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  Orthodontists are frequently making recommendations for removal of third molars. We may base_decision on_lack of sufficient space for eruption, potential for pericoronitis, possible affect of third molars on orthodontic results or compromised bone support for the second molars. What about the effect of third molars on the strength of the mandible and the susceptibility_the fracture?

  The literature has mixed conclusion on the relationship. A new study of Jordan by Dr. Ma'aita provided additional informations regarding the risk of mandibular fracture in patients with third molars. This report appears on the february 2000 issue of Oral Surg Oral Med Oral Pathol.

  The author retrieved patient records on radiographs for 685 consecutive mandibular fractures occurring between 1993 and 1998 in a group of military hospitals in Jordan. Seventy patients had incomplete records_could not be included, which left the study group of 615. The panoramic radiographs were used to determine the presence of third molars. If third molars were present, they were further classified as to the angulation and depth of impaction. The mechanism of injury was recorded and the age and sex of the patient noted. The mean age of the fracture patient was 33 years.

  Not surprisingly, males made up really 80 percent of the fracture group. The most frequent cause of the fracture was motor vehicle accident which made up almost 60 percent followed by falls, fights, sport injuries and others. Almost 70 percent of study group had third molars present. Analysis of the data reveal that the patients with third molars present were more than two times more likely to have angle fracture compared to those without third molars. The risk of angle fracture was found to be related to the severity of impaction as well, that is the patients with distoangular, vertical,_horizontal impaction whether greater risk for angle fracture.

  This data supports the theory that_presence of unerupted third molar in angle region of the mandible interrupt such a becular bone pattern thereby creating area relative weaknes.
  What this study doesn't tell us is whether removal of the third molars can help prevent fracture due to the trauma or whether the fracture may just occur in a different place.
  If you like to see more details of this study the entire article, the title "Is The Mandibular Third Molar A Risk Factor For Mandibular Angle Fracture?" is found in the February 2000 issue of Oral Surg Oral Med Oral Pathol.

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Orthodontists are frequently making recommendations for removal of third molars. We may base the decision on the lack of sufficient space for eruption, potential for pericoronitis, possible effects of third molars on orthodontic results or compromised bone support for the second molars. What about the effect of third molars on the strength of the mandible and the susceptibility to the fracture?

The literature has mixed conclusion on this relationship. A new study of Jordan by Dr. Ma'aita provided additional informations regarding the risk of mandibular fracture in patients with third molars. This report appears on the February 2000 issue of Oral Surg Oral Med Oral Pathol.

The authors retrieved patient records on radiographs for 685 consecutive mandibular fractures occurring between 1993 and 1998 in a group of military hospitals in Jordan. Seventy patients had incomplete records, and could not be included, which left the study group of 615. The panoramic radiographs were used to determine the presence of third molars. If third molars were present, they were further classified as to the angulation and depth of impaction. The mechanism of injury was recorded and the age and sex of the patient noted. The mean age of the fracture patient was 33 years.

Not surprisingly, males made up really 80 percent of the fracture group. The most frequent cause of the fracture was motor vehicle accident which made up almost 60 percent, followed by falls, fights, sports injuries and others. Almost 70 percent of study group had third molars present. Analysis of the data revealed that the patients with third molars present were more than two times more likely to have angle fracture, compared to those without third molars. The risk of angle fracture was found to be related to the severity of impaction as well, that is the patients with distoangular, vertical, or horizontal impaction were in the greater risk for angle fracture.

This data supports the theory that the presence of unerupted third molar in angle region of the mandible interrupts a trabecular bone pattern thereby creating a relative weakness.  What this study doesn't tell us is whether removal of the third molars can help prevent fracture due to the trauma or whether the fracture may just occur in a different place.  If you like to see more details of this study, the entire article, entitled "Is The Mandibular Third Molar A Risk Factor For Mandibular Angle Fracture?" is found in the February 2000 issue of Oral Surg Oral Med Oral Pathol.

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People who have undergone splint treatment for internal derangement of the temporomandibular joint may undergo subsequent orthodontic treatment to stabilize the occlusion. Are these patients at risk of having the symptoms return during orthodontics? Some practitioners advocated continuing with splint therapy during orthodontic treatment, another discontinued the splint when beginning treatment.

A group, led by Dr. Tohru Imai from Hokkaido University in Japan, recently published the findings of the study that compared groups treated orthodontically after initial splint therapy. All patients in the study were diagnosed to having internal derangement of the TMJ and has splint therapy initially.

The first group of 18 patients then underwent orthodontic treatment with fixed appliances in conjunction with continuous use of splints. The second group of 27 patients underwent fixed orthodontic treatment without the further use of splints. The third group of 13 patients did not receive any orthodontic treatment, only the splint therapy.

This was a retrospective study and the authors indicated those patient in the first group that did receive splint therapy along with orthodontic treatment received continuous splint treatment, because they had a changed mandibular positions or had recurring symptoms. This indicates the study groups may have a different at the beginning_ orthodontic treatment so that comparisons after treatment may not be the results at the different treatment method employed.

The results in this investigation show that both groups undergoing orthodontic treatment had an improvement of symptoms during the orthodontic treatment periods. About 80% of all patients had pain on movement before any treatment. This decreased to about 40% after initial splint therapy and decreased further to less than 10% at the end of orthodontic treatment. One year after the completion of orthodontic treatment, the number with some pain on movement increased slightly to about 20%. That was about the same as the control group who had splint treatment only. There was no difference noted between those who patients who had orthodontic treatment with splints and those who had orthodontic treatment without.

The authors also looked at the type of malocclusion found in treatment groups. They found about 40% had anterior openbites and 12% had posterior crossbites. This is a greater than the prevalence of this type of malocclusions in the general population and may indicate susceptibility of this patients to TMD problems.

This study does give us some comfort and the returning of TMD symptoms during or after orthodontic treatment is very low. Again the outhors did not find any difference between a group with continued splint's use during fixed appliance treatment and a group that had no splint during orthodontic treatment.

More details on this study can be found in the February 2000 EJO in an article entitled "Long-term follow of clinical symptoms in TMD patients who underwent occlusal reconstruction by orthodontic treatment."

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People who have undergone splint treatment for internal derangement of the temporomandibular joint may undergo subsequent orthodontic treatment to stabilize the occlusion. Are these patients at risk of having the symptoms return during orthodontics? Some practitioners advocated continuing use of splint therapy during orthodontic treatment, another discontinued the splint when beginning treatment.

A group, led by Dr. Tohru Imai from Hokkaido University in Japan, recently published the findings of the study that compared groups treated orthodontically after initial splint therapy. All patients in the study were diagnosed to having internal derangement of the TMJ and has splint therapy initially.

The first group of 18 patients then underwent orthodontic treatment with fixed appliances in conjunction with continuous use of splints. The second group of 27 patients underwent fixed orthodontic treatment without the further use of splints. The third group of 13 patients did not receive any orthodontic treatment, only the splint therapy.

This was a retrospective study and the authors indicated those patients in the first group that did receive splint therapy along with orthodontic treatment received continuous splint treatment, because they had a changed mandibular positions or had recurring symptoms. This indicates the study groups may have a difference at the beginning of orthodontic treatment so that comparisons after treatment may not be the results at the different treatment method employed.

The results in this investigation show that both groups undergoing orthodontic treatment had an improvement of symptoms during the orthodontic treatment periods. About 80% of all patients had pain on movement before any treatment. This decreased to about 40% after initial splint therapy and decreased further to less than 10% at the end of orthodontic treatment. One year after the completion of orthodontic treatment, the number with some pain on movement increased slightly to about 20%. That was about the same as the control group who had splint treatment only. There was no difference noted between those patients who had orthodontic treatment with splints and those who had orthodontic treatment without.

The authors also looked at the type of malocclusion found in treatment groups. They found about 40% had anterior openbites and 12% had posterior crossbites. This is a greater than the prevalence of this type of malocclusions in the general population and may indicate susceptibility of this patients to TMD problems.

This study does give us some comfort and the returning of TMD symptoms during or after orthodontic treatment is very low. Again the authors did not find any difference between a group with continued splint's use during fixed appliance treatment and a group that had no splint during orthodontic treatment.

More details on this study can be found in the February 2000 EJO in an article entitled "Long-term follow-up of clinical symptoms in TMD patients who underwent occlusal reconstruction by orthodontic treatment."

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 How would you like to bond orthodontic brackets with only 2 seconds of light curing time. This is the promise offered by a new Xenon Arc Curing Light described in_ february 2000 issue of the journal of clinical orthodontics. Dentistry first began using light_cured composite materials more than 30 years ago.

This first system used_initiator that was sensitive to_wavelength of ultraviolet light. This early light_cured systems required extended curing times and there is some concern about the long term safety of using the ultraviolet light. Visible light curing was introduced in about 1980. The composite need system used camphoroquinone as initiator that is sensitive to light in the range of 470 nanometers, a wavelength which is within the visible light range. This newer system also require less curing time and had a greater depths of cure than the ultraviolet light counterparts. This is the type of composite system that is widely used to orthodonics today.

  In the early 1990's, Argon lasers were introduced. They could greatly reduced the curing time. This have not been widely used in orthodonics due to the high cost of the lasers and concerns about the safety of the laser light.

  Most recently, the Plasma Arc Curing System has been introduced for use in Dentistry. This Xenon Arc Light is filtered to provided_intense light focus on_470 nanometer wavelength to activate the camphoroquinone initiator. The author is referenced literature showing that the Xenon Light System provides the same strength 24 hours after curing has the standard visible light or argon laser. The claim is made that this new curing light can cure composite through enamel so that curing from the lingual is possible when bonding brackets.

  In orthodonic bonding technique is described by the authors that is conventional in everyway except that it requires only 2 seconds of curing time per tooth with_Xenon Arc Light. If you are bonding 20 teeth you could save 20-30 seconds per tooth decadely into a time savings about to 10 minutes. Unfortunately, this report is purely descriptive in nature and is not investigative. It leads a little like an advertisement for the manufacturer.
  The authors are currently conducting a clinical investigation looking at the retention of brackets bonded with this securing light. The Xenon Arc Curing Light has the potential to help improved clinical efficiency in bonding orthodonic brackets.

  In apparently, it can also be used to bleach teeth, although the technique to do so is not described in this report. To read this article for yourself, see a Xenon Arc Light-Curing Unit for Bonding and Bleaching, in the February 2000 issue of the journal of clinical orthodontics.

[¼öÁ¤¿ø°í]

How would you like to bond orthodontic brackets with only 2 seconds of light curing time. This is the promise offered by a new Xenon Arc Curing Light described in the February 2000 issue of the Journal of Clinical Orthodontics. Dentistry first began using light-cured composite materials more than 30 years ago.

These first systems used the initiator that was sensitive to the wavelength of ultraviolet light. These early light-cured systems required extended curing times and some concern about the long term safety of using the ultraviolet light. Visible light curing was introduced in about 1980. The composites and need system used camphoroquinone as initiator that is sensitive to light in the range of 470 nanometers, a wavelength which is within the visible light range. These newer systems also require less curing time and had a greater depths of cure than the ultraviolet light counterparts. This is the type of composite system that is widely used in orthodontics today.

In the early 1990's, Argon lasers were introduced. They could greatly reduced the curing time. These have not been widely used in orthodonics due to the high cost of the lasers and concerns about the safety of the laser light.

Most recently, the Plasma Arc Curing System has been introduced for use in Dentistry. This Xenon Arc Light is filtered to provide the intense light focuses on the 470 nanometer wavelength to activate the camphoroquinone initiator. The authors referenced literature showing that the Xenon Light System provides the same strength 24 hours after curing has the standard visible light or argon laser. The claim is made that this new curing light can cure composite through enamel so that curing from the lingual is possible when bonding brackets.

An orthodontic bonding technique is described by the authors that is conventional in everyway, except that it requires only 2 seconds of curing time per tooth with the Xenon Arc Light. If you are bonding 20 teeth, you could save 20-30 seconds per tooth decadely into a time savings about to 10 minutes. Unfortunately, this report is purely descriptive in nature and is not investigative. It leads a little like an advertisement for the manufacturer. The authors are currently conducting a clinical investigation looking at the retention of brackets bonded with this securing light. The Xenon Arc Curing Light has the potential to help improved clinical efficiency in bonding orthodontic brackets.

It apparently can also be used to bleach teeth, although the technique to do so is not described in this report. To read this article for yourself, see a Xenon Arc Light-Curing Unit for Bonding and Bleaching, in the February 2000 issue of the Journal of Clinical Orthodontics.

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Imagine the clinical situation. Wherein 9-year old is referred to your office due to the fact that maxillary left central incisor has not yet erupted. Your clinical evaluation shows all other dental development is normal for the middle maxillary dentition. If panoramic x-ray is taken and shows the presence of the supernumerary tooth associated with the unerupted incisor, the root of the unerupted incisor is between one-half and two-thirds formed. What is the proper course of an action to allow the eruption of the left central incisor? Should the supernumerary tooth and the retained primary tooth be removed? Should the unerupted tooth be exposed? Should you plan to proceed with uncovering and bonding of unerupted tooth and apply orthodontic traction? All these are possible to approach to this problem.
Do we have any evidence as to which approach is best? An article in the February 2000 issue of the British journal of oral and maxillofacial surgery gives the some insight into the particular problem. 100 patients were identified retrospectively for this study that had unerupted maxillary incisor associated with supernumerary teeth. The records all reviewed and radiograph used to classify the degree of the root formation of the unerupted incisor. Notations were made regarding the need for additional surgical procedure later to facilitate eruption. Here is_the outer bound. The mean age in these patients was 9-years and 3 months. Males predominated 2 to 1. The 100 patients had total of 127 unerupted incisors. The supernumerary tooth was palatal to the unerupted incisors at 99 of 100 cases. Here is the important part. The teeth were classified_ immature at the any unerupted incisor that had 2/3 of the root formation. Teeth that had more than 2/3 root formation were classified as mature. Most of the immature teeth in this study were treated by the removal of supernumerary tooth and retained primary tooth. Of this group, nearly 3/4 of these teeth were erupted spontaneously afterwards. Of the 16 mature teeth treated with this conservative approach of removal of supernumerary and retained primary teeth, more than 60% were required additional later surgery for the uncover. One other interesting factor of this study,_average time for eruption of permanent incisor was 11 month after the removal of supernumerary tooth. Now, if we think again about the clinical situation involving the 9-year old with supernumerary tooth and unerupted left central incisor, we have a good idea how to proceed. Based on the evidence in this study, we would recommend the removal of the supernumerary tooth and retained primary tooth. But not to any further uncover since the root development was last until 2/3. Furthermore, we can tell the patient and parents that it will likely_near a year before they can expect the permanent tooth to erupt. But there is 75% chance. It will do so on and its on. Further detail about this study from the Eastman dental institute in London can be found any article in_ retrospective study of unerupted maxillary incisor associated with supernumerary teeth_ which appears for the February 2000 issue of the British journal of the oral and maxillo facial surgery.

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Imagine the clinical situation. Wherein 9-year old is referred to your office due to the fact that maxillary left central incisor has not yet erupted, your clinical evaluation shows all other dental development is normal for the middle mixed dentition. If panoramic x-ray is taken and shows the presence of the supernumerary tooth associated with the unerupted incisor, the root of the unerupted incisor is between one-half and two-thirds formed, what is the proper course of an action to allow the eruption of the left central incisor? Should the supernumerary tooth and the retained primary tooth be removed? Should the unerupted tooth be exposed? Should you plan to proceed with uncovering and bonding of unerupted tooth and apply orthodontic traction? All these would be possible approaches to this problem.
Do we have any evidence as to which approach is best? An article in the February 2000 issue of the British Journal of Oral and Maxillofacial Surgery gives the some insight into the particular problem. One hundred patients were identified retrospectively for this study that had unerupted maxillary incisors associated with supernumerary teeth. The records all reviewed and radiographs used to classify the degree of the root formation of the unerupted incisor. Notations were made regarding the need for additional surgical procedures later to facilitate eruption. Here is what the authors found. The mean age in these patients was 9-years and 3 months. Males predominated 2 to 1. The 100 patients had total of 127 unerupted incisors. The supernumerary tooth was palatal to the unerupted incisors at 99 of 100 cases. Here is the important part. The teeth were classified as immature at the unerupted incisor that had 2/3 of the root formation. Teeth that had more than 2/3 root formation were classified as mature. Most of the immature teeth in this study were treated by the removal of supernumerary tooth and retained primary tooth. Of this group, nearly 3/4 of these teeth erupted spontaneously afterwards. Of the 16 mature teeth treated with this conservative approach of removal of supernumerary and retained primary teeth, more than 60% required additional later surgery for uncovering. One other interesting factor of this study, the average time for eruption of permanent incisor was 11 months after the removal of supernumerary tooth. Now, if we think again about the clinical situation involving the 9-year old with supernumerary tooth and unerupted left central incisor, we have a good idea how to proceed. Based on the evidence in this study, we would recommend the removal of the supernumerary tooth and retained primary tooth. But not to any further uncovering since the root development was last until 2/3. Furthermore, we can tell the patient and parents that it will likely be near a year before they can expect the permanent tooth to erupt. But there is 75% chance. It will do so on and its on. Further details about this study from the Eastman Dental Institute in London can be found in the article "A retrospective study of unerupted maxillary incisors associated with supernumerary teeth", which appears in the February 2000 issue of the British Journal of the Oral and Maxillofacial Surgery.

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We are known that cleft lip and palate deformities have a significant effect on the shape and position of the teeth, alveolus, palate and nose. How far this effect of cleft extend on the developing phase of the child._ Do they effects_on the mouth and nose_do they extend further into the face.

Previously this is very difficult question to the answer because analysis was limited to measurement taken directly from faces all from facial molls. Modern technology has provided better tools for investigation involving facial shape and contours. Dr. Duffy and Kally in the England used such a tools in a recent study reported in a Cleft Palate Craniofacial Journal. Let me first describe this new tools for looking at faces.

It is a laser scanning technique that project the thin laser line on the contour of face and then recorded with video camera. Scanning this line across the whole faces and putting all the images_line together can construct complete three dimensional contour map of the face. The effluence used_this study takes about ten second to scan on the face. But newer scanner is now available that reduced this time under one second.

Now let's look at how the authors used this laser scanning tool used this particular study. They recorded 39 volunteers from_cleft population between 8-11 years old that had not_any bone grafting surgery. This cleft patients were subdivided into bilateral complete cleft lip and palate, unilateral complete cleft lip and palate, unilateral cleft lip and alveolus, and cleft palate alone. They also recruited 25 unaffected subjects with no obvious skeletal discrepancy_acts as controls. This control patients were also 8-11 years old. All patients underwent_facial scanning procedure that I described.

The authors took_scan_two ways. They may measurement between the found landmarks to look at such things nasal base width, mouth width and so on. They also produced average scan based on the mathematical average_scan_ each group. This average scan could then be superimpose to visualized differences_contours and shape beyond_linear measurement. The computer image processing also allowed the investigator to compare all unilateral cleft as_they were left side cleft. The right side cleft were mirror image by the computer to produce left side cleft result. The result of this study show some expected and some surprising result. That nasal base width of cleft patient with wider and mouth narrower. They were significant nasal asymmetry in most cleft subjects. The differences from_control subject were greatest in the bilateral cleft group. The surprising thing to me was that differences on the face extend well beyond oral and nasal region. The cleft patient had_narrower interocclular width and narrower face over all. the contour on the mandibular width stingily different cleft group as well. The difference seen bilateral cleft side may be due to related developmental disturbance or could be due to secondary effect of ungrowth_early cleft surgery. The study could not tell us each.

I believed that we will be seeing more reported on treatment of facts_outcome using the facial scanning technology. To see more details_this technology and_study I discussed reported_march 2000 issue of_Cleft Palate Craniofacial Journal and_article entitled_Three-Dimensional Analysis of the Child Cleft Face._

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We all know that cleft lip and palate deformities have a significant effect on the shape and position of the teeth, alveolus, palate and nose. How far these effects of cleft extend on the developing phase of the child? Do the effects end on the mouth and nose? Or, do they extend further into the face?

Previously, this is very difficult question to answer because analysis was limited to measurements taken directly from faces or from facial morphs.  Modern technology has provided better tool for investigations involving facial shapes and contours. Dr. Duffy and colleagues in England used such a tool in a recent study reported in the Cleft Palate Craniofacial Journal. Let me first describe this new tool for looking at faces.

It is a laser scanning technique that projects thin laser lines on the contour of face and then records with video camera. Scanning this line across the whole faces and putting all the images of the line together can construct complete three dimensional contour map of the face. The apparatus used in this study takes about ten seconds to scan the face. But newer scanner is available that reduces this time under one second.

Now, let's look at how the authors used this laser scanning tool in this particular study. They recruited 39 volunteers from the cleft population between 8 to 11 years old that had not had any bone grafting surgery. These cleft patients were subdivided into bilateral complete cleft lip and palate, unilateral complete cleft lip and palate, unilateral cleft lip and alveolus, and cleft palate alone. They also recruited 25 unaffected subjects with no obvious skeletal discrepancies to act as controls. This control patients were also 8-11 years old. All patients underwent the facial scanning procedure that I described.

The authors looked at the scans in two ways. They made measurements between the found landmarks to look at such things, nasal base width, mouth width and so on. They also produced average scans based on the mathematical average of the scans in each group. These average scans could then be superimposed to visualize differences in contours and shapes beyond just linear measurements. The computer image processing also allowed the investigators to compare all unilateral clefts as if they were left side clefts. The right side clefts were mirror images by the computer to produce left side cleft results. The results of this study show some expected and some surprising results. The nasal base width of cleft patient was wider and mouth narrower. They were significant nasal asymmetry in most cleft subjects. The differences from the control subjects were greatest in the bilateral cleft group. The surprising thing to me was that differences on the faces extended well beyond oral and nasal region. The cleft patients had a narrower interocular width and narrower face over all. The contours on the mandible were stingily different cleft group as well. The differences seen far from the  cleft side may be due to related developmental disturbances or could be due to secondary effects on growth of early cleft surgery. The study could not tell us which.

I believe that we will be seeing more reports on treatment effects and outcomes using the facial scanning technology. To see more details of this technology and the study I discussed, refer to the March 2000 issue of the Cleft Palate Craniofacial Journal, and the article entitled "Three-Dimensional Analysis of the Child Cleft Face".

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Let me ask you a question. Do you treat more patients with extraction or non-extraction therapy today? If I were to ever ask that question 25 years age, extraction treatment would have predominated. 25 years ago, extraction of 4 first premolars was very common. Today we tend to be near of arch development and non-extraction treatment. If you treat more patients with non-extraction approach, why? I think the many condition would give facial aesthetics as the main reason. But is that really true? What patients are treated with nonextraction? Do their facial profiles improve? Are they maintained? Or Do they get worse? And what about one premolars extracted. How is that profile perceived by laypersons and dentists? Those important questions were addressed and studied and published in the Feb 2000 issue of the Angle orthodontist. The title of article is_the esthetic impact of extraction and non-extraction treatments on Cocacian patients._ This paper was co-author by Jay Bowman and Lysle Johnston from the University of Michigan. The professor of their paper was retrospective to compare the profile changes in extraction and non-extraction patients to determine dentists and laypersons impression of whether_not the profile have been improved. The sample consisted of 120 Cocacian orthodontic patients. 70 individuals had extraction_teeth. 50 patients, on the other hand, were treated with non-extraction. The methodology was pretty straightforward. The pretreatment and posttreatment cephalometric radiographs were traced only to show the soft tissue profile. These are when the position is side by side or the drawing on the slide. On some occasions the pretreatment profile was placed  on the left and the posttreatment was placed on the right. In other situations this was reversed. Then a panel of 40 dentists and sixty laypersons evaluated these profiles. They were asked first to rate which of the two profiles look better? And then they're asked to judge the intensity of the preference by placing a mark on the visual analogue scale. This was simply 100mm line placed below the photographs. The reviewer places mark some along that line, and that degree_ preference can be compared between the panels. O.K. What do you think this research was done? Actually the result was quite interesting. First of all, the esthetical factor of treatment on facial profile was a function of three factors. That is 1. the type of treatment. 2. the amount of initial protrusion of the profile_ 3. the background of the observer. That is whether was a dentist or laypersons. Lets look at each of these three individually 1. The esthetical factor of extracting teeth was directly proportional to the amount_protrusion prior to treatment. This was in contrast to non-extraction treatment_ or the effect on facial esthetics was small regardless of initial protrusion In fact_panels straight_profiles of most_extraction patients had been improved by treatment. The only exceptions were those individuals whose lips were about 2-3mm behind the Rickets E-plane prior to treatment. This_makes sense. But I think the bottomline of this study was how the panels perceived the improvement or like of the improvement in the facial profile. In this study, it is pure that the extraction treatment_had about a 50%-60% probability of producing and improvement in facial esthetics. On the other hand, the non-extraction treatment had much less likelihood of improving the profile. So what is the only condition. Today theres a lot of non-extraction therapy. The whole concept of arch development has been taken, I believe, a bit too far. I think that many individuals_ practiced would agree on some occasions when you stretch to fit all the teeth in. The patient can actually look worth after treatment than better. There really should be a balance. A patient could be treated with nonextraction of teeth no matter what the diagnostic criteria may show and based upon the result this study that could prove disastrous in terms of the facial profile. If youre interested in reviewing this excellent study and esthetic impact of extraction and nonextraction treatment. You'll find it in the Feb. 2000 issue of the Angle orthodontist.

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Let me ask you a question. Do you treat more patients with extraction or non-extraction therapy today? If I were to ever ask that question 25 years ago, extraction treatment would have predominated. Twenty five years ago, extraction of 4 first premolars was very common. Today we tend to be in the era of arch development and non-extraction treatment. If you treat more patients with non-extraction approach, why? I think the many clinicians would give facial aesthetics as the main reason. But, is that really true? What patients are treated with nonextraction? Do their facial profiles improve? Are they maintained? Or, do they get worse? And what about one premolars extracted. How is that profile perceived by laypersons and dentists? Those important questions were addressed and studied, and published in the February 2000 issue of the Angle Orthodontist. The title of the article is "The esthetic impact of extraction and non-extraction treatments on Caucasian patients". This paper was co-authored by Jay Bowman and Lysle Johnston from the University of Michigan. The purpose of their paper was retrospectively to compare the profile changes in extraction and non-extraction patients to determine dentists and laypersons' impressions of whether or not the profile have been improved. The sample consisted of 120 Caucasian orthodontic patients. Seventy individuals had extraction of teeth. Fifty patients, on the other hand, were treated with non-extraction. The methodology was pretty straightforward. The pretreatment and posttreatment cephalometric radiographs were traced only to show the soft tissue profile. These are when the position is side by side or the drawing on the slide. On some occasions, the pretreatment profile was placed  on the left and the posttreatment on the right. In other situations, this was reversed. Then a panel of 40 dentists and sixty laypersons evaluated these profiles. They were asked first to rate which of the two profiles look better? And then they're asked to judge the intensity of the preference by placing a mark on the visual analogue scale. This was simply 100mm line placed below the photographs. The reviewer places a mark some along that line, and the degree of preference can be compared between the panels. O.K. What do you think this researchers has found? Actually, the result was quite interesting. First of all, the esthetic factor of treatment on facial profile was a function of three factors. That is number one, the type of treatment. number two. the amount of initial protrusion of the profile, and number three. the background of the observer. That is whether was a dentist or laypersons. Let's look at each of these three, individually. First, the esthetical factor of extracting teeth was directly proportional to the amount of protrusion prior to treatment. This was in contrast to non-extraction treatment where the effect on facial esthetics was small, regardless of initial protrusion. In fact, the panels felt the profiles of most of the extraction patients had been improved by treatment. The only exceptions were those individuals whose lips were about 2 to 3 mm behind the Rickets E-plane prior to treatment. This would make sense. But I think the bottom-line of this study was how the panels perceived the improvement or likelihood of the improvement in the facial profile. In this study, if you did extraction treatment, it had about a 50 to 60% probability of producing and improvement in facial esthetics. On the other hand, the non-extraction treatment had much less likelihood of improving the profile. So what is show-me to the clinician. Today there's a lot of non-extraction therapy. The whole concept of arch development has been taken, I believe, a bit too far. I think that many individuals in practice would agree on some occasions when you stretch to fit all the teeth in, the patient can actually look worse after treatment than better. There really should be a balance. A patient could be treated without extraction of teeth, no matter what the diagnostic criteria may show, and based upon the results this study, that could prove disasters, in terms of the facial profile. If you're interested in reviewing this excellent study on the esthetic impact of extraction and nonextraction treatments, you'll find it in the February 2000 issue of the Angle Orthodontist.

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Let me describe a clinical situation, then I will ask you a couple of questions. Suppose you are beginning treatment on a 25-year old female with a 5 mm anterior open bite. She has a long anterior face height and when you evaluate her records, you determine the best treatment would involve orthodontics and orthognathic surgery to intrude the maxilla. No surgery will be necessary in the mandible. Now when the maxilla is impacted, the open bite will close so that face height will be perfect. You explain the plan to the patient. She is very interested in treatment. Then she asks you the big question. If an open bite is corrected with jaw surgery, will it relapse? Will it change afterwards? In other words, if maxillary surgery is used to impact the posterior maxilla and close_ open bite, will be open bite reappear after healing has occurred. What's the percentage risk of open bite relapse after orthognathic surgery of the maxilla? That question was answered in an article that was published_ _April 2000 issue of The Angle Orthodontist. The title of_ article is "Long-Term Stability of Surgical Open Bite Correction by Le Fort I Osteotomy." This article is co-authored by William Proffit and L Tanya Bailey from The University of North Carolina in Chapel Hill.

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Let me describe a clinical situation, then I will ask you a couple of questions. Suppose you are beginning treatment on a 25-year old female with a 5 mm anterior open bite. She has a long anterior face height and when you evaluate her records, you determine the best treatment would involve orthodontics and orthognathic surgery to intrude the maxilla. No surgery will be necessary in the mandible. Now when the maxilla is impacted, the open bite will close so that face height will be perfect. You explain the plan to the patient. She is very interested in treatment. Then she asks you the big question. If an open bite is corrected with jaw surgery, will it relapse? Will it change afterwards? In other words, if maxillary surgery is used to impact the posterior maxilla and close the open bite, will be open bite reappear after healing has occurred. What's the percentage risk of open bite relapse after orthognathic surgery of the maxilla? That question was answered in an article that was published in the April 2000 issue of The Angle Orthodontist. The title of the article is "Long-Term Stability of Surgical Open Bite Correction with Le Fort I Osteotomy." This article is co-authored by William Proffit and L Tanya Bailey from The University of North Carolina in Chapel Hill.

Now the purpose of this study was to evaluate the long-term results after Le Fort I osteotomy to correct anterior open bites. The stability was evaluated 1 to 3 years after the surgery. The sample consisted of 28 patients who had undergone surgery of the maxilla only and additional 26 patients who had undergone surgery of both maxilla and of the mandible. Cephalometric radiographs were taken immediately before surgery, after surgery, and at least 1-year postoperatively. The degree of overbite change was measured during these three-time intervals to determine_ _open bite relapse after the surgery.

Now the purpose of this study was to evaluate the long-term results after Le Fort I osteotomy to correct anterior open bites. The stability was evaluated 1 to 3 years after the surgery. The sample consisted of 28 patients who had undergone surgery of the maxilla only and additional 26 patients who had undergone surgery of both maxilla and of the mandible. Cephalometric radiographs were taken immediately before surgery, after surgery, and at least 1-year postoperatively. The degree of overbite change was measured during these three-time intervals to determine if the open bite relapse after the surgery.

O.K. What do you think would happen? Does the anterior overbite tend to change and causing open bite recurs after orthognathic surgery? The answer to that question is no, most of the time. What do I mean by that? Actually from most of this sample, there was a change that occurs. Remember these were non-growing individuals. In spite of that, in 30 to 40% of both 1- and 2- jaw surgeries, the maxilla moved inferiorly greater than 2 mm, 1 year after jaw surgery. In some of these individuals, the molars and incisors erupted to compensate for the change. So no open bite relapse occurred in those individuals. But in about 10% of the patients, the incisors did not erupt as much as the molars. In these individuals the overbite tend to decrease which caused_ tendency toward recurrence of the open bite. So what was the bottom line? In the past, many of us believed that after maxillary surgery in adults, the vertical results were absolutely stable. This is untrue. The maxilla can tend to move downward and the teeth may erupt in these individuals. The authors discussed_ issues but didn't come to any concrete conclusions regarding the reason for this change. The authors concluded that perhaps the changes due to adaptation of_ muscles after surgery, which allows the teeth to erupt in some individuals and not in others.

O.K. What do you think would happen? Does the anterior overbite tend to change and causing open bite recurs after orthognathic surgery? The answer to that question is no, most of the time. What do I mean by that? Actually from most of this sample, there was a change that occurs. Remember these were non-growing individuals. In spite of that, in 30 to 40% of both 1- and 2- jaw surgeries, the maxilla moved inferiorly greater than 2 mm, 1 year after jaw surgery. In some of these individuals, the molars and incisors erupted to compensate for the change. So no open bite relapse occurred in those individuals. But in about 10% of the patients, the incisors did not erupt as much as the molars. In these individuals the overbite tend to decrease which caused a tendency toward recurrence of the open bite. So what was the bottom line? In the past, many of us believed that after maxillary surgery in adults, the vertical results were absolutely stable. This is untrue. The maxilla can tend to move downward and the teeth may erupt in these individuals. The authors discussed those issues but didn't come to any concrete conclusions regarding the reason for this change. The authors concluded that perhaps the changes due to adaptation of the muscles after surgery, which allows the teeth to erupt in some individuals and not in others.

Whatever the reason in about 10% of the open bite surgery cases, the overbite will tend to decrease long-term after surgery. So back to the original scenario, remember the young lady that will be having jaw surgery in your practice. Now you know the answer to a question. If she asks whats the potential for relapse following surgery, you could say it is an about 10% of the cases, that some relapse will occur in overbite long term after surgery. If you have interested in reviewing the study, you will find it in the April 2000 issue of The Angle Orthodontist.

Whatever the reason in about 10% of the open bite surgery cases, the overbite will tend to decrease long-term after surgery. So back to the original scenario, remember the young lady that will be having jaw surgery in your practice. Now you know the answer to a question. If she asks whats the potential for relapse following surgery, you could say it is an about 10% of the cases, that some relapse will occur in overbite long term after surgery. If you have interested in reviewing the study, you will find it in the April 2000 issue of The Angle Orthodontist.

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Suppose you've just completed orthodontic treatment on a fourteen year old male patient, who wasn't a very good cooperative. He didn't have good an oral hygiene, therefore, he's got several white spot lesions at the gingival area on the maxillary incisors. His parents don't like the results, they aren't happy with the white spots. He try to explain to them that it was led his faults for not cleaning. But, what they like to know is whether this can be corrected.

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What would your answer be? Can white spot lesions be remineralized?
This questions were addressed in the study which was published on a February, two thousand issue of Acta Odontologica Scandinavica.

The title of the article is "Effect of acid-etching on remineralization of enamel white spot lesions". The paper is co-authored by Susan Al-Khateeb and three other researchers associated on the department of Cariology, at Karolinska Institute in Sweden.

Then a purpose of the study was to evaluate the effectiveness of fluoride on remineralization of white spot lesions. This was done experimentally, but in this study, the purpose was to see if the benefits could be accentuated with and without the use of an etchant. The sample for this study consisted seventy four enamel blocks, taken from extracted teeth. These blocks were then embedded in plastic. Then, an artificial lesion was created in each of the teeth to simulate dental caries. Then this caries lesions were treated in four different manners. In two of the subgroups, the lesions were etched first with a typical phosphoric acid etchant. The other two groups were not etched. Then two different types of remineralizing agents were used to determine if there were any differences between the two. One was a liquid solution and the other was, believe or not, a tooth paste. The remineralization process was carried on for ten weeks. Now what do you think happened?

Remember the principle question of the study is whether or not etching prior to application of fluoride will enhance the mineralization process. And again, remember that fluoride was supplied in this experiments in two ways, one is re-mineralizing liquid, and the other is the commercially available tooth paste. The answer of the questions? Yes! That is, etching does provide a better site for remineralization. Extensive statistical analysis were used in this study, and when the research was reviewed the data, they found the significantly higher level of re-mineralization occured in the sample that was etched and re-mineralized with the tooth paste. Other re-mineralization did occur in other groups with in the sample, the level of the re-mineralization was the highest, the highest, when an etchant was used, and then, a slurry of tooth paste containing fluoride was used to re-mineralize.

OK, so, let's do take a message out of the study. If you are going to give fluoride to your patients to re-mineralize white spot lesions, there's two things to remember. First of all, you might wanted etch the teeth initially thus all-around, for more effective re-mineralization. And second, the fluoride contained in the tooth paste tended to produce the best results in this study.

So, back to our reasonable question. Remember the young patients who's fourteen years of age with these horrible white spot lesions, This would be best treated by initially, etching the surface, number two, applying fluoride on a regular basis possibly through a tooth paste, and the number three, of course, attempt to improve the patient's oral hygiene.

If you are interested in reading the study on the best method for ensuring re-mineralization of white spots, you will find it in the February, two thousand issue of Acta Odontologica Scandinavica.

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My impression is that more experienced clinicians tend to relay less on specific cephalometric measurements and more on pattern recognitions when reviewing the lateral cephalometric film. Specific measurements are used to quantifying discrepancies from the norms rather than provide specific diagnosis. Many clinicians forego measurements completely and rely only on visual inspection of the film for diagnostic information while others delegate analysis to auxiliary to save time. Wouldn't be nice to have an analysis for cephalometric film that with quick and easy to do looked overall facial patterns and could be quantified when needed.

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Doctors Carano, Rotunno, and Siciliani from Italy have recently published. A visual cephalometric analysis in the May issue of the Journal of Clinical Orthodontics that they believe, provides this advantages. The authors have created new set-up templates for analysis that a based on the Bolton's study and some of the information from the Richett's analysis. Template of course is a nothing new but these templates have some unique differences. First, their design to be superimposed on a vertical reference to determine by natural head position which the authors believe this more valuable than using Frankfort horizontal or sella-nasion line as a reference. Second, the templates are produced on graphic paper background, which allows any discrepancy to be quickly, and easily quantified. Thirdly, variations of one standard deviations are indicated under template for some reference planes like mandibular plane and for some landmark locations like A point and B point.

The templates were produced for males and females from ages 6 to 18 in 2-year increments. The authors state however that they find the unisex templates for ages 8, 12 and 16 are suitable for most cases. The template is used as follows. The correct sized template is selected based more on sella-nasion length than chronological age. The template is than superimposed at nasion and rotated until the true vertical reference on the film aligns with the vertical line on the template. These of course suggest that the cephs are taken in natural head position. Deviations from the template can be visualize and quantify by using the millimeter graph paper background. Regional superimpositions can be done by moving the patient's tracing over the template the orient on the mandible or maxilla while keeping the vertical reference allow align with the vertical line on the graphic paper.

A view of the templates are reproduced in the article however in the copy of the article but I had the background mesh did not measure in millimeter increments so that may be some magnification errors in the journal reproduction. I would not use those templates directly without verification. The authors state that the complete set up templates are available from them who those were interested. Is this technique a curable all the limitations the conventional cephalometric analysis? Certainly not, however it is good way to visualize the discrepancies from the norms and may be useful to help the patient and patents understand certain orthodontic problems. You can find this article in the May issue of the Journal of Clinical Orthodontics

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Have you ever dealt with this type of clinical situation? Suppose you are about to begin orthodontic treatment on a 55-year old female. She has a relatively healthy periodontium. She has severe crowding at her teeth and your plan is to extract four first premolars and close extraction spaces to eliminate the crowding. This should be a routine case. But when you review her health history, you note that the patient is taking corticosteroids. Specifically the patient is taking prednisolone. Now she's taking it in small doses because of her medical problem.

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Now for my question, we know that synthetic corticosteroids like prednisolone interfere with bone resorption. This has been well established in the literature but what will the effect be on your patient? Will the corticosteroids reduce ability to move the teeth?  And if so, how will you close extraction spaces. I believe that this is an important question for orthodontists who treat adult patients. Some of these adults may be taking corticosteroids. The answers to these questions are found in the article that was published in the April 2000 issue of the Angle Orthodontist. The title of the article is orthodontic tooth movement in the prednisolone-treated experimental animal.

This study is coauthored by Colin Ong and several research colleagues from the University of Queensland in Australia. The purpose of this study was to give low doses of prednisolone to laboratory animals and then to evaluate the ability to move teeth in these animals. In order to accomplish the project, the authors used rats for the laboratory experiment and orthodontic appliance with coil spring was used to place mesially directed force on the maxillary molar on one side. The opposite molar was used as control then the samples divided into two groups. One group was given prednisolone at a therapeutic dosage, The other group was not given any drug. Then the animals reevaluated after 12 days to determine the effects of prednisolone on the rate and amount of tooth movement.

OK, what do you think happened? Remember the main question! Does the therapeutic dose of prednisolone reduce or hamper the amount or rate of tooth movement. The answer of those questions is no. In this study, there were no statistically significant differences between the amount of tooth movement in the control or prednisolone-treated animals. When the bone was evaluated histologically, both animals showed resorption of bone and movement of the teeth. There was a slight difference however. The authors did show that root resortion was reduced in the animals that were treated with prednisolone. So this does indicate that there was reduction in clastic activity in the prednisolone-treated animals. But this alteration didn't produce any changes in the amount of tooth movement.

So back to the original clinical question. Remember your patient who's taking prednisolone? Now you have an answer to the question. Based upon this study in laboratory animals, a therapeutic dosage of prednisolone dose not seem to alter the ability to move teeth. The only effect was a slight reduction in the amount of root resorption in the treated animals.

If you are interested in reviewing this information, you'll find the study in the April 2000 issue of the Angle Orthodontist.

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The literature presents completing results. When evaluated in the changes that occur with wire versus rigid fixation for patients who undergo surgical mandibular advancement. This may well be due to the fact that most studies were either limited case studies or were retrospective studies. In article, in the June 2000 issues, the American Journal of Orthodontics and Dentofacial Orthopedics by Stephen Keeling et al, which was titled A comparative study of skeletal and dental stability between rigid and wire fixation for mandibular advancement presents the results of a multisite, prospective, randomized, clinical trial of rigid versus wire fixation for mandibular advancement surgery.

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I believe this is the only prospective randomized clinical trial that has looked at the difference between wire and rigid fixation. The surgery was conducted at the University of Texas health Science Center at San Antonio, Emory University in Atlanta, and the University of Florida in Gainesville. Patients were randomly assigned to the wire or fixation groups, and there were 64 patients in the wire group, and 63 patients in the rigid fixation group. The patients who were treated with wire fixation received inferior border wires and were placed in skeletal maxillomandibular fixation for 6 weeks. Cephalometric radiographs were taken at 1 week, 8 weeks, 6 months, 1 year and 2 years after surgery.

The results of the study are very interesting. At 8 weeks the mandible in the wire group had moved posteriorly approximately 1.2 mm or 21% whereas in the rigid group, the mandible at 8 weeks moved very slightly anteriorly. At 8 weeks, dental changes were also detected involve the Mandibular incisors and the molars of the wire group which moved approximately 1 mm anteriorly. These dental compensations have previously been reported and might be expected for patients whose mandible is relapsing posteriorly but whose teeth are held together with intermaxillary fixation. As the mandible moves distally, The wired teeth compensate by moving anteriorly. At 1 year after surgery, skeletal relapse continued in the wire group, while the rigid group remains stable. The mandible in the wire group moved posteriorly approximately 25%, while the rigid group remained essentially stable.

The major finding of this study was that in the wire group, the mandible was repositioned more posteriorly than in the rigid group after release of fixation at 8 weeks and this relapse persisted for up to 2 years without any indication of catch-up. These differences were due to absolute posterior relapse of the mandible in the wire group, whereas the rigid group was essentially stable. It is also important to know that in the wire group, the dental compensation that occurred to maintain overjet correction during fixation that is forward movement of the mandibular incisors relapse to their immediate post-surgical position at 1 year and persisted at 2 years.

Based on the results of this study, it is clear that rigid fixation provided greatest stability at the osteotomy site. This is good news for patients undergoing mandibular advancement surgery, because the use of rigid fixation eliminates the 6 weeks of post-surgery intermaxillary fixation usually associated with wire fixation and also results in a more stable change.

This article appeared in the June, 2000 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

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Orthopedic treatment for developing Class III patients has tended to favor maxillary protraction rather than Mandibular chin cup therapy in recent years,. This is probably due to studies that have shown that some degree of maxillary deficiency is present in a number of these patients as well as treatment studies that have indicated difficulty in maintaining long term changes following chin cup therapy. Another factor, however, has the newest impression that chin cup therapy may lead to affects in the temporomandibular joint. The thought is that the orthopedic force may displace the condyle posteriorly placing the disc in a more anterior position and thus making the joint susceptible to internal derangement or an anteriorly displaced disc.

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Orthopedic treatment for developing Class III patients has tended to favor maxillary protraction rather than mandibular chin cup therapy in recent years,. This is probably due to studies that have shown that some degree of maxillary deficiency is present in a number of these patients as well as treatment studies that have indicated difficulty in maintaining long term changes following chin cup therapy. Another factor, however, has the newest impression that chin cup therapy may lead to effects in the temporomandibular joint. The thought is that the orthopedic force may displace the condyle posteriorly, placing the disc in a more anterior position and thus making the joint susceptible to internal derangement or an anteriorly displaced disc.

Does early chin cup therapy lead to a change in this position? the recent study published in the European Journal of orthodontics by Hatice G kalp and colleagues from Turkey tries to answer this question. Their study is titled "The changes in temporomandibular joint disk position and configuration in early orthognathic treatment; A magnetic resonance imaging evaluation." The authors recruited 15 subjects, 10 females and 5 males who underwent mandibular chin cup therapy for their Class III skeletal malocclusion. The subjects ranged in age of 5 to 11 years old. A group of 10 Class I subjects were used as controls. The treatment group had a chin cup force of 600 mg supplied for at least 16 hours a day. The chin cup treatment was continued until 6 months after the elimination of the anterior cross bite and the Class III molar relationship. In this study, the treatment time averaged 16 months. The treatment group received the unilateral MRI before and after the chin cup therapy the control group received no treatment during the study time, but did received the MRI before and after. The authors made the series of measurements from the MRIs to determine condylar position and disk position. The measurements were compared before and after treatment as well as between the treatment and control groups.

 Does early chin cup therapy lead to a change in this position? The recent study published in the European Journal of Orthodontics by Hatice G kalp and colleagues from Turkey tried to answer this question. Their study is titled "The changes in temporomandibular joint disk position and configuration in early orthognathic treatment; A magnetic resonance imaging evaluation." The authors recruited 15 subjects, 10 females and 5 males who underwent mandibular chin cup therapy for their Class III skeletal malocclusion. The subjects ranged in age of 5 to 11 years old. A group of 10 Class I subjects were used as controls. The treatment group had a chin cup force of 600 gm supplied for at least 16 hours a day. The chin cup treatment was continued until 6 months after the elimination of the anterior cross bite and the Class III molar relationship. In this study, the treatment time averaged 16 months. The treatment group received the unilateral MRI before and after the chin cup therapy. The control group received no treatment during the study time, but did received the MRI before and after. The authors made the series of measurements from the MRIs to determine condylar position and disk position. The measurements were compared before and after treatment as well as between the treatment and control groups.

Here's what the authors found. The treatment in control groups differed at the beginning of the treatment when measured by the ¥á-angle. This measurement located at the condyle relative to the ramus and neck of the condyle.
This differences are not surprising since the treatment group consisted of skeletal Class III patients and the control group patients were Class I. No significant change was found in the disk position or configuration during the treatment time or in the control group during the observation time.

 Here's what the authors found. The treatment in control groups differed at the beginning of the treatment when measured by the ¥á-angle. This measurement located at the condyle relative to the ramus and neck of the condyle.
This differences are not surprising since the treatment group consisted of skeletal Class III patients and the control group patients were Class I. No significant change was found in the disk position or configuration during the treatment time or in the control group during the observation time.

There was a slight tendency for the disk position to be more anterior after treatment and the treatment group and it would be interesting to look at the patients again in a few years. The conclusion of this study is that early chin cup therapy does not have an affect on the disk position.

 There was a slight tendency for the disk position to be more anterior after treatment in the treatment group and it would be interesting to look at the patients again in a few years. The conclusion of this study is that early chin cup therapy does not have an effect on the disk position.

This leads us to believe that the use of early chin cup therapy will not lead to internal derangement of the temporomandibular joint. At this time, I think it's fair to say that the fear of inducing internal derangement should not keep you from using chin cup therapy. The use of chin cup therapy should be determined based on another factors,   such as treatment efficiency and long term effectiveness. This entire study is available for you to read in the June, 2000 issue of the European Journal of Orthodontics.

 This leads us to believe that the use of early chin cup therapy will not lead to internal derangement of the temporomandibular joint. At this time, I think it's fair to say that the fear of inducing internal derangement should not keep you from using chin cup therapy. The use of chin cup therapy should be determined based on another factors,   such as treatment efficiency and long term effectiveness. This entire study is available for you to read in the June, 2000 issue of the European Journal of Orthodontics.

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Has this ever happened to you? You're examining adult male patient who's 30 years of age. He has a mild crowding of his teeth. And he's referred by the restorative dentistry to be doing some major restoration of his teeth after orthodontics. When you evaluate the patient clinically, you know that he has severe erosion on the maxillary and mandibular posterior teeth. When you ask the patient to brux his teeth, he says, "No." Or what could be the cause of this type of erosion. The answer of that question is on June, 2000 issue of _ Journal of Prosthetic Dentistry. The title of the article is "Evaluation of dental erosion in patients with gastroesophageal reflux disease." The article was coauthored by Belinda L. Gregory and 3 research colleagues from the University of Pacific, School of Dentistry in San Francisco.

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Has this ever happened to you? You're examining adult male patient who's 30 years of age. He has a mild crowding of his teeth. And he's referred by the restorative dentist to be doing some major restoration of his teeth after orthodontics. When you evaluate the patient clinically, you know that he has severe erosion of the maxillary and mandibular posterior teeth. When you ask the patient to brux his teeth, he says, "No." Or what could be the cause of this type of erosion. The answer of that question is found in the June, 2000 issue of The Journal of Prosthetic Dentistry. The title of the article is "Evaluation of dental erosion in patients with gastroesophageal reflux disease." The article was coauthored by Belinda Gregory and 3 research colleagues from the University of Pacific, School of Dentistry in San Francisco.

The professors' paper was to evaluate sample _ individuals to determine if gastroesophageal reflux can cause erosion of posterior teeth. In order to accomplish this, the authors gathered records on 20 consecutively treated adult patients who had appeared at _ university hospital in the division of gastroenterology.

The purpose of their paper was to evaluate sample of individuals to determine if gastroesophageal reflux can cause erosion of posterior teeth. In order to accomplish this, the authors gathered records on 20 consecutively treated adult patients who had appeared at the university hospital in the Division of Gastroenterology.

Preparing for investigation of gastroesophageal crack disease, the first step was determined if thses patients actually have a reflux type of problem. So specific tests were done to determine that. That was accomplished first. Out of the samples of 20, 10 or half of the subjects actually had the reflux that produced an increased in the acidity of the saliva. Then these researchers evaluated with the dentitions of thses two samples. The authors want to determine if the increased acid in part of the sample in the saliva produce tooth wear in those individuals. This process using the TWI or tooth wear index. I will get into the description of the index, but it is commonly used to assess tooth wear in research studies.

Preparing for investigation of gastroesophageal crack disease, the first step was to determine if these patients actually had a reflux type of problem. So specific tests were done to determine that. That was accomplished first. Out of the samples of 20, 10 or half of the subjects actually had reflux that produced an increase in the acidity of the saliva. Then these researchers evaluated the dentitions of thses two samples. The authors wanted to determine if the increased acid in part of the sample in the saliva produced tooth wear in those individuals. The teeth were assessed using the TWI or tooth wear index. I won't get into the description of this index, but it is commonly used to assess tooth wear in research studies.

OK. Let me give _ the bottom line. When the authors compared _ two groups, they found _ those individuals suffering from gastric reflux disease had significantly high rate of erosion _ teeth than those individuals that did not have this extra acidity in the saliva. The difference occurred in all areas except the mandibular anterior region. For some reason, the mandibular anterior teeth were not worn in either group.

OK. Let me give you the bottom line. When the authors compared the two groups, they found that those individuals suffering from gastric reflux disease had significantly higher rate of erosion of the teeth than those individuals that did not have this extra acidity in the saliva. The difference occurred in all areas except the mandibular anterior region. For some reason, the mandibular anterior teeth were not worn in either group.

OK. Now, let's go back to the original patient I described. Remember the 30-year-old adult male with erosion that you are going to treat orthodontically. When you see deep cratering kinds of defects around maxillary and mandibular posterior teeth. That exists even around the restoration. There is a good chance in this types of individuals at the patients has gastric reflux disease. I think it's good for the patients to be aware of this. And some of these patients may need an evaluation from _ gastroenterologic position to confirm the diagnosis.

OK. Now, let's go back to the original patient I described. Remember the 30-year-old adult male with erosion that you are going to be treating orthodontically. When you see deep cratering kinds of defects around maxillary and mandibular posterior teeth that exist even around the restoration, there is a good chance in this types of individuals at the patients has gastric reflