Dictation - 전남대학교 치과대학 교정과 대학원 세미나

Surgically Assisted Rapid Maxillary Expansion Compared with Orthopedic Rapid Maxillary Expansion. Altug Atac AT, Karasu HA, Aytac D. Angle Orthodontist 2006;76:353-9 March 2, 2007 Dr. Sang-Su Han
[초벌원고] What would you do in this situation? You're planning treatment for a nineteen year old female. She has mild crowding on both arches and classⅠocclusion. Here is the problem. She has bilateral posterior crossbites, and again she is nineteen years of age. What would you use conventional rapid maxillary expansion to correct the crossbites? Or would you have surgically assisted expansion performed for this patient? What there be any differences between the two? Those questions were addressed in the study that was published in May 2006 issue of the Angle Orthodontist. The title of the article is “Surgically Assisted Rapid Maxillary Expansion Compared with Orthopedic Rapid Maxillary Expansion.” This study is co-authored by Dr's Atac and Karasu from the department of orthodontics of Ankara university in Turkey.	[수정원고]
The purpose of their study was to evaluating, compare the dental and skeletal changes during the active phase of treatment for both rapid maxillary expansion and surgically assisted rapid maxillary expansion. In order to accomplish this subjective, the authors gathered samples of 20 subjects. All subjects had posterior crossbites. The main difference in the sample was age. In fact, they were divided into 2 groups according to age. The first group of 10 patients was treated with surgically assisted rapid maxillary expansion, and their average age was nineteen years. The second group of 10 subjects had an average age of fifteen and a half years, and they were treated with conventional maxillary expansion. All expanders in both groups had occlusal coverage and were hyrax type expanders. The occlusal coverage eliminate the premature contacts during expansion. Now, in each group the expander was turned one-quarter turn in the morning and one-quarter turn in the evening. And the expansion continued until the crossbites were corrected. At the end, the average amount of expansion for both groups was similar at about seven and a half millimeters.
In order to document the differences between the two groups, lateral cephalometric radiographs and posteroanterior radiographs were taken for each subject. In addition, occlusal radiographs were also obtained and these were then measured and compared. Okay! I think you get the idea of the experiment. What happened? Let me give you the comparison between the two groups. First of all there was no clinical difference in the amount of expansion. The expansion process worked in both groups and the patients' response was similar between the surgical and conventional groups.
When the authors compared the lateral cephalometric findings, conventional expansion was more effective in forward displacement of the maxilla compared to the surgical group. On the other hand, the SNB increased more in the surgical group compared to the conventional expansion group. In addition, in the surgical group there was posterior rotation of the maxilla, while in the conventional expansion group the maxilla rotated in an anterior direction. As a result, the upper facial height showed a significant increase in the surgical group, and a decrease in the conventional expansion group. When the authors compare the posteroanterior cephalometric radiographs, the main difference between the two approaches was in the mandibular molar width and the tipping of the maxillary base. The mandibular molar width increased significantly more in the conventional expansion group, but the maxillary base was tipped slightly more in the surgical group. So there, we have it. Both modes of expansion obviously worked. But there were some minor differences which were of course do to the separation of the bones surgically compared to simply using the suture as the source of expansion.
If you're interested in reviewing in this material and comparing the data, you can find this article in the May 2006 issue of the Angle Orthodontist.

Self- Etching Primer and a Non-Rinse Conditioner versus Phosphoric Acid ; Alternative Methods for Bonding Brackets Vincent A. Bravo LA. Romero M. Eur J Orthod 2006;28:173-8 March 9, 2007 Dr. Hyo-young, Song
[초벌원고] The proper bonding of orthodontic brackets to enamel is one of the most important things that we do clinically. We would like to have brackets that stay on as long as we need them, but then are easily removed with little clean up when we are done. In addition, we would like to conserve as much enamel in this whole process as possible.	[수정원고]
In recent years, self etching primers have been available that simplify the bonding process by eliminating the rinsing and drying. But there have been conflicting results about the bond strength they provide. Now there is an additional option. A non-rinse conditioner which eliminates the rinsing of the conditioner, but still requires a primer. To help provide more information about these two alternatives compared to conventional acid etching, Dr. Vincent and colleagues from Spain published the results of their research In the April, 2006 issue of European Journal of Orthodontics. This research was done in the laboratory on extracted human premolars.
65 premolars were divided into 3 groups for bond strength testing. The first group had conventional phosphoric acid etching followed by a primer and light cured composite. The second group used self etching primer followed by the same light cured composite. The third group used non rinse conditioner which was placed on the tooth, then quickly air dried and followed by primer and the light cured composite. All materials were used according to manufactures and instructions. After 24 hours the brackets were tested for shear bond strength in a universal testing machine, and the remaining composite on the tooth scored using the adhesive remnant index. 12 additional premolars were conditioned using the three techniques and then viewed in the scanning electron microscope to look at the etching pattern that occurred.
The results showed no significant bond strength differences among the three conditioning techniques. After the bonding, however, there is less composite left on the enamel when the self etching primer or the non rinse conditioner were used. The electron micro-graphs showed a less aggressive etching pattern with the non rinse conditioner, whereas the self etching primer looked more similar to a conventional phosphoric acid etch. The authors were quick to point out that this was a laboratory test only, and the laboratory results have not always translated to clinical success.These results were encouraging though, since the use of the alternative conditioning techniques showed similar bond strength results, but potentially less enamel loss and easier enamel clean up.
If you are interested in more details of the study investigating alternative enamel conditioning systems, Look for the article entitled “Self-Etching Primer and the Non-Rinse Conditioner versus Phosphoric Acid, Alternative Methods for Bonding Brackets”in the April, 2006 issue of the European Journal of Orthodontic.

Relative Plaque Removal of Three Toothbrushes in a Nine-Period Crossover Study Terézhalmy GT, Bartizek RD, Biesbrock AR. J Periodontol 2005;76:2230-5 March 16, 2007 Dr. Jin-Myoung Song
[초벌원고] Do you recommend manual or power toothbrushes for your orthodontic patients? Does it make any difference? Does the power toothbrush actually remove more plaque than a manual toothbrush in a fair comparison of subjects who actually use both of the brushes? Now that power brushes have been around for a while, I think it's a good time to review what they really will do in a well structured study. I found an article in the December 2005 Issue of the Journal of Periodontology that compares two types of manual toothbrushes with the power toothbrush in a large sample of patients. The title of the article is “Relative Plaque Removal of Three Toothbrushes in a Nine-Period Crossover Study”. This study was co-authored by G za Ter zhalmy and two other research colleagues from the University of Texas Health Science Center in San Antonio.	[수정원고]
The purpose of their study was to measure the ability of 3 toothbrushes to remove plaque following 3 single brushing episodes with each toothbrush. Now this was a very involved study. Over 70 adult subjects between the ages of 18 and 70 years of age participated. So you can see a sampled, a good cross-section of ages. This study was conducted over a 3-month period and each subject was evaluated using 3 different brushes. One was an electric power toothbrush and the other two were two varieties of a manual toothbrush. So this was a randomized, controlled, examiner-blind, crossover study and the yielded excellent data. At each visit with each toothbrush, the subjects were asked to clean their teeth and the disclosing solution was used to identify any remaining plaque on the teeth. These areas were evaluated in scored using in specific plaque index that maps out the amounts and locations of plaque remaining on teeth. All subjects were examined by a single examiner who was also blinded at each of this appointment.
OK. I think you get the idea. Each subject used 3 different toothbrushes and blinded examiners evaluated their performances. What did they find? The results were reasonably straightforward. The authors found that a power toothbrush demonstrated a statistically significantly greater reduction in plaque than both of the manual toothbrushes. In fact, the power toothbrush had an average 40% and 30% greater plaque removal scores than each of the experimental manual toothbrushes, respectively. Even in the interproximal and gingival regions, there was greater plaque removal compared to the controlled manual toothbrush. So there you have it. The power toothbrushes still win. They are much more efficient at removing plaque and in orthodontic population. It would certainly make sense to have patients use these types of brushes compared to manual toothbrushes.
If you'd like to review this data, you can find this study in the December 2005 Issue of the Journal of Periodontology.

A Clinical Comparison between Nickel Titanium Springs and Elastomeric Chains Bokas J, Woods M. Aust Orthod J 2006;22:39-46 March 23, 2007 Dr. Seok-Pil Kim
[초벌원고] How do you close extraction spaces in the maxillary arch? Suppose you have patient with significant protrusion of the maxillary anterior teeth. And the only way to reduce the protrusion is to extraction of maxillary first premolars. But in this situation, you typically will have four premolar spaces to close. So, do you use titanium springs to close space? Or do you use elastomeric chains? Most clinicians have the preferences between these two types of space closing mechanics. But is there any difference? For example, do elastomeric chains close space any quicker or slower than nickel titanium springs?	[수정원고]
That information would be useful to us clinicians. Well, that information was published in a study that I found in the May 2006 issue of the Australian Orthodontic Journal. Because of its clinical relevance, I thought this would be a great study for us to review on this month tape. The title of the article is “A Clinical Comparison between Nickel Titanium Springs and Elastomeric Chains.” This study was co-authored by Jim Bokas and Michael Woods from the department of orthodontics at the University of Melbourne in Australia.
Now the purpose of this study was to compare the rates of maxillary canine retraction and molar anchorage loss, when using either standard nickel titanium springs or elastomeric chains delivering a known force with sliding edgewise mechanics.
First of all, the authors identified the sample of 12 healthy individuals who about 13.5 years of age. This sample was divided evenly between 6 males and 6 females. All patients were undergoing routine orthodontic treatment and had had maxillary first premolars extracted. But on one side of the arch, the authors used elastomeric chains that had been calibrated with the force of 200 grams. And on the other side of the arch, the authors used nickel titanium springs with the same force level of 200 grams. These patients were monitored every 28 days. At this follow appointment, the nickel titanium spring was reactivated to a 200 gram force and the elastomeric chain was replaced, and each force level was again calibrated at 200 grams.
Also at each 28 day appointment, a maxillary impression was made of the dental arch that could be poured been stone. These dental casts were scanned. And the images in the computer were used to identify specific anatomic points in the palate that could be reproduced and used as reference points to measure the amount of canine retraction as compared to the amount of molar anchorage loss during the space closure. You see the author want to compare whether or not as the space close one of the method space closure were produce more or less anchorage loss than the other.
Okay. I think you get the idea. What happened? First of all, was there any difference between either the later space closure or the amount of molar anchorage loss when the nickel titanium springs were compared to the elastomeric chains? And the answer that question is “No” and “No.” The average rate of space closure for the nickel titanium springs was 1.85 mm/month. With the elastomeric chains, the space closure average 1.68 mm/month. The mean difference between the rates of space closure produce by these two methods was 0.17mm/month. So you see, the difference was very little.
How about the amount of maxillary molar anchorage loss? In this study, the authors showed that the mean rates of anchorage loss for the nickel titanium springs compared to the elastomeric chains were relatively the same and were both about 0.05 mm/month. Obviously this was not statistically significant.
So there you have it. Both nickel titanium springs and elastomeric chains obviously close extraction spaces. But when the compared using the split mouth design in the same patients, the differences were insignificant. In fact, the authors concluded their paper by stating that the rates of space closure using either pre-calibrated nickel titanium closing springs or pre-measured elastomeric chains are likely to be similar. If you'd like to review this study, you will find it in the May 2006 issue of the Australian Orthodontic Journal.

The Effect of Oral Splint Devices on Sleep Bruxism: a 6-week Observation with an Ambulatory Electromyographic Recording Device Harada T, Ichiki R, et al J Oral Rehabil 2006;33:482-8 March 30, 2007 Dr. Kyoung-Im, Kim
[초벌원고] Night time bruxism can be a damaging activity both to the dentition itself and to the temporomandibular joints and muscles. The use of an occlusal splint is frequently recommended for those individuals with sleep bruxism. But, there is a debate over whether the splint simply protects the teeth from wear or whether the balanced occlusal contacts of a probably designed splint actually reduce the bruxing activity. A recent study reported in the July 2006 Issue of the Journal of Oral Rehabilitation adds additional evidence to this debate. The article is called “The effect of oral splint devices on sleep bruxism: a 6-week observation with an ambulatory electromyographic recording device".	[수정원고]
The study was designed to be a prospective randomized trial with crossover. Let me tell you how it worked because a good study design makes the results more valuable. First, the authors tested two splint designs: a stabilization splint with occlusal coverage and balanced occlusal contacts. And, also a palatal splint that have no occlusal coverage but, otherwise cover the same tissue areas. The idea behind the palatal splint was to determine whether the occlusal contacts or occlusal coverage were important to any effect the splints may have. Sixteen subjects with a diagnosis of sleep bruxism were recruited for this study. All 16 subjects wore both splints for 6 weeks each in random order. This is the crossover part of the design. There was a 2-month break or washout period between the two splints to eliminate any carryover. The bruxism activity was monitored with a portable EMG recorder that the subjects were carefully instructed how to use. The EMG activity was monitored prior to splint use, and immediately after studying whether the splint and then 2, 4, and 6 weeks into regular night time splint wear.
So, this study helps to answer two questions. First, was any difference in the bruxing response between the two splint designs? The answers to this question was "No". The two splints behaved in exactly the same way indicating that occlusal coverage or balanced contacts on the splint did not seem to be an important factor. The second question was whether the splints could actually reduce the night time bruxing activity. The answer to this question is that the EMG activity was reduced for both splint designs immediately after placement, but had increased back to baseline values when measured at 2, 4, or 6 weeks into the splint wear. The effect of reducing muscle activity seems to be transient, lasting only a short time. The result of this study would support the view that splint wear for bruxism protects the teeth from wear, but does not necessary do anything to actually reduced bruxing activity. The results do not support the theory that balanced occlusal contacts with ideal guidance reduce bruxing activity. This was a small study only 16 subjects, but a strong study design lends strength to the authors' conclusions.
For more detailed information about this research and to read the informative discussion session, you can find this article by Harada and colleagues in the July 2006 Issue of the Journal of Oral Rehabilitation.

