiographs over_period of the time after the surgery. A special technique was used to evaluate mandibular movement. This is called the stereophotogrammetric method. In advance taking radiographs from different angles and then combining the evaluation of these radiographs to determine three dimensionally whether or not movement occurred at these sites. These stereogramic evaluations were made at 2 days and then at 1, 3, 6 and 12 months after the surgery. In all cases, the sagittal osteotomy was followed by the placement of either many plates in screws or bicortical screws to stabilize the fragments, then at each stereogramic radiographic section, two separate images were made. One with a patient relaxed in centric occlusion, and the other with a patient biting hard on a piece of rubber material between the two central incisors. In other words, the osteotomic site was loaded significantly using the masseter muscles, then the radiographic images were compared to see if any movement occurred across the osteotomic sites. OK. I think you get the idea. The question is "Do the fragments move after surgery or not?" and the answer is "Yes, they move." In fact, significant movement according to the authors had occurred. After 2 days, more than 2/10 of millimeters of movement was found in 8 out of 10 patients. After 6 months, 6 patients still showed significant movement and finally after 12 months, 3 patients still showed movement of greater than 2/10 of the millimeters across the osteotomic sites.

Since rigid internal fixation is routinely used today following sagittal split osteotomy. I believe this is important information for any clinician who's involved in treating these types of patients. The title of the article is radiographic stereogramic evaluation of intersegmental stability after sagittal split osteotomy with rigid fixation. This study is coauthored by Gert Wall and Bo Rosenquist from the University of Lone in Sweden. The purpose of their paper was to determine if rigid fixation is truly rigid or not. In order to accomplish this evaluation, the authors prospectively identified the sample of 10 patients, who would be undergoing sagittal split osteotomy at the University of Lone in Sweden. All patients also had orthodontic treatment. Prior to the surgery, small metallic markers were placed in both rami, and in the body of the mandible. Three were placed in each region so that the position of both rami and the body of mandible could be seen on radiographs over a period of the time after the surgery. A special technique was used to evaluate mandibular movement. This is called the stereophotogrammetric method, involve taking radiographs from different angles and then combining the evaluation of these radiographs to determine three dimensionally whether or not movement occurred at these sites. These stereogramic evaluations were made at 2 days and then at 1, 3, 6 and 12 months after the surgery. In all cases, the sagittal osteotomy was followed by the placement of either miniplates in screws or bicortical screws to stabilize the fragments, then at each stereogramic radiographic section, two separate images were made. One with a patient relaxed in centric occlusion, and the other with a patient biting hard on a piece of rubber material between the two central incisors. In other words, the osteotomy site was loaded significantly using the masseter muscles, then the radiographic images were compared to see if any movement occurred across the osteotomy sites. OK. I think you get the idea. The question is "Do the fragments move after surgery or not?" and the answer is "Yes, they move." In fact, significant movement according to the authors had occurred. After 2 days, more than 2/10 of millimeters of movement was found in 8 out of 10 patients. After 6 months, 6 patients still showed significant movement and finally after 12 months, 3 patients still showed movement of greater than 2/10 of the millimeters across the osteotomic sites.

So what does this mean? Actually, I'm not really certain. You see, this study didn't evaluate relapse. It only evaluated movement across the osteotomic sites. Perhaps the more important question would be is there any correlation between continued movement across an osteotomic sites and relapse after orthognathic surgery. Because if the fragments are still rigidly attached, so the skeletal relapse does not occur is that really important that movement could occur across an osteotomic sites after orthognathic surgery. I'm not certain, but hopely these authors will answer that next question in a future study. In the mean time, I command the authors for an excellent study and an interesting finding. Although we typically call this type of fixation rigid, in fact it's only semi-rigid.

Movement will exist across the osteotomy sites. We simply don't know if this significant and the healing process. For the studies hopely will illustrate this information if you'd like to review this present study, you'll find it in the December 2001 issue of the Journal of Oral & Maxillofacial Surgery.

So what does this mean? Actually, I'm not really certain. You see, this study didn't evaluate relapse. It only evaluated movement across the osteotomic sites. Perhaps the more important question would be is there any correlation between continued movement across an osteotomic sites and relapse after orthognathic surgery. Because if the fragments are still rigidly attached, so the skeletal relapse does not occur it is  really important that movement could occur across an osteotomic sites after orthognathic surgery. I'm not certain, but hopely these authors will answer that next question in a future study. In the mean time, I command the authors for an excellent study and an interesting finding. Although we typically call this type of fixation rigid, in fact it's only semi-rigid.

Movement still exist across the osteotom sites. We simply don't know if this significant and the healing process. For the studies hopely will illustrate this information if you'd like to review this present study, you'll find it in the December 2001 issue of the Journal of Oral & Maxillofacial Surgery.

Nightguard Vital Bleaching: A Long-Term Study on Efficacy, Shade Retention, Side Effects, and Patients' Perceptions

Leonard RH Jr, Bentley C, et al
J Esthet Restor Dent 2001;13:357-369

December 13, 2002
Dr. Jin-myoung, Song

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A few months ago, I reviewed an article that showed that vital bleaching of teeth following orthodontic bonding and debonding may take longer than untreated teeth but that it was still effective. Since the demand for tooth whitening seems to remain high, if we are to recommend vital nightguard bleaching procedures to our patients we also need information about the long-term stability of the color change after bleaching and about the safety of the procedure. These questions were recently addressed in an article that appeared in ¡°The Journal of Esthetic and Restorative Dentistry¡±. The researchers were from the University of North Carolina and this research was designed to look at the long-term color stability and safety following vital nightguard bleaching. The study was initially a randomized clinical trial where 51 patients were randomly assigned to a bleaching group or a control group. The bleaching group had a custom bleaching tray constructed and was given 10% carbamide peroxide bleaching solution to use nightly for 14 days. The control group had identical treatment except that their bleaching solution was a placebo. It was missing the act of peroxide ingredient. After 6 months, the patients in the control group crossed-over into the bleaching group and were given the opportunity to use the act of bleaching solution for 14 days. All subjects were extensively examined, radiographed and pulp-tested prior to treatment and at 3, 6, and 47 months after bleaching. A questionnaire was also used to determine patients' perceptions of the bleaching process. Using a definition for effectiveness defined by the ADA, bleaching was judged to be effective if at lightened tooth color at least 2-shades. Let's review the results. The bleaching was 98% effective right after treatment. That means almost every patient received lightening tooth color of at least 2-shades. In fact the average was 7-shades lighter. After 4 years, the bleaching was still effective in more than 80% of the patients. That is long-term 4 out of 5 subjects still had at least a 2-shade improvement with the average after 4 years being 5-shades lighter. About two thirds of the patients had some tooth sensitivity or gingival irritation during the bleaching process. But there were no long-term changes in gingival health, tooth vitality or radiographic appearance. This research gives a sound scientific basis to recommend vital nightguard bleaching to patients. We have solid evidence that bleaching is highly effective following treatment and the color change remains in 80% of patients at least 4 years later. In addition, and most importantly, we can be assured that the bleaching is not going to create long-term problems for the health of the teeth or the gingiva. To review the article entitled ¡°Nightguard Vital Bleaching: a Long-term Study on Efficacy, Shade Retention, Side Effects, and Patients' Perceptions¡±. You need to find a copy of the final 2001 issue of ¡°The Journal of Esthetic and Restorative Dentistry¡±. There is more information about patients' perceptions about the bleaching procedure and not surprisingly more than 90% were very pleased with the outcome and would recommend it to their friends.

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A few months ago, I reviewed an article that showed that vital bleaching of teeth following orthodontic bonding and debonding may take longer than untreated teeth but that it was still effective. Since the demand for tooth whitening seems to remain high, if we are to recommend vital nightguard bleaching procedures to our patients we also need information about the long-term stability of the color change after bleaching and about the safety of the procedure. These questions were recently addressed in an article that appeared in ¡°The Journal of Esthetic and Restorative Dentistry¡±. The researchers were from the University of North Carolina and this research was designed to look at the long-term color stability and safety following vital nightguard bleaching. The study was initially a randomized clinical trial where 51 patients were randomly assigned to a bleaching group or a control group. The bleaching group had a custom bleaching tray constructed and was given 10% carbamide peroxide bleaching solution to use nightly for 14 days. The control group had identical treatment except that their bleaching solution was a placebo. It was missing the active peroxide ingredient. After 6 months, the patients in the control group crossed-over into the bleaching group and were given the opportunity to use the active bleaching solution for 14 days. All subjects were extensively examined, radiographed and pulp-tested prior to treatment and at 3, 6, and 47 months after bleaching. A questionnaire was also used to determine patients' perceptions of the bleaching process. Using a definition for effectiveness defined by the ADA, bleaching was judged to be effective if it lightened tooth color at least 2-shades. Let's review the results. The bleaching was 98% effective right after treatment. That means almost every patient received lightening up at least 2-shades. In fact the average was 7-shades lighter. After 4 years, the bleaching was still effective in more than 80% of the patients. That is long-term 4 out of 5 subjects still had at least 2-shades improvement with the average after 4 years being 5-shades lighter. About two thirds of the patients had some tooth sensitivity or gingival irritation during the bleaching process. But there were no long-term changes in gingival health, tooth vitality or radiographic appearance. This research gives a sound scientific basis to recommend vital nightguard bleaching to patients. We have solid evidence that bleaching is highly effective following treatment and the color change remains in 80% of patients at least 4 years later. In addition, and most importantly, we can be assured that the bleaching is not going to create long-term problems for the health of the teeth or the gingiva. To review the article entitled ¡°Nightguard Vital Bleaching: a Long-term Study on Efficacy, Shade Retention, Side Effects, and Patients' Perceptions¡±. You need to find a copy of the final 2001 issue of ¡°The Journal of Esthetic and Restorative Dentistry¡±. There is more information about patients' perceptions of the bleaching procedure and not surprisingly more than 90% were very pleased with the outcome and would recommend it to their friends.

Influence of Distraction Rates on the Temporomandibular Joint Position and Cartilage Morphology in a Rabbit Model of Mandibular Lengthening.

Kruse-L sler B, Meyer U, et al
J Oral Maxillofac Surg 2001;59:1452-1459

December 20, 2002
Dr. Ji-Young Park

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Have you heard the procedure called distraction osteogenesis? Today I think most of the orthodontists have heard of this term and some orthodontists have been involved in treating patients using this technique. Distraction osteogenesis is a procedure which allows for lengthening of a bone by merely creating an osteotomy site, allowing callas of union to form and then separating the two bones at the rate of about 1mm per day in order to lengthen them. This procedure was developed by a now famous surgeon,  from Russia. These results are phenomenon, since their introduction into clinical science several years ago, orthodontic researchers have been planned the principles of distraction osteogenesis to correct malformations of both maxilla and the mandible. In fact, distraction osteogenesis has been used to enhance growth of the mandible in individuals who have severe mandibular hypoplasia, and the results coming out of these clinical trials are fairly impressive but what if distraction force is placed across osteotomy site in the mandible there is a resultant of rotational effect on the condyle. Does these rotation cause destructional matter of effect in the growth of the condyle. That question was addressed in the study that was published in the December 2001 issue of the Journal of Oral & Maxillofacial Surgery. As orthodontists, we may be involved in the future with applying the principles of distraction osteogenesis in some of our patients with severe craniofacial abnormalities. I think, it's good for us to keep up on the literature and be aware of potential problems with this procedure.

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The title of this article is ¡°Influence of Distraction Rates on the Temporomandibular Joint Position and Cartilage Morphology during Mandibular Lengthening. This study was coauthor by Birgit Kruse-L sler and three research colleagues from the Department of Oral & Maxillofacial Surgery at the University of M nster in Germany. The purpose of this study was to use animal model and apply distraction osteogenesis force across the osteotomy site  in the body of the mandible. Then the condyles of these animals were evaluated to determine whether or not and in negative had occurred in the condylar cartilage over 50 rabbits were used for this experiment. Now without getting into details I can tell you that the author's methodology was excellent. After the distraction apply were placed across the osteotomy site, then they applied different rates and strains across this sites during the distraction procedure. Then the researchers evaluated the condyle both macroscopically, and microscopically to determine any negative changes. What do you think they found? Actually the results were illuminating. First of all, both the clinical and radiographic evaluations at the end of the distractions showed no evidence of joint luxation even when the distraction was performed at maximum rates. But when the condyles were evaluated histologically, the authors found a positive correlation between the amount of mechanical loading and the development of degeneration of the cartilage. When the distraction was performed at a rapid rate, all of the cartilaginous layers of the temporomandibular joint were exposed to higher pressure and were reduced in thickness. In fact the fibrous layer became completely destroyed. When the distraction was performed more gradually, no negative alteration occurred in the joint due to less pressure on the condylar head. So what's the point of the article? I think this was an excellent study. It points out that more gradual distraction actually allows the condylar head to adapt and plays less pressure on the condyle which allows for less distraction of the cellular layer within the condylar cartilage. Although these were experimental animals, I would imagine that the same general principles of bone biology would probably apply to the human. So anyway now you know a little bit more about the effects of distraction osteogenesis. If you'd like to review this study, you can find it in the December 2001 issue of the Journal of Oral & Maxillofacial Surgery.  

Bite force in pre-orthodontic children with unilateral crossbite

Sonnnesen L, Bakke M, Solow B:
Eur J Orthod 2001;23:741-9

December 27, 2002
Dr. Seong Joon Park

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When do you think is the best time to treat the unilateral posterior crossbite? As soon as it is detected, even in the primary dentition? May be in the mixed dentition when the permanent first molars have fully erupted? How about in the late nest to early permanent dentition when its separate treatment phase is now required. EMG studies have shown differences in muscle function on the 2 size when the unilateral posterior crossbite is presented and their speculation at prolonged lateral function may lead-asymmetric mandibular growth. In the December 2001 issue of the European Journal of Orthodontics. Dr. Sonnesen in collage from Denmark have provided further evidence of the changes that can be observed in children with posterior crossbite.

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When do you think is the best time to treat the unilateral posterior crossbite? As soon as it is detected, even in the primary dentition? May be in the mixed dentition when the permanent first molars have fully erupted? How about in the late mixed to early permanent dentition when its separate treatment phase is not required. EMG studies have shown differences in muscle function on the tooth size when the unilateral posterior crossbite is presented and their speculation at prolonged lateral function may lead to asymmetric mandibular growth. In the December 2001 issue of the European Journal of Orthodontics. Dr. Sonnesen in collage from Denmark have provided further evidence of the changes that can be observed in children with posterior crossbite.

Their paper, bite force in pre-orthodontic children with unilateral crossbite provides additional evidence that may help us in determining the best treatment timing. This study looked at 26 children with the unilateral posterior crossbite. The children were evenly divided between boys and girls and were an average just over 9 years old. This was an experimental group. A control group of additional 26 children was identified that was matched for age, gender, and stage of dental development. All the children were examined clinically to determine their occlusal status and the number of teeth in contact. They were also screened for signs and symptoms of TMD by the examination and questionnaire since some studies have associated unilateral crossbite with increase risk of TMD. Finally, the children had their maximum bite force measured on each side by the use of a pressure transducer. This study was well-done in terms of processing and the method of theirs and the reliability of their examinations.

 Their paper, bite force in pre-orthodontic children with unilateral crossbite provides additional evidence that may help us in determining the best treatment timing. This study looked at 26 children with the unilateral posterior crossbite. The children were evenly divided between boys and girls and were an average just over 9 years old. This was an experimental group. A control group of additional 26 children was identified that was matched for age, gender, and stage of dental development. All the children were examined clinically to determine their occlusal status and the number of teeth in contact. They were also screened for signs and symptoms of TMD by examination and questionnaire since some studies of the associated unilateral crossbite with increase risk of TMD. Finally, the children had their maximum bite force measured on each side by the use of a pressure transducer. This study was well-done in terms of processing and the method of theirs and the reliability of their examinations.

Were any differences found between the crossbite children and the non-crossbite controls? Yes, there were differences. First, the control group had significantly greater bite force than the crossbite group. This difference was presented in all age groups.  Second, there were indications of increase signs and symptoms of TMD in the crossbite group. The crossbite children had greater frequency of headache and more tenderness of the masticatory muscles. Third, the crossbite group had fewer teeth in occlusal contact. This may be related to the lower bite force, since some research has shown lower bite force measurement in patient with fewer occlusal contacts. The authors believe that_new evidence shows that there is a link between the present of the posterior crossbite and altered muscle function. They further believe that this evidence supports the early treatment of the unilateral crossbite to normalize muscle function and development. It would be interesting at the authors with continued follow up the patient in this study, to see if after treatment for the crossbite, the bite force truly does normalize.

 Were any differences found between the crossbite children and the non-crossbite controls? Yes, there were differences. First, the control group had significantly greater bite force than the crossbite group. This difference was presented in all age groups.  Second, there were indications of increase signs and symptoms of TMD in the crossbite group. The crossbite children had greater frequency of headache and more tenderness of the masticatory muscles. Third, the crossbite group had fewer teeth in occlusal contact. This may be related to the lower bite force, since some researches were shown lower bite force measurement in patient with fewer occlusal contacts. The authors believe that this new evidence shows there is a link between the present of the posterior crossbite and altered muscle function. They further believe that this evidence supports the early treatment of the unilateral crossbite to normalize muscle function and development. It would be interesting at the authors with continued follow up the patient in this study, to see if after treatment for the crossbite, the bite force truly does normalize.

 For now, this is another piece of evidence that indicates the early treatment of the unilateral posterior crossbite is probably a good thing. We still need more evidence to determine exactly the most advantageous time for treatment. But for now I would say that the treatment of the crossbite should be done or can be done efficiently and comfortably for the patient. If you like to read this article, to get more details on the study, you can find it in the December 2001 issue of European Journal of Orthodontics.

 For now, this is another piece of evidence that indicates the early treatment of the unilateral posterior crossbite is probably a good thing. We still need more evidence to determine exactly the most advantageous time for treatment. But for now I would say that the treatment of the crossbite should be done or can be done efficiently and comfortably for the patient. If you like to read this article, to get more details on the study, you can find it in the December 2001 issue of European Journal of Orthodontics.

A Clinical Retrospective Evaluation of 2 Orthodontic Band Cements.

Millett DT. Hallgren A. McCluskey LA
Angle Orthod 2001;71:470-476

January 3, 2003
Dr. Go-Woon Kim

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What's the failure rate of your band cement? First of all what kind of cement do you use to cement molar bands to teeth? I'm sure that many orthodontists still use bands at least on maxillary and mandibular first molars. If so, do you use glass ionomer cement or modified composite cement to adhere the band to the tooth. Is one of these cements more successful than the other in reducing band failure? That question was answered in the study that was published in the December 2001 issue of the Angle Orthodontist.

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What's the failure rate of your band cement? First of all what kind of cement do you use to cement molar bands to teeth? I'm sure that many orthodontists still use bands at least on maxillary and mandibular first molars. If so, do you use glass ionomer cement or modified composite cement to adhere the band to the tooth. Is one of these cements more successful than the other in reducing band failure? That question was answered in the study was published in the December 2001 issue of the Angle Orthodontist.

The title of this article_¡°A Clinical Retrospective Evaluation of 2 Orthodontic Band Cements¡±. This study was coauthored by Mr. Millett and several research associates from the department of orthodontics at the university of Glasgow in Scotland. The purpose of their study was to compare two different cements clinically to determine if the success rates for band cementation were similar or not. The two cements were Band-Lok, a modified composite and the other material is AquaCem, which is conventional glass ionomer cement.

The title of this article is¡°A Clinical Retrospective Evaluation of 2 Orthodontic Band Cements¡±. This study was coauthored by Mr. Millett and several research associates from the department of orthodontics at the university of Glasgow in Scotland. The purpose of their study was to compare two different cements clinically to determine if the success rates for band cementation were similar or not. The two cements were Band-Lok, a modified composite and the other material is AquaCem, which is conventional glass ionomer cement.

Now in this retrospective study, the authors evaluated over two hundred bands that had been cemented with Band-Lok and nearly four hundred bands that had been cemented with AquaCem. The authors wanted_determine what was the percentage of band failure. Number 2 the time to first band failure, and then number 3 to determine if age or gender, type of treatment or type of malocclusion had any effect on band failure.

Now in this retrospective study, the authors evaluated over two hundred bands that had been cemented with Band-Lok and nearly four hundred bands that had been cemented with AquaCem. The authors wanted to determine what was the percentage of band failure. Number 2, the time to first band failure, and then number 3, to determine if age or gender, type of treatment or type of malocclusion had any effect on band failure.

OK! let's take these issues one at a time. First of all what was the overall failure rate for the sample, 25% of those individuals with Band-Lok had at least one band failure, for the glass ionomer cement group the failure rate was 30%. So these really didn't differ that much. So one important finding from the study is that the type of cement really didn't make difference. The failure rate was about_same. What about the type of malocclusion? no difference. What about so patient's age and gender relative to bracket failure? Again no difference. Were there any significant differences that did cause increased band failure? The answer is ¡°Yes¡±-

OK! let's take these issues one at a time. First of all what was the overall failure rate for the sample, 25% of those individuals with Band-Lok had at least one band failure, for the glass ionomer cement group the failure rate was 30%. So these really didn't differ that much. So one important finding from the study is that the type of cement really didn't make difference. The failure rate was about the same. What about the type of malocclusion? No difference. What about the patient's age and gender relative to bracket failure? Again no difference. Were there any significant differences that did cause increased band failure? The answer is ¡°Yes¡±.

As you might expect the authors found that_was significantly related to band failure. No big surprise. Those patients that wore headgear had greater band failure rate despite the type of cement that was used. So in conclusion the authors believed that headgear was a pretty good predictor for band failure but more importantly either cement band about the same band failure rate in this study.

As you might expect the authors found that the use of headgear was significantly related to band failure. No big surprise. Those patients that wore headgear had greater band failure rate despite the type of cement that was used. So in conclusion the authors believed that headgear was a pretty good predictor for band failure but more importantly either cement had about the same band failure rate in this study.

If you'd like to review this study, you'll find it in the December 2001 issue of the Angle Orthodontist.

If you'd like to review this data, you'll find it in the December 2001 issue of the Angle Orthodontist.

Overbite and Overjet are not Related to Self-report of Temporomandibular Disorder Symptoms

John MT, Hirsch C, et al
Journal of Dental Research 2002;81:164-169

January 10, 2003
Dr. Jae-Nam Kim

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Suppose you are sitting in your desk in your private office later in the afternoon on a Tuesday. You've just completed your clinic day in your clinic off your desktop. You've reviewed the patients you've seen for the day and you note that you had two adult examinations in the afternoon. Both individuals had significant temporomandibular disorders. This included popping, limitation of opening, and some pain in the area of the TMJs. One of these individuals had_class II division II malocclusion with a deep impinging overbite. The other individual had class II division I malocclusion with mild overbite but an eccessive overjet_8mm. Here is my question! Are the temporomandibular  symptoms related to either the deep overbite or eccessive overjet? What's your answer? Are overbite and overjet if there are extreme_associated with TMD? you know_as orthodontist_I think-were often confronted with this question. So let me give you data from a recent extensive study that will help you to answer that question in your own mind.

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Suppose you are sitting at your desk in your private office late in the afternoon on a Tuesday. You've just completed your clinic day and you're clining off your desktop. You've reviewed the patients you've seen for the day and you note that you had two adult examinations in the afternoon. Both individuals had significant temporomandibular disorders. These included popping, limitation of opening, and some pain in the area of the TMJs. One of these individuals had a Class II division 2 malocclusion with a deep impinging overbite. The other individual had Class II division 1 malocclusion with mild overbite but an excessive overjet of 8mm. Here is my question! Are the temporomandibular  symptoms related to either the deep overbite or excessive overjet? What's your answer? Are overbite and overjet if they are extreme, associated with TMD? You know, as orthodontist, I think we are often confronted with this question. So let me give you data from a recent extensive study that will help you to answer that question in your own mind.

This article was published in the march 2002 issue of the Journal of Dental Research. It's title is ¡°Overbite and Overjet and their Relationship to Temporomandibular Disorder Symptoms¡±. This study was coauthored by M. John and several researchers associated from the department of prosthodontics and preventive dentistry at universities in Germany and ortho in the United States. This was a broad based study which examined a large number of individuals together the data. The sample consists of over 3,000 subjects, about a third of these were adolescents and the rest of the sample was devided between adult and senior adult subjects, all individuals were completly dentulous_that would held all the teeth and they all live in Germany. The subjects had_variety of  occlusions and malocclusions. The objective of the authours was to determine the amount of  overbite and overjet and relate the severity of either of these measurements to the incidence of temporomandibular symptoms. These symptoms included limitation of mouth opening, locking during opening, joint noises and pain. These clinical symptoms were obtained from each subject using a questionaire. In addition_the amount of the subjects overbite and overjet was also recorded. Then the symptoms and the variables were statistically compared to determine if there were any correlations.

 This article was published in the March 2002 issue of the Journal of Dental Research. It's title is ¡°Overbite and Overjet and Their Relationship to Temporomandibular Disorder Symptoms¡±. This study was coauthored by M. John and several researchers associates from the Department of Prosthodontics and Preventive Dentistry at universities in Germany and also in the United States. This was a broad based study which examined a large number of individuals together the data. The sample consisted of over 3,000 subjects. About a third of these were adolescents and the rest of the sample was divided between adult and senior adult subjects. All individuals were completely dentulous, in other word, had all the teeth and they all lived in Germany. The subjects had a variety of occlusions and malocclusions. The objective of the authours was to determine the amount of overbite and overjet and relate the severity of either of these  measurements to the incidence of temporomandibular symptoms. These symptoms included limitation of mouth opening, locking during opening, joint noises and pain. These clinical symptoms were obtained from each subject using a questionnaire. In addition, the amount of the subject's overbite and overjet was also recorded. Then the symptoms and the variables were statistically compared to determine if there were any correlations.

So what do you think? Do you think the severity of overjet and overbite are related to severity of symptoms of TMD. The answer_that question is "NO". The findings from this study clearly support the idea that wide ranges of overbite and overjet are compatible with normal function of the masticatory muscles and the TMJs. There was no association between the incidence of TMD and the severity of overjet and overbite. So the authors concluded that attempting to prevent TMD by creating more normal values of overbite and overjet with dental treatment is not supported by their findings.

 So what do you think? Do you think the severity of overjet and overbite are related to severity of symptoms of TMD? The answer to that question is "NO". The findings from this study clearly support the idea that wide ranges of overbite and overjet are compatible with normal function of the masticatory muscles and the TMJs. There was no association between the incidence of TMD and the severity of overjet and overbite. So the authors concluded that attempting to prevent TMD by creating more normal values of overbite and overjet with dental treatment is not supported by their findings.

I thought this was a very interesting study_it's hard to argue with their data. The sample was extensive, the methodology was reliable, and the statistical analysis were accomplished correctly.

 I thought this was a very interesting study. It's hard to argue with their data. The sample was extensive, the methodology was reliable, and the statistical analyses were accomplished correctly.

If you would like review this study_you can find it in the march 2002 issue of the Journal of Dental Research.

 If you would like review this study, you can find it in the March 2002 issue of the Journal of Dental Research.

Effects of Maxillary Protraction on Craniofacial Structures and Upper-Airway Dimension

Hiyama S, Suada N, et al
Angle Orthod 2002;72:43-47

February 7, 2003
Dr. Eun-Hee Koh

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Do you use maxillary protraction on patients with maxillary hypoplasia? I think that most orthodontist who been in practice for several years have used maxillary protraction in an attempt to correct minor Class III malocclusions related to undergrowth of the maxilla. And if the problem is identified early enough and if the patient is cooperative and if future growth is reasonable in terms of its pattern, maxillary protraction can correct minor Class III malrelationships. So they appear to be a positive effect of maxillary protraction on maxillary forward growth. But my question is ¡°Does this improvement in maxillary growth produce an increase in the upper airway?¡± It was seemed to make sense that if the maxilla were moved farther forward relative to the based skull that the upper airway size at least measured in the sagittal plane would increase. But, is that really true? That question was addressed in the study that was published in the February 2002 issue of the Angle Orthodontist.

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The title of the article is ¡°Effects of Maxillary Protraction on Craniofacial Structures and Upper-Airway Dimension." This research project was coauthored by Shigetoshi Hiyama and several research colleagues from Tokyo Medical and Dental University in Japan. Now and the past many studies of the correction of class III malocclusions have come from Japan. Of course, this type of dental malrelationship is very common among the Japanese people.

In this most recent project, the authors attempt to determine if the use of maxillary protraction what have an effect on the upper airway space as it's measured in the sagittal plane. So, in order to accomplish this, the authors gathered the sample of 25 patients who had a mean age of about 10 years. Each individual had a Class III malocclusion with the retrusive maxilla. All subjects were treated with only maxillary protraction using an appliance that was worn about 12 hours a day. The appliances were continued until the anterior crossbite was completely corrected. Cephalometric radiographs were taken before appliance therapy and then at 12 months after the beginning of treatment. Then, the authors devised the method of evaluating the upper airway space by measuring specifical landmarks that with the fine this parameter in the sagittal plane. Of course, this did not measure airway three dimensionally and this was mentioned by the authors.

OK what happen? Does maxillary protraction increase the size of the upper airway? Actually, the answer is Yes and No. When the authors measure the absolute distances that the fine the upper airway? They didn't find statistically significant differences between pre and post treatment cephalometric radiographs. And when the authors used regression analysis to determine any correlation between changes in certain cephalometric landmarks that they pick the position of the maxilla and mandible? The authors found a positive correlation. I may be thinking, "What does that mean?" The authors found that alterations in SNA and alterations in head posture had a significantly positive influence on changes in upper airway space. But this is only an anatomical measurement. I guess the real question is ¡°Whether or not this had any positive effect on the patients ability to breathe to the nose." That question was not addressed in this study. This study merely evaluated the cephalometric radiographs and not the mode of breathing. So anyway, the study has shown that there is a correlation between some of the cephalometric alterations and the size of the upper airway with maxillary protraction. Hopefully future studies coming from these authors will attempt to correlate these alterations with measurements of breathing.

If you're interested in reviewing this article, you can find it in the February 2002 issue of the Angle Orthodontist.