Dictation - 전남대학교 치과대학 교정과 대학원 세미나

Effects of a Modified Acrylic Bonded Rapid Maxillary Expansion Appliance and Vertical Chin Cap on Dentofacial Structures Basciftci FA, Karaman AI Angle Orthod 2002;72:61-71 March 7, 2003 Dr. Hang-ik, Jang
[초벌원고] Do you ever use bonded palatal expanders to widen the maxilla to correct posterior cross-bites? If so, do you have concerns about using this type of an appliance in a patient who has a vertical growth pattern?	[수정원고] Do you ever use bonded palatal expanders to widen the maxilla to correct posterior cross-bites? If so, do you have concerns about using this type of appliance in a patient who has a vertical growth pattern?
First of all, we know that in some instances, palatal expansion can increase lower facial height slightly. Could bonded expander exaggerate this effect? How do you control this in your patients if you use bonded expanders in vertical growth? That subject was discussed in an article that I found in the February 2002 issue of the Angle Orthodontist. The title of this article is “Effects of a Modified Acrylic Bonded Rapid Maxillary Expansion Appliance on Dentofacial Structures”. This paper is co-authored by Dr. Basciftci and Karaman from Selcuk University in Turkey.	First of all, we know that in some instances, palatal expansion can increase lower facial height slightly. Could bonded expander exaggerate this effect? How do you control this in your patients if you use bonded expanders in vertical growers? That subject was discussed in an article that I found in the February 2002 issue of the Angle Orthodontist. The title of this article is “Effects of a Modified Acrylic Bonded Rapid Maxillary Expansion Appliance on Dentofacial Structures”. This paper is co-authored by Dr. Basciftci and Karaman from Selcuk University in Turkey.
The purpose of this study was rather straightforward. The authors want to evaluate the vertical effects of acrylic bonded expanders with and without the application of a vertical chin cap. In order to accomplish this goal, the authors gather the sample of around 30 patients. They were divided into 2 groups. And in both groups, palatal expansion appliances were placed to widen the maxilla. In addition, in one of the groups, a vertical chin cap was worn about half the day during the time of_expansion. Cephalometric radiographs were made before treatment, after expansion and after about 12 weeks of retention. These radiographs were compared to determine the vertical changes that had occurred.	The purpose of study was rather straightforward. The authors want to evaluate the vertical effects of acrylic bonded expanders with and without the application of a vertical chin cap. In order to accomplish this goal, the authors gather the sample of around 30 patients. They were divided into 2 groups. And in both groups, palatal expansion appliances were placed to widen the maxilla. In addition, in one of the groups, a vertical chin cap was worn about half the day during the time of the expansion. Cephalometric radiographs were made before treatment, after expansion and after about 12 weeks of retention. These radiographs were compared to determine the vertical changes that had occurred.
Ok! What do you think happened? Remember the main question. Were the vertical-pull chin cap have any effect on vertical changes during rapid palatal expansion? And the answer_that question is yes. When the authors evaluate the group without the vertical pull chin cap, there was consistent opening of the mandibular plane angle and consistent increase in lower facial height. But when the authors evaluate the patients with the vertical pull chin cap, there were no increases in facial height and no opening of the mandibular plane angle.	Ok! What do you think happened? Remember the main question. Were the vertical-pull chin cap have any effect on vertical changes during rapid palatal expansion? And the answer to that question is yes. When the authors evaluate the group without the vertical pull chin cap, there was consistent opening of the mandibular plane angle and consistent increase in lower facial height. But when the authors evaluate the patients with the vertical pull chin cap, there were no increases in facial height and no opening of the mandibular plane angle.
Now the differences between the two groups, although statistically significant, were not clinically large differences. But if your patient is growing vertically and if your goal is not to increase facial height during expansion, the use of a vertical-pull chin cap could be beneficial.	Now the differences between the two groups, although statistically significant, were not clinically large differences. But if your patient is growing vertically and if your goal is not to increase facial height during expansion, the use of a vertical-pull chin cap could be beneficial.
Anyway, if you like to review this study for yourself, you will find it in the February 2002 issue of the Angle Orthodontist.	Anyway, if you like to review this study for yourself, you will find it in the February 2002 issue of the Angle Orthodontist.

Epidemiology of Clinical Attachment Loss in Adolescents Lopez R, Fernandez O, et al J Periodontol 2001;72:1666-1674 March 14, 2003 Dr. Seong-Chool, Lee
[초벌원고] What's the incidence of early attachment loss of periodontal disease in adolescents? As orthodontist the majority of our patients are in the age range of between 12 and 20 years. How many of those individuals already have some early signs of periodontal breakdown? Do you perform any sort of periodontal exam to uncover this type of problems? How prevalent might they be? Those questions were answered in this study that was published in the December 2001 issue of The Journal of Periodontology. I chose this study to review on this month tape because this is one of the largest samplings of this age range. That's ever been attempted to evaluate periodontal problems.	[수정원고]
The title of the study is “Epidemiology of Clinical Attachment Loss in Adolescents”. This study is coauthored by Dr. Lopez and 3 research colleagues from Denmark and Chile. The purpose of their study was to asses the epidemiology of periodontal attachment loss among adolescent subjects. This was very large study. The sample was consisted over 9,000 individuals between ages of 12 and 20 years. Of course, that's exactly the age range of patients that we predominantly treat as orthodontist. The sample was taken over 600 high schools in the very large metropolitan area. In each of these individuals of subjects in this study periodontal examination including circular probing of the maxillary and mandibular 1st molars, 2nd molars and all incisors was performed. The amount of periodontal attachment loss in each of these areas was determined. Now clinical attachment loss in this study is defined as the distance from the bottom of the pocket or sulcus to the cementoenamel junction. If the circular depth is located apical to the CEJ, then that's considered attachment loss. These measurements were made for all of the 9,000 subjects. Then the subjects were divided into the various age ranges to determine the relationship between age and severity of periodontal problems.
OK! So much for the methodology. Let`s get to the data. First of all in the entire sample how many of these students or subjects were examined? Do you think at least one area with clinical attachment loss greater than 1 mm? The results were surprise you. These authors found that 70% of these students had at least one site with clinical attachment loss with circular depth was apical to the CEJ by greater than 1 mm. In addition the authors found that about 16% of the students had attachment loss that was greater than 2 mm. Finally there are about 5% of the students who had attachment loss greater than 3 mm. This was surprising to me. I believe that probably the most severe problem that adolescent would get is gingival inflammation with edema and bleeding of the gingival tissues. But seldom with the clinical attachment loss in these individuals that is apparently not true.
In this population from this metropolitan area the attachment loss was significant considering the age of these individuals. Now this was only an epidemiologic study. What would really be interested to know is what happens to these individuals over time. Our patients with early attachment loss at young age more highly susceptible to periodontal disease at later ages. Hopefully future studies of the same populations will be able to answer that question.
In the mean time I think this is good information for any orthodontist. We need to monitor adolescent patients. Occasionally we may find patients who have mild to moderate attachment loss. These patients may need special attention by us during their orthodontic therapy. If you are interested in the reviewing the study you can find it in the December 2001 issue of The Journal of Periodontology.

Changes in root length during orthodontic treatment: advantages for immature teeth Mavragani M, Boe OE, et al Eur J Orthod 2002;24:91-97 March 21, 2003 Dr. Seon-Mi Kim
[초벌원고] The many Class II studies that have been completed in recent years, generally have not indicated any advantage to beginning treatment early. That is in the mixed dentition versus beginning treatment at the permanent dentition. They have not been able to demonstrate greater skeletal correction or better ultimate occlusal correction by intervening early in these cases. In light of these findings, I was intrigued by an article that recently appeared in the February 2002 issue of the European Journal of Orthodontics entitled "Changes in root length during orthodontic treatment: advantages for immature teeth".	[수정원고]
This study, authored by Dr. Mavragani and colleagues from Norway, provides some evidence that early treatment of Class II division 1 malocclusions may result in less root resorption of the maxillary incisors compared with later treatment.
The purpose of this study was to determine the effects of age and stage of root development on changes is maxillary incisor root length during orthodontic treatment. This was a longitudinal study of 80 patients undergoing treatment for Class II division 1 malocclusions. These patients were treated with at least 2 premolars extractions and with either a standard or preadjusted edgewise technique. Root lengths were measured from peri-apical x-rays and adjusted image distortion. From the x-rays, the roots were also classified as complete or incomplete, depending upon whether the apex is closed.
The authors also developed two cross-sectional control groups of untreated individuals, age and sex matched to the pre-treatment and post-treatment groups. Various statistical techniques were used to compare the root lengths before and after treatment, and to get an indication of the effect of age and root development on the changes in root length.
The result of the study showed that patients undergoing edgewise treatment from Class II division 1 malocclusions had on average a shortening of the maxillary incisor roots of almost 2 mms, but 50 of the 280 roots studies had lengthening of the roots during treatment.
Those that had root lengthening had just as much lengthening as the matched, untreated controls during the same time period. As would be expected, the incomplete roots were more likely have this root lengthening during treatment than the teeth with complete roots.
Those patients with incomplete roots at the beginning of treatment ended up with longer roots at the end of treatment than those that started with roots. This study indicates that beginning orthodontic treatment at a younger age before the root is complete does not interfere with completion of root development. And, in fact, seems to be protective against root resorption during treatment.
I'm not completely sold on the methodology of this study since they don't really describe their method of correcting the x-ray measurements for image distortion. But it does provide a piece of evidence that suggests that early treatment may be better for the health of the incisor roots.
To see if you believe that this study supports early treatment for Class II patients, you may want to read the entire article in the February 2002 issue of the European Journal of Orthodontists.

An Experimental Study on Mandibular Expansion: Increase in Arch Width and Perimeter Motoyoshi M, Hirabayashi M, et al Eur J Orthod 2002;24:125-130 March 28, 2003 Dr. Kwang-Taek, Koh
[초벌원고] Imagine that you're sitting at your desk in the office, working on the treatment plan of a 14-year-old boy named Robert. Robert has a lower arch width molar constriction due to complete buccal cross bite of the upper molars. As you plan the treatment for this case, you determine that about 8-9 mm of intermolar expansion will be required in the lower arch to properly upright the buccal segments. In addition, Robert has about 5 mm of crowding in the lower arch and your treatment goal is to try and maintain the present lower incisor position, that is, you dont want to throw the lower incisors forward to provide room for alignment. The question is whether the lateral expansion of this plan will provide adequate space for alignment.	[수정원고]
This question becomes easier if you know about the study recently published in the April 2002 European Journal of Orthodontics by Dr. Motoyshi and his colleagues from Japan. The study is titled, An Experimental Study on Mandibular Expansion: Increases in Arch Width and Perimeter. The authors used a combination of computer modeling techniques to look at the relationship between lateral expansion of the mandibular buccal segments and the result in change in arch perimeter. The model was built from a CT scan of an East Indian human skeleton mandible.
First, a finite element model of a two-tooth buccal segment was constructed to determine the center of rotation of the teeth when subjected to lateral expansion courses. Secondly, this information was used in the complete lower arch model to determine the changes that would occur with 10 degrees of lateral molar uprighting. This full arch simulation model was then used to measure the arch perimeter changes that occurred with the lateral uprighting.
The results of this study showed that 10 degrees of lateral molar uprighting resulted in nearly 4 mm of expansion per side, or a nearly 8 mm total increase in intermolar width. This nearly 8 mm increase in width was associated with a little less than 3 mm increase in arch perimeter. If you convert this to a ratio, you can expect about 1 mm increase in arch perimeter for each 3 mm increase that is obtained in intermolar width.
Now that I have this information, how does it apply to our patient Robert that is going to need an 8-9 mm increase in molar width? Well, this study would suggest that 8-9 mm of molar expansion would contribute about 3 mm to the arch perimeter. Since we determined that Robert had 5 mm of lower arch crowding, we still need to find an additional 2 mm of space through interproximal reduction or other means if we are to meet our goal of maintaining the original incisor position. This simple 1:3 ratio of perimeter increase to molar expansion can help you make more informed treatment planning decisions. The details of the original research project from Japan that determined this ratio can be found in the April 2002 issue of the European Journal of Orthodontics.

A comparison between zinc polycarboxylate and glass ionomer cement in orthodontic band cementation Dincer B, Erdinc AME. J Clin Pediatr Dent 2002;26:285-288 April 4, 2003 Dr. Hye-young, Ryu
[초벌원고] It seems thought everymonth there are many studies published about strength of retention of boning of orthodontic brackets to enamel. I still routinely band most of first molars my practice and so I am also interested in studies looking at band retention with different cements. I primarily use the zinc polycarboxylate cement for many years due to its good performance ,easy clean up, the time of removal. But I know many orthodontists use glass ionomer cements due to the fluoride release characteristics.	[수정원고]
It recent report in the Journal of Clinical Pediatric Dentistry compared band cement with glass ionomer and zinc polycarboxylate in regards to the number of loose bands during treatment and incidence of the calcification associated with loose bands.
This study was done in the University orthodontic clinic in Izmir Turkey and reported title it “A comparison between zinc polycarboxylate and glass ionomer cement in orthodontic band cementation”.
The study included 148 patients that had total of 486 band placed. 282 bands were cemented with zinc polycarboxylate cement(PolyF plus) and 204 bands were cemented with Glass ionomer cements(3M Rely-X). The cements were mixed according to manufacturer`s directions and place on teeth had been pumiced and dried. The bands were followed during the time of active treatment. It was average just over 2 years. If bands came loosed during treatment, it was recorded along with any evidence of decalcification on that tooth. In addition, the amount of his left on the tooth was know that. Here`s what the researchers found?
First, the glass ionomer`s bands were retained better with only 10% coming loose during treatment compared with 27% for the zinc polycarboxylate. Second, when there were loose bands, there was least decalcification on teeth were the bands re-cemented with glass ionomer cement. 32% of the loose bands cemented with zinc polycarboxylate cement show some enamel decalcification but none of loose bands cemented with glass ionomer show the associated decalcification.
Third, when the band come loose, more heap was left on the enamel with glass ionomer cement than with zinc polycarboxylate. And finally, the difference on band retention was even greater with the use headgear. 50% of the zinc polycarboxylate bands subjected extraoral force became loose compared with only 10% of glass ionomer bands.
Of all the scientific merit of study could been much stronger if split mouth technique with random assignment had been used. This study concludes glass ionomer is superior he suffer cementic orthodontic bands at least considering retention and decalcification. If you wish review details of this study, it can be founded spring 2002 issue of Journal of Clinical Pediatric Dentistry.

Effects of headgear Herbst and mandibular step-by-step advancement versus conventional Herbst appliance and maximal jumping of the mandible Du X, Hagg U, et al. Eur J Orthod 2002;24:167-174 April 11, 2003 Dr. Kweon -Hee, Jeong
[초벌원고] If you were treating severe Class II division 1 patient, at made decision to the Herbst appliance, how did you design Herbst appliance treatment to maximize skeletal contribution to the correction of malocclusion? What will be helpful to headgear to the Herbst appliance to maximize skeletal change? It is better to advance mandible step-by-step rather than all of ones. This question was addressed in recent study completely in the Peoples Republic of China and reported in the April 2002 issue of the European Journal of Orthodontics.	[수정원고]
This study was authored by scientists from the Peoples Republic and from the Hong Kong and entilted "Effects of headgear Herbst and mandibular step-by-step advancement versus conventional Herbst appliance and maximal jumping of the mandible".
The purpose was looked at the treatment outcome differences between the conventional Herbst samples and groups that has Herbst treatment with headgear and step-by-step advancement of the mandible. Both groups in this study consisted of consecutively treated samples, so this was not selective cases of the study. The patients has cephalometric X-ray done before and after the Herbst treatment and cephalometric measurements were used to comparisions.
All subjects were severe Class II division 1 patients with every overjet about almost 10 ㎜. 8 comparisions of 2 samples before treatment will be their similarly age just over 13 years old. and you know significnat differences of cephalometric measurement before treatment began. The headgear Herbst step-by-step advancement group used a high- pull headgear with Herbst appliance for 12 hours per day. This group also had mandibular advancement done in 2 ㎜ increments, 3 hours treatments rather than all of ones like the conventional Herbst groups.
The treatment time is about one year in both groups. The cephalometric analysis didn`t view some treatment between the groups. The headgear Herbst with step-by-step advancement had a greater skeletal contribution to the correction of Class II almost 3 ㎜ more than the conventional Herbst group. This skeletal difference was significantly greater in the maxilla and had a tendency with being greater than mandible, but didn`t which is satistically significant. I thought that perhaps groups with step-by-step advancement would show less forward movement of lower dentition because of less forward stretching. But the proof is not to be the case. Both groups has a similar forward movement of lower dentition during treatment. There are also some differences in the vertical change during treatment with headgear in treating the upper molar in the headgear Herbst group.
That conclusion is that it seems to be some differences treatment effects with a headgear Herbst with step-by-step advancement, but with this study design, we cannot tell what it is difference is an addition of the headgear or the changes the step-by-step mandibular advancement. It seems to me that they use of the Herbst appliances lives in the United States is in the temp to a Rumanic patient compliance in the use of gross mother of furcation of appliances so adding an need for headgear wear may not be embraced, even for the greater skeletal effect. If the step-by-step advancement is the key component together greater skeletal changes however, that may be easy it just to make.
There is a considerbly more details information in the paper and I have a chance to relate to you. If you are interested in the Herbst appliance treatment, I would suggest to look at the article by Dr. Du colleagues that appeared in the April 2002 issue of the European Journal of Orthodontics.

Relationship Between Congenitally Missing Lower Third Molars and Late Formation of Tooth Germs Baba-Kawano S, Toyoshima Y, et al Angle Orthod 2002;72:112-117 April 25, 2003 Dr. Eun-Hee, Koh
[초벌원고] Suppose you've recently completed orthodontic treatment on a fourteen-year-old female. Her occlusal result turned out perfectly. You debanded her and placed her an orthodontic retainers. And as you do with all your patients, you sit down with the parents and the child after treatment to review the results. When you look together at the posttreatment panoramic radiograph, you know this, that the patient doesn't show any sign a formation of mandibular third molar tooth buds.	[수정원고]
Now all of the patient's teeth developed anyway in fact the apices of the mandibular second molars a still not quite fully closed. But the parents ask you an interesting question. They want to know if you think the daughter will ever develop mandibular third molars, since all of teeth developed anyway, is it possible with the third molars will appear at a later time? Or will be absent? How do you answer that question? Well lapping give you some information that the help you with that type of question in the future. It's based on the study that was published in the April 2002 issue of the Angle Orthodontists. The title of the article is “Relationship Between Congenitally Missing Lower Third Molars and Late Formation of Tooth Germs”. This paper was coauthored by doctors Kawano and Toyoshima from the department of orthodontics at Kyushu University in Fukuoka, Japan.
The purpose of this study was to determine if there was a relationship between the time of appearance of the lower third molars and the formative stages of other mandibular molars and premolars. Now in order to accomplish this retrospective analysis the authors gathered panoramic radiographs on one hundred individuals. They were chosen from a larger sample of nearly six hundred subjects who had no congenital diseases. The primary requisite with that each individual had a minimum of five panoramic radiographs taken every two years starting at ten years of age.
You see what these authors wanted to do was determine if they could relate the presence or absence of third molar development with the formation of the roots of the other mandibular molars and premolars. Ok, what do you think they found? Well, first of all the prevalence of missing third molars in the sample of one hundred individuals was 20%. Next question, at what age could this be noticed? When the authors evaluated of the data, they found that there was an association between the development of the roots of the second molar and the presence or absence of the third molar in the mandibular arch.
Specifically what they found? Was that if the mandibular third molar is not present by the time the second molar has reached near closure of the apices of the roots? Then the third molar will be missing one hundred percent of the time. Furthermore, if the mandibular second molar shows half root development? And if the third molar is absent? Little be congenitally missing 80% of the time.
I think this is very useful information for assist orthodontist. Let's go back now to the scenario that I described that the outset. Remember? The fourteen-year-old female whose missing the third molar and if just completed orthodontic treatment? Remember, I said that her mandibular second molars didn't have quite complete closure of the apices, but were near completion of root development.
In this situation, there's a hundred percent chance that this young girl will be congenitally missing her mandibular third molars. I think this is useful for us as orthodontist who complete treatment on patients of roughly thirteen to fifteen years of age and maybe asked these types of questions by the parents. Anyway, if you like to review this study, you can find it in the April 2002 issue of the Angle Orthodontist.

Shear Bond Strengths of Plastic Brackets with a Mechanical Base Liu J-K, Chang L-T, et al Angle Orthod 2002;72:141-145. May 9, 2003 Dr .Chang-Hun, Park
[초벌원고] Supposing you're doing consultation of forty-year old female patient, she has class I malocclusion with moderately crowded teeth. Since those teeth are also protrusive, you decide extraction of four premolar unrelieving crowding and then close any residual extraction space. It's very straightforward treatment plan.	[수정원고]
Now, you explain to the patient if you could either use tooth color bracket or metal bracket in treating her and then she asks you the big question. Will it be any difference in performance of either of this type of bracket? Specifically she wants to know if she is confronted with problem of loosing bracket if she chooses tooth color bracket compared metal bracket. Of which answer will be? Is there any difference in debonding rate between tooth colored and metal bracket?
That question was addressed and study was published 2002 issue of Angle of Orthodontist. The title of article is “Shear Bond Strengths of Plastic Brackets with a Mechanical base”. This paper was coauthored by Dr. Liu and three researcher associate from the division of orthodontics national Cheng Kung University in Taiwan. The primary objective of this study was to compare shear bond strength of plastic bracket with a mechanical base to metal bracket using two different adhesives.
Sample of study consisted of forty premolar that had been extracted. They were stored in water and then be used experimental surface to bond bracket. Two type of bracket were pretested. One was metal bracket with a mesh base and the other was plastic bracket with a mechanical base. Two different adhesives were also tested. One was a no-mixed, nonlight-cured adhesive and the other was a light-cured composite. Brackets were divided into four subgroups. Each bracket was bonded with either no-mixed, nonlight-cured or light cured composite. Then after suitable setting time bracket were removed and then the amount of force necessary to debracket tooth was recorded by using testing machine.
Ok, what would you think have? First of all, is there any difference between metal bracket and plastic bracket respect to shear bond strengths? The answer to that question is yes. Definitely shear bond strength of metal bracket is actually about twice than plastic bracket. Ok, second question was the any difference between using no mix nonlights-cured composite compared to light cured.
The answer to that question was yes disorderly. This used metal bracket had no difference between the two composite systems but in the plastic bracket there was significant difference. Light cured composite had greater shear bond strengths than no mix no light cured composite. Ok but what is all this means for the clinician? It will be outer subject.
If you do use plastic bracket on your patient, you probably should use light cured composite. This will give you greater shear bond strengths. But, is relative same bond strengths metal bracket? Unfortunately this answer to that question is no. Even with light cured composite and plastic bracket with mechanical base shear bond bracket strengths still have half than metal bracket. So when your adult patient asks you “is any difference performance of plastic versus metal bracket”, answer is yes. But hopefully if adult patient maintain reasonably diet and take care of their appliances, this probably wouldn't produce big clinical problem in the treatment adult patient. If you like to review this study you could find it April 2002 issue of the Angle Orthodontist.

The Effects of Reconditioning on the Slot Dimensions and Static Frictional Resistance of Stainless Steel Brackets S.P.Jones, C.C.H. Tan, et al Eur J Orthod 2002;24:183-190 May 16, 2003 Dr. Heung-Gyo, Lee
[초벌원고] Commercially recondition brackets often look almost better than new due to the electro-polishing process that is only use. Do this good looks translation, good performance. In other words do recondition brackets perform justice wellness new corner of part when use for orthodontic treatment. That have answer is the question.	[수정원고]
Research was university of college London on the talking study looking at the effects of reconditioning on sliding friction and report the result in the April 2002 issue of the European Journal of Orthodontics. The article is title “The effects of reconditioning on the slot dimensions and static frictional resistances of stainless steel brackets”
The article purpose was to compare new brackets, to recondition brackets of the same type the see of change slot dimensions all in measurement static sliding friction. The study consist of 90 stainless steel brackets 45 new and 45 recondition. The reconditioned brackets were sent to commercially reconditioner the use the process of chemical solvent and electro-polishing to restore the brackets. 15 new and 15 recondition brackets were measured for the microscope to determine axial slot dimensions. 30 new and 30 recondition brackets were of subjects testing for static sliding friction. The friction testing was done using the brackets against the .016 stainless steel wire with brackets wire angulations 0, 5, and 10 degrees.
The result of testing were analysed the statistically to determine whether any difference could be found between the new and recondition brackets. How do you think that reconditioning affected measured slot width the brackets. The study show the slot width increase step reconditioning and this increase was statistically significant. The slot dimension data from this study like most study found the axial arch wire slot is wider than nominal of dimension given by the manufacture. In this case .018 slot brackets had in axial slot width about most .020 when new and slightly over .020 when reconditioned.
The second question is whether this increase slot width translate in to difference sliding friction testing further of the study. Those result show that width no difference in the static friction testing between the new and recondition brackets 0, 5, or 10 degrees. Many manufacturers allow labelling brackets single use only products. This means that orthodontist are going to re-use them they most have evidence that the recondition brackets perform same as new brackets. This study from April 2002 issue of the European Journal of Orthodontics provide evidence that at least terms of friction sliding mechanics recondition bracket no different new.

Stability and Relapse: Early Treatment of Arch Length Deficiency Little Robert M. Am J Orthod Dentofacial Orthop 2002;121:578-581 May 30, 2003 Dr. Chun-Sun, Eun
[초벌원고] The question of the efficacy of early treatment seems to come and go on a regular basis. And as you might be aware, was recently the topic of an international symposium sponsored by the AAO. In the June 2002 issue of the American Journal of orthodontics and Dentofacial Orthopedics, articles based on some of the presentations at this symposium are presented. In an article titled stability and relapse, early treatment of arch length deficiency by Robert Little, Dr. Little discusses a number of early treatment philosophies and evaluates how well they are supported by the long term retention research studies at the University of Washington in Seattle.	[수정원고]
In this article, he addresses the following questions. What is the treatment of choice for a preadolescent patient with arch length deficiency? What happens if nothing is done? What if the arches are enlarged to accommodate the permanent teeth? What if premolars are extracted early that is serial extraction, followed by full treatment plus retention? What if arch length is preserved in the mixed dentition to accommodate the future permanent successors? Addressing the question of what happens if nothing is done, Dr. Little references, Dr. Coienraad Moorrees, classic 1959 textbook, which demonstrated the arch length at age 5 is greater than at age 18. The conclusion is that without treatment, a short arch length will only get worse.
Addressing what happens if the dental arches are enlarged, Dr. Little notes that based on the Washington studies the cases that had early arch enlargement although they looked clinically acceptable at the end of active treatment actually demonstrated the poorest long term results of any strategies that have been studied. On the question of arch expansion he therefore concludes that without lifetime retention this strategy of arch development will lead to unacceptable results.
What about the use of serial extraction? On this topic he notes that his study of 30 first premolar serial extraction cases that has subsequent orthodontic treatment and retention show is also really identical to those treated with full first premolar extraction in the permanent dentition. Although the serial extraction cases became simpler during the observation stage before active treatment, they did not show greater stability that premolar extraction cases in the permanent dentition. Dr. Littles conclusion is that serial extraction use no greater long-term improvement of premolar extraction in the full dentition and routine treatment.
The final question he addresses is what if arch length is preserved in the mixed dentition to accommodate the future permanent successors? To address this question, Dr. Little referred to the work of Dr. Hays Nance in 1947, which occupied leeway space that is the space difference between the permanent premolars and the primary molars. This space ranged from 8mm to 0mm. He emphasizes that Dr. Nance recommended a passive lingual arch when the space was equal to or greater than the degree of anterior crowding, and it was therefore critical to the exact amount of crowding and the exact amount of leeway space for each individual patient.
Dr. Little used the 5 year post retention record provided by Dr. Steve Dugoni, of 25 patients treated with a mandibular lingual arch designed to maintain but not advance all mandibular incisors to evaluate the long term stability of arch maintenance. He noted that these cases had excellent long-term stability and fared much better in the long-term than did the premolar extraction in arch development cases from University of Washington. He suggests that Hays Nance was correct and that we can use the full leeway space to our advantage, he further concludes that for mixed dentition cases in which leeway space is favorable compared with anterior crowding, use of the passive lingual arch is appropriate and is also appears to be quite stable.
The bottom line of this article related to early treatment is that doing nothing will result in a greater arch length deficiency, extension of the arches will result in a greater relapse, serial extraction appear to be no more stable than premolar extraction in the permanent dentition, and the most effective way to alleviate the crowding and maintain the arch length in the mixed dentitions is with the use of passive lingual arch.
The only one of this conclusions which found surprising based on my own experience, is that there was no greater stability to serial extraction patients. In this regard, it is interesting to note that one of the other papers presented at the symposium by Dr. Jimmy Boley suggested that serial extraction cases with 30 years records didn't affect your excellent results. You can find this article in the June 2002 issue of the American Journal of Orthodontics and Dentofacial orthopedics.

Impact of Lossy Compression on Diagnostic Accuracy of Radiographs for Periapical Lesions Eraso FE, Analoui M, et al. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;93:621-5 June 13, 2003 Dr. Jin-myoung, Song
[초벌원고] I'm going to review an article with you that you may think has no relevance to Orthodontics. The study looked at diagnosing periapical lesions from digital x-rays for endodontic purposes. Although the specific diagnostic problem may not interest us, the purpose of the study conducted by Dr. Erasso and colleagues was that to determine how much digital radiographic images could be compressed without losing diagnostic values. This question is very important to us as orthodontist migrate toward greater use of digital x-rays. The research is published in the May 2002 issue of the Journal of Oral Surgery, Oral Medicine, and Oral Pathology. And is titled “Impact of Lossy Compression on Diagnostic Accuracy of Radiographs for Periapical Lesions”.	[수정원고]
To understand this research you first need to know a little bite about the compression of digital images. Digital images either photographs or radiographs can be very large when they are first captured, often many megabites. In order to make them easier to store and to transfer from computer to computer it is useful to compress them. They can be compressed in a lossless way but only with small gains. Most software systems use a lossy compression scheme called JPEG that reduces the file size greatly but throws away some of the information, hopefully the unimportant information. The JPEG compression ratio can be varied but again the question is how much compression can be used without effecting diagnostic accuracy.
Back to the study we are reviewing, the researchers took 50 periapical x-rays and compressed them at 8 different levels each from no compression to a ratio of 1 to 64. They then took the resulting 400 images and determined whether expert clinicians could accurately diagnose the presence of a periapical lesion from each of the images. How much compression was acceptable? This study found that compression ratios more than 1 to 32, significantly reduced the diagnostic accuracy. They also found a very high correlation between diagnostic accuracy and the compression ratio. That is as the compression ratio went up the diagnostic accuracy went down. What does this mean for the orthodontist? You can expect that at some point the compression ratio will affect the diagnostic accuracy of orthodontic images. This study indicates that 1 to 32 would be the highest compression ratio tolerable. One problem we face is that often the compression ratio for our software is not determined by scientific evidence but rather to enhance the speed and performance of our software.
If you want to read more about the details of image compression and how this compression may effect the diagnostic accuracy of digital radiographs, I suggest you refer to the May 2002 issue of the triple O. Hopefully we will soon see a similar project done to look at how image compression affects our ability to locate cephalometrical landmarks or interpret panoramic films but for now I would be very careful to limit compression to less than 1 to 32.

Effect of a Fluoride-releasing Self-etch Acidic Primer on the Shear Bond Strength of Orthodontic Brackets. Bishara SE, Ajlouni R, et al. Angle Orthod 2002;72:199-202. June 20, 2003 Dr. Ye-Na, Jeon
[초벌원고] Do you use self etching primers when placing or bonding orthodontic brackets? In the past, most of us used phosphoric acid to etch the teeth as an initial step in bonding. Then a sealant or primer was painted onto that tooth. This was followed by bonding of the composite on the bracket. But in the past couple of years self etching primers have been available.	[수정원고]
These were simply painted on the tooth and the etching and priming process are combined into one. This simplifies the process and eliminates one step. And these products have reasonably good success. But now a new product is available. A self etching primer with fluoride attitude. We don't like to have fluoride incorporated into the composite. But will the addition of the fluoride attack the shear bond strength? That question was answered in the study that was published in June 2002 issue of the Angle Orthodontist.
The title of the article is effect of a fluoride releasing self etch primer on the shear bond strength of orthodontic brackets. This study was co-authored by Samir E. Bishara and three research colleagues from the department of orthodontics at the University of IOWA in IOWA city.
Now, the purpose of the study was rather straightforward. It was to compare the shear bond strength of a self etch primer containing fluoride with conventional bonding techniques. In order to accomplish this subjective, the authors gathered freshly extracted human molars. In one group, the typical bonding process was used, that is etching with phosphoric acid followed by rinsing, painting of sealant primer, and then bonding of the bracket. In the other group, a self etch primer with fluoride was used in the one step priming process followed by bonding with the same composite. Then a testing machine was used to determine the shear bond strength. Very straightforward methodology.
What do you think happened? Well, the answer was also pretty straightforward. When fluoride was added to self priming material, the shear bond strength was drastically reduced. Now conventional bond strength are in the neighborhood of ten mega pascals. For the self etch primer with fluoride, the mean bond strength was five mega pascals or about half. So this clearly answers the question.
If you use a self etch primer with fluoride, you will have much higher debond rates due to reduced shear bond strength. I think this is good information for orthodontists who may be considering using one of the new self-etch primers with fluoride. If you like to review the study, you can find it in the June 2002 issue of the Angle Orthodontist.

The results of microneurosurgery of the inferior alveolar and lingual nerves Pogrel MA; J Oral Maxillofac Surg 2002;60:485-9. June 27, 2003 Dr. Seong-joon Park
[초벌원고] Has this ever happened to you? You are in the middle of orthodontic treatment on a 32 year-old adult female. The plan for this patient is orthodontic alignment, mandibular advancement surgery and then completion of the orthodontics. She's to be treated none extraction. So you early completed initial alignment and the surgery was just performed. Unfortunately during the surgery the mandibular right inferior alveolar nerve was severed. Yes, that's right cut in half.	[수정원고]
Now of course, it was accidental and occurred during the sagittal split of the mandibular ramus, but the patient is distraught. After the surgery, she complains of continuous numbness on the right side full face and lips. Of course you feel badly. Here's my question. Can the nerve fragments be reattached? Would it be possible with some of the newer microscopic surgical procedures to actually regenerate this nerve and return it to normal? That question was addressed in the study that was published in the May 2002 issue of the Journal of Oral and Maxillofacial Surgery.
The title of the article is results of microneural surgery of the inferior alveolar and lingual nerves. This study was coauthored by anthony pogrel from the department of oral and maxillofacial surgery at the University of California in Sanfrancisco.
This is a very interesting study. The sample included all patients who referred to the University of Sanfrancisco oral surgery clinic with a diagnosis of injury to the inferior alveolar or lingual nerves during a 5 year period ending in 1999. All individuals were examined and there was conformation of lack of sensation due to injury of the nerve. These patients then underwent microneural surgical repair of the nerve fragments. A total of 50 on the patients were operated. Now the type of repair consisted of physical anastomosis of the nerve or excision in grafting. The sample was actually distributed evenly between these two types of repairs.
O.K. What do you think it happened? The question is do these repairs work. Can a surgeon actually reattach nerve fragments if they've been severed and what's the probability that little work. Actually the results were reasonably good. Over half the sample showed improvement. Slightly less than half the sample showed no improvement in nerve sensation. So in conclusion, the procedures that were performed in this study actually do work. So for our patients who experienced trauma or severing of the nerve during surgery, there is the possibility of repairing the nerve.
I think probably one of the most critical factors is the experience of the surgeon. Based upon the results of this extensive study the chances of the improvement after surgery are about 50 percent. If you are interested in reviewing this study, you will find it in the May 2002 issue of the journal of oral and maxillofacial surgery.

Do Mandibular Third Molars Alter the Risk of Angle Fracture? Fuselier JC, Ellis EE, Dodson TB. J Oral Maxillofac Surg 2002;60:514-8 July 4, 2003 Dr. Go-woon, Kim
[초벌원고] What reasons do you give when recommending extraction of mandibular third molars in post-orthodontic patients? Suppose you've just completed orthodontic therapy on a 15 year old male, you're reviewing the post treatment panoramic radiograph with the parents and the child. You note the mandibular third molars are positioned low in the alveolus, and they are angulated slightly to the mesial, but they appear to be enough room for them to erupt.	[수정원고]
What's your recommendation? Are there any reasons to recommend extraction of these third molars? Suppose this young boy is very active in sports and play soccer or football. Will the presence of those mandibular third molars create a risk for fracture of the mandible in that reason, if he sustained a facial injury? All of these questions were addressed in the study that was published in May 2002 issue of the Journal of Oral and Maxillofacial Surgery.
The title of the article is “Do Mandibular Third Molars Alter the Risk of Angle Fracture?” This paper was coauthored by James Fuselier and Edward Ellis from the department of oral and maxillofacial surgery at the University of Texas Southwestern Medical center in Dallas.
Now this was a retrospective multi-center study. These investigators evaluated over 1200 patients who had have mandibular trauma. The objective was simple. They wanted to determine if during the trauma, the presence of mandibular third molars created a high level for angle fracture of mandible. And the answer to that question was yes. In this study, the authors found if the mandibular third molars were present, the subjects had two times greater chance of angle fracture than those patients who did not have mandibular third molars. In addition, if the mandibular third molars were low in the alveolus and angle to the mesial, this further increased the risk of angle fracture.
So what is this mean? Well if we go back to the 15 year old boy with submerged third molars, if this boy is active in physical sports, he could cause trauma to his mandible. If so, he would have a two times greater risk of fracturing angle of the mandible, because the third molars are still impacted. In this situation, it could be wise to recommend extraction of the third molars, which would allow bone to filling in this site, and give protection to the mandible in that area.
Anyway I think this information is valuable to us orthodontists who have the opportunity to evaluate post orthodontic patients at a point in time were decisions need to be me regarding extraction of third molars. Here's at another reasons in certain patients were developing third molars if extracted could prevent problems such as angle fracture of the mandible. If you're interested in reviewing this study, you can find it in the May 2002 issue of the Journal of Oral and Maxillofacial Surgery.

Maxillary Tooth Size Variation in Dentitions With Palatal Canine Displacement Becker A, Sharabi S, Chaushu S Europ J Orthod 2002;24:313-318 July 11, 2003 Dr. Seok-Pil Kim
[초벌원고] Why is it that most patients with palatally impacted maxillary canines tend to be non extraction cases? Are teeth generally smaller in this cases, or are they the same size as normal. Professer Adrian Becker from Israelli published the paper in the June 2002 issue of the European Journal of Orthodontics that examines some of these questions and provide us some answers.	[수정원고]
The paper is titled “Maxillary Tooth Size Variation in Dentitions With Palatal Canine Displacement”. And the purpose of this study was to examine maxillary tooth size measurement in patients with impacted maxillary canines compared to maxillary tooth size measurement in patients with normal canine eruption. In an attempt to reduce bias in the sample, the study used consecutively treated case series. The study group was 58 consequtevely treated patients with at least 1 impacted maxillary canine, 37 of these were females and 21 were males. The controled group was 40 consequtive cases without canine impaction, 20 males and 20 females. Plaster casts of the maxillary arch were attempt for all the patients in both groups and the maxillary teeth from the first molar forward were measured to determine the mesiodistal and the buccolingual dimensions.
The study found some interesting things. 1. The tooth size dimensions of the male patients with impacted canines were reduced compared to the unaffected male patients. 2. The tooth size of the females with impacted canines was generally not different from the unaffected females. But both these groups were very similar to the males with impacted canines. 3. In cases with the unilateral canine impaction, the tooth sizes on the impaction side did not differ from the unaffected side. This association of the tooth size reduction with canine impaction at least on males may suggest a common genetic cause, and alternate explanation would be at the impaction are result of the reduced two size.
Some authors has suggested that excess spacing in the maxillary arch responsible for impactions in order to help explain why small or missing lateral in sizes are commonly associated with impacted canines. If this is true then generally small maxillary teeth has bound in male sample may be the cause of the impaction.
This, however, would not explain why the females developed impactions since thier tooth size were comparable. we obviously have a lot get to learn about cause of maxillary canine impactions. But this research suggests that overall maxillary tooth size should be examined in male patients with impacted canines. This study did not measure the mandibular teeth to see if they were similarly affected or whether tooth size descrepancy exists on these patients between upper and lower. There are many tables of information available on the article, if you are interested in further details at this research study. If you wish to find it, look in the June 2002 issue of the European Journal of Orthodontics.

Stability of Le Fort I Osteotomy for Maxillary Advancement Using Rigid Fixation and Porous Block Hydroxyapatite Grafting Mehra P, Castro V, et al Oral Surg Oral Med Oral Pathol 2002;94:18-23 July 18, 2003 Dr. Ji-Young, Park
[초벌원고] Imagine that you are about to present your treatment plan to a 28 year old female named Marcy. Marcy has a skeletal class III malocclusion with maxillary deficiency and she also displays maxillary transverse deficiency. You determine that optimal surgical correction will require 2-jaws surgery with maxillary advancement and a mild mandibular set-back. In addition, to coordinate the transverse width, the maxilla should be surgically expanded and to improve her incisor display, you would prefer to have maxilla inferiorly repositioned 3-4mm at the time of surgery. You are confident that your plan will address all of Marcy's concerns but you're worried of surgical procedure involving maxillary advancement and downgrafting especially with maxilla will be segmented to increased width. Can you tell Marcy its confident that this combination of surgical movement can predictably result in a stable long-term outcome?	[수정원고]
I'm going to review with you the result of study recently published in the July, 2002 issue of Oral Surgery, Oral Medicine, and Oral Pathology. This study was done the Baylor College of Dentistry and was based on cases operated on by Dr. Larry M. Wolford. The study is titled“Stability of Le Fort I Osteotomy for Maxillary Advancement Using Rigid Fixation and Porous Block Hydroxyapatite Grafting". The study is retrospective case review 78 patients (55 females and 23 males). All of these patients had surgical maxillary advancement of at least 5 mm and they were divided into 3 groups depending upon the vertical surgical change. About 1/3 had superior repositioning, 1/3 inferior repositioning or downgrafting, and about 1/3 moved straightforward. The changes in skeletal position were measured from lateral cephalograms that were obtained before surgery, immediately after surgery, and a long-term follow-up of at least 15 months. Measurements were made before surgical relapse and the 3 different vertical change groups were compared. I should tell you that Dr. Wolford did all of the surgeries and that they all had rigid fixation and porous block hydroxyapatite grafting for stabilization. They also all had segmented maxillas and had mandibular sagittal split osteotomies done at the same time.
So what can you tell your patient's Marcy about surgical stability of the maxillary advancement based on this study? Well, the researchers found that the average relapse of the horizontal advancement was less than 1/2 mm. This excellent stability was found for all 3 vertical groups. The Maxilla that was advanced and downgrafted was just as stable as the maxilla that was advanced and impacted or the maxilla that moved straightforward. Based of results of this study, you can tell Marcy that the surgical procedures you're recommending have been shown to be very stable and good fixation was obtained at the time of surgery. I was impressed that the stability of surgical results described in this paper. The author was believed that the results are related to the achievement of excellent bony stability at the time of surgery through the combination of rigid fixation using 4 plates in the maxilla and the additional porous block hydroxyapatite graft material to fill the bony gaps.
If you'd like to review this article in its entity or if you'd like to share with your surgeon, it can be found in July 2002 issue of the triple O.

Comparison of Ultrasonography with Magnetic Resonance Imaging in the Diagnosis of Temporomandibular Joint Internal Derangements: A Preliminary Investigation Uysal A, Kansu H, et al Oral Surg Oral Med Oral Pathol 2002;94(1):115-121 July 25, 2003 Dr. Chun-Sun, Eun
[초벌원고] MRI has become the gold standard imaging technique for visualizing the disk in the temporomandibular joint. MRI images, however, can be very expensive and some patients do not do well in the claustrophobic environment of the MRI imaging tube. A group of researchers from Ankara, Turkey has published a preliminary study looking at the ability of ultrasound imaging to provide information about the disk position in the TMJoint.	[수정원고]
The study is titled “Comparison of Ultrasonography with Magnetic Resonance Imaging in the Diagnosis of Temporomandibular Joint Internal Derangements: A Preliminary Investigation”. And appears in the July 2002 issue of the journal Oral Surgery Oral Medicine and Oral Pathology.
The purpose of this study was to look at the ability of ultrasound, provide information about disk position compared to the gold standard technique of MRI. 32 patients were recruited for this study. 23 of the patients had a clinical diagnosis of internal derangement in at least one joint. 9 of the patients were asymptomatic volunteers with no history of joint problems and a negative clinical exam. All 32 patients had imaging of the TMJ done by both MRI and Ultrasound. The MRI exam was done with a standard protocol with images required in the mouth open and closed positions. An experienced radiologist read the MRI images, and the disk position in the joint was classified as normal, disk displacement with reduction, or disk displacement without reduction. The ultrasound exam was done by placing a 7.5 MHz probe against patients face while in a supine position. Again a radiologist experienced an ultrasound interpreted the imaging and the disk was classified as normal, displacement with reduction, or displacement without reduction.
That describes the basic mechanics of the study. What about the results? How does ultrasound compared to MRI in this situation? The MRI exams identified 9 patients with normal disk position the asymptomatic volunteers, 11 with disk displacement with reduction, and 12 were identified with disk displacement without reduction. The amazing thing was that the ultrasound results were exactly the same. The same patients received the same diagnosis with ultrasound as with an MRI. The authors state the investigators were blinded during the interpretation of the images which make the 100% agreement, very surprising.
Their conclusion of this pilot study is that ultrasound imaging of the TMJoint maybe an excellent cause to effective alternative to MRI imaging to determine soft tissue relationships. The authors themselves state that further studies with larger samples should be conducted before widespread use of ultrasound is advocated. If you would like more details about the use of ultrasound imaging for the temporomandibular joint this article can be found in the July 2002 issue of Oral surgery Oral medicine and Oral pathology.

Microbial Profile on Metallic and Ceramic Bracket Materials Anhoury P, Nathanson D, et al Angle Orthod 2002;72:338-343. August 1, 2003 Dr. Ye-Na, Jeon
[초벌원고] In another summary on this month tape, I discussed an article that used the present of caries in a primary teeth to predict the incidence of caries in the permanent dentition. OK. Suppose now that you will be providing orthodontic treatment for an adolescent who does have a high caries risk. You know that information based upon the data that I provide you in the other summary.	[수정원고]
My question is, it will you use any different type of an appliance for this patient when you're placing brackets on the teeth? Today we have two choices, we can use metal brackets or we could use ceramic brackets. If a patient has a higher caries risk it allows accumulations of Streptococcus mutans or Lactobacillus to form around teeth, Is one of these brackets preferred over the other? In other words, will caries producing bacteria accumulate more greately on a ceramic bracket or metal bracket? The answer to that question can be found in article that was published at the August 2002 issue of the Angle orthodontist. The title of the article is ‘Microbial Profile on Metallic and Ceramic Bracket Materials’. The study was co-authored by Patrick Anhoury and several other research colleagues from the department of Orthodontics and Restorative dentistry at Boston Univ. school of dental medicine.
The purpose of this paper was to determine if bacteria in general and more specifically caries producing bacteria accumulated any more rapidly on a ceramic or metallic bracket. Of course this information would be useful for an orthodontist who has concern about caries susceptibility for any particular patient. Now in order to accomplish the subjective, the authors gathered sample of about 30 subjects who had undergone orthodontic therapy. About half of these wore metal bracket and the other half wore ceramic brackets. At bracket removal, two brackets were sampled from each of these individuals. One bracket was the maxillary central incisor and the other was the maxillary second premolar. After bracket removal, special care was taken to preserve, isolate and identify the types of bacteria that were present and the amounts of bacteria that existed on each of the different types of brackets. The authors used DNA probes to identify each of the bacteria.
Now the authors provided information about many different intraoral bacteria, but the key bacteria that I want to discuss are the caries producing bacteria. Are day any more likely to form on one bracket type compared to another. And the answer to the question is no. When authors sampled the ceramic and metallic brackets, they founded that there was no difference in the accumulation of S. mutans or L. bacillus between either of these two samples. So there is your answer.
It really doesn't make any difference which type of bracket is used. Caries producing bacteria will accumulate on either type of bracket. And the amounts did not different. So if you have a patient who has potential for caries during orthodontic treatment, you simply can't rely on one bracket over another to help reduce that risk. You'll have to rely on good oral hygiene to help reduce the risk of caries. If you are interested in reviewing this article, you can find it in the August 2002 issue of the Angle orthodontist.

Changes in alveolar morphology during open bite treatment and prediction of treatment result Stefan H. Beckmann and Dietmar Segner Eur J Orthod 2002;24:391-406 September 5, 2003 Dr. Hang-ik, Jang
[초벌원고] Treatment of anterior open bites can be very frustrating. To aid to understanding of open bite patients, I'm going to review two articles with you this month. The first article from the August 2002 issue of the European Journal of Orthodontics is called Changes in alveolar morphology during open bite treatment and prediction of treatment result.	[수정원고] Treatment of anterior open bites can be very frustrating. To add to understanding of open bite patients, I'm going to review two articles with you this month. The first article from the August 2002 issue of the European Journal of Orthodontics is called “Changes in alveolar morphology during open bite treatment and prediction of treatment result”.
The primary author of this study is Stefan Beckmann from Tel Aviv University in Israel. The authors purpose was to look for morphologic characteristics in pretreatment cephalograms that could predict treatment outcome for anterior open bite patients. This was relatively standard retrospective study that was done by identifying 83 patients from the case files at the department of orthodontics at the University of Hamburg in Germany. These patients all had anterior open bite malocclusions. And also had cephalometric films available before treatment, and after retention was completed. Twenty-two of the patients also had cephalometric x-ray available from the completion of active treatment. All patients had orthodontic treatment for their anterior open bite. About half had removable appliance treatment only, and half had some degree of fixed appliance treatment. The cephalograms of these patients were traced and digitized and series of common and unique cephalometric measurement were made.	The primary author of this study is Stefan Beckmann from Tel Aviv University in Israel. The authors purpose was to look for morphologic characteristics in pretreatment cephalograms that could predict treatment outcome for anterior open bite patients. This was relatively standard retrospective study that was done by identifying 83 patients from the case files at the department of orthodontics at the University of Hamburg in Germany. These patients, all had anterior open bite malocclusions. And also had cephalometric films available before treatment, and after retention was completed. Twenty-two of the patients also had cephalometric x-ray available from the completion of active treatment. All patients had orthodontic treatment for their anterior open bite. About half had removable appliance treatment only, and half had some degree of fixed appliance treatment. The cephalograms of these patients were traced and digitized and series of common and unique cephalometric measurements were made.
These various cephalometric measurements were then correlated with the overbite correction and the series of regression analysis were done to help explain the relationship between over bite and the morphologic variables.	These various cephalometric measurements were then correlated with the overbite correction and the series of regression analysis were done to help explain the relationship between over bite and the morphologic variables.
There were a few interesting findings from this study. First, The authors found that the retraction of the upper incisors was correlated with open bite correction and long-term stability. Second, the correction of the open bite was largely due to a vertical increase in the symphysis. However, excessive vertical increase in the symphysis area was also associated with relapse after treatment. Third, the retraction of the lower incisors in order to correct open bite was associated with relapse during retention. And last, relating to the authors original intent by identifying morphologic characteristics predictive of successful open bite treatment, the authors find that the angle between a line from nasion to gonion and the mandibular plane was the best predictor. In the successfully treated patients, this angle averaged about 75 degrees. In the unsuccessful patients, this angle averaged about 80 degrees.	There were a few interesting findings from this study. First, The authors found that the retraction of the upper incisors was correlated with open bite correction and long-term stability. Second, the correction of the open bite was largely due to a vertical increase in the symphysis. However, excessive vertical increase in the symphysis area was also associated with relapse after treatment. Third, the retraction of the lower incisors in order to correct open bite was associated with relapse during retention. And last, relating to the authors original intent by identifying morphologic characteristics predictive of successful open bite treatment, the authors find that the angle between a line from nasion to gonion and the mandibular plane was the best predictor. In the successfully treated patients, this angle averaged about 75 degrees. In the unsuccessful patients, this angle averaged about 80 degrees.
So, as a result of this information in this article, you may want to measure the angle between the nasion-gonion line and the mandibular plane in your anterior open bite patients. If this angle is about 75 degrees or less, this study would suggest that you have a good chance of successful orthodontic treatment to close the open bite. If this angle is 80 degrees or more, this information would suggest that long term open bite closure may be difficult.	So, as a result of the information in this article, you may want to measure the angle between the nasion-gonion line and the mandibular plane in your anterior open bite patients. If this angle is about 75 degrees or less, this study would suggest that you have a good chance of successful orthodontic treatment to close the open bite. If this angle is 80 degrees or more, this information would suggest that long term open bite closure may be difficult.
To learn more about this study which included much more detailed information that I had time to share with you, look in the August 2002 European Journal of Orthodontics.	To learn more about this study which included much more detailed information that I had time to share with you, look in the August 2002 European Journal of Orthodontics.

Vertical Changes Following Orthodontic Extraction Treatment in Skeletal Open Bite Subjects Aynur Aras Eur J Orthod 2002;24:407-416 September 19, 2003 Dr.Seong-Chool, Lee
[초벌원고] I commented earlier that I had a second article to review with you on the treatment of open bite patients. This article was also published in August 2002 issue of the European Journal of Orthodontics and was the result of clinical research done in Turkey. The title of this article is“Vertical Changes Following Orthodontic Extraction Treatment in Skeletal Open Bite Subjects”.	[수정원고]
The purpose was to observe the vertical changes that occurred during fixed appliance orthodontic treatment in open bite patients depending upon extraction pattern used. The theory the authors were testing is that more posterior extractions were result in more forward movement of the posterior teeth out of the wedge and therefore allow closing rotation of the mandible.
The authors completed this study in a prospective manner. 32 open bite patients were identified. 15 were determined to have an anterior open bite only and were treated by the removal of four first premolars. The remaining 17 patients had an open bite that extended into the posterior teeth and were treated with extraction of second premolars or permanent first molars. The decision to remove first molars was made if the first molars had extensive caries or restorations.
The other important point about patient selection was that all patients were determined to be passed the pubertal growth peak as determined by hand wrist radiographs resulting in an average patient age is about 15 years. All patients had fixed appliance treatment and had lateral cephalographic X-rays taken before and after treatment for analysis. Although the two groups differed in the dental open bite appearance the vertical skeletal cephalometric measurements were similar before treatment.
Do you think that was any difference in vertical measurements after treatment? Did the patients had first premolars extracted react differently than those second premolars or first molars extracted? The answer is yes. The patients that had second premolars or first molars extracted had exhibited a closing rotation of the mandible during treatment that was statistically significant. Those patients receiving first premolars extractions maintain the pretreatment mandibular plane angle.
The authors also found that the posterior teeth moved furthest forward in the group that had first molars removed. I would say that this research supports the theory that more posterior tooth extractions are advantageous in the treatment of open bite malocclusions where the prospective for the growth is limited. At least in this study the extraction of second premolars or first molars allowed slight closing rotation of the mandible during orthodontic treatment. If you would like to find out more about the study on the correction of open bite malocclusions you can find it along with the other articles are reviewed open bites in the August 2002 issue of the European journal of orthodontics.

The Applicability of Half-Mouth Examination to Periodontal Disease Assessment in Untreated Adult Populations Dowsett S, Eckert G, Kowolik MJ J Periodontol 2002;73:975-981. September 26, 2003 Dr. Eun-Hee, Koh
[초벌원고] In the following summary, the author describe in abbreviated periodontal exam that could be very useful for orthodontists who treat adult patients. What periodontal factors do you evaluate when you are examining an adult orthodontic patient. I'm certain in the most of state, specific radiographs including vertical bitewings of the posterior teeth, so we can assess whether or not theres been any bone loss. But we know that certain types of osseous defects such as in a proximal craters and often 2 and 3 walled osseous defects could be undetectable on radiograph.	[수정원고]
How then do you discover these problems in a preorthodontic adult patient? Of course, a thorough periodontal examination will be appropriate and that with include probing the circular depth of all the teeth, doing a gingival index, a plaque index, evaluating clinical attachment loss and of course examining for gingival recession. But as orthodontist, do we really have time to do all of that for every adult patient? What I mean is“Is it necessary to evaluate every tooth in the mouth, when you are assessing the periodontal health of an adult patient?”
A study published in the September 2002 issue of the Journal of Periodontology suggest that an abbreviated exam could be just as reliable and could be useful for orthodontist. The title of the article is“The Applicability of Half-Mouth Examination of Periodontal Disease Assessment in Untreated Adult Populations”. This study is coauthored by Sherie Dowsett and two other research colleagues from Indiana University School of Dentistry.
The purpose of their paper was to determine if assessing half the teeth in a patient's mouth could be as reliable as a full mouth periodontal exam in uncovering periodontal problems. Two untreated populations of patients were evaluated and these were large samples. In these individuals the entire mouth was evaluated to determine plaque index, gingival index, probing depth, and clinical attachment level. Then the authors test it whether or not using diagonal quadrants within each mouth, with of the same data relative to the overall periodontal health. When the authors compare the results they found that the half mouth evaluation using diagonal quadrants was very effective compare to the full mouth examination. Not the accuracy was not as good for patients who had severe periodontal disease, but I was expectable for patients with little or moderate periodontal disease. This reliability apply to gingival index, plaque index, probing depth, and also clinical attachment loss.
So what does this mean to us as orthodontist? Were based upon this study, if you want to conserve time on evaluating in adult patient who doesn't have severe periodontal breakdown, you could evaluate the maxillary right and mandibular left quadrants and based upon that information could have a reliable overview of the periodontal health of any given patient.
If you like to review the study, you can find it in the September 2002 issue of the Journal of Periodontology.

Periodontal Pathology Associated With Asymptomatic Third Molars George H.Blakey, Robert D.Marciani et al. J Oral Maxillofac. Surg 2002;60:1227-1233. October 10, 2003 Dr. Heung-gyo, Lee
[초벌원고] In this next article, the author evaluate the incidence_a periodontal disease in the adult patient to have erupted third molars. At the end of orthodontic treatment_how often do you recommend_extraction of third molars. Personally_I recommend_extraction if the teeth are hopelessly impacted. But if this teeth appear that there erupt, I will_decision up to the general dentist permit that evaluation.	[수정원고] In this next article, the authors evaluate the incidence of a periodontal disease in the adult patient who have erupted third molars. At the end of orthodontic treatment, how often do you recommend the extraction of third molars? Personally I recommend the extraction if the teeth are hopelessly impacted. But if the teeth appear that they will erupt, I will leave the decision up to the general dentist to make that evaluation.
But_what is the third molars are erupted, do you recommend that they be captive younger adult. what should_be extracted, Again personally_my typical recommendation the depend on whether_not_patients can keep the teeth clean, if this teeth have no careless, they don't care take the patients_and then in there proper occlusal position. I generally don't recommend extraction. But will be third molars cause future periodontal problems.	But, what if the third molars are erupted? Do you recommend that they be kept in younger adult? Or should they be extracted? Again personally, my typical recommendation depends on whether or not the patient can keep this teeth clean. If this teeth have no caries, they don't irritate the patients, and they are in their proper occlusal position, I generally don't recommend extraction. But will these third molars cause future periodontal problems?
That questions was answer in a study_was published in a November 2002 issue of the journal of oral-maxillofacial surgery. Since with orthodontist_often asked for our recommendation about utility of mandibular third molars after orthodontic treatment. I talked with be interesting in hearing the result of this study. The title of_article is "Periodontal pathology of associated with asymptomatic third molars"	That question was answered in a study that was published in a November 2002 issue of the Journal of Oral and Maxillofacial Surgery. Since we, as orthodontists are, often asked for our recommendation about utility of mandibular third molars after orthodontic treatment, I thought you would be interested in hearing the results of this study. The title of the article is "Periodontal Pathology Associated With Asymptomatic Third Molars"
This study was coauthored by Gorge H. Brakey and long distance participant_university of kentucky and north carolina department of oral and maxillofacial surgery and department periodontics. This was_very large study. It was that epidemiologic can analysis of over 300 patients_were enrolled during a 30 month-period. Not to be included in_study all individuals had have third molars erupted and second molars present so that the attachment level between the teeth_be evaluate the age of_sample range from about 15 years after 45 years_age. During the analysis portion_the pocket depth between the second and third molars and around the third molar were measured.	This study was coauthored by Gorge Blakey and a long listed participants from Universities of Kentucky and North Carolina, Department of Oral and Maxillofacial Surgery and Department Periodontics. This was a very large study. It was an epidemiologic analysis of over 300 patients who were enrolled during a 30 month-period. Not to be included in this study all individuals had had third molars erupted and second molars present so that the attachment levels between the teeth could be evaluated. The age of the sample range from about 15 years up to 45 years of age. During the analysis portion, the pocket depth between the second and third molars and around the third molar were measured.
Now in addition_gingival index or bleeding index was also evaluate. In finely vertical bitewing radiographics were use to assess the bone level between the second and third molars in both maxillary and mandibular dental arch. Then this areas are evaluate to determine if there were any areas of periodontal destruction. What a this authors fined? Well_the finding a probably a bit different than more you might_imagine.	Now in addition, the gingival index or bleeding index was also evaluated. And finally vertical bitewing radiographs were used to assess the bone levels between the second and third molars in both maxillary and mandibular dental arches. Then these areas were evaluated to determine if there were any areas of periodontal destruction. What would these authors find? Well, the findings are probably a bit different than what you might have imagined.
In general_when young adult individuals are evaluated for the periodontal healthy. The incidence of destruction is generally low in this age range. Any fact_in the mouth of this 300 place individuals? They were no periodontal problems. The gingival index_in most areas_were low and the periodontal healthy was good. But in this sample_25 percent of this normal subjects had greater than 5mm_pocket depth around there asymptomatic mandibular third molars. Increase pocket depth or predominant refound in the mandibular and not in the maxillary arch. In this areas_authors found increased gingival inflammation and also bleeding. This was_in spite of the fact_but these third molars were generally asymptomatic. So what is this study suggest? Forbid or no it's difficult protect future.	In general, when young adult individuals are evaluated for the periodontal health? The incidence of destruction is generally low in this age range. In fact, in the mouth of these 300 plus individuals, they were no periodontal problems. The gingival indices, in most areas, were low and the periodontal health was good. But in this sample, 25 percent of these normal subjects had greater than 5mm of pocket depth around the asymptomatic mandibular third molars. Increased pocket depth were predominantly found in the mandibular and not in the maxillary arch. In these areas, the authors found increased gingival inflammation and also bleeding. This was, in spite of the fact, that these third molars were generally asymptomatic. So what is this study suggest? What we all know is it's difficult to predict the future.
But_a 5mm_pocket_retains plaque in bleeding is not a good situation in any individual. If these patient should be comes susceptible to periodontal disease in_future_these differ pocket could result in bond loss and these by fact periodontal health of the second molars. So that recommendation of this author is to carefully evaluate erupted 3rd molars_Even though they may not be symptomatic. Increased pocket depth could suggest. these teeth may be can need for extraction rather than preservation_in order to an hence the automatic health of the second molars. If you like to review this study, you can find it in the November 2002 issue of the Journal of oral & maxillofacial surgery.	But, a 5 mm of pocket that retains plaque and bleeds is not a good situation in any individual. If these patients should become susceptible to periodontal disease in the future, these deeper pockets could result in bone loss and therby affect periodontal health of the second molars. So the recommendation of these authors is to carefully evaluate erupted 3rd molars, even though they may not be symptomatic. Increased pocket depth could suggest that these teeth may be candidates for extraction rather than preservation, in order to enhance the ultimate health of the second molars. If you like to review this study, you can find it in the November 2002 issue of the Journal of Oral and Maxillofacial Surgery.

A Comparison Between Masticatory Muscle Pain Patients and Intracapsular Pain Patients on Psychosocial Domains Lindroth JE, Schmidt JE, et al. J Oro Pain 2002;16:277-283. October 17, 2003 Dr. Chang-Hun Park
[초벌원고] This next preview compared with difference between patient with intracapsular temporomandibular pain and those patients with purely myofacial pain in the masseter and masticatory oral muscles. On Tuesday_last week_suppose your examine two adult patient. Both were female. Both individuals had crowded Class I malocclusion that would be required nonextraction orthodontic therapy. But there are concerned with both of these patients. One female is thirty-two years_age and she has significant intracapsular pain of_right TMJ. The other female is thirty-four years_age and she had significant muscle pain in the region of_masseter muscle on the left side. So traditionally we would classified both_these individuals as having symptoms of TMD.	[수정원고] This next review compares the differences between patients with intracapsular temporomandibular pain and those patients with purely myofacial pain in the masseter and masticatory muscles. On Tuesday of last week, suppose you examined two adult patients. Both were females. Both individuals had crowded Class I malocclusions that would require nonextraction orthodontic therapy. But there are concerns with both of these patients. One female is thirty-two years of age and she has significant intracapsular pain of the right TMJ. The other female is thirty-four years of age and she has significant muscle pain in the region of the masseter muscle on the left side. So traditionally we would classify both of these individuals as having symptoms of TMD.
But are they similar? Are they difference? Do your patients with intracapsular pain differ from patients with predominantly muscle pain? Those questions were addressed in the study_was published the fourth of 2002 issue of_Journal of Orofacial Pain. Since we-are orthodontist occasionally treat patient who has_temporomandibular disorder. I believed that_important press to be the research in_area was documenting not only_differences but also_similarity. The title of this article is“A Comparison Between Masticatory Muscle Pain Patients and Intracapsular Pain Patients”.	But are they similar? Are there differences? Do patients with intracapsular pain differ from patients with predominantly muscle pain? Those questions were addressed in the study that was published the Fall 2002 issue of the Journal of Orofacial Pain. Since we, as orthodontists, occasionally treat patients who have these temporomandibular disorders, I believe that it is important for us to be aware of the research in this area which documents not only the differences but also the similarities. The title of this article is“A Comparison Between Masticatory Muscle Pain Patients and Intracapsular Pain Patients”.
This paper was coauthored by John Lindroth and John Schmidt from the University of Kentucky Orofacial Pain Center in Lexington. This paper involved_retrospective analysis_over 500 patients who present to the Orofacial Pain Center at the university of Kentucky with temporomandibular disorder over 5 year periods. Now these individual provided patients were divided into two basic groups, those with intracapsular pain and those with muscle pain. Then_each group was given overlarge-test. This test included assessment of intensity on the rational pain, the quality of_patients sleep and the patient ability to cope_stress. Then the each group compared to see if there was difference between them. Generally_I had start most TMD patients were reexamined if these various_test_evaluated. But that not true. There are significant difference between patient with intracapsular pain and those individual with muscle pain.	This paper was coauthored by John Lindroth and John Schmidt from the University of Kentucky Orofacial Pain Center in Lexington. This paper involved the retrospective analysis of over 500 patients who presented to the Orofacial Pain Center at the University of Kentucky with temporomandibular disorders over 5 year periods. Now these individuals were divided into two basic groups, those with intracapsular pain and those with muscle pain. Then, each group was given a variety of tests. These tests included assessments of intensity and duration of the pain, the quality of a patient's sleep and the patient's ability to cope with stress. Then these two groups were compared to see if there were differences between them. Generally, I had thought that most TMD patients would react similarly if these various variables were tested or evaluated. But that's not true. There were significant differences between patients with intracapsular pain and those individuals with muscle pain.
Firs of all, the duration and intensity of_pain all the same between the two groups. That is there were no differences in_pain severity or_duration of pain between patients with intracapsular or muscle pain. But that of similarity is stopped. In general_these authors reports that patient with intracapular pain tend to be adaptive. They tend to cope with_pain much better than individuals who have muscle pain. On the research of available_quality of sleep, the dysfunctional behavior and psychological stress_individual with muscle pain scored higher in all_these areas. That is to say individual who has muscle pain have poor quality of sleep. They don't cope well with stress_and then demonstrated more dysfunctional behavior profile. They find it form the_study the otters believed_important point is any clinician who_treating TMD patient to delineate well_pain_coming from high pray treating the patient.	First of all, the duration and intensity of the pain were the same between the two groups. That is there were no differences in the pain severity or the duration of pain between patients with intracapsular or muscle pain. But that's were similarities stop. In general, these authors report that patients with intracapular pain tend to be adaptive. They tend to cope with the pain much better than individuals who have muscle pain. When the researchers evaluated the quality of sleep, the dysfunctional behavior and psychological stress, the individuals with muscle pain scored higher in all of these areas. That is to say individuals with muscle pain have poor quality of sleep, they don't cope well with stress, and they demonstrate more dysfunctional behavior profiles. Based upon the data from study the authors believed that it's important for any clinician who is treating TMD patients to delineate where the pain is coming from prior to treating the patient.
The result on study under score_important is on assessing the psychological distress and behavial adaptation_associated with muscle pain_intracapsular_patients. So_in conclusion_study showed that pain level is equivalent between_two groups. The muscle pain group was more psychologically distress and showed more dysfunctional adaptation in intracapsular pain group. If you like to review this study, you can find it in the fourth of 2002 issue of the Joural of Orofacial Pain.	The result of the study underscore the importance of assessing the psychological distress and behavioral adaptation that is associated with muscle pain and intracapsular pain patients. So, in conclusion, although the data of the study showed that pain level and duration are equivalent between these two groups, the muscle pain group was more psychologically distressed and showed more dysfunctional adaptation than the intracapsular pain group. If you like to read this study, you will find it in the Fall 2002 issue of the Joural of Orofacial Pain.

Effect of Varying the Force Direction on Maxillary Orthopedic Protraction Keles A, Tokmak EC, et al Angle Orthod 2002;72:387-396. October 24, 2003 Dr. Kweon-Hee Jeong
[초벌원고] This next article, evaluated the differences in direction of forces on a plane maxillary protraction to patients with class III malocclusions. Do you use maxillary protraction as a method of correcting class III malocclusion in young orthodontic patients? I think most orthodontists have_retried maxillary protraction. Other one some patients_result is not stable in long term, in other patients_I_had_good luck with maxillary protraction if I_initiated_procedure at a very young age.	[수정원고] This next article evaluates the differences in direction of force when applying maxillary protraction to patients with Class III malocclusions. Do you use maxillary protraction as a method of correcting Class III malocclusions in young orthodontic patients? I think most orthodontists have at least tried maxillary protraction. Although in some patients, the result is not stable in long term, in other patients, I have had a good luck with maxillary protraction if I have initiated the procedure at a very young age.
One of this concerning the problem about maxillary protraction is that if the force is not applied proferly, the effect tends to rotate_maxilla downward and open_mandibular plane. In this way_it results in higher relapse potential after treatment, but_can_direction of force with maxillary protraction be altered so _this negative outcomes can be avoided.	One of the disconcerting problems about maxillary protraction is that if the force is not applied properly, the effect tends to rotate the maxilla downward and open the mandibular plane. In this way, it results in higher relapse potential after treatment. But, can the direction of force with maxillary protraction be altered so that these negative outcomes can be avoided.
That topic was addressed in the study_was published in the October 2002 issue of the Angle Orthodontist. The title of the article is“Effect of Varying the Force Direction on Maxillary Orthopedic Protraction”. This paper is coauthored by Ahmet Keles and Ravindra Nanda. Now_Dr. Keles is the_professor of Department of Orthodontics at Marmara University in Istanbul, Turkey.	That topic was addressed in the study that was published in the October 2002 issue of the Angle Orthodontist. The title of the article is“Effect of Varying the Force Direction on Maxillary Orthopedic Protraction”. This paper is coauthored by Ahmet Keles and Ravi Nanda. Now, Dr. Keles is a professor in the Department of Orthodontics at Marmara University in Istanbul, Turkey.
The Purpose of their paper was to assess the effects of varying force direction on maxillary orthopedic protraction. In order to accomplish this subject, the authors gathered twenty patients who been it accepted for orthodontic treatment at the Marmara University Department of Orthodontics. All individuals had class III malocclusions. They underlines cephalometric analysis reveal that the problems would do to maxillary hypoplasia. The individuals were randomly sided to two groups. Both groups_received_maxillary occlusal splint and a pull traction face mask_be used to protract maxilla. But in group one, the attachment to the maxillary splint with applied in the canine region, and the force on the splint what is at a about 30°angle to the occlusal plane so therefore pull the maxilla downward and forward. In the second group, a face bow was had it to the maxillary splint and it extended extraorally an sided face similar to_headgear face bow. This latter pull traction forces_be applied above the level of the occlusal plane or above the level of existence of_maxilla and maxillary teeth. It sees it would authors_tempting to do whose determing it altering the position in direction of force would result in differences in the effect of rotation of the maxilla after protraction.	The Purpose of their paper was to assess the effects of varying force direction on maxillary orthopedic protraction. In order to accomplish this subjective, the authors gathered twenty patients who been accepted for orthodontic treatment at Marmara University Department of Orthodontics. All individuals had Class III malocclusions. Their underlying cephalometric analysis revealed the problems due to maxillary hypoplasia. The individuals were randomly assigned to two groups. Both groups would receive a maxillary occlusal splint and the protraction face mask would be used to protract maxilla. But in group one, the attachment to the maxillary splint was applied in the canine region, and the force on the splint was at an about 30°angle to the occlusal plane so therefore pull the maxilla downward and forward. In the second group, a face bow was added to the maxillary splint and it extended extraorally on the side of the face similar to a headgear face bow. This allowed the protraction force to be applied above the level of the occlusal plane or above the level of resistance of the maxilla and maxillary teeth. You see what the authors were attempting to do also if altering the position and direction of force does result in differences in the effect of rotation on the maxilla after protraction.
What are you thinking to happen? The authors work very careful in evaluating the result cephalometrically. They made many measurements of different angles and planes. But_let me give you the parameter. First of all, both methods result in pull traction of the maxilla_but they were significant differences_the amount of rotation that occured between the_groups. First of all, in the group were 30°angle of force with use_they were significant counterclockwise rotation of the maxilla. But_one pull traction of force with the appliance above the level of occlusal plane as in group two, the maxilla translated forward and they were no rotation of the maxilla.	What do you think it happened? The authors worked very carefully in evaluating the result cephalometrically. They made many measurements of different angles and planes. But, let me give you the bottom line. First of all, both methods resulted in protraction of the maxilla, but there were significant differences in the amount of rotation that occured between the two groups. First of all, in the group where a 30°angle of force was used, there was significant counterclockwise rotation of the maxilla. But, when the protraction force was placed above the level of occlusal plane as in group two, the maxilla translated forward and there was no rotation of the maxilla.
The author is, believed the reason for this is that the direction of force was above the level of existence of maxilla. The other differences occur in the occlsal plane. In the group were 30°angle of force with use the maxillary occlusal plane did not rotate, but_one the force with appliance above the occlusal planes_they were clockwise rotation of the maxillary teeth which rotated maxillary incisors downward.	The authors, believed the reason for this is that the direction of pull was above the level of resistance of the maxilla. The other difference occured in the occlusal plane. In the group where a 30°angle of force was used, the maxillary occlusal plane did not rotate. But, when the force was placed above the occlusal plane, there was a clockwise rotation of the maxillary teeth which rotated maxillary incisors downward.
Now_I hoped and doesn’t sound to be confused. But here is_take-home message. This study shows_the maxilla and the maxillary dentition are obviously two separate units and their centers of resistance are not_the same location. So, the authors believed that varying the direction and location of the force shows in the some existence of_maxilla may rotate_and in other_on the occlusal plane all maxillary dentition were rotated. What’s the condition masterkeylized? It’s that one applying the force_they must apply in a way they were assisted in the treatment in any particular patient. So, if you would like to review this study, you can find it in the October 2002 issue of the Angle Orthodontist.	Now, I hope that this doesn't sound too confusing. But here is the take-home message. This study shows that the maxilla and the maxillary dentition are obviously two separate units and their centers of resistance are not at the same location. So, the authors believed that varying the direction and location of the force shows in some instances of the maxilla may rotate, and in others, the occlusal plane or maxillary dentition will rotate. What the clinician must recognize? It’s that when applying the force, they must apply in a way they will assist in the treatment of any particular patient. So, if you would like to review this study, you can find it in the October 2002 issue of the Angle Orthodontist. (Correction by Dr. Bon Chan Koo)

Treatment of a Class Ⅰ Crowded Malocclusion with an Ankylosed Maxillary Central Incisor Sabri R. Am J Orthod Dentofacial Orthop 2002;122:557-565. November 14, 2003 Dr. Hye-Young Ryu
[초벌원고] An article titled“Treatment of a Class Ⅰ Crowded Malocclusion with an Ankylosed Maxillary Central Incisor”by Roy Sabri which appear in the November 2002 issue of the American Journal_Orthodontics and Dentofacial Orthopedics. Initially, cut my attention for two reasons. One, because it involved_treatment of an apically and labially displaced maxillary central incisor that was ankylosed and had the previous history of trauma_and second, because of the excellent aesthetic results that were achieved with treatment. While I do not usually review case articles, I decided to review this article not only because of the achieved excellent aesthetic results, but also because identified and discussed a number of the critical decisions that had to be addressed to achieve an excellent result.	[수정원고] An article titled“Treatment of a Class Ⅰ Crowded Malocclusion with an Ankylosed Maxillary Central Incisor”by Roy Sabri which appeared in the November 2002 issue of the American Journal of Orthodontics and Dentofacial Orthopedics, initially cut my attention for two reasons. One, because it involved the treatment of an apically and labially displaced maxillary central incisor that was ankylosed and had a previous history of trauma. And second, because of the excellent aesthetic results that were achieved with treatment. While I do not usually review case articles, I decided to review this article not only because it achieved excellent aesthetic results, but also because identified and discussed a number of the critical decisions that had to be addressed to achieve an excellent result.
The patient was treated with_extraction of three first premolars and the ankylosed maxillary right central incisor. The maxillary right lateral incisor was substituted for the central incisor with_canine substituted as_lateral_and_first premolar as_canine. By moving the lateral incisor slowly into the central incisor position, the significant vertical and buccolingual defect that was created with the extraction of_central incisor was gradually restored to normal.	The patient was treated with the extraction of three first premolars and the ankylosed maxillary right central incisor. The maxillary right lateral incisor was substituted for the central incisor with the canine substituted as a lateral, and the first premolar as a canine. By moving the lateral incisor slowly into the central incisor position, the significant vertical and buccolingual defect that was created with the extraction of the central incisor was gradually restored to normal.
When the lateral incisor was positioned in the central position, the gingival margin on the lateral incisor remains slightly more incisorly than an adjacent central incisor. To have optimal esthetics, the gingival contour of_substituted lateral and the adjacent central incisor should be at the same height. Because the labial sulcus was slightly greater on the lateral incisor, a gingivectomy was performed to move the contour slightly apically and match the adjacent central incisor.	When the lateral incisor was positioned in the central position, the gingival margin on the lateral incisor remains slightly more incisally than on the adjacent central incisor. To have optimal esthetics, the gingival contour of the substituted lateral and the adjacent central incisor should be at the same height. Because the labial sulcus was slightly greater on the lateral incisor, a gingivectomy was performed to move the contour slightly apically and match the adjacent central incisor.
The treatment plan was to restore the lateral incisor with composite resin. To mimic the appearance of_central incisor, the lateral incisor was placed in contact with_mandibular incisors and less space was left mesial to the lateral incisor than was left distal to it. This was done to allow a flatter contour of the mesial surface of_lateral incisor and allow more build_up on the distal with simulated_appearance of_true central incisor.	The treatment plan was to restore the lateral incisor with composite resin. To mimic the appearance of a central incisor, the lateral incisor was placed in contact with the mandibular incisors and less space was left mesial to the lateral incisor than was left distal to it. This was done to allow a flatter contour of the mesial surface of a lateral incisor and allow more build-up on the distal which simulated the appearance of a true central incisor.
These_about a few of the considerations discussed_this article that let to the excellent aesthetic result that was achieved. If you have_patient with an ankylosed central incisor or_patient for whom you're planing lateral or canine substitution, I would strongly urge_to read this article in detail. It makes_clear that excellent results can be achieved even under difficult circumstances. If attention is paid to the many small details, that result in aesthetic excellents. This article is a must_read, you can find it in the November 2002 issue of the American Journal_Orthodontics and Dentofacial Orthopedics.	These are about a few of the considerations discussed in this article that let to the excellent aesthetic result that was achieved. If you have a patient with an ankylosed central incisor or a patient for whom you're planning lateral or canine substitution, I would strongly urge you to read this article in detail. It makes it clear that excellent results can be achieved even under difficult circumstances. If attention is paid to the many small details, that results in aesthetic excellence. This article is a must-read, you can find it in the November 2002 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Do Functional Appliances Affect Mandibular growth? Chen JY, Will LA, Niederman R. Am J Orthod Dentofacial Orthop 2002;122:470-476 November 21, 2003 Dr. Kwang-Taek Koh
[초벌원고] If you have gone to courses, heard lectures or read articles by proponents of different functional appliances, you have probably heard them infer that their appliance quote stimulates or quote enhances mandibular growth. I believe terms like enhance or stimulate have been used to avoid addressing, basically, due to a lack of strong clinical evidence, the main question that should be addressed and that is simply do functional appliances increase mandibular growth? Is the patient likely to have a larger or more protrusive mandible if he or she wears a functional appliance versus not wearing one or using some other form of conventional orthodontic treatment? A recent article by Jean Chin, et al. which appeared in the November 2002 issue of The American Journal of Orthodontics and Dentofacial Orthopedics directly addressed this question. The article was titled“Analysis of Efficacy of Functional Appliances on Mandibular Growth.”	[수정원고] If you have gone to courses, heard lectures or read articles by proponents of different functional appliances, you have probably heard them infer that their appliance quote "stimulates" or quote "enhances" mandibular growth. I believe terms like "enhance" or "stimulate" have been used to avoid addressing, basically due to a lack of strong clinical evidence, the main question that should be addressed. And that is simply "do functional appliances increase mandibular growth"? Is the patient likely to have a larger or more protrusive mandible if he or she wears a functional appliance versus not wearing one or using some other form of conventional orthodontic treatment? A recent article by Jean Chin, et al. which appeared in the November 2002 issue of The American Journal of Orthodontics and Dentofacial Orthopedics directly addressed this question. The article was titled“Analysis of Efficacy of Functional Appliances on Mandibular Growth.”
The purpose of the study was to examine the hypothesis that functional appliances enhance mandibular growth in the treatment of skeletal ClassⅡ malocclusions. A Medline search strategy was developed and was used to identify articles that addressed the effects of functional appliances on mandibular growth and length, the search included articles from 1966 to 1999 and was limited to studies performed on humans and written in English. Of the 23,393 orthodontic articles written in the past 33 years, 155 articles were categorized as randomized control trials or meta-analyses. These articles were identified because randomized control trials and meta-analyses are viewed as providing the highest level of evidence quality. Only 6 of these articles met the strict inclusion and validity criteria established set by the authors. All of the studies had to pertain to functional appliance use in the early treatment of Class Ⅱ malocclusions, include a randomized study and have measurable mandibular cephalometric values. When the 6 studies that met all the criteria were evaluated, what do you think that the authors found? The bottom line is that based on these scientific articles, functional appliances appear to have very little clinical effect on mandibular length.	The purpose of the study was to examine the hypothesis that functional appliances enhance mandibular growth in the treatment of skeletal Class Ⅱ malocclusions. A Medline search strategy was developed and was used to identify articles that addressed the effects of functional appliances on mandibular growth and length. The search included articles from 1966 to 1999 and was limited to studies performed on humans and written in English. Of the 23,393 orthodontic articles written in the past 33 years, 155 articles were categorized as randomized control trials or meta-analyses. These articles were identified because randomized control trials and meta-analyses are viewed as providing the highest level of evidence quality. Only 6 of these articles met the strict inclusion and validity criteria established by the authors. All of the studies had to pertain to functional appliance use in the early treatment of Class Ⅱ malocclusions, include a randomized study and have measurable mandibular cephalometric values. When the 6 studies that met all the criteria were evaluated, what do you think that the authors found? The bottom line is that based on these scientific articles, functional appliances appear to have very little clinical effect on mandibular length.
The authors note that randomized control trials and discriminate analysis studies produce similar results, therefore further strengthening their conclusion that functional appliances have little effect on mandibular length. I should know that the conclusions of this study do not suggest that functional appliances do not work. Obviously they do. Like many other forms of orthodontic treatment that disturb occlusal interdigitation during a period of growth, they allow the natural growth of the mandible to be reflected in an occusal change, from class Ⅱ toward class Ⅰ occulsion.	The authors note that randomized control trials and discriminate analysis studies produce similar results, therefore further strengthening their conclusion that functional appliances have little effect on mandibular length. I should know that the conclusions of this study do not suggest that functional appliances do not work. Obviously they do. Like many other forms of orthodontic treatment that disturb occlusal interdigitation during a period of growth, they allow the natural growth of the mandible to be reflected in an occusal change, from class Ⅱ toward class Ⅰ occulsion.
Therefore, if you are using functional appliances or presenting them to your patients, as a means to allow the correction of a Class Ⅱ occulsion during active growth, you are on solid ground. However, if you are suggesting that the use of functional appliances will result in increased growth of the mandible, you are on thin ice. You can find this article in the November 2002 issue of The American Journal of Orthodontics and Dentofacial Orthopedics.	Therefore, if you are using functional appliances or presenting them to your patients, as a means to allow the correction of a Class Ⅱ occulsion during active growth, you are on solid ground. However, if you are suggesting that the use of functional appliances will result in increased growth of the mandible, you are on thin ice. You can find this article in the November 2002 issue of The America Journal of Orthodontics and Dentofacial Orthopedics.

Effects of Modifying the Adhesive Composition on the Bond Strength of Orthodontic Brackets Bishara SE, Ajlouni R, et al. Angle Orthod 2002;72:464-467 November 28, 2003 Dr. Seon-Mi Kim
[초벌원고] In the next summary were are interested in examining the productivity of each type of adhesive bracket use? Or I can consider using precoated orthodontic brackets. In early years ago, orthodontic bracket manufactures began coating brackets with me adhesive they had in a factory. Precoated brackets done in the factory was to save chairtime and garantee consistancy in the amount adhesive that was being appled to each based bracket.	[수정원고]
But in order to facilitate the material being consistent, the incoperation of the composite at the factory had to be modified. The composition of the bonding material has be modified slightly. Study is shear bonding strength of the early precoated metal brackets. Auxillary showed that shear bonding strength was produced and increased significantly compared to conventional brackets. In order to overcome this problem, manufactures have now modified the composite material, that's coated on the bracket.
The new improves brackets that were previously an available. But it has been improved in the shear bond strength that question was study published in the October 2002 issue of the Angle Orthodontist. Samir Bishara & Research Colleague University of IOWA Orthodontics carried out this study. The title of the article contains that the information is“Effects of Modifying the Adhesive Composition on the Bond Strength of Orthodontic Brackets.”
Now, in order to answer this question, the authors gathered 60 extracted molars. These were human molars. These teeth were cleared and the usual method of the etching & rinsing was performed. Then, the author's bond brackets studies using of 3 different materials. All of the materials are manufactured by uniteks. One is an APC precoated material. The 2nd is the APC Ⅱ. We adjusted precoated bracket. The 3rd composite was tested is transbond XT. The teeth traditional light cured composite. The differences in these composites were related to the percentages of fillers and composite material contained within each. The fillers are used to improve flow and consistency of the precoated brackets. I participated in a technical discussion about the percentages, but a few the information you can read from the article. After the brackets were bonded. A machine was used to test and determine shear bond strength versus other bracket materials.
What happened? As I had previously informal studies precoated brackets had less shear bond strength compared to traditional bonding. But in the present study, there were no significant differences in the bone strengths of any of the three composites. So they show to answer the new modification of the precoated brackets has made the shear bone strength comparable with tradional means bonding bracket. If you use these brackets. you should be satisfied. If you're interested in a review of the study, you can find it in the 10, 2000 issue of the Angle Orthodontist.

Long-term Results of Distraction Osteogenesis of the Maxilla and Midface Wiltfang J, Hirschfelder. Br J Oral Maxillofac Surg 2002;40:473-9 December 5, 2003 Dr. Seong-Joon Park
[초벌원고] In this month reviews, I would you like to share with you two recent articles that have been published on distraction osteogenesis for the treatment of midface deficiency. The first article comes from the December 2002 issue of the British Journal of Oral and Maxillofacial Surgery and this titled "Long-term Results of Distraction Osteogenesis of the Maxilla and Midface." The paper comes from the University Hospital at Erlangen-Nuremberg_Germany.	[수정원고] In this month reviews, I would like to share with you two recent articles that have been published on distraction osteogenesis for the treatment of midface deficiency. The first article comes from the December 2002 issue of the British Journal of Oral and Maxillofacial Surgery and is titled "Long-term Results of Distraction Osteogenesis of the Maxilla and Midface." The paper comes from the University Hospital at Erlangen-Nuremberg, Germany.
The purpose of this study was to described_changes in skeletal and soft tissue relationships following distraction of the midface and also to look at this stability of these changes during the post-treatment follow-up time. This was a small study consisting of only 8 patients. All of the patients had significant midface deficiency as a result of Apert syndrome, ectodermal dysplasia,_variety_ clefting disorders. And important detailed_that the average age of the patients in this study was just under 14 years of age and the procedure was done on patients as young as eight. Five of the patients require distraction of the maxilla only and so had an osteotomy done at the LeFort I level and had intraoral distractors placed. Three of the patients required more aggressive midface movement and so had the osteotomy done at the LeFort II or III level and in extraoral Heillo distractor was used. The distraction was done in a typical fashion with a 5 day-latency period after the osteotomy, distraction about _ half a millimeter per day until the objects were met. And then at consolidation period of 12 weeks before_distractor removal. Sounds_lot like rapid maxillary expansion_doesn't it.	The purpose of this study was to describe the changes in skeletal and soft tissue relationships following distraction of the midface and also to look at the stability of these changes during the post-treatment follow-up time. This was a small study consisting of only 8 patients. All of the patients had significant midface deficiency as a result of Apert syndrome, ectodermal dysplasia, or a variety of clefting disorders. And important detail is that the average age of the patients in this study was just under 14 years of age and the procedure was done on patients as young as eight. Five of the patients require distraction of the maxilla only and so had an osteotomy done at the LeFort I level and had intraoral distractors placed. Three of the patients required more aggressive midface movement and so had the osteotomy done at the LeFort II or III level and an extraoral Heillo distractor was used. The distraction was done in the typical fashion with a 5 day-latency period after the osteotomy, distraction of a half a millimeter per day until the objects were met, and then a consolidation period of 12 weeks before the distractor removal. Sounds a lot like rapid maxillary expansion, doesn't it?
Following distraction_those patients still likely the growth significantly_were asked to wear_protraction face-mask up to 16 hours a day as_skelectal retainer. Mesurements and analysis were done in a typical way using cephalometric films taken before and after distraction and it again 1 or 2 years later. The results of the distraction are impressive. The extraoral distractor group had an average midface advancement of 20mm while the internal distractors had almost 10mm. The SNA angle was increased up to 20 degrees. During the follow-up time_these changes were largely maintained with relapse limited to about 10 percents.	Following distraction, those patients still likely to grow significantly, were asked to wear a protraction face-mask up to 16 hours a day as a skelectal retainer. Measurements and analysis were done in a typical way using cephalometric films taken before and after distraction and again 1 or 2 years later. The results of the distraction are impressive. The extraoral distractor group had an average midface advancement of 20 mm while the internal distractors had almost 10 mm. The SNA angle was increased up to 20 degrees. During the follow-up time, these changes were largely maintained with relapse limited to about 10 percents.
The authors believe_these results support the use of distraction osteogenesis at in early age in cases of severe maxillary or midface deficiency. They theorized that something they called distraction histogenesis that is_expansion of the surrounding soft tissue as the hard tissue with expanded_may improved the soft tissue envelop and therefore reduced the tendency for relapse_compare to traditional surgical advancement which leaves little time for soft tissue adaptation.	The authors believe that these results support the use of distraction osteogenesis at in early age in cases of severe maxillary or midface deficiency. They theorized that something they called distraction histogenesis that is the expansion of the surrounding soft tissue as the hard tissue is expanded, may improve the soft tissue envelope and therefore reduce the tendency for relapse, compared to traditional surgical advancement which leaves little time for soft tissue adaptation.
It is difficult to draw too many conclusions from the small study but certainly the magnitude of the maxillary advancement possible more than 20mm with the external distractors makes the procedure to consider for the severe midface deficiency. For the details about the distraction process and more detailed cephalometric analysis of the treatment effects and post-treatment changes can be found in the December 2002 issue of the British Journal of Oral and Maxillofacial Surgery.	It is difficult to draw too many conclusions from the small study but certainly the magnitude of the maxillary advancement possible more than 20 mm with the external distractors makes this procedure to consider for the severe midface deficiency. Further details about the distraction process and more detailed cephalometric analysis of the treatment effects and post-treatment changes can be found in the December 2002 issue of the British Journal of Oral and Maxillofacial Surgery.

Autotransplantation of a Permanent Maxillary Incisor Gleiser D, Jaramillo C. J Clin Orthod 2002;36:671-675. December 12, 2003 Dr. Ye-Na Jeon
[초벌원고] Here is a situation. You see a 12-year-old female for orthodontic consultation and in addition to a classⅡ malocclusion, she has a maxillary central incisor not erupted. Radiographs reveal the central incisor is inverted and there is also a supernumerary tooth obstructing its path. Since the tooth is completely inverted with the crown towards the nose, do you have the oral surgeon remove it along with the supernumerary tooth and plan for a later prosthetically placement? If you read a case report from Chile that is published in the December 2002 issue of the Journal of Clinical Orthodontics, you may consider autotransplantation to reposition an inverted incisor. The case report is presented in an article called “Autotransplantation of a Permanent Maxillary Incisor”.	[수정원고] Here is a situation. You see a 12-year-old female for orthodontic consultation and in addition to a classⅡ malocclusion, she has a maxillary central incisor not erupted. Radiographs reveal the central incisor is inverted and there is also a supernumerary tooth obstructing its path. Since the tooth is completely inverted with the crown towards the nose, do you have the oral surgeon remove it along with the supernumerary tooth and plan for a later prosthetic replacement? If you read a case report from Chile that is published in the December 2002 issue of the Journal of Clinical Orthodontics, you may consider autotransplantation to reposition an inverted incisor. The case report is presented in an article called “Autotransplantation of a Permanent Maxillary Incisor”.
The author's purpose is to present a case, just like the one I mentioned, that successfully repositioned the impacted, inverted incisor. Here's how it's done. The supernumerary tooth and the retained primary tooth were extracted. A full thickness flap was developed to allow facial access to the inverted incisor. The incisor was carefully extracted with special care taken not to demage the periodontal ligament.	The author's purpose is to present a case, just like the one I mentioned, that successfully repositioned the impacted, inverted incisor. Here's how it's done. The supernumerary tooth and the retained primary tooth were extracted. A full thickness flap was developed to allow facial access to the inverted incisor. The incisor was carefully extracted with special care taken not to demage the periodontal ligament.
The incisor was then placed in its desired position using a new tooth socket that was largely formed by the removal of the supernumerary tooth. The author stressed the importance of allowing 1 to 2 millimeters of clearance in this new tooth socket so that the PDL can stimulate new bone formation around the transplantated tooth. The gingival tissue was sutured and placed and the tooth was stabilized by the placement of 2 4 appliance using a light 0.014 SS arch wire. It is important for the tooth to be stabilized but not be rigidly fixed. After 3 weeks, because the root apex was closed, the pulp was removed, and calcium hydroxide dressings were placed until the definitive root canal treatment was completed at 7 months. At the time of this report, the tooth was doing well with good periodontal attachment, and no evidence of external resorption.	The incisor was then placed in its desired position using a new tooth socket that was largely formed by the removal of the supernumerary tooth. The author stressed the importance of allowing 1 to 2 millimeters of clearance in this new tooth socket so that the PDL can stimulate new bone formation around the transplantated tooth. The gingival tissue was sutured and placed and the tooth was stabilized by the placement of 2 4 appliance using a light 0.014 SS arch wire. It is important for the tooth to be stabilized but not be rigidly fixed. After 3 weeks, because the root apex was closed, the pulp was removed, and calcium hydroxide dressings were placed until definitive root canal treatment was completed at 7 months. At the time of this report, the tooth was doing well with good periodontal attachment, and no evidence of external resorption.
This case report should make us think of autotransplantation as a treatment alternative in children with a severely impacted or inverted tooth. Although the tooth may not last forever, it will be very beneficial, for to be in place through_ adolescent years to maintain esthetics and to maintain alveolar bone. As this case demonstrates, the orthodontist can be helpful in the stabilization face using orthodontic appliances. Orthodontic movement of the autotransplantated tooth can be done after three to nine months of healing. I would encourage you to look at this article in the December 2002 issue of the Journal of Clinical Orthodontics. If you have an interest in this technique, the clinical photographs of the procedure a quite helpful, and the entire article will be worth sharing with your surgical colleagues.	This case report should make us think of autotransplantation as a treatment alternative in children with a severely impacted or inverted tooth. Although the tooth may not last forever, it will be very beneficial, for to be in place through the adolescent years to maintain esthetics and to maintain alveolar bone. As this case demonstrates, the orthodontist can be helpful in the stabilization phase using orthodontic appliances. Orthodontic movement of the autotransplantated tooth can be done after three to nine months of healing. I would encourage you to look at this article in the December 2002 issue of the Journal of Clinical Orthodontics. If you have an interest in this technique, the clinical photographs of the procedure are quite helpful, and the entire article will be worth sharing with your surgical colleagues.

Soft Tissue Profile Changes of the Midface in Patients with Cleft Lip and Palate following Maxillary Distraction Osteogenesis: A Preliminary Study. Harada K, Baba Y, et al Oral Surg Oral Med Oral Pathol 2002;94:673-7. December 19, 2003 Dr. Chun-Sun Eun
[초벌원고] The first study we reviewed on this recording according regarding the advancement of the maxilla or midface using distraction osteogenesis. Show this that significant advancement of the maxilla was possible with resulting soft tissue improvement. This next study looks at the soft tissue improvement more closely and compares the soft tissue changes with maxillary distraction to conventional orthognathic surgery. This study appears in the December 2002 issue of Oral surgery, Oral medicine and Oral Pathology. It reports on research done in Japan and this called "Soft Tissue Profile Changes of the Midface in Patients with Cleft Lip and Palate following Maxillary Distraction Osteogenesis: A Preliminary Study".	[수정원고] The first study we reviewed on this according regarding the advancement of the maxilla or midface using distraction osteogenesis, shows this that significant advancement of the maxilla was possible with resulting soft tissue improvement. This next study looks at the soft tissue improvement more closely and compares the soft tissue changes with maxillary distraction to conventional orthognathic surgery. This study appears in the December 2002 issue of Oral surgery, Oral medicine and Oral Pathology. It reports on research done in Japan and is called "Soft Tissue Profile Changes of the Midface in Patients with Cleft Lip and Palate following Maxillary Distraction Osteogenesis: A Preliminary Study".
As the titles suggests_this study was done on patients with cleft lip and palate. The experimental group was 9 patients with maxillary deficiency that were treated with distraction osteogenesis. The average age of this group was about 15 years. The osteotomies for the distraction were done at the Le fort I level and external distractors were used that were fixed to the skull. Before 5 day latency period was followed by distraction at a rate of 1 ㎜ per day. Until_desired advancement was achieved_the distractor was left in place an additional 4 or 5 weeks and then was followed by 8 to 12 weeks a facemask used at night for retention. The comparison group was 9 similar cleft patients who underwent conventional Le Fort surgery for advancement. This control group was older_an average_22 years. Cephalometric films were used to measure the treatment changes and to compare the two groups. The forwards skeletal changes found_distraction group were 8 to 10 ㎜_about twice for the 5 ㎜ seen in the conventional surgery group. In addition, the ratio of soft tissue to hard tissue change was larger in the distraction group resulting and a much greater improvement in soft tissue profile.	As the title suggests, this study was done on patients with cleft lip and palate. The experimental group was 9 patients with maxillary deficiency that were treated with distraction osteogenesis. The average age of this group was about 15 years. The osteotomies for the distraction were done at the Le Fort I level and external distractors were used that were fixed to the skull. Before 5 day latency period was followed by distraction at the rate of 1 ㎜ per day, until the desired advancement was achieved. The distractor was left in place an additional 4 or 5 weeks and then was followed by 8 to 12 weeks a facemask used at night for retention. The comparison group was 9 similar cleft patients who underwent conventional Le Fort surgery for advancement. This control group was older, an average of 22 years. Cephalometric films were used to measure the treatment changes and to compare the two groups. The forward skeletal changes found in the distraction group were 8 to 10 ㎜, about twice for the 5 ㎜ seen in the conventional surgery group. In addition, the ratio of soft tissue to hard tissue change was larger in the distraction group resulting in a much greater improvement in soft tissue profile.
The conclusion is that the treatment of maxillary deficiency in cleft patient using the distraction osteogenesis is more effective in improvement_soft tissue profile than conventional surgery. The results of this study fit nicely with the first study we reviewed. Both demonstrated that forwards skeletal maxillary movement of 9 to 10 ㎜was possible with distraction of the Le fort I level. In addition, both study showed significant improvement on soft tissue profile following distraction treatment with a second study from Japan showing the soft tissue of the lip will move 70 to 80% of the hard tissue movement. More details of this study including a comparison of vertical changes that occurred during the distraction of the maxilla are available in the December issue of the Journal Oral Surgery, Oral Medicine and Oral Pathology.	The conclusion is that the treatment of maxillary deficiency in cleft patients using distraction osteogenesis is more effective in improving the soft tissue profile than conventional surgery. The results of this study fit nicely with the first study we reviewed. Both demonstrated that forward skeletal maxillary movement of 9 to 10 ㎜ was possible with distraction at the Le Fort I level. In addition, both study showed significant improvement on soft tissue profile following distraction treatment with a second study from Japan showing the soft tissue of the lip will move 70 to 80% of the hard tissue movement. More details of this study including a comparison of vertical changes that occurred during the distraction of the maxilla are available in the December issue of the Journal Oral Surgery, Oral Medicine and Oral Pathology.

Effect of Using Self-etching Primer for Bonding Orthodontic Brackets. Yamada R, Hayakawa T, Kasai K. Angle Orthod 2002;72:558-564. December 26, 2003 Dr. Seok-Pil Kim
[초벌원고] In this next article_the author determines whether self-etch primers were enhanced the shear bonding strength of glass ionomer cement. Today_orthodontics_has two general techniques for bonding brackets to teeth. One consists of using a composite to here the bracket, and the other uses glass ionomer cement. The etching process for the composite both used phosphoric acid. But with the glass ionomer cement, polyacrylic acid is used_etching the tooth.	[수정원고] In this next article, the author determines whether self-etch primers enhance the shear bond strength of glass ionomer cement. Today in orthodontics, there are two general techniques for bonding brackets to teeth. One consists of using a composite to here the bracket, and the other uses glass ionomer cement. The etching process for the composite involves the use of phosphoric acid. But with the glass ionomer cement, polyacrylic acid is used to etch the tooth.
In the past_most study reception, that glass ionomer cement have much less shear bond strength than like to a composite. But with_additional self-etch primers to prepare the tooth for bonding, is it possible that the shear bond strength of glass ionomer cement could be improved? That question was asked in the studied was published in the December 2002 issue of the Angle Orthodontist.	In the past, most studies have shown, that glass ionomer cements have much less shear bond strength than light-cured composites. But with the additional self-etch primers to prepare the tooth for bonding, is it possible that the shear bond strength of glass ionomer cements could be improved? That question was asked in the study that was published in the December 2002 issue of the Angle Orthodontist.
The title of the article is“Effect of Using self-etch Primer for Bonding Orthodontic Brackets”. The study was coauthored by Rieko Yamada and Tohru Hayakawa from Nihon University in Chiva, Japan. The general purpose of this study was to determine the effects of the self-etch primer on both composite bonding and glass ionomer bonding of orthodontic brackets.	The title of the article is“Effect of Using self-etch Primer for Bonding Orthodontic Brackets”. The study was coauthored by Rieko Yamada and Tohru Hayakawa from Nihon University in Chiva, Japan. The general purpose of this study was to determine the effects of the self-etch primer on both composite bonding and glass ionomer bonding of orthodontic brackets.
In other to accomplish these subjects, the author to gather 72 extracted teeth. They were divided in the 4 groups. In the first group, typical phosphoric acid etching techniques were used and orthodontic brackets for bonded whose like to a composite. In the second group, the self-etch primer was used instead of phosphoric acid in the bracket was bonded using like to a composite. In the 3rd and 4th groups, glass ionomer cement was used to here the brackets. And in one of this groups_the self-etch primer was applied before the glass ionomer cement. So you see the authors were determined the effects of self-etch primer on both of these different bonding techniques. After bonding of the brackets_a testing machine was used to determined_shear bond strength of each technique.	In order to accomplish this subject, the authors gathered 72 extracted teeth. They were divided in the 4 groups. In the first group, typical phosphoric acid etching techniques were used and orthodontic brackets were bonded with a light-cured composite. In the second group, the self-etch primer was used instead of phosphoric acid and the bracket was bonded using light-cured composite. In the 3rd and 4th groups, glass ionomer cement was used to here the brackets. And in one of these groups, the self-etch primer was applied before the glass ionomer cement. So you see the authors wanted to determine the effect of self-etch primer on both of these different bonding techniques. After bonding of the brackets, a testing machine was used to determine the shear bond strength of each technique.
OK! Let's get to_take home message. First question, does the self-etch primer have the same shear bond strength as the phosphoric acid when using the like to a composite? And the answer_the question is No! There was 33% reduction in bonding strength using the self-etch primer compared to the phosphoric acid. OK. Second question, does the self-etch primer enhance bonding strength of glass ionomer cement? The answer_the question is No! The shear bond strength with and without the use of the self-etch primer was the same for glass ionomer cement. Last question, how did glass ionomer and composit compare for shear bond strength? This study showed the same results as previous studies and that is that shear bond strength of glass ionomer cement is about 35% less than the shear bond strength of like to a composite.	OK! Let's get to the take home message. First question, does the self-etch primer have the same shear bond strength as the phosphoric acid when using the light-cured composite? And the answer to the question is No! There was 33% reduction in bond strength using the self-etch primer compared to the phosphoric acid. OK. Second question, does the self-etch primer enhance bond strength of glass ionomer cement? The answer to that question is No! The shear bond strength with and without the use of the self-etch primer was the same for glass ionomer cement. Last question, how did glass ionomer and composite compare for shear bond strength? This study showed the same results as previous studies and that is that shear bond strength of glass ionomer cement is about 35% less than the shear bond strength of light-cured composite.
So they you have it, if you use glass ionomer cements, self-etch primers won't enhance the shear bond strength. If you like to review the study you find it in the December 2002 issue of the Angle Orthodontists.	So there you have it. If you use glass ionomer cements, self-etch primers won't enhance the shear bond strength. If you like to review the study you'll find it in the December 2002 issue of the Angle Orthodontist.

Orthodontic Treatment of Palatally Impacted Maxillary Canines Olive RJ. Aust Orthod J 2002;18:64-70. January 2, 2004 Dr. Chun-Sun Eun
[초벌원고] In the next article_the author describes on non-surgical method for treating palatally impacted maxillary canines. Let me ask you a question. Do palatally impacted canines always require surgical uncovering? In my orthodontic practice_the answer of that question would be “Yes”! If left untreated_ palatally impactions don't typically self-correct. But what of palatally impacted canine erupt if extra space could be created in the dental arch. That possibility was addressed in the studied_was published in November 2002 issue of the Australian Orthodontic Journal. The title of the article is “Orthodontic Treatment of Palatally Impacted Maxillary Canines”. This article is authored by Richard Olive from Brisbane_Australia.	[수정원고] In the next article, the author describes a non-surgical method for treating palatally impacted maxillary canines. Let me ask you a question. Do palatally impacted canines always require surgical uncovering? In my orthodontic practice, the answer to that question would be “Yes”! If left untreated, palatally impactions don't typically self-correct. But would a palatally impacted canine erupt if extra space could be created in the dental arch. That possibility was addressed in the study that was published in November 2002 issue of the Australian Orthodontic Journal. The title of the article is “Orthodontic Treatment of Palatally Impacted Maxillary Canines”. This article is authored by Richard Olive from Brisbane, Australia.
The purpose of this study was to retrospectively evaluated_series of individuals in whom space was opened in the dental arch in patients with palatally impacted canines. In these cases, all the tempers may to determine the frequency with which these teeth would erupted spontaneously into the arch after space was created. The sample consisted of 28 children who were treated consecutively by the author. They range the age from 11 to 16 years. Now in these children, there were 32 palatally impacted canines.	The purpose of this study was to retrospectively evaluate a series of individuals in whom space was opened in the dental arch in patients with palatally impacted canines. In these cases, an attempt was made to determine the frequency with which these teeth would erupt spontaneously into the arch after space was created. The sample consisted of 28 children who were treated consecutively by the author. They ranged an age from 11 to 16 years. Now in these children, there were 32 palatally impacted canines.
Initially_primary canines were extracted as early as possible when the author recognized that the canines were displaced in the palate. Then_in all cases_orthodontic appliances were placed on the maxillary incisors and molars. A stopped round arch wire was used to create extra space in each of_dental arches for the impacted tooth. In many cases, the author states that the space created in the arch was about 1 cm more than the width of an impacted tooth. In these situations, the maxillary incisors were proclined and displaced up to 3 mm across the midline. In other words, the authors created excess space for the unerupted canine.	Initially, primary canines were extracted as early as possible when the author recognized that the canines were displaced in the palate. Then, in all cases, orthodontic appliances were placed on the maxillary incisors and molars. A stopped round arch wire was used to create extra space in each of the dental arches for the impacted tooth. In many cases, the author states that the space created in the arch was about 1 cm more than the width of an impacted tooth. In these situations, the maxillary incisors were proclined and displaced up to 3 mm across the midline. In other words, the authors created excess space for the unerupted canine.
His question was in what % of cases does the permanent canine spontaneously erupt without surgical uncovering? And what % of cases does at least_tooth position improve? After retrospectively evaluating the sample_the author find that 75 % of the previously impacted canines emerged following orthodontic space opening in the dental arch. You heard me correctly! None of the 75 % had surgery to uncover the canine. They merely erupt on their own after extra space was created. In 25 % of the cases, surgical uncovering was necessary. In addition, the author found that over 90 % of the palatally impacted canines at least showed improvement in the position with creation of space in the dental arch.	His question was in what % of cases does the permanent canine spontaneously erupt without surgical uncovering? And what % of cases does at least the tooth position improve? After retrospectively evaluating the sample, the author found that 75 % of the previously impacted canines emerged following orthodontic space opening in the dental arch. You heard me correctly! None of the 75 % had surgery to uncover the canine. They merely erupted on their own after extra space was created. In 25 % of the cases, surgical uncovering was necessary. In addition, the author found that over 90 % of the palatally impacted canines at least showed improvement in their position with creation of space in the dental arch.
So in this study the authors shown that simply creating space for palatally impacted tooth can stimulate the permanent canine to erupt into_proper position within the dental arch. This was then eliminated the need for surgical procedure. Now, I_like to make a couple of commends regarding the severity of the impaction relative to the root of the lateral incisor in this study. In most of the cases that were successful in this paper. The crown of the palatally impacted canine was not located anymore mesial than the mesial contour of the lateral incisal root. If the palatally impacted canine were positioned passed the mesial outline of the lateral incisor root, then the chance of success from merely opening space was not as good.	So in this study the author's shown that simply creating space for palatally impacted tooth can stimulate the permanent canine to erupt into its proper position within the dental arch. This would then eliminate the need for surgical procedure. Now, I'd like to make a couple of comments regarding the severity of the impaction relative to the root of the lateral incisor in this study. In most of the cases that were successful in this paper, the crown of the palatally impacted canine was not located anymore mesial than the mesial contour of the lateral incisor root. If the palatally impacted canine were positioned passed the mesial outline of the lateral incisor root, then the chance of success from merely opening space was not as good.
So in patients who have palatally impacted canines and you're planning in early phase orthodontic treatment anyway and the impaction is not that severe, you might consider this approach of opening extra space to allow the palatally impacted canine to self-correct. If you like to see the photographs, and read to data of the study for yourself, you will find it in the November 2002 issue of the Australian Orthodontic Journal.	So in patients who have palatally impacted canines and you're planning in early phase orthodontic treatment anyway and the impaction is not that severe, you might consider this approach of opening extra space to allow the palatally impacted canine to self-correct. If you like to see the photographs, and read the data of the study for yourself, you will find it in the November 2002 issue of the Australian Orthodontic Journal.

The Effect of Saliva Contamination on Shear-bond Strength of Orthodontic Brackets When Using a Self-etch Primer Bishara S, Oonsombat C, et al. Angle Orthod 2002;72:554-557. January 9, 2004 Dr. Ye-Na Jeon
[초벌원고] This next article describes the impact or affect of saliva contamination during the bonding of orthodontic brackets. Most orthodontists have at least heard about the new self-etch primers that are available on the market today. With these materials, the etchant and the sealant or primer are combined into one liquid so to eliminate one step during the bonding of orthodontic brackets. Since isolation of teeth can be a problem in certain areas of the mouth, reducing the number of steps certainly makes sense.	[수정원고]
Studies have been performed in the past to compare the shear bond strength of these new self etch primers with the traditional bonding techniques with separate etching and priming steps. The past studies have shown that self etch primers have satisfactory shear bond strength if they are applied properly. But we all know that during the bonding process in the mouth, saliva contamination can be a problem. But does saliva contamination affect the bond strength of self etch primers? That question was addressed in a study that was published in the December 2002 issue of the Angle orthodontist.
The title of the article is“The Effect of Saliva Contamination on Shear-bond Strength of Orthodontic Brackets When Using a Self-etch Primer”. This study was co-authored by Samir Bishara and three other colleagues from the University of IOWA College of Dentistry. Now in order to accomplish this study, the authors gathered 50 extracted human molars. They were divided into four groups. The first group was a control. In this situation, a self etch primer was placed on the tooth for 15 seconds, it was allowed to evaporate with air and then light cure for 10 seconds. Then a metal bracket was bonded to the tooth, and then it was also cured with a light. Then in the second, third and forth groups, saliva contaminated the tooth at varying points during the bonding process.
Let me explain. In group 2, the tooth was contaminated with human saliva just before the application of the self-etch primer. In the third group, human saliva contaminated the tooth surface after application of the self-etch primer but before the bracket was bonded. Finally in the fourth group, saliva contamination was introduced before and after the application of the self-etch primer. So you see these researchers really wanted to fully test what the effect of saliva contamination will be at varying points during the bonding procedure. Then the brackets were subjected to a testing machine which debracketed the teeth and brackets using a shear force. The force required to debracket the tooth was recorded and then was compared between the groups.
I think you get the idea. Let's get to the bottom line. Does saliva contamination affect shear bond strength? The answer to that question is definitely“yes”. In fact, the authors calculated the differences in percentages, which I think, is the easiest way for me to provide the results for you on this tape. Here we go. If saliva contaminated the tooth before application of the primer, the reduction in shear bond strength was 25%. Similarly, if saliva contamination occurred after application of the primer but before the bonding of bracket, the reduction in shear bond strength was also 25%. But if saliva contamination occurred before and after application of the primer, average reduction in shear bond strength was 75%. So what does this mean to clinicians? Well, the authors believed the reduction of 25% in shear bond strength really wouldn't clinically affect the strength of the bonded bracket in most cases.
So remember, if saliva contamination occurred during the bonding a brackets in your patient mouth, and it occurred either before or after application of the self etch primer, you really don't have to start process over again. But if the saliva contamination occurred before and after application of the self etch primer, then you probably should restart the bonding process. Anyway, I thought this was an excellent study that provided good clinical information. If you like to review this article, you can find it in the December 2002 issue of the Angle orthodontist.

Maxillary Canine Displacement; Further Twists in the Tale Chate RAC. Eur J Orthod 2003;25:43-47. January 16, 2004 Dr. Seok-Pil Kim
[초벌원고] Have you ever reviewed the panoramic x-ray and found in impacted maxillary canine that is adjacent to a first premolar with significant deviation or dilaceration of the palatal root? If you have, did you wonder whether that root deviation may have caused the impaction or maybe the impaction caused the root deviation?	[수정원고] Have you ever reviewed the panoramic x-ray and found an impacted maxillary canine that is adjacent to a first premolar with significant deviation or dilaceration of the palatal root? If you have, did you wonder whether that root deviation may have caused the impaction or maybe the impaction caused the root deviation?
This is the question that is the focus of an article from Essex County Hospital in the United Kingdom. The title of the article is_Maxillary Canine Displacement; Further Twists in the Tale_.	This is the question that is the focus of an article from Essex County Hospital in the United Kingdom. The title of the article is “Maxillary Canine Displacement; Further Twists in the Tale”.
Now I have to admit that part of_reason I selected this article was that it had this catchy title that sounds more like_who done it novel then_usual dry scientific descriptors that I usually get to read. But the biggest reason_this paper attract to me was that it is the result of one person seeing an unusual clinical situation. And then studying the available scientific data to see_could be explained or understood. What a good practices would it be for all of us to do more often! The author presents two females. One aged 13 and one 16, that each have_impacted maxillary canine associated with_significant deviation of the palatal root on the adjacent premolar.	Now I have to admit that part of the reason I selected this article was that it had this catchy title that sounds more like a who done it novel than the usual dry scientific descriptors that I usually get to read. But the biggest reason that this paper attracted me was that it is the result of one person seeing an unusual clinical situation, and then studying the available scientific data to see if it could be explained or understood. What a good practices would it be for all of us to do more often! The author presents two females, one aged 13 and one 16, that each have an impacted maxillary canine associated with a significant deviation of the palatal root on the adjacent premolar.
The author theorizes 3 possibilities. (1) The deviated palatal root caused the impaction of the canine by obstructing its path. (2) The impacted canine caused root deviation due to the proximity of the canine during premolar root formation. Or (3) The appearance of the two strictly coincidental was no cause or relationship.	The author theorizes 3 possibilities. (1) The deviated palatal root caused the impaction of the canine by obstructing its path. (2) The impacted canine caused root deviation due to the proximity of the canine during premolar root formation. Or (3) The appearance of the two strictly coincidental was no causal relationship.
To gain insight_the author first reviewed literature on tooth eruption and root development. From this review_he can concluded that Hertwig's sheath, where root development is occurring, normally is not displaced in the bone but rather the tooth growth away from it in a occlusal direction. This evidence makes the author believe that it is a unlikely that the developing root would displace or obstruct and erupting canine. Secondly, the author reviewed evidence of root resorption caused by ectopic canines, and concludes that if the root got in the way of_canine chances are high that there could be some evidence of resorption on the premolar root. Lastly, the author examined_usual timing of root developing and eruption, and concluded that_at least in females_the proximity of the canine crown tooth developing premolar root would be such the deviation of_root could be possible due to the canines presents.	To gain insight, the author first reviewed literature on tooth eruption and root development. From this review, he concluded that Hertwig's sheath, where root development is occurring, normally is not displaced in the bone but rather the tooth growing away from it in occlusal direction. This evidence makes the author believe that it is unlikely that the developing root would displace or obstruct an erupting canine. Secondly, the author reviewed evidence of root resorption caused by ectopic canines, and concludes that if the root got in the way of the canine chances are high that there would be some evidence of resorption on the premolar root. Lastly, the author examined the usual timing of root development and eruption, and concluded that, at least in females, the proximity of the canine crown to the developing premolar root would be such the deviation of the root could be possible due to the canines presents.
So_after examination of his clinical cases and the available scientific evidences, this author believes that it is more likely_the impacted canine caused root deviation of_developing premolar rather than the deviated root on the premolar causing impaction of the canine. Whether you agree or not, with the author_conclusions_I think that the way that he approaches this question could be a lesson for us all.	So, after examination of his clinical cases and the available scientific evidence, this author believes that it is more likely that the impacted canine caused root deviation of the developing premolar rather than the deviated root of the premolar causing impaction of the canine. Whether you agree or not with the author's conclusions, I think that the way that he approaches this question could be a lesson for us all.
If you would like to read_Maxillary Canine Displacement; Further Twists in the Tale_, you can find it in the February 2003 Issue of the European Journal of Orthodontics.	If you would like to read“Maxillary Canine Displacement; Further Twists in the Tale”, you can find it in the February 2003 issue of the European Journal of Orthodontics.

An Investigation of Root-fractured Permanent Incisor Teeth in Children Feely L, Mackie IC, Macfarlane T. Dent Traumatol 2003;19:52-4 February 6, 2004 Dr. Jin-myoung Song
[초벌원고] A 9-year-old-boy named Robert is seen in your office for a routine recall appointment. Robert had early maxillary expansion treatment to correct unilateral crossbite and now is being monitored with the expectation that he will have comprehensive orthodontic treatment in the early permanent dentition likely about 3 years from now. Robert's mother hands you an X-ray and a note from pediatric dentist that explains that he suffered root fracture of his left maxillary central incisor about 3 months ago. Mother is quite anxious about how this fractured teeth and wonder if that tooth even still be around 3 years when you plan to treat him. You will be more prepared to discuss this issue with Robert's mother. After you learn about an article that was published in the February 2003 issue of Dental Traumatology. The title of the article is "An Investigation of Root-Fractured Permanent Incisors Teeth in Children" and that comes from University Dental Hospital in Manchester England.	[수정원고]
The purpose of this investigation was to review the records of 33 children age 8 to 15 with the total of 34 incisor root fractures. Just see if any conclusions could be drawn with a half predicted outcome of future root fractures. The patient's age, gender were collected along with information about the location of the root fracture, type of treatment and the degree of root formation at the time of the trauma.
Two investigators reviewed the radiographs of the fractured teeth to determine the mode of healing. That healing was classified as calcified tissue healing, connective tissue healing, a combination of calcified and connective tissue healing or granulation tissue healing. The first 3 were group together as good healing and the last granulation tissue was judged to be poor healing. Chi-square testing was done to look for factors that maybe able to predict good healing.
The result showed that overall 80%, or 4 out of 5 fractures showed good healing, only one of five showed poor healing. All 34 teeth will still present after 3 years of follow up. Age, gender, treatment and fracture location were not related to healing in this group. The one factor that was related to healing was the degree of the root formation those teeth with immature roots were more likely to have good healing compared those fractured teeth with the complete roots.
Now when you speak with Robert's mother, you can tell her that because Robert's root formation was not completely the time of fracture the tooth has an excellent chance of good healing. In addition, you can tell her that the chance of the tooth still being present and 3 years is very high. Unfortunately, this study does not give us any information about orthodontic tooth movement of incisors with root fracture, a situation that you may face in a few years.
If you would like further information from this article an incisor root fractures in children, it can be found in the February 2003 issue of Dental Traumatology.

Bond Strength of Orthodontic Brackets using different light and self curing cements Toledano M, Osorio R, et al. Angle Orthod 2003;73:56-63. February 13, 2004 Dr. Go-Woon Kim
[초벌원고] In this next summary, the authors compare different types of bonding materials to determine which is the most effective clinically. Today orthodontists have many choices of bonding materials to adhere bracketed teeth. Originally we have one choice that was chemically cured composite. There is the story of dentist began to use more composite for restorations light cured materials be available. In order to enhance the bonding of wetty glass ionomer cement for develop in further modifying by adding resin creating the resin modified glass ionomer cement. Now on the past I have reviewed studies comparing some of these materials. But it is always nice to review studies that compare all four of these different materials in one experiment. That's the purpose of this article. That is in one repertory experiment, the authors compared chemically cured, light cured, glass ionomer cement, and resin-modified glass ionomer cement to determine their shear bond strength.	[수정원고]
The title of the article is“Bond Strength of Orthodontic Brackets Using Different Light and Self-Curing Cements”. The study comes out of the University of Granada in Spain and this is coauthored by Manuel Toledano and Raquel Osorio. Self further study consist the fifty extracted human molars. They were divided into groups and the buccal and lingual surfaces of each crown were cleaned and prepared for bonding. Four different bonding materials were used. I wont give you brand names of these products. I would rather focus on the type of bonding material and the success rate.
Again in one group the brackets were bonded with chemically cured composite, in the second group a light cured composite was used, in the third and forth groups either glass ionomer cement or resin-modified glass ionomer cement was used to adhere the brackets. Then instron testing machine was used to debracket the teeth and the shear bond strength was determined, a pretty straight forward experiment. So that the authors find actually the results are a bit atypical. If I would ask you which would have provided the greatest bond strength? I believe that most of you would guess the light cured composite. But that was not the case. In this experiment the chemically cured composite provided the significantly higher shear bond strength. In fact, the light cured composite and the glass ionomer and resin-modified glass ionomer cement were nearly equivalent. As the authors stated they were all within a clinically acceptable range for shear bond strength. In recent years, I believe that most studies have shown that light cured composite have greater bond strength than chemically cured composite. The authors stated these differences in the discussion and suggested possibly more curing time or thermo cycling of the brackets after placement before debonding might have given some different results. So what's the bottom line? Based on this study the authors suggested that most bonding materials are clinical. All have shear bond strength that are adequate for orthodontic patients, if the techniques I will follow actually.
The author's this suggest when using glass ionmer cement or resin modified glass ionomer cement, that the surface of tooth be etched with phosphoric acid prior to the placement of brackets rather than be lining on the polyacrylic acid of glass ionomer cement for the etching. If you like to read this study, you can find it in the February 2003 issue of the Angle Orthodontist.