The Tissue, Cellular, and Molecular Regulation of Orthodontic Tooth Movement: 100 Years after Carl Sandstedt Meikle MC. Eur J Orthod 2006;28:221-40 April 6, 2007 Dr. Yoon-Jung Choi
[초벌원고] I was recently sitting in on the thesis defense of one of my students who's project used rather sophisticated molecular biology techniques to better understand the signalling mechanisms of osteoclasts. As I listen to the presentation I struggle to make sense of the molecular biology lingo and keep all the cytokines straight in my head. I couldn't help but be amazed at the progress that we were making and understanding the mechanisms behind orthodontic tooth movement but also to reflect on how complexity makes it difficult for me as a clinician to understand. Shortly after that day, I saw an article in the June 2006 European Journal of Orthodontics that helped me to put this progress in understanding tooth movement into prospective. It is a comprehensive review article called “The Tissue, Cellular, and Molecular Regulation of Orthodontic Tooth Movement: 100 Years after Carl Sandstedt”. I have mentioned in the past about the difficulty in trying to review for you, a review article but my main objective is to stimulate you to read this entire article nearly 20 pages of it written by professor Murray Meikle.	[수정원고]
The story begins with Sandstedt in the early 1900s, he moved incisors of dogs and observed the histologic response. He first described the appearance of hyalinization and undermining resorption under compression side of teeth with high force levels. Oppenheim continued to improve our understanding of tooth movement through his work in the 1930s and many of his observations and theories at that time supported the non-extraction techniques taught by Angle.
In the middle of century, Reiten improved our understanding of the responses to different types of forces and levels of force. He also look at the remodeling of the PDL and gingival fibers which provided the bases for some of a retention techniques. Through the 1960s and 70s experimental techniques improved and more was learned about the cellular events occurring during tooth movement. Also during this time renewed interest in bone bending as a part of the process occured. The 1970s, also brought better in vitro models of tooth movement with tissue cultures which could more precisely control pressure on cells and better measure of the cellular reactions. Truly these techniques interest in prostaglandins, leukotrien and cyclic AMP was generated as possible signalers for the tooth movement process. In the last 20 years the molecular biology techniques have allowed the identification of cytokine like interleukin, TNF and osteoprotegerin as possible mediators as mechanically induced bone remodeling.
After the review the author concludes that we have made tremendous progress in last 100 years in understanding tooth movement especially at the tissue and cellular level. He also believes there is plenty of work left to do primarily at the molecular level to really understand the systems so that we can control it in a clinically useful way. I would again recommend that each of you read this article so that you get a feel for where we are as a profession in the understanding tooth movement, the underline foundation for all that we do. The June 2006 issue of the European Journal of Orthodontics is a place to look.

Nickel in Dental Plaque and Saliva in Patients with and without Orthodontic Appliances Fors R, Rersson M. Eur J Orthod 2006;28:292-7 April 13, 2007 Dr. Hee-Kyoung Kim
[초벌원고] There is continued debate about whether there is release of nickel from orthodontic appliances and whether patients with a nickel contact allergy need be concerned. Several previous studies have failed to demonstrate increased concentration of nickel in the saliva of subjects with orthodontic appliances, but the debate continues. What do we tell our patients that have a history of nickel contact allergy. Do we use non-nickel containing appliances? A study from Sweden was published in the June 2006 issue of the European Journal of Orthodontics that provides additional information for this debate. The paper is titled “Nickel in Dental Plaque and Saliva in Patients with and without Orthodontic Appliances.”	[수정원고]
The subjects for the study were two groups of adolescents. The first group of 24 boys and girls had fixed orthodontic appliances in place for more than a year. This group averaged just less than 15 years of age. The second group of 24 was age matched to the first, but had no appliances in place. All subjects had a saliva sample collected and a plaque sample taken with extra care not to contaminate the samples with nickel. In addition of 48-hour dietary history was completed to control for recent nickel intake.
The saliva was filtered, and the filtered saliva was tested separately from the salivary sediment. The results were interesting. The testing of the filtered saliva showed no difference in nickel content between those with braces and those without. This supports previous studies. The salivary sediment and the plaque, however, showed twice the level of nickel in those subjects with braces compared to controls. In addition, in patients with braces, plaque taken from metal surfaces had greater nickel content than plaque from adjacent tooth surfaces. These results would suggest that nickel release does occur from orthodontic appliances but, that it accumulates in plaque in salivary sediment not in saliva itself. If this is the case, then we should be encouraging excellent oral hygiene in patients with a history of contact allergy to nickel to remove all plaque and avoid nickel accumulation.
The study still does not answer the question of whether the increased nickel amounts found in plaque have any significance. Even the subjects without appliances had some nickel content in their plaque from other sources. But, it does confirm that nickel release is possible. It can accumulate in plaque, and that clinical decisions on a appliance type should be made accordingly. More information about this well done study from Sweden including a thorough literature review is available in the June 2006 issue of the European Journal of Orthodontics.

Post-Treatment Development of the Curve of Spee Lie F, Kuitert R, Zentner A. Eur J orthod 2006;28:262-8 April 20, 2007 Dr. Sang-Rok Kim
[초벌원고] What expectations do you have for the curve of Spee in your patients after orthodontic treatment? Do you treat all patients to a flat curve of Spee thinking that they will relapse to a mild curve? Do you base your curve on the cephalometric findings? A group of researchers from the Netherlands published a research project in the June 2006 issue of the European Journal of Orthodontics that provides information about the stability of the curve of Spee following orthodontic treatment. The study is called “post treatment development of the curve of Spee”.	[수정원고]
The purpose of this study was to retrospectively look at a series of treated orthodontic cases that had long term follow-up records and to look specifically at changes in the curve of Spee. The sample was a group of one hundred thirty five patients that were treated in the 1970s. One hundred had upper and lower treatment and thirty-five had upper arch only treatment. The post retention records were three to twenty four years after retention with the average being about twelve years. So records were available for this group of patients at the beginning of treatment, the end of treatment, and at long term follow-up. A standardized photographic technique was used to measure the curve off the models and various cephalometric measurements were used to look for predictors of change.
The results are a bit confusing. The average arch was leveled about 1mm during treatment and relapsed about one third of that by follow-up. But this is a case where averages are misleading. Most very flat arches that had mild curves produced during treatment returned to being very flat at follow-up. Very deep curves that were leveled during treatment were actually quite stable, more stable than those with small changes. From the statistical analysis it appears that a curve of Spee of about 2mm was most stable. This curve was measured as the greatest depth from a line contacting the lateral incisor and the most distal molar cusp.
Another surprising result for me was that the authors were unable to find any cephalometric variable that predicted the curve changes after treatment. Overall, about 50% of the treated cases showed relative stability of the curve of Spee at long term follow-up. About 30% had relapse back towards the original curve. The unexpected changes were the 20% that changed further in the direction of treatment, like a deep curve that was leveled to a mild curve during treatment and then continued to flatten during the post retention time.
I'm not sure this information will change the way I treat patients relative to their curve of Spee, but I won't be as surprised next time I see a post treatment patient with an unexpected change in the lower curve. I'll know this can happen about 20% of the time. More information about curve of Spee changes during and after treatment can be found in this article from the Netherlands that appears in the June 2006 issue of the European Journal of Orthodontics.
Factors Affecting the Clinical Success of Screw Implants Used as Orthodontic Anchorage Park HS, Jeong SH, Kwon OW. Am J Orthod Dentofacial Orthop 2006;130:18-25 April 27, 2007 Dr. Sang-Woon Jeon
[초벌원고] As I am sure you are aware by now, the use of many microscrew implants for orthodontic anchorage continues to grow in popularity. In an article titled "Factors Affecting the Clinical Success of Screw Implants Used as Orthodontic Anchorage" by Hyo-Sang Park et al., which appeared in the July 2006 Issue of the American Journal of Orthodontics and Dentofacial Orthopedics. The authors who are from Korea evaluated a number of factors related to the success of screw implants.	[수정원고]
In this study they evaluated 87 consecutive patients with the mean age of 15 and a half years who received microscrew implants for orthodontic anchorage. I was some what surprised to see, the relatively young mean age for the sample and even more so, when I realized that the standard deviation was 8.3 years, indicating that there were obviously patients as young as six or seven in the sample.
The study was performed to evaluate every possible factors that could affect the success of screw implants. Four different types of screw implants were used. The screw implants were placed at different angulations and in different locations in the maxilla and the mandible, including attached gingiva and mucosa and oral hygiene was evaluated. Screw implants that were maintained in the bone to the end of treatment or to their intentional removal regardless of mobility were considered successful. If the screw implants loosened during treatment, they were considered to have failed.
The overall success rate of the screw implants using this definition, was slightly over 91%, with an average time of 15 months of force application. I should note that when screw implants failed, new ones were placed in the neighboring area and 11 of 19 screws that failed and were replaced, were successful at the end of treatment. Giving it an overall success rate of over 96%, which I thought was impressive.
I found it interesting that when all the many variables used in this study were analyzed, only four turned out to be risk factors. Namely mobility, screw implants placed in the mandible versus the maxilla, implants placed on the right side versus the left, and inflammation. There was no difference between the different types of screws, angulation, timing of activation and the number of factors related to screw placement.
When I evaluated the four risk factors, two seemed logical to me, namely mobility and inflammation. However the other two did not. I would have expected that with the thicker bone in the mandible there would be a higher success rate in the mandible, however this was not true. As far as left side having a higher success rate than the right, the authors suggested that this may be explained by better hygiene on the left side of the dental arch by right-handed patients who are most of the population. This last suggestion was a little stretch for me, and although the sample size of 87 consecutive patients was large, I wonder if it was large enough to provide an accurate statistical analysis for so many variables.
I also was some what surprised that the surgical procedure included local anesthesia, a small vertical stab incision, reflection of flaps, a pit made with a round bur, a hole made with a pilot drill, and placement of the screw implants with a screwdriver. Many of the new microscrew implants can be placed directly through soft tissue to the bone without creating a surgical flap or pilot hole and require very minimal, if any local anesthesia. The bottom line of this study, however, is that the even with the use of a different types of implants, the success rate is very high.
You can read this article in the July 2006 Issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Perceptions of Dental Professionals and Laypersons to Altered Dental Esthetics: Asymmetric and Symmetric Situations Kokich VO, Kokich VG, Kiyak HA. Am J Orthod Dentofacial Orthop 2006;130:141-51 May 4, 2007 Dr. Mi-Young Kim
[초벌원고] Achieving excellent dental and facial esthetics has become an increasingly important goal not only amongst orthodontists but laypeople as well. What are the characteristics of an esthetic smile and more importantly, how much can theses characteristics vary before they become noticeable by an orthodontist or a general dentist or a layperson? Also, if deviations from the ideal are asymmetric, are they more noticeable than if they are symmetric? A study titles"Perceptions of Dental Professionals and Laypersons to Altered Dental Esthetics: Asymmetric and Symmetric Situations" by Vincent Kokich Junior and Vincent Kokich Senior and Asuman Kiyak which appeared in the August 2006 Issue of the American Journal of Orthodontics and Dentofacial Orthopedics address this question.	[수정원고]
A previous study compared the perceptions of dentists and laypeople to altered dental esthetics. However, in that study the alterations were symmetric. The purpose of this current study was to determine whether asymmetric and symmetric anterior dental discrepancies are detectable by various groups of evaluators. To do this the authors used digitally altered smile photographs that were randomly evaluated by orthodontists and general dentists and laypersons. 7 different aspects of an ideal smile were gradually altered in 0.5 or 1.0 mm increments. The bottom line of this study is that asymmetric alterations make teeth more unattractive not only to dental professionals but also to laypersons. This article contains excellent photographs of the alterations that were used and detailed statistical information related to the perceptions of the 3 different groups.
What I'm going to do is to review what I thought were some of the more interesting findings with the understanding that you can review the entire article to obtain more in-depth results. I was somewhat surprised that a maxillary lateral incisor had to be 3 mm narrower than ideal before it was rated significantly less attractive by orthodontists and 4 mm narrower by laypersons. Deviations in length had to be 2 mm or more to be identified as unattractive by laypeople. I would have guessed that smaller alterations in crown width and length would have been noticed. The important finding of this study, however, is that if these discrepancies are asymmetric, they are definitely more noticeable. Also, when crown width and length were altered proportionally, they were less noticeable. Obviously maintaining the proper proportion of crown width to length is important to achieving good esthetics.
The maxillary midline diastema had to be 2 mm or more before being evaluated as unattractive by general dentists and laypeople. Again I thought a smaller diastema probably would have been noticed. The amount of maxillary gingival display is critical when evaluating esthetic smiles. Based on the data from this and the previous study, at least 1 or 2 mm of gingival display during smile is not generally regarded as unesthetic. The authors note that this is an important point, because it is probably better for the patient to show some gingival display during smile than not at all. With the understanding that aging, less of the maxillary anterior teeth show, and, with loss of tonicity and facial muscles, the lip will move less.
This and the previous study reported by the authors provide some excellent guidelines for making treatment decisions related to establishing an esthetic smile. I believe the important take-home point from this study is that if deviations from ideal are symmetric they are less likely to be considered unattractive especially by laypeople. You can find this study in the August 2006 Issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Class III Nonextraction Treatment with Miniscrew Anchorage. Paik CH, Nagasaka S, Hirashita Am J Clin Orthod 2006;40:480-84 May 11, 2007 Dr. Kyung-Min Lee
[초벌원고] What treatment options do you consider for a mild skeletal class III case where the family does not want to have surgery? I have had some success in these cases by retracting the lower incisors to compensate for the skeletal imbalance. If the soft tissue can tolerate this compensation, often the result can be very acceptable. One limitation that I have found is that obtaining the desired incisor position often means extracting lower, but not upper premolars. This results in a class III molar finish and unopposed upper second molars. So, although the anterior relationship works out well, there is some compromise posteriorly.	[수정원고]
A case report that appears in the August 2006 Issue of the Journal of Clinical Orthodontics demonstrates that it may be possible to compensate this type of class III patient without lower arch extractions. This approach uses retromolar miniscrews for anchorage and retracts the whole lower arch to compensate the dentition. The authors of this article called “Class III Nonextraction Treatment with Miniscrew Anchorage” are from Japan. This case report documents of a treatment of a 16 years old female patient with a mild class III skeletal malocclusion. There was little to no crowding in either arch and the left side was more class III than the right. The goals of the treatment were to retract the lower arch to provide optimal posterior interdigitation and overbite, overjet. Miniscrew anchors were placed in the retromolar areas on both the right and the left. Alignment was done with the braces in the conventional way and then the miniscrews were used for the retraction of the lower arch. The case was completed in 16 months.
The result showed the ANB angle was largely and changed as would be expected. The upper incisors came forward slightly and the lower incisors were retracted and upright about 7 degrees. The superimposition showed the upper dentition remain relatively stable, but there was significant retraction of lower molars and incisors. The lower incisors also elongated several millimeters. Photographically, the face and occlusion looked excellent and I would say the overall outcome was very good.
What a case report like this tells us “Is this type of response is possible? but not how likely or predictable it is”. It could be this sort of positive result would happen in 9 out of 10 times or this could be a 1 in 10 outcomes. Hopefully, more scientific evidence is forth coming regarding the predictability of the miniscrew anchors in various applications. I would suggest that you look at the pictures and tracings in this article, if you are considering this treatment alternative for one of your patients. It would help you visualize what sort of treatment result may be possible.
The treatment records along with more detailed information about the mechanics used in this case can be found in the August 2006 Issue of the Journal of Clinical Orthodontics.

The Enigma of Facial Beauty: Esthetics, Proportions, Deformity, and Controversy Naini FB, Moss JP, Gill DS. Am J Orthod Dentofacial Orthop 2006;130:277-82 May 25, 2007 Dr. Suk-Cheol Lee
[초벌원고] As orthodontist, we are all intimately involved with facial beauty and attractiveness. Is the origin of the human perception of facial beauty dependent on each person's sense perception, or is this sense common to all people? How do we know that a face is beautiful? What guides and validates judgment? These questions were addressed in a very interesting article titled “The Enigma of Facial Beauty: Esthetics, Proportions, Deformity, and Controversy”, by far hard 90, at all, which appeared in the September ,2006 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. In addressing the question of whether the perception of facial beauty is dependent on each person's sense perception, or is a sense that is common to all people, the authors list a number of popular quotes which suggests that it is an individual perception. These popular and well known quotations include,“Beauty in things exists in the mind which contemplates them”, and“Beauty is in the eye of the beholder.” On the other hand, the 18th century philosopher Francis Hutcheson said,“Esthetic judgments are perceptual and take their authority from a sense that is common to all that make them,” and in 1790, the philosopher Immanuel Kant said,“The beautiful is that which pleases universally without a concept.” There's obviously support for both sides of this question. However, as orthodontists, it seems to me that we have to accept that at least to some degree, that there are some universally accepted concepts of facial beauty. Otherwise, there would no need to develop facial esthetic treatment goals.	[수정원고]
The second question addressed in this article is‘How do we know that a face is beautiful?’What guides and validates our judgment? If you have been practicing orthodontics for a reasonable period of time, I am sure you have seen numerous illustrations in articles and textbooks dividing the face into facial thirds vertically, and into fifths laterally. What is basis of these norms and where did they come from? You might be surprised to know that the concept, the facial thirds, goes as far back as the first century B.C., when the Roman architect Marcus Vitruvius Pollio wrote his famous work, The Ten Books of Architecture. About 1490, Leonardo da Vinci created his famous figure, Vitruvian man showing that proportionate human form fits perfectly in perfect geometric shapes that is a circle and the square and relates facial vertical proportions to standing height. Also in about 1490, Da Vinci created the male head in profile with proportions with the hairline to eyebrows, eyebrows to the base of the nose, and base of the nose to the chin creating vertical facial thirds. The lower facial third is again divided into upper third, which is the upper lip, and lower two-thirds. I find it very interesting that we are still using these facial proportions in treatment planning today. The big question is‘Are they still valid?' I am not sure we will ever be able to reduce facial beauty to a mathematical formula. However, we are currently doing research at the University of Iowa that should shed some light onto validity of using these ancient facial proportions or canons in today's society.
I found this article to be very interesting, and I suggest that if you are interested in getting a better understanding of facial proportions, that you read it in its entirety. It appears in the September, 2006 issue of the American Journal of Orthodontics and Dental facial Orthodontics.

Quantitative Determination of Adhesion Patterns of Cariogenic Streptococci to Various Orthodontic Adhesives Ahn SJ, Lim BS, Lee YK, Nahm DS. Angle Orthod 2006;76:869-75. June 8, 2007 Dr. Hak-Hee Choi
[초벌원고] Do you use a fluoride releasing adhesive to bond brackets to teeth? Some of you listening to this tape probably do. But is it effective? The theory is that the release of fluoride from a bracket adhesive will prevent bacteria from adhering to tooth, which could reduce the amount of decalcification around brackets during orthodontics. But is that really true? In fact, is there any difference in adhesion patterns of caries producing bacteria surrounded around any of the different orthodontic adhesives? That question was addressed in the study that was published in the September 2006 issue of the Angle Orthodontist. This was an excellent and extensive study and I'd like to review for you on this month edition. The title of the article is “Quantitative Determination of Adhesion Patterns of Cariogenic Sterptococci to Various Orthodontic Adhesives”. This study come out of Korea and was authored by Sug-Joon Ahn and three other orthodontic colleagues from the department of orthodontics at Seoul National University in South Korea.	[수정원고]
The purpose of this study was to observe the amount of cariogenic Streptococci adhesion to various orthodontic adhesives and to compare the effect of fluoride release on the adhesion amount regarding the type of bacteria. In the study two types of cariogenic bacteria were used. One is Streptococcus mutans, the other is Streptococcus sobrinus. These authors tested five different light cured orthodontic adhesive including one fluoride releasing composite, three non fluoride releasing composites and one resin modified glass ionomer cement. Thirty specimens of each adhesive were incubated with real whole human saliva for about 2 hours. Bacteria from the saliva that accumulated on and around the adhesive were assessed using radioactive labels that labeled each of the bacteria. So, as you can see this was a laboratory experiment but it was very extensive with a large number of specimens.
But what did they find? First of all, is there any difference in the adhesion of different bacteria to orthodontic adhesives? The answer is yes. Streptomutans showed the highest amount of adhesion, whereas Streptococcus sobrinas showed very low amount of adhesion. Okay, question number two. Does fluoride releasing adhesive have any effect on reducing adhesion of bacteria? The answer to that question is absolutely not. The release of fluoride had no effect on adhesion compared to the non fluoride containing adhesives. Question number three. Was there any difference between glass ionomer adhesive and traditional light cured composite? Again the answer is definitely yes. Cariogenic streptococci adhered to the glass iononmer significantly more than to the composite. In addition, there was no significant difference in the adhesion among the four composites. So there you have it. If you use glass ionomer cement, your patients were prone to higher susceptibility for adhesion of bacteria to the cement surfaces. If you use a fluoride releasing composite, don’t expect to alter the adhesion patterns of the cariogenic bacteria because it simply does not have any effect.
If you are interested in reviewing this study that compares adhesion patterns of cariogenic bacteria to orthoadhesive, you can find it in the September 2006 issue of Angle Orthodontist.

The Horseshoe Molar Derotator Gautma P, Valiathan A, et al. J Clin Orthod 2006;40:438-41 June 22, 2007 Dr. Hyung-Min Kim
[초벌원고] What methods do you use to derotate upper molars that are severly rotated to the mesial? You know that type where the molar buccal tooth is right against the premolar so not even the most flexible archwire could be inserted. The classic solution would be to use the transpalatal arch. This can be effective but some patients don't tolerate well and the limited range of action may require several reactivations to be effective. What about a labial wire bent to allow a distal molar insertion? This is a solution suggested by authors from India, in an article called "The Horseshoe Molar Derotator" that appears in the September 2006 issue of the Journal of Clinical Orthodontics.	[수정원고]
This article is a description of the Molar Derotator and 2 brief case reports showing its clinical use. I'm going to try to describe this appliance to you but the pictures in the article are probably the best way to get the idea how this works. This device is a labial wire made from .018 .025 stainless steel or .017 .025 beta titanium. A vertical overlapping closed loop is bent into each side of the wire in the premolar area. This allows the flexibility for distal insertion. At the distal of the molar, the wire is bent lingually at 90 and then a couple of millimeters further bent anteriorly at about 90 and until it is just past parallel with the main arch wire section. This same series of bends is done on the other side. The end result is a wire that looks somewhat like a closing loop wire but the distal ends have the segments that turn back anteriorly. The wire is then inserted into the molar tubes from the distal; a much easier thing to do if the molar is rotated significantly. Again the flexibility if the vertical loops is what allows the wire to be inserted from the distal on both sides. The anterior portion of the wire is either inserted into the anterior brackets or tied to a segmental wire that is in the brackets. After insertion, the appliance can be reactivated by using a three prong plier to create a V-bend distal to the vertical loops. The case reports showed significant molar rotation accomplished in 2 to 3 months using this device. One of the cases required molar rotation only on one side so the appliance was made unilaterally at the segment. This design does not require vertical loop since distal insertion is possible without it. This idea is another tool that you can have in your bag to solve unique problems. It would be ideal for severe molar rotation in a patient that cannot tolerate a lingual appliance but requires efficient molar rotation early in treatment.
Once again I would suggest that if you would like to try this Molar Derotator, you'll find this article in the September 2006, JCO to see the photographs and diagrams of the appliance. It will help you visualize what I have been describing and make it much easier to fabricate.

Infant Orthopedics and Facial Appearance: A Randomized Clinical Trial (Dutchcleft) Prahl C, Prahl-Andersen B, et al. Cleft Palate Craniofac J 2006;43:659-64 September 7, 2007 Dr. Sang-Rok Kim
[초벌원고] I have worked with facial plastic surgeons that prefer to have infant orthopedics done on cleft children prior to lip closure. Their rationale is that the orthopedic treatment approximates the lip segments prior to surgery and therefore there is less tension on their lip repair during healing. This reduced tension would theoretically result in less scarring and therefore a more attractive lip closure and more attractive face. This seems like a reasonable rationale, but is it true? Does infant orthopedic treatment prior to lip closure result in a more attractive face for the cleft patient? This was one of the questions that were asked as part of the Dutchcleft study that involved a randomized clinical trial of infant orthopedic treatment. The results of this part of the trial were reported in the November 2006 issue of The Cleft Palate Cranial Facial Journal in an article called 'Infant Orthopedics and Facial Appearance: A Randomized Clinical Trial'.	[수정원고] I have worked with facial plastic surgeons that prefer to have infant orthopedics done on cleft children prior to lip closure. Their rationale is that the orthopedic treatment approximates the lip segments prior to surgery and therefore there is less tension on their lip repair during healing. This reduced tension would theoretically result in less scarring and therefore a more attractive lip closure and more attractive face. This seems like a reasonable rationale, but is it true? Does infant orthopedic treatment prior to lip closure result in a more attractive face for the cleft patient? This was one of the questions that were asked as part of the Dutchcleft study that involved a randomized clinical trial of infant orthopedic treatment. The results of this part of the trial were reported in the November 2006 issue of The Cleft Palate- Craniofacial Journal in an article called 'Infant Orthopedics and Facial Appearance: A Randomized Clinical Trial'.
The Dutchcleft study includes the treatment of unilateral cleft infants and three cleft treatment centers in the Netherlands. The subjects in the study were randomly assigned to the infant orthopedic group or the group without infant orthopedics. For this part of the study there were forty-one subjects; twenty-one with infant orthopedics and twenty without. The forty-one subjects were judged for facial appearance from photographs taken at age eighteen months. The ratings were made by a group of professionals and a separate group of lay adults. The appearance of each subject was judged using a full-face photograph and a photo that was cropped to show only the nose and mouth. So, did this study support the use of infant orthopedics based on improved facial appearance at age eighteen months? The answer is no. There was no difference in the facial appearance ratings between the group that was randomly assigned to have infant orthopedics and the group that had no infant orthopedic treatment.	The Dutchcleft study included the treatment of unilateral cleft infants at three cleft treatment centers in the Netherlands. The subjects in the study were randomly assigned to the infant orthopedic group or the group without infant orthopedics. For this part of the study, there were forty-one subjects; twenty-one with infant orthopedics and twenty without. The forty-one subjects were judged for facial appearance from photographs taken at age eighteen months. The ratings were made by a group of professionals and a separate group of lay adults. The appearance of each subject was judged using a full-face photograph and a photo that was cropped to show only the nose and mouth. So, did this study support the use of infant orthopedics based on improved facial appearance at age eighteen months? The answer is no. There was no difference in the facial appearance ratings between the group that was randomly assigned to have infant orthopedics and the group that had no infant orthopedic treatment.
The study did not find that there was any harm from the early orthopedic treatment, only that they could not find a benefit. It is possible that the benefit in facial appearance could show up at a later age after more facial growth has taken place. It is also possible that there is a difference but just not large enough to find with the sample of forty-one infants. But, the bottom line of this well-designed investigation is that no benefit of infant orthopedic treatment could be found in terms of the facial appearance at eighteen months.	The study did not find that there was any harm from the early orthopedic treatment, only that they could not find a benefit. It is possible that the benefit in facial appearance could show up at a later age after more facial growth has taken place. It is also possible that there is a difference but just not large enough to find with the sample of forty-one infants. But, the bottom line of this well-designed investigation is that no benefit of infant orthopedic treatment could be found in terms of the facial appearance at eighteen months.
If you are involved in the treatment of cleft infants, you may want to discuss the results of the Dutchcleft study with your cleftteam to determine weather changes to your treatment routine should be made. To find the complete paper, look in the November 2006 issue of The Cleft Palate Cranial Facial Journal.	If you are involved in the treatment of cleft infants, you may want to discuss the results of the Dutchcleft study with your cleftteam to determine whether changes to your treatment routine should be made. To find the complete paper, look in the November 2006 issue of The Cleft Palate-Craniofacial Journal.

Long-Term Follow-Up of Orthodontically Treated Deep Bite Patients. Schu tz-Fransson U, Bjerklin K, Lindsten R. Eur J Orthod 2006;28:503-512 September 14, 2007 Dr. Hyo-young Song
[초벌원고] I want to imagine a scenario where you are discussing the orthodontic correction of girl name Lisa. Lisa has generally good alignment of teeth, but it's deep overbite in the anterior. You tell Lisa's mother how you plan to correct the deep bite and she responses by showing you her teeth with really 100% overbite. She states that she had correction as adolescence and as wondering if Lisa's deep bite is corrected, will it be stable or will it relapse like her's deep. It may be a little more comfortable talking with Lisa's mother once I review with result from the research project from Sweden that was published in the October 2006 issue of the European Journal of orthodontics. The article is tilted "Long-term follow up of orthodontically treated deep bite patients."	[수정원고] I want to imagine a scenario where you are discussing the orthodontic correction of girl named Lisa. Lisa has generally good alignment of her teeth, but a deep overbite in the anterior. You tell Lisa's mother how you plan to correct the deep bite and she responds by showing you her teeth with a nearly 100% overbite. She states that she had correction as an adolescent and is wondering if Lisa's deep bite is corrected, will it be stable or will it relapse like hers did? You may be a little more comfortable talking with Lisa's mother once I review with you the results of a research project from Sweden that was published in the October 2006 issue of the European Journal of Orthodontics. The article is titled,"Long-term follow up of orthodontically treated deep bite patients."
The purpose of this project was to measure how the overbite changed in patients were treated for deep bite as adolescence. The subject were 30 patients about 12 years of age that were treated for it deep bite malocclusion. Most of this were treated with fixed appliances, but 7 had treatment with functional appliances. Records were available from the start of treatment, the end of treatment, about 5 years after treatment, and about 10 years after treatment. There was also a control group which was untreated individuals with normal alignment at occlusion, which had record from similar but not exactly the same time period. All measurements were made from the plaster casts or from the lateral cephalograms.	The purpose of this project was to measure how the overbite changed in patients that were treated for deep bite as adolescents. The subjects were 30 patients about 12 years of age that were treated for a deep bite malocclusion. Most of these were treated with fixed appliances, but 7 had treatment with functional appliances. Records were available from the start of treatment, the end of treatment, about 5 years after treatment, and about 10 years after treatment. There was also a control group which was untreated individuals with normal alignment and occlusion, which had records from similar but not exactly the same time periods. All measurements were made from plaster casts or from the lateral cephalograms.
Let me share some other study's findings. The treatment group started with average overbite of almost 6mm. This was reduced to 2.8mm at the end of treatment, exactly equal to the control group. So we can say that the treatment was successful at reducing the overbite. But how did overbite then changes from the end of treatment to more than 10 years later? Well, it did replase some, but quite a small amount 0.8mm. During the same time, the control groups which had the same overbite as the treatment groups at the end of treatment had slight reduction of overbite. So those treated for deep bite tend to have a minor increase overbite while untreated individuals tend to have a small reduction overbite during the same time.	Let me share some of the study's findings. The treatment group started with average overbite of almost 6 mm. This was reduced to 2.8 at the end of treatment, exactly equal to the control group. So we can say that the treatment was successful at reducing the overbite. But how did the overbite then change from the end of treatment to more than 10 years later? Well, it did relapse some, but quite a small amount 0.8 mm. During the same time, the control group which had the same overbite as the treatment group at the end of treatment had slight reduction in overbite. So those treated for deep bite tend to have a minor increase in overbite while untreated individuals tend to have a small reduction in overbite during the same time.
So as you talk to Lisa's mother about the stability of overbite correction, you can tell her that the evidence suggests that all there may be small relapse. The long term success of the correction is quite good and Lisa is unlikely that have total relapse for deep bite if it's corrected. For more information about the long term stability of overbite correction, look for this article from Sweden in the October 2006 issue of the European Journal of orthodontics.	So as you talk to Lisa's mother about the stability of overbite correction, you can tell her that the evidence suggests that although there may be some small relapse, the long-term success of the correction is quite good and Lisa is unlikely to have a total relapse of her deep bite, if it is corrected. For more information about the long term stability of overbite correction, look for this article from Sweden in the October 2006 issue of the European Journal of Orthodontics.

A comparison of the methods for predicting the size of the unerupted canines and premolars. Legovic M, Novosel A, Skrinjaric, et al Eur J Orthod 2006;28:485-90 September 21, 2007 Dr. Sang-Su Han
[초벌원고] While treatment planning mixed dentition cases, we all want to know the size of the unerupted canines and premolars to properly estimate the eventual space needs. Many different prediction methods have been proposed over time to predict unerupted tooth size from the measured size of the incisors and sometimes first molars.	[수정원고] While treatment planning mixed dentition cases, we all want to know the size of the unerupted canines and premolars to properly estimate eventual space needs. Many different prediction methods have been proposed over time to predict the unerupted tooth size from the measured size of the incisors and sometimes first molars.
Which methods do you use? Investigators in Croatia recently tested eight prediction methods for their ability to predict the size of the premolars and canines. The results were published in October 2006 issue of the European Journal of Orthodontics and the article titled "A comparison of the methods for predicting the size of the unerupted permanent canines and premolars."	Which method do you use? Investigators in Croatia recently tested eight prediction methods for their ability to predict the size of the premolars and canines. The results are published in the October 2006 issue of the European Journal of Orthodontics in an article titled,"A comparison of methods for predicting the size of unerupted permanent canines and premolars."
The subjects for this study were one hundred twenty Croatian children between the age of fourteen and eighteen. They were evenly divided between boys and girls. The study models of these children were carefully measured using a digital calipers for accuracy. The size of the canines and premolars was predicted using the eight different prediction methods and this predicted size was compared to the actual measured size of these teeth.Correlation coefficients were used to describe the reliability of the prediction and the difference between the predicted and actual tooth size was recorded for each method on each subject.	The subjects for this study were one hundred twenty Croatian children between the ages of fourteen and eighteen. They were evenly divided between boys and girls. The study models of these children were carefully measured using a digital calipers for accuracy. The size of the canines and premolars was predicted using the eight different prediction methods, and this predicted size was compared to the actual measured size of these teeth. Correlation coefficients were used to describe the reliability of the prediction, and the difference between the predicted and actual tooth size was recorded for each method on each subject.
The results of this study found that the worst prediction method was one proposed by Berendonk and Nawrath 1960s. The best predictor was the method of Bachmann, which uses the mesio-distal dimension of the upper and lower left laterals and the upper left first molar for prediction. These 3-dimensions are used in the regression equation to predict the unerupted tooth size.	The results of this study found that the worst prediction method was one proposed by Berendonk and Nawrath in the 1960s. The best predictor was the method of Bachmann, which uses the mesio-distal dimension of the upper and lower left laterals and the upper left first molar for prediction. These 3-dimensions are used in a regression equation to predict the unerupted tooth size.
A limitation of this method in my mind is that the authors found this algorithm to slightly underpredict tooth size instead of my preference to slightly overpredict. In addition, the regression equation, although not terribly complex, is not easy to remember or easy to compute in my head. The method of Tanaka-Johnston also performs very well in this population. The prediction coefficients were only slightly less than the best performer, and this method tended to slightly overpredict the actual tooth size in 80% of the cases. As I recall, the Tanaka-Johnston method was designed to overpredict tooth size in 75% of the cases, almost exactly how performed in this study. The reason I prefer slight over prediction is that I would rather be surprised by teeth slightly smaller than I plan for rather than the other way around.	A limitation of this method in my mind is that the authors found this algorithm to slightly underpredict tooth size instead of my preference to slightly overpredict. In addition, the regression equation, although not terribly complex, is not easy to remember or easy to compute in my head. The method of Tanaka-Johnston also performed very well in this population. The prediction coefficients were only slightly less than the best performer, and this method tended to slightly overpredict the actual tooth size in 80% of the cases. As I recall, the Tanaka-Johnston method was designed to overpredict tooth size in 75% of the cases, almost exactly how it performed in this study. The reason I prefer slight over prediction is that I would rather be surprised by teeth slightly smaller than I planned for rather than the other way around.
After reading this study, I will still tend to use Tanaka-Johnston method for prediction. This method is easy to remember and I can do the calculations rapidly in my head. In addition, because it only requires lower incisors measurements, it can also be done directly on the patients, without making a study model at the situation arises. For more informations about the comparison of the prediction methods, take a look the October 2006 issue of the European Journal of Orthodontics and read the study written by Dr Legovic and colleagues.	After reading this study, I will still tend to use Tanaka-Johnston method for prediction. This method is easy to remember and I can do the calculations rapidly in my head. In addition, because it only requires lower incisor measurements, it can also be done directly on the patient, without making a study model if the situation arises. For more information about the comparison of prediction methods, take a look at the October 2006 issue of the European Journal of Orthodontics and read the study written by Dr. Legovic and colleagues.

Antimicrobial Effectiveness of a Highly Concentrated Chlorhexidine Varnish Treatment in Teenagers with Fixed Orthodontic Appliances Attin R, Ilse A, et al. Angle Orthod 2006;76:1022-7 September 28, 2007 Dr. Kyoung-Im Kim
[초벌원고] How do you avoid decalcification in your teenage orthodontic patients with poor oral hygiene? No matter how much we try, every orthodontist has a few patients at any one time in their practice who have poor oral hygiene. Of course, the result is decalcification around the brackets. Decalcification is due to the acid produced by the caries-producing bacteria such as Streptococcus mutans. But, is there a way to prevent the attachment of these bacteria to the teeth around the brackets. What about application of a highly concentrated chlorhexidine varnish around the brackets? Would this decrease the ability for the bacteria to decalcify the teeth? That idea was developed in an article that was published in the November 2006 issue of the Angle Orthodontist. Since most orthodontists have a small number of these types of patients who could use this type of therapy, I decided to review this article for you this month.	[수정원고] How do you avoid decalcification in your teenage orthodontic patients with poor oral hygiene? No matter how much we try, every orthodontist has a few patients at any one time in their practice who have poor oral hygiene. Of course, the result is decalcification around the brackets. Decalcification is due to the acid produced by the caries-producing bacteria such as Streptococcus mutans. But, is there a way to prevent the attachment of these bacteria to the teeth around the brackets? What about application of a highly concentrated chlorhexidine varnish around the brackets? Would this decrease the ability for the bacteria to decalcify the teeth? That idea was developed in an article that was published in the November 2006 issue of the Angle Orthodontist. Since most orthodontists have a small number of these types of patients who could use this type of therapy, I decided to review this article for you this month.
The title of this article is “Antimicrobial Effectiveness of a Highly Concentrated Chlorhexidine Varnish in Teenagers with Fixed Orthodontic Appliances”. This paper was co-authored by Rengin Attin and four other research colleagues from the Departments of Operative and Preventive Dentistry at the University of Göttingen in Göttingen, Germany. The purpose of this study was to investigate the time period in which Streptococcus mutans in patients with densely colonized teeth and fixed orthodontic appliances return to baseline values after one single treatment with a highly concentrated chlorhexidine varnish. Sounds complicated, but the study design was rather straight-forward. The authors gathered a sample of 20 patients who were in fixed orthodontic appliances. But, to fit into this study protocol these individuals had to have high bacterial counts of S. mutans in their saliva. The average age of the sample was about 14 years, so it was a typical orthodontic population. Initially, each of these orthodontic patients received professional tooth cleaning. Then, a highly concentrated 36% chlorhexidine varnish was applied to all the teeth for 8 minutes. Then, two weeks later, each of these patients returned and the bacterial plaque around the teeth was cultured to determine the levels of S. mutans in the plaque in these areas. In other words, the question was “Does the concentrated chlorhexidine varnish reduce the levels of S. mutans in the plaque because of its antibacterial effect?”. And the answer to that question is “not really”. The authors did find that after two weeks, S. mutans counts were reduced as compared to the baseline values, but the reduction did not meet statistical significance. It was only a weak reduction in the amount of bacteria. So, there you have it. Even though a highly concentrated chlorhexidine varnish was applied to the tooth surfaces around the brackets, there was little measurable effect on the level of S. mutans in the plaque around these teeth. So, the authors concluded that a single chlorhexidine varnish application is not effective in suppressing S. mutans to a clinically relevant degree in patients with fixed orthodontic brackets.	The title of this article is “Antimicrobial Effectiveness of a Highly Concentrated Chlorhexidine Varnish in Teenagers with Fixed Orthodontic Appliances”. This paper was co-authored by Rengin Attin and four other research colleagues from the Departments of Operative and Preventive Dentistry at the University of Göttingen in Göttingen, Germany. The purpose of this study was to investigate the time period in which Streptococcus mutans in patients with densely colonized teeth and fixed orthodontic appliances return to baseline values after one single treatment with a highly concentrated chlorhexidine varnish. Sounds complicated, but the study design was rather straight-forward. The authors gathered a sample of 20 patients who were in fixed orthodontic appliances. But, to fit into this study protocol, these individuals had to have high bacterial counts of Strep. mutans in their saliva. The average age of the sample was about 14 years, so it was a typical orthodontic population. Initially, each of these orthodontic patients received professional tooth cleaning. Then, a highly concentrated 36% chlorhexidine varnish was applied to all the teeth for 8 minutes. Then, two weeks later, each of these patients returned and the bacterial plaque around the teeth was cultured to determine the levels of Strep. mutans in the plaque in these areas. In other words, the question was “Does the concentrated chlorhexidine varnish reduce the levels of Strep. mutans in the plaque because of its antibacterial effect?” And the answer to that question is “not really”. The authors did find that after two weeks, Strep. mutans counts were reduced as compared to the baseline values, but the reduction did not meet statistical significance. It was only a weak reduction in the amount of bacteria. So, there you have it. Even though a highly concentrated chlorhexidine varnish was applied to the tooth surfaces around the brackets, there was little measurable effect on the level of Strep. mutans in the plaque around these teeth. So, the authors concluded that a single chlorhexidine varnish application is not effective in suppressing Strep. mutans to a clinically relevant degree in patients with fixed orthodontic brackets.
If you’re interested in reading this article, you’ll find it in the November 2006 issue of the Angle Orthodontist.	If you’re interested in reading this article, you’ll find it in the November 2006 issue of the Angle Orthodontist.

Speech Outcome and Velopharyngeal Function in Cleft Palate: Comparison of Le Fort I Maxillary Osteotomy and Distraction Osteogenesis-Early Results Chanchareonsook N, Whitehill TL, Samman N Cleft Palate Craniofac J 2007;44:23-32 October 5, 2007 Dr. Yoon-Jung Choi
[초벌원고] One of the common problems in patients with cleft lip and palate is maxillary horizontal deficiency. This often requires surgical maxillary advancement at the time of definitive orthodontic treatment to create a reasonable occlusion and facial appearance. This need for maxillary advancement creates a problem at times for the speech and pharyngeal function of these individuals. Since advancement of the maxilla may make it harder to obtain adequate velopharyngeal closure for proper speech production.	[수정원고] One of the common problems in patients with cleft lip and palate is maxillary horizontal deficiency. This often requires surgical maxillary advancement at the time of definitive orthodontic treatment to create a reasonable occlusion and facial appearance. This need for maxillary advancement creates a problem at times for the speech and pharyngeal function of these individuals. Since advancement of the maxilla may make it harder to obtain adequate velopharyngeal closure for proper speech production.
Some authors have suggested that doing the maxillary advancement with distraction osteogenesis may be a better way to advance maxilla in cleft cases to provide the opportunity for soft tissue adaptation during the time of distraction. Since the evidence is not clear on whether distraction osteogenesis would be better for maxillary advancement in cleft patients, a team of researchers in Hongkong divided the clinical study to test the hypothesis. The early results of their study are reported in the January 2007 issue of the Cleft Palatte Craniofacial Journal in an article called "Speech Outcome and Velopharyngeal Function in Cleft Palate: Comparison of Le Fort I Maxillary Osteotomy and Distraction Osteogenesis-Early Results."	Some authors have suggested that doing the maxillary advancement with distraction osteogenesis may be a better way to advance the maxilla in cleft cases to provide the opportunity for soft tissue adaptation during the time of distraction. Since the evidence is not clear on whether distraction osteogenesis would be better for maxillary advancement in cleft patients, a team of researchers in Hong Kong divised a clinical study to test this hypothesis. The early results of their study are reported in the January 2007 issue of the Cleft Palate-Craniofacial Journal in an article called, "Speech Outcome and Velopharyngeal Function in Cleft Palate: Comparison of Le Fort I Maxillary Osteotomy and Distraction Osteogenesis-Early Results."
What makes this study design powerful is that the subjects, 22 cleft patients needing maxillary advancement, were randomly assigned to have either conventional Le Fort I surgery or to have advancement with distraction osteogenesis. In addition, the assessments of velopharyngeal function and speech were all made by blinded examiners. That is they did not know which treatment a subject had when making assessment the outcomes. So, all 22 subjects had assessment of speech and pharyngeal function prior to surgery and again three months after surgery and had a lateral cephalogram taken at both those times to measure the amount of actual maxillary advancement.	What makes this study design powerful is that the subjects, 22 cleft patients needing maxillary advancement, were randomly assigned to have either conventional Le Fort I surgery, or to have advancement with distraction osteogenesis. In addition, the assessments of velopharyngeal function and speech were all made by blinded examiners. That is, they did not know which treatment the subjects had when making assessments of the outcomes. So, all 22 subjects had assessment of speech and pharyngeal function prior to surgery and again three months after surgery and had a lateral cephalogram taken at both those times to measure the amount of actual maxillary advancement.
The result showed that although there is no difference in the plan the amount of advancement between the two groups the actual measured advancement was greater in the distraction group. The pharyngeal function or ability for the palate to seal off the nose from oral pharynx got better in some subjects, worsened in some, and were unchanged in some. The important finding was that there was no difference between the two types of the advancement surgery. The same was true for speech. Some improved, some got worse, and some were unchanged but was not related to the type of surgery. So this well designed clinical trial was not able to show that the speech or function was better with the distraction osteogenesis compare to conventional Le Fort I advancement at the least at these early follow up time. Even though the evidence from this study is strong due to the study design, comparisons are more difficult because of the significant difference in actual measured advancement between the two groups.	The results showed that although there was no difference in the planned the amount of advancement between the two groups, the actual measured advancement was greater in the distraction group. The pharyngeal function or ability for the palate to seal off the nose from the oral pharynx got better in some subjects, worse in some, and was unchanged in some. The important finding was that there was no difference between the two types of the advancement surgery. The same was true for speech. Some improved, some got worse, and some were unchanged but was not related to the type of surgery. So this well designed clinical trial was not able to show that the speech or function was better with distraction osteogenesis compared to conventional Le Fort advancement, at least at this early follow up time. Even though the evidence from this study is strong due to the study design, comparisons are more difficult because of the significant difference in actual measured advancement between the two groups.
The authors plan continued follow up of this two groups over a longer period of time, but at this time we can only say that the evidence to date does not demonstrate any advantage of using distraction osteogenesis rather than conventional Le Fort procedure for maxillary advancement in cleft cases. If you are interested in more details from randomized clinical trial, you can find entire article in the January 2007 issue of the Cleft Palatte Craniofacial Journal.	The authors plan continued follow-up of these two groups over a longer period of time, but at this time we can only say that the evidence to date does not demonstrate any advantage of using distraction osteogenesis rather than conventional Le Fort procedures for maxillary advancement in cleft cases. If you are interested in more details from this randomized clinical trial, you can find the entire article in the January 2007 issue of the Cleft Palate-Craniofacial Journal.

Microleakage Between Ceramic and Metal Brackets Bonded with a Conventional and an Antibacterial Adhesive System Arhun N, Arman A, et al. Angle Orthod 2006;76:1028-34 October 12, 2007 Dr. Hee-Kyoung Kim
[초벌원고] Does your bonding composite permit leakage underneath the bracket during orthodontic treatment? As orthodontist, we assume that the material we use to bond brackets to teeth actually seal the area beneath the bracket so that bacteria, saliva, or plaque cannot permit that area. But is that assumption really true? Can plaque and bacteria actually get beneath the orthodontic bracket with certain types of bonding materials. Does it make any differences if one uses metal brackets or ceramic brackets? If you have someone particularly young adult who is considering the placement of ceramic veneers as a post orthodontic treatment, you might want to use this article as a reference to help guide their decision. You can want conventional and an antibacterial adhesive system. This paper was coauthored by Neslihan Arhun and several other researchers associated from Baskent university in Ankara Turkey.	[수정원고] Does your bonding composite permit leakage underneath the bracket during orthodontic treatment? As orthodontists, we assume that the material we use to bond brackets to teeth actually seal the area beneath the bracket so that bacteria, saliva, or plaque cannot permeate that area. But is that assumption really true? Can plaque and bacteria actually get beneath the orthodontic bracket with certain types of bonding materials? Does it make any difference if one uses metal brackets or ceramic brackets? If you have someone, particularly a young adult, who is considering the placement of ceramic veneers as a post orthodontic treatment, you might want to use this article as a reference to help guide their decision. You can want conventional and an antibacterial adhesive system. This paper was coauthored by Neslihan Arhun and several other research associates from Baskent University in Ankara, Turkey.
The purpose of this study was to determine and compare the microleakage under both ceramic and metal brackets bonded with fluoride releasing antibacterial light cured self etch adhesive system compare to a conventional light cured adhesive system.	The purpose of this study was to determine and compare the microleakage under both ceramic and metal brackets bonded with a fluoride releasing, antibacterial, light-cured, self-etch adhesive system compared to a conventional light cured adhesive system.
The samples for this study was consisted with 40 intact human premolars that had been extracted for orthodontic purposes. The teeth were devided into 4 groups. The bonding material that were tested in this study were either Transbond XT or Clearfil Protect bond. This latter bonding material was developed recently and has a fluoride releasing and antibacterial effect. It`s also a self etching adhesive systems.	The sample for this study consisted of 40 intact human premolars that had been extracted for orthodontic purposes. The teeth were divided into 4 groups. The bonding materials that were tested in this study were either Transbond XT or Clearfil Protect bond. This latter bonding material was developed recently, and has a fluoride releasing antibacterial effect. It`s also a self-etching adhesive system.
Now the authors want to test each of these adhesive systems as well as determinate any differences occured between metal or ceramic bracket. So the sample was actually divided into 4 groups. In which each adhesive systems we were used to bond either metal brackets or ceramic brackets to the teeth. So this was laboratory study, after the bracket in the author thermocycle these bonded teeth for 500 cycles what that means is placing the bonded tooth in simulated oral environment with the deionized water. For each cycle the brackets were placed for 30 seconds in water and then 10 seconds out of water, and the process was repeated 500 times. Then a dye was applied to the teeth. The dye would be able to penetrate beneath any areas around the bracket to determine if any microleakage actually had occurred. Then the authors sectioned the teeth so the microleakage if present could be scored in different areas. Okay, what do you think happened? Does the adhesive allow microleakage and, if so is it greater around metal or ceramic brackets?	Now the authors wanted to test each of these adhesive systems as well as determine if any differences occured between metal or ceramic brackets. So, the sample was actually divided into 4 groups, in which each of these adhesive systems were used to bond either metal brackets or ceramic brackets to the teeth. So, this was laboratory study. After bracketing, the authors thermocycled these bonded teeth for 500 cycles. What that means is placing the bonded tooth in simulated oral environment with the deionized water. For each cycle, the brackets were placed for 30 second in water, and then 10 seconds out of water, and the process was repeated 500 times. Then, a dye was applied to the teeth. The dye would be able to penetrate beneath any areas around the bracket to determine if microleakage actually had occurred. Then, the authors sectioned the teeth so the microleakage, if present, could be scored in different areas. Okay, what do you think happened? Does the adhesive allow microleakage and, if so, is it greater around metal or ceramic brackets?
Question No.1 : Do either of these adhesives permit microleakage? the answer for this question is yes. And there were no statiscally significant differences between either of these two materials. Question 2 : Which brackets allow more microleakage metal or ceramic? Are those differences were not great. The metal brackets allowed more microleakages than the ceramic brackets. Question 3 : What is the significance of this microleakage? The authors of this study believed that the microleakage occurs and perhaps the antibacterial agent in the self etched adhesive system could be beneficial to avoid bacterial decalcification beneath the bracket seems these brackets have microleakage anyway. But the authors were very clear in stating that their study did not test the actual effectiveness of antibacterial adhesive systems. So in conclusion, the authors have clearly shown that all brackets showed microleakage and that metal bracket showed more microleakages than ceramic brackets. If you interested in reviewing and finding of this study, you can find it in November 2006 issues of the Angle Orthodontics.	Question No.1: Do either of these adhesives permit microleakage? The answer to that question is yes. And there were no statiscally significant differences between either of these two materials. Question 2: Which brackets allow more microleakage, metal or ceramic? Although the differences were not great, the metal brackets allowed more microleakage than the ceramic brackets. Question 3: What is the significance of this microleakage? The authors of this study believe that the microleakage occurs then perhaps the antibacterial agent in the self etched adhesive system could be beneficial to avoid bacterial decalcification beneath the bracket since these brackets have microleakage anyway. But the authors were very clear in stating that their study did not test the actual effectiveness of the antibacterial adhesive system. So in conclusion, the authors have clearly shown that all brackets showed microleakage and that metal brackets showed more microleakage than ceramic brackets. If you are interested in reviewing the findings of this study, you can find it in November 2006 issue of the Angle Orthodontist.

Which Orthodontic Archwire Sequence? A Randomized Clinical Trial Mandall NA, Lowe C, et al. Eur J Orthod 2006;28:561-6 October 19, 2007 Dr. Seok-Pil Kim
[초벌원고] Have you ever noticed that most orthodontists have their own favorite archwire sequence for alignment and that we all think ours is best? Some a big believer is put in flexible rectangular wires initially like copper Ni-Ti, while others use round wire predominantly until they able to place rectangular stainless steel working wire. Which of us are doing it right?	[수정원고] Have you ever noticed that most orthodontists have their own favorite archwire sequence for alignment, and that we all think ours is best? Some are big believers in putting flexible rectangular wires in initially, like copper Ni-Ti, while others use round wires predominantly until they able to place the rectangular stainless steel working wire. Which of us are doing it right?
A team of researchers, as Great Britain, decided put the question of archwire sequence to the test. Their results were published in the December 2006 issue of the European Journal of Orthodontics in an article called “Which orthodontic archwire sequence? A randomized clinical trial.” Because the researchers want to their result to be meaningful, they designed the study as a prospective clinical trial. This means that they recruited 154 adolescent patients to participate in the study and then assign them randomly to be treated with 1 of 3 archwire sequences. All the patients required full fixed orthodontic treatment and an 0.022 slot appliance was used for everyone.	A team of researchers in Great Britain, decided to put the question of archwire sequence to the test. Their results are published in the December 2006 issue of the European Journal of Orthodontics in an article called, “Which orthodontic archwire sequence? A randomized clinical trial.” Because the researchers wanted their results to be meaningful, they designed the study as a prospective clinical trial. This means that they recruited the 154 adolescent patients to participate in this study, and then assigned them randomly to be treated with 1 of 3 archwire sequences. All the patients required full fixed orthodontic treatment and an 0.022 slot appliance was used for everyone.
The 3 archwire sequences were as follows. Group A, received an initial 0.016 round Ni-Ti, then an 0.018 × 0.025 Ni-Ti, and then the full size working wire a 0.019 × 0.025 stainless steel. Group B, received a 0.016 round Ni-Ti, a 0.016 round stainless steel, a 0.020 round stainless steel, and then the full size 0.019 × 0.025 stainless steel. And Group C, started with a 0.016 × 0.022 copper Ni-Ti, then had a 0.019 × 0.025 Copper Ni-Ti and then the 0.019 × 0.025 stainless steel. The time for each patient to receive their 0.019 × 0.025 stainless steel wire was recorded. And the number of visits to reach that point was determined. In addition the researchers wanted to know if the arch wire sequences differed in patient discomfort or root resorption. So patients were asked to record their ratings of discomfort following each archwire placement, and root resorption was measured from periapical radiographs.	The 3 archwire sequences were as follows. Group A received an initial 0.016 round Ni-Ti, then an 0.018 × 0.025 Ni-Ti, and then the full size working wire a 0.019 × 0.025 stainless steel. Group B received a 0.016 round Ni-Ti, a 0.016 round stainless steel, a 0.020 round stainless steel, and then the full size 0.019 × 0.025 stainless steel. And Group C started with a 0.016 × 0.022 copper Ni-Ti, then had a 0.019 × 0.025 Copper Ni-Ti, and then the 0.019 × 0.025 stainless steel. The time for each patient to receive their 0.019 × 0.025 stainless steel wire was recorded. And the number of visits to reach that point was determined. In addition the researchers wanted to know if the archwire sequences differed in patient discomfort or root resorption. So patients were asked to record their ratings of discomfort following each archwire placement, and root resorption was measured from periapical radiographs.
Which of the 3 archwire sequences got the patients to the full size stainless steel wire most rapidly? The truth was that in this randomized trial there was no difference. There was a trend for sequence B to have slightly longer time, but it was not statistically significant. Sequence B, with a 0.016 Ni-Ti, 0.016 and 0.020 round stainless steel, and then a 0.019 × 0.025 stainless steel, did have more treatment visits than Sequence A, but not more overall time.	Which of the 3 archwire sequences got the patients to the full-sized stainless steel wire most rapidly? The truth was that in this randomized trial, there was no difference. There was a trend for Sequence B to have a slightly longer time, but it was not statistically significant. Sequence B, with a 0.016 Ni-Ti, 0.016 and 0.020 round stainless steel, and then a 0.019 × 0.025 stainless steel, did have more treatment visits than Sequence A, but not more overall time.
There was also no difference found in the patient degree of discomfort or the amount of measured resorption. Based on these result, it seems a specific archwire sequence is not a large determinant of initial alignment time, patient’s discomfort or root resorption. This suggest that we are free to make determinations of archwire sequence another factors such as cost, office routine, easy of placement, etc.	There was also no difference found in the patient's degree of discomfort or the amount of measured resorption. Based on these results, it seems as if the specific archwire sequence is not a large determinant of initial alignment time, patient discomfort or root resorption. This suggests that we are free to make determinations of archwire sequence on other factors such as cost, office routine, ease of placement, etc.
This study was designed to be able to fine treatment time differences as 3 months more. So this possible that certain archwire sequences may be more efficiency, but with a difference of a few weeks not a few months. So I guess at this point it is not surprising that many difference archwire sequences are propered by difference orthodontist. This reports would suggest that they all reached the rectangular working wire stage at about the same time. For more information about this randomized clinical trial from Great Britain, take it detail look at this article by Mandall and associate in the December 2006 European Journal of Orthodontics.	This study was designed to be able to find treatment time differences of 3 months of more. So it is possible that certain archwire sequences may be more efficient, but with a difference of a few weeks, not a few months. So, I guess at this point it is not surprising that many different archwire sequences are preferred by different orthodontists. This report would suggest that they all reached the rectangular working wire stage at about the same time. For more information about this randomized clinical trial from Great Britain, take a detailed look at this article by Mandall and associate in the December 2006 European Journal of Orthodontics.

The Passion for dentistry Levin RP J Am Dent Assoc 2007;138:104-5 October 26, 2007 Sang-Woon Jeon
[초벌원고] Do you remember how exited you were to start practicing orthodontics when you finished your residency. Assuming you have been in practice for a numbers of years, do you still feel that excitement when you go to work each day? If you don't it is probably not that unusual. You may have got in to the point that you are just getting through the day rather looking forward to going to work each day. If you have lost some of your excitement about practicing orthodontics, I would suggest that you read an article titled “A better practice, a passion for dentistry” by Roger Levin which appeared in the January 2007 issue of the journal of the American Dental Association. In this article Dr. Levin suggest some specific steps that you can take to reinvigorate yourself and your practice.	[수정원고] Do you remember how excited you were to start practicing orthodontics when you finished your residency? Assuming you have been in practice for a number of years, do you still feel that excitement when you go to work each day? If you don't, it is probably not that unusual. You may have gotten to the point that you are just getting through the day, rather than looking forward to going to work each day. If you have lost some of your excitement about practicing orthodontics, I would suggest that you read an article titled, “A better practice, a passion for dentistry” by Roger Levin, which appeared in the January 2007 issue of the journal of the American Dental Association. In this article, Dr. Levin suggests some specific steps that you can take to reinvigorate yourself and your practice.
These include creating a vision statement, establishing clear goals, designing appropriate systems, providing training and continuing education opportunities for staff members and using advisors when needed. These seem like pretty simple and basic steps to take and they are also practical common sense suggestions that are easy to implement. It is not unusual for orthodontists who are excited about practicing orthodontics to get bogged down in many of the none treatment management activities of the practice.	These include creating a vision statement, establishing clear goals, designing appropriate systems, providing training and continuing education opportunities for staff members and using advisors when needed. These seem like pretty simple and basic steps to take, and they are also practical common sense suggestions that are easy to implement. It is not unusual for orthodontists who are excited about practicing orthodontics to get bogged down in many of the none treatment management activities of the practice.
Dr. Levin notes that typically, the less a dentist has to do outside patient related activities the less stressful a practice becomes. As your staff is able to resolve more of the day_to_day responsibilities, of running your practice, typically the need for micromanaging becomes unnecessary, the quality of care increases, and stress level decrease dramatically. Also having a vision and establishing clear goals establishes a purpose for the future of your practice which can leave you more energized and excited as oppose to simply showing up to work each day. Although this article was directed primarily at general data, I believe it applies as equally as well to orthodontists if you are concerned about losing your enthusiasm for practicing each day I would strongly suggest that you read this article.	Dr. Levin notes that typically, the less a dentist has to do outside patient related activities, the less stressful a practice becomes. As your staff is able to resolve more of the day-to-day responsibilities of running your practice, typically the need for micromanaging becomes unnecessary, the quality of care increases, and stress levels decrease dramatically. Also, having a vision and establishing clear goals establishes a purpose for the future of your practice which can leave you more energized and excited as opposed to simply showing up to work each day. Although this article was directed primarily at general dentists, I believe it applies as equally as well to orthodontists. If you are concerned about losing your enthusiasm for practicing each day, I would strongly suggest that you read this article.
You can find it in the January 2007 issue of the journal the American Dental Association.	You can find it in the January 2007 issue of the Journal of the American Dental Association.

Enamel Deminelalization in Primary and Permanent Teeth Wang LJ, Tang R, et al. J Dent Res 2006;85:359-63 November 16, 2007 Dr. Jin-myoung Song
[초벌원고] Do you treat many patients during the mixed dentition? Although the idea of early treatment has been challenged recently based upon randomized clinical trials, I think the most orthodontist still do some early orthodontic treatment. So if you do render early treatment, then it's routine for you to place bands and brackets on permanent teeth while primary teeth may still be present the in the dental arch but not bracketed.	[수정원고] Do you treat many patients during the mixed dentition? Although the idea of early treatment has been challenged recently based upon randomized clinical trials, I think that the most orthodontists still do some early orthodontic treatment. So if you do render early treatment, then it's routine for you to place bands and brackets on permanent teeth while primary teeth may still be present in the dental arch, but not bracketed.
In fact, sometimes I think our arch wires tend to prevent cleaning of some of the buccal primary tooth surfaces. Is this a problem? If plaque forms on these primary teeth will there be a higher tendency for decalcification on these primary tooth surfaces? And is there any difference between the decalcification on a primary compared to a permanent tooth surface? Is there a structural difference in primary and permanent tooth enamel that renders one or the other more susceptible to decalcification?	In fact, sometimes I think our archwires tend to prevent cleaning of some of the buccal primary tooth surfaces. Is this a problem? If plaque forms on these primary teeth, will there be a higher tendency for decalcification on these primary tooth surfaces? And is there any difference between the decalcification on a primary compared to a permanent tooth surface? Is there a structural difference in primary and permanent tooth enamel that renders one or the other more susceptible to decalcification?
You know, I didn't know the answer to that question, but I found it in an article that was published to the April 2006 issue of the Journal of Dental Research. I thought this would be an interesting article for orthodontists to be aware of, since we do occasionally treat patients with the mixture of primary and permanent teeth. The title of the article is "Enamel Demineralization in Primary and Permanent Teeth". The study comes out of the State University of New York in Buffalo. The lead author is Dr. Wang who is from the Department of Chemistry at his university.	You know, I didn't know the answer to that question, but I found it in an article that was published in the April 2006 issue of the Journal of Dental Research. I thought this would be an interesting article for orthodontists to be aware of, since we do occasionally treat patients with a mixture of primary and permanent teeth. The title of the article is "Enamel Demineralization in Primary and Permanent Teeth". This study comes out of the State University of New York in Buffalo. The lead author is Dr. Wang who is from the Department of Chemistry at his university.
The purpose of the study was to determine the susceptibility to acid-induced demineralization of enamel in vitro, and the difference is in ultra-structure and dissolution of primary and permanent tooth enamel. In order to accomplish their objective, the authors gathered twenty freshly extracted primary and permanent molars. First of all, the roots were separated from the crowns and the crown portion was used in the experiment. Now this was a laboratory study. The authors placed solution of hydrochloric acid and sodium chloride to the tooth surfaces to measure dissolution of the enamel of primary compared to permanent teeth. Then scanning electron microscopy was used to calculate the differences in decalcification between the two groups.	The purpose of this study was to determine the susceptibility to acid-induced demineralization of enamel in vitro, and the differences in ultra-structure and dissolution of primary and permanent tooth enamel. In order to accomplish their objective, the authors gathered twenty freshly extracted primary and permanent molars. First of all, the roots were separated from the crowns and the crown portion was used in the experiment. Now this was a laboratory study. The authors placed solution of hydrochloric acid and sodium chloride to the tooth surfaces to measure dissolution of the enamel of primary compared to permanent teeth. Then, scanning electron microscopy was used to calculate the differences in decalcification between the two groups.
What are the authors find? Is primary enamel more susceptible to decalcification by the acid in dental plague than permanent enamel? The answer of the question is "yes" definitely. The authors clearly found that the demineralization rates showed significant differences with primary enamel having greater susceptibility to dissolution compared to permanent enamel. Actually I wouldn't have thought there would be a difference, but there was.	What did the authors find? Is primary enamel more susceptible to decalcification by the acid in dental plaque than permanent enamel? The answer to that question is "yes, definitely." The authors clearly found that the demineralization rates showed significant differences, with primary enamel having greater susceptibility to dissolution compared to permanent enamel. Actually, I wouldn't have thought there would be a difference, but there was.
What is this suggested to us? When we are treating patients in the mixed dentition and our arch wires prevent patients from cleaning their primary teeth, they, in fact, are at greater risk of having decalcification in breakdown of their primary teeth than the permanent teeth. Now, of course, ultimately this is not a big problem, since the primary teeth were exfoliated and be replaced by the permanent successors. But in some of these patients that are congenitally missing for example second premolars, we may want to maintain the primary teeth for some time. Therefore, efforts should be made during orthodontic treatment to avoid appliances that would make it more difficult for patients to clean and maintain their primary teeth.	What does this suggest to us? When we are treating patients in the mixed dentition and our archwires prevent patients from cleaning their primary teeth, they, in fact, are at greater risk of having decalcification and breakdown of their primary teeth than the permanent teeth. Now, of course, ultimately this is not a big problem, since the primary teeth will exfoliated and be replaced by the permanent successors. But in some of these patients that are congenitally missing for example, second premolars, we may want to maintain the primary teeth for sometime. Therefore, efforts should be made during orthodontic treatment to avoid appliances that will make it more difficult for patients to clean and maintain their primary teeth.
If you like to read this interesting article comparing the enamel dissolution of primary versus permanent teeth, you will find it in the April 2006 issue of the Journal of Dental Research.	If you'd like to read this interesting article comparing the enamel dissolution of primary versus permanent teeth, you will find it in the April 2006 issue of the Journal of Dental Research.

Longitudinal development of caries lesions after orthodontic treatment evaluated by quantitative light-induced fluorescence Monique H. van der Veen et all Am J Orthod Dentofacial Orthop 2007;131:233-8 November 23, 2007 Dr. Gi-Soo Uhm
[초벌원고] I suspect that there is no one listening to this month's program who has not had a patient develop a white spot carious lesion druing orthodontic treatment. When you deband a patient with a white spot lesion, what naturally happens to this lesion after debanding. A study title “Longitudinal development of caroius lesions after orthodontic treatment evaluated by quantitative light-induced fluorescence” by Monique H. van der Veen et all which appeared in the Feb. 2007 issue of the American Journal of Orthodontics & Dentofacial Orthopedics addressed this question.	[수정원고] I suspect that there is no one listening to this month's program who has not had a patient develop a white spot caries lesion during orthodontic treatment. When you deband a patient with a white spot lesion, what naturally happens to this lesion after debanding? A study titled, “Longitudinal development of caries lesions after orthodontic treatment evaluated by quantitative light-induced fluorescence” by Monique van der Veen et al., which appeared in the Feb. 2007 issue of the American Journal of Orthodontics & Dentofacial Orthopedics addressed this question.
In this study, the author evaluated the sample of fifty-eight consecutive recruited patients who were at least twelve years old and who had been treated with a fixed orthodontic appliance for at least one year. In the department of orthodontics at the Academic Center for Dentistry in Amsterdam, the Netherland. In this study, the authorused quantitative light induced fluorescence to study the natural behavior of white spot lesions that develop in this group of orthodontic patients.	In this study, the authors evaluated a sample of fifty-eight consecutively recruited patients who were at least twelve years old and who have been treated with a fixed orthodontic appliance for at least one year in the Department of Orthodontics at the Academic Center for Dentistry in Amsterdam, The Netherlands. .In this study, the authors used quantitative light-induced fluorescence to study the natural behavior of white spot lesions that developed in this group of orthodontic patients.
Quantitative light-induced fluorescence allows researchers to monitor changes in enamel overtime and document mineral changes in incipient enamel lesion. White spot lesions were evaluated at the debracketing visit and two retention visits, 6 weeks and 6 months after debracketing. I should know that the dentists for the participants in this study were informed of their participation in the study and asked not to administer extra fluoride during the study. The presents or absence and the extent of lesions on the buccal surfaces of all teeth except the 2nd and 3rd molars were determined at the debracketing visit and at 6 weeks and 6 months after debracketing.	Quantitative light-induced fluorescence allows researchers to monitor changes in enamel over time and document mineral changes in incipient enamel lesions. White spot lesions were evaluated at the debracketing visit and two retention visits, 6 weeks and 6 months after debracketing. I should note that the dentists for the participants in this study were informed of their participation in this study and asked not to administer extra fluoride during the study. The presence or absence and the extent of lesions on the buccal surfaces of all teeth except the second and third molars were determined at the debracketing visit and at 6 weeks and 6 months after debracketing.
What do you think happen to this lesions when they relapse to remineralize on their own? Well, the answer to this question is good news and bad news. The good news is that a small lesion improvement was seen 6 weeks after debracketing and a further lesion improvement was seen after 6 month. Surprisingly, incipient lesions on average showed a smaller improvement than larger lesion. The bad news is that despite the small overall lesion improvement, some lesions progressed for became worse and nearly 10% of lesions followed longitudinally showed significant progression of caries after debracketing. The bottom line of this study is that removal of plaque stagnation site or removal of fixed appliances alone is not enough to induce adequate remineralization of many white spot lesions. I found it very interesting that the severity of the lesion did not hamper its ability for remineralization. And significant improvement was seen even in more advanced lesions. The author said that they had no basis for understanding why the incipient lesions often progress more than the advanced lesions. The take-home message from this study is that some white spot lesions will probably improve after debracketing while others will get worse and you just have to observe them under individual basis. You can find this study in the Feb. 2007 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.	What do you think happened to these lesions when they were left to remineralize on their own? Well, the answer to this question is good news and bad news. The good news is that a small lesion improvement was seen 6 weeks after debracketing and a further lesion improvement was seen after 6 months. Surprisingly, incipient lesions, on average, showed a smaller improvement than larger lesions. The bad news is that despite the small overall lesion improvement, some lesions progressed or became worse and nearly 10% of the lesions followed longitudinally showed significant progression of caries after debracketing. The bottom line of this study is that removal of plaque stagnation sites by removal of fixed appliances alone is not enough to induce adequate remineralization of many white spot lesions. I found it very interesting that the severity of the lesion did not hamper its ability for remineralization. And significant improvement was seen even in more advanced lesions. The authors said that they had no basis for understanding why the incipient lesions often progressed more than the advanced lesions. The take-home message from this study is that some white spot lesions will probably improve after debracketing, while others will get worse and you just have to observe them on an individual basis. You can find this study in the Feb. 2007 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Evaluation of the Effects of Rapid Maxillary Expansion in Growing Children Using Computer Tomography Scanning A Pilot Study Podesser B, Williams S, et al. Eur J Orthod 2007;29:37-44 November 30, 2007 Dr. Kyung-Min Lee
[초벌원고] Most of the studies dental and skeletal contributions to expansions using rapid palatal expanders have been done using dental casts and PA cephalograms. This technique makes measurement of the skeletal contributions difficult due to image magnification and thus not allow direct measurement of sutural expansion. It would be much easier to measure the dental and skeletal contributions using some type of CT imaging. but this has been difficult due to the radiation exposure. A small pilot study done in Austria was able to get review board approval to take before and after CT images on children undergoing RPE. The results of this pilot study are published in an article called Evaluation of the Effect of Rapid Maxillary Expansion in Growing Children Using Computer Tomography Scanning, A Pilot study. The article appears in February 2007 issue of the European Journal of Orthodontics.	[수정원고] Most of the studies of dental and skeletal contributions to expansion using rapid palatal expanders have been done using dental casts and PA cephalograms. This technique makes measurement of the skeletal contributions difficult due to image magnification and does not allow direct measurement of sutural expansion. It would be much easier to measure the dental and skeletal contributions using some type of CT imaging, but this has been difficult due to the radiation exposure. A small pilot study done in Austria was able to get review board approval to take before and after CT images on children undergoing RPE. The results of this pilot study are published in an article called, "Evaluation of the Effects of Rapid Maxillary Expansion in Growing Children Using Computer Tomography Scanning: A Pilot Study." The article appears in the February 2007 issue of the European Journal of Orthodontics.
The study sample was limited to 9 children that were about 8 years old and were going to have rapid palatal expansion in the mixed dentition. Records including the low dose CT image were taken before treatment and after active expansion. The expansion was done with bonded expander that was activated 2 turns per day and tell to screw activation reached 7mm. According to the method section of the paper, the expander was removed after active expansion to allow for post-expansion records, and then replaced on left for 3 to 5 months of stabilization. The CT imaging allowed for construction of frontal plane sections through the canine and molar regions that could be measured. Measurement included the width of the suture, width of maxillary skeletal base, and the width of the molars.	The study sample was limited to 9 children that were about 8 years old and were going to have rapid palatal expansion in the mixed dentition. Records, including the low dose CT image, were taken before treatment and after active expansion. The expansion was done with a bonded expander that was activated 2 turns per day until the screw activation reached 7 mm. According to the method section of the paper, the expander was removed after active expansion to allow for post-expansion records, and then replaced and left for 3 to 5 months of stabilization. The CT imaging allowed for construction of frontal plane sections through the canine and molar regions that could be measured. Measurements included the width of the suture, width of maxillary skeletal base, and the width of the molars.
The results were somewhat surprising, although the screw was reportedly expanded 7mm, the expansion of the molars was measured at less than 4mm on average. The sutural expansion was measured at 1.6mm, and the maxillary skeletal base expansion at 1.7mm, so the overall skeletal contribution to the expansion was only about 50%. This was somewhat surprising since common wisdom would expect a larger contribution of skeletal expansion using RPE in mixed dentition. I have a significant question about the method that may have affect the outcome of this study.	The results were somewhat surprising, although the screw was reportedly expanded 7 mm, the expansion of the molars was measured at less than 4 mm on average. The sutural expansion was measured at 1.6 mm, and the maxillary skeletal base expansion at 1.7 mm. So the overall skeletal contribution to the expansion was only about 50%. This is somewhat surprising since common wisdom would expect a larger contribution of skeletal expansion using RPE in the mixed dentition. I have a significant question about the method that may have affected the outcome of this study.
Remember that I said that the expander was removed after active expansion for the records to be taken. This was probably important to reduce CT artifacts, but It makes me wonder about how long the appliance was out of the mouth before the CT image was taken. It seems to me that immediately after active expansion, the expansion is quite unstable. That is why we leave the appliance in for stabilization. How much change in width would occur in a short time when the appliance was removed at that stage? I would like to see this study repeated with imaging done without appliance removal to see if the results were differ. My guesses that may change results significantly.	Remember that I said that the expander was removed after active expansion for the records to be taken. This was probably important to reduce CT artifacts, but it makes me wonder about how long the appliance was out of the mouth before the CT image was taken. It seems to me that immediately after active expansion, the expansion is quite unstable. That is why we leave the appliance in for stabilization. How much change in width would occur in a short time when the appliance is removed at that stage? I would like to see this study repeated with imaging done without appliance removal to see if the results would differ. My guess is that may change results significantly.
If you're like to more information about this study of rapid palatal expansion in children, you can find this article from Austria in the February 2007 issue of the European Journal of Orthodontics.	If you'd like more information about this study of rapid palatal expansion in children, you can find this article from Austria in the February 2007 issue of the European Journal of Orthodontics.

The Influence of Drugs and Systemic Factors on Orthodontic Tooth Movement Gameiro GH, Pereira-Neto JS, et al. J Clin Orthod 2007;41:73-8 December 7, 2007 Dr. Mi-young Kim
[초벌원고] As we learn more about the details of orthodontic tooth movement, we also understand more about possible factors that may affect the speed of this amazing event that allows us to do what we do everyday. Some of the factors that may influence bone metabolism are certain commonly prescribed drugs and the level of some systemic hormones. Although we still have much to learn about all of these mechanisms, we do have some information about how these drugs and systemic factors may affect the speed of our treatment. The review of this information was the subject of an article that appears in the February 2007 issue of the Journal of Clinical Orthodontics called, “The Influence of Drugs and Systemic Factors on Orthodontic Tooth Movement”.	[수정원고]
The article specifically reviews 4 types of drugs and 5 systemic factors or hormones which may affect tooth movement. The first type of medication is the commonly seen non-steroidal anti-inflammatory drugs, such as ibuprofen. These drugs tend to inhibit prostaglandins which are important in the tooth moving process and therefore can reduce the rate of tooth movement. Acetaminophen or Tylenol is a slightly different type of drug that can still be effective for pain relief but this not appear to affect tooth movement.
Corticosteroids are another commonly used drugs that some of your patients may be taking. These steroids appeared to have a different affect on bone metabolism whether taken short term or long term. If taken short term, such as phrenics medication having in acute episode, the drug may inhibit bone remodeling and reduce short term tooth movement. However, if taken long term, say, for immunosuppression in a transplantation, the corticosteroids may actually increase bone turnover and could potentially allow for more rapid tooth movement.
Bisphosphonates are the other type of drug discussed in this review. As we all know by now, these drugs use most commonly to treat osteoporosis in postmenopausal women inhibit osteoclastic activity and could reduce or halt tooth movement.
The systemic factors discussed in this article can either inhibit or enhance tooth movement. Estrogen can potentially reduce tooth movement by slowing bone turnover. On the other hand, increased levels of thyroid hormone, parathyroid hormone, relaxin, or vitamin D could possibly increase bone activity and the rate of tooth movement.
The take-home message from this review is that a number of drugs and systemic factors have the potential to dramatically affect the rate of orthodontic tooth movement. If the practitioner is aware of these potential affects, the patients and parents can be properly informed and the treatment intervals can be adjusted appropriately. I have treated a couple of adolescent males on a bisphosphonate for osteogenesis imperpecta and it was obvious that the medication did affect the rate of tooth movement. Fortunately, I'd informed families in advance that this was likely to be the case and so nobody would surprised when treatment took longer than would normally be expected.
If you would like to read this review about how drugs and hormones could affect tooth movement in your patients, this article is available in the February 2007 issue of the Journal of Clinical Orthodontics.

Technique to Manage Simultaneously Impacted Mandibular Second and Third Molars in Adolescent Patients Motamedi MHK, Shafeie HA. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:464-466 December 14, 2007 Dr. Suk-cheol Lee
[초벌원고] Consider this clinical situation. You have a fourteen year old male presenting for routine orthodontic treatment with the chief complaint of regular alignment. Everything seems pretty straight forward except that on the lower left, the second molars impacted and the third molars now slightly more vertically advanced than the second molar. Your assessment is at the second molars impacted because of obstruction not some failure of eruption. Do you have the third molar removed now, or because the third molar is making progress, do you take out the second molar knowing that it may delay the completion of your treatment to do the final alignment of the third molar? A recent article published in the journal of oral surgery, oral medicine, oral pathology, oral radiology and endodontology has suggested a technique to deal with this situation.	[수정원고]
The authors acknowledge the difficulty in deciding which of the two molar to remove in this type of case but believe that the best choice is usually to remove the third molar and orthodontically position the second. Here is what they suggest for the surgical procedure. First, a full thickness flap is elevated over the impacted molars. Next, the buccal bone is removed over the third molar to allow access for removal. The third molar is then sectioned and removed. The buccal bone around the second molar is then removed to expose the entire crown all the way to the cervical margin. The bone is then leveled on the buccal and to the distal. This is where this technique is somewhat unique. Normally, it would be difficult to keep the crown of the second molar exposed to allow the bonding by orthodontists. The authors keep the flap position apically by drilling a small hole in the cortical bone margin just distal to the second molar crown. A suture is passed through this hole and used to hold the flap in this reposition spot. The end result is that the crown of the tooth stays exposed and the attached tissue is conserved for better periodontal health. This maybe a technique to discuss with your surgeon to have as an option the next time you run across the clinical situation of having impacted lower second and third molars.
The article presents a case report demonstrating this technique and radiographically showing an excellent result in a patient where this situation occurred bilaterally. More specific information about the surgical technique to help in the management the impacted lower second and third molars can be found in the April 2007 issue of the Tripleo. The article is called technique to manage simultaneously impacted mandibular second and third molars in adolescent patients. I would suggest you make a copy of this article for your local oral surgeons and use it as basis to discuss options produce clinical challenge.

Cervical Headgear Effects on the Morphology of the Cervical Vertebrae and Cervical Posture Yavuz I, Uzun B, et al. Angle Orthod 2007;77:273-9 December 28, 2007 Dr. Hak-hee Choi
[초벌원고] Do you use cervical headgear in the treatment of the class II malocclusions? Although this type of plan is not that popular among patients, I think many orthodontists still use cervical headgear and find that it is effective at correcting class II malrelationships in the cooperative child. Of course it requires growth. So here is my question. If child wears cervical head gear well during the growth interval, will the force around neck region cause any morphologic changes in the cervical vertebrae? Now, that is an interesting question. I found answer in the study that was published in the March 2007 issue of Angle Orthodontist. I thought this would be an interesting study for us to review. The title of the article is "Cervical Headgear Effects on the Morphology of the Cervical Vertebrae and Cervical Posture". This study was co-authored by Ibrahim Yavuz and Betul Uzun from the Department of Orthodontics at the Turkey University in Erzurum, Turkey.	[수정원고]
The purposes of this study were to, first of all, examine the changes in morphology of cervical vertebrae and number two, to evaluate cervical posture after the use of cervical headgear and to compare this changes with an untreated control group. The sample consisted of 30 subjects, 15 females and 15 males who receiving cervical headgear therapy as a part of their orthodontic treatment. All of subjects had class II malocclusions and all around age of 12 years. All subjects wore the headgear for an average of about 16 to 18 hours per day and the length of wearing the headgear was about 10 months. Before and after treatment cephalometric radiographs were taken and various measurements were created to determine the morphology and also the posture of the cervical vertebrae on the radiograph. These were then compared between the group wearing the headgear and control group that did not wear any headgear over that same period of time.
Okay, what did authors find? First, let's just take the question of morphology of cervical vertebrae. Was there any difference between the control and headgear groups? The answer to the question is definitely yes, but the difference was primarily at the change that occured because of growth, and not because of the force of neck strap of the cervical headgear. Second question, did the cervical posture of these patient show any change because the cervical headgear was being worn? The answer to the question is no. The authors found that cervical posture exhibited no significant changes over the 10 months period in either the control or the group treated with cervical headgear.
So, there we have it. The authors found no significant change between the groups when cervical headgear was or was not worn. There are no effects on cervical vertebrae morphology or cervical posture. So if you one of those orthodontist who still uses cervical headgear therapy regularly on your patients, you need not worry about altering the morphology of the patient's neck. This study shows that at least over one year period time there were no changes effected by the neck strap of the cervical headgear.
If you are interested in reviewing the study, you can find it in the March 2007 issue of the Angle Orthodontists.

Mechanical Properties and Surface Characterization of Beta Titanium and Stainless Steel Orthodontic Wire Following Topical Fluoride Treatment Walker MP, Ries D, et al Angle Orthod 2007;77:342-8 January 4, 2008 Dr. Gi-Soo Uhm
[초벌원고] Do you recommend topical fluoride treatment for your adolescent patients to perhaps have poor oral hygiene? We know that topically applied fluoride will cause remineralization of enamel and it does have an affect on bacteria and the destruction of tooth surface by decalcification. So many orthodontists will recommend one of the two popular topical fluorides for their patients to use in between their orthodontic appointments. One of these is called Phos-flur gel made by Colgate Pharmaceuticals, the other is Prevident 5000 which is also made by Colgate. The Phos-flur gel has a lower pH at 5. The Prevident is a neutral solution with pH of about 7. And if these are used, they can be very effective to prevent decalcification and caries during orthodontics.	[수정원고]
But here's the concern; what's the effect of repeated use of fluoride on arch wires? After all, this is a chemical which could influence the metallic properties of orthodontic appliances. Could this have a potential negative effect on the surface of an arch wire as well as the arch wire's ability to align the teeth? Those questions were addressed in the study that was published in the March 2007 issue of the Angle orthodontist. The title of this article is “Mechanical Properties and Surface Characterization of Beta Titanium and Stainless Steel Wire following Topical Fluoride Treatment.”
This study's co-authored by Mary P. Walker and Katherine Kula, from the department of orthodontics at the university of Missouri in Kansas City. The purpose of their study was to evaluate the effect of fluoride prophylactic agents on the loading and unloading the chemical properties and surface quality of beta titanium and stainless steel orthodontic wires. In this research project, two topical fluorides were used. As I mentioned earlier, one was Phos-flur gel and the other was Prevident 5000. Two arch wires were tested; one being the stainless steel and the other a beta titanium wire. This experiment was done in the laboratory. Samples of each wire were placed in each of these different topical fluorides for about one and a half hours.
You see the authors were trying to simulate a daily one-minute application of the topical fluoride in between orthodontic appointments which would end up being about 30 days in length. Then after removing the wire from the topical fluoride, they were rinsed and placed in a water bath for mechanical testing. The mechanical testing involved bending of the arch wire using a three point bending test with the universal testing machine. You see what this tester's to measure flexural loading which provides a collective measure both compressive and tensile stress on each arch wire. So for each specimen, the authors assessed the flexural stress as a function of flexural strain. Lastly the authors viewed each of the arch wires under a scanning electron microscope to determine if any corrosion occurred on the surface of the arch wires.
What did these authors find? First question; was there a change in the flexural stress of the arch wires by placing the arch wires in the topical fluoride? The answer is definitely yes. Both the beta titanium and the stainless steel orthodontic wires exhibited a statistically significant decrease in their unloading mechanical properties. Because unloading forces produce tooth movement, this decrease could actually affect the speed of movement of the teeth, because the fluoride gel renders the arch wire less effective.
Question number two; did this fluoride treatments affect the surface of the arch wire? The answer of that question is also yes. In that both arch wires exhibited qualitative surface changes following exposure to both neutral and acidulated phosphate fluoride gels.
Question number three; was there any difference between the fluoride gels? And the answer of that question is no. Both forms of fluoride appeared to affect the arch wires similarly. So if you are using topical fluoride, watch out for the changes occurring in your arch wires.
If you would like to review this information, you will find this study in the March 2007 issue of the Angle orthodontist.
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Periodontal response to early uncovering, autonomous eruption, and orthodontic alignment of palatally impacted maxillary canines Schmidt AD, Kokich VG. Am J Orthod Dentofacial Orthop 2007;131:449-55 January 11, 2008 Dr. Kyung-Min Lee
[초벌원고] In the past, most orthodontists routinely treated impacted maxillary canines by uncovering them, placing an attachment and activating them with some form of elastic or spring force to initiate orthodontic movement. More recently many orthodontists have modified their treatment of impacted maxillary canines by adopting the procedure that involves open exposure of palatally impacted canine and allowing natural eruption of the canine prior to initiating comprehensive orthodontic treatment.	[수정원고]
This procedure usually involves uncovering the palatally impacted canine by raising a mucoperiosteal flap and removing all palatal bone down to the cementoenamel junction so that the tooth can erupt unimpeded. A hole is made when the flap is replaced and sometimes periodontal dressing is placed to prevent soft tissue from covering the exposed maxillary canine crown. No active force is placed on the impacted canine and it is allowed to erupt on its own. Once it has erupted to approximately the level of the occlusal plane, an attachment is placed on canine and active orthodontic treatment is initiated. This early uncovering of impacted canine and allowing them spontaneously to erupt has several potential advantages including fewer subsequent re-exposures, shorter treatment time, and improved hygiene during treatment. What are the periodontal effects of this procedure? This question was addressed in an article titled “Periodontal response to early uncovering, autonomous eruption, and orthodontic alignment of palatally impacted maxillary canines” by Andrew D. Schmidt and Vincent G. Kokich which appeared in the April 2007 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.
In this study, the authors evaluated 16 patients with unilaterally impacted canines and 6 with bilaterally impacted canines treated with passive eruption. The visible plaque index, the gingival bleeding index, and the distance from cementoenamel junction to the gingival margin was measured, and used to compare the periodontal status of the treated canines and adjacent teeth with the contralateral control teeth. Additionally periapical radiographs were used to measure crestal bone height and root length. When the treatment and control teeth was statistically evaluated, no differences were found in gingival bleeding index or the visible plaque index when the impacted canines and adjacent teeth were compared with control teeth. Probing attachment level was found to be significantly greater at the distoligual aspect of the lateral incisors on the impacted side and distobuccal aspect of the premolars on the impacted side when compared with control teeth but these differences were small. No other significant differences in probing attachment level were found. Crestal bone height was lower at the distal and mesial side of lateral incisor adjacent to the impacted canine when compare to the contralateral lateral incisors. However again these differences were very minimal and less than a millimeter. No differences in crestal bone height or probing attachment level were found around the previously impacted canines when compared with control canines.
The bottom line of the study is that treating palatally impacted canines with open surgical exposure, natural eruption of the canine and orthodontic alignment has minimal effects on periodontium. Also although no direct comparison was made in this study between canines treated in this manner, and canines treated in the traditional manner of surgical exposure and an immediate attachment. Based on previous studies, it appears that the periodontal effects of treating impacted canine with passive eruption are less than treating canines with traditional manner. The bottom line is that you can take advantage of all the benefits of using passive eruption for impacted maxillary canines without worrying about any significant negative periodontal effects.
If you are not using early uncovering and passive eruption of impacted maxillary canines in your office, I strongly recommend that you read this article which appears in the April 2007 issue of the American Journal of Orthodontics and Dentofacial Orthopedics and contains excellent photographs of this procedure.

Long-Term Follow-Up after Maxillary Distraction Osteogenesis in Growing Children with Cleft Lip and Palate Huang C-S, Harikishnan P, et al. Cleft Palate Craniofac J 2007;44:274-7 January 18, 2008 Dr. Mi-young Kim
[초벌원고] Distraction osteogenesis has become a more common treatment approach for maxillary deficiency in cleft lip and palate patients. As orthodontists, it is important for us to know about the stability of the maxillary distraction in these patients since we are usually trying to finish the occlusion in the post-treatment period. A paper published in the May 2007 issue of the Cleft Palate Craniofacial Journal provides us with some additional information about the stability of distraction treatment in cleft children. The paper comes from Taiwan and it's titled “Long Term Follow-Up after Maxillary Distraction Osteogenesis in Growing Children with Cleft Lip and Palate”.	[수정원고]
This is a small retrospective study which has characteristics of many cleft studies. 6 children about 10 years of age made up the study group. The children had unilateral or bilateral cleft lip and palate and were evenly divided between boys and girls. Lateral cephalometric films were available from just before distraction, immediately after distraction, six month later and more than one year later. Careful cephalometric measurements were used to define the maxillary dental and skeletal position. The distraction was done using a high Le FortⅠ osteotomy and then external distracter mechanism pulling on the maxillary dentition. All subjects had concurrent orthodontic treatment.
The results showed that the maxilla came forward an average of more than 9 mm during distraction and about 1 mm of that was lost in the first six months. By the longer term follow-up, about 3 mm of forward movement has been lost, leaving about 70% of the original distraction outcome horizontally. No further horizontal growth was noted after distraction.
The vertical dimension behaved a bit differently. The maxilla came down an average of a 3.5 mm during distraction and then relapse back up about 2 mm in the first six months. But unlike the horizontal dimension, there was continued vertical growth of several millimeters by the longer term follow-up, resulting in a vertical position with further down than immediately after distraction.
I think this study provides some general guidelines for us if we are planning a distraction case with a cleft patient. First, the horizontal correction should be planned to overcorrect the maxilla by about 30%. Failure to do this will make it hard to maintain positive overjet during orthodontic finishing. The vertical dimension does not require overcorrection because further vertical maxillary growth can be expected after distraction treatment.
Remember though, that this guidelines are based on small retrospective study, so we want to keep our eyes open for stronger evidences as tide goes on. But for now, it gives some idea what to expect. If you would like more information about the treatment of maxillary deficiency in cleft children by distraction osteogenesis, you can find this article by Dr. Huang and colleagues in the May 2007 issue of the Cleft Palate Craniofacial Journal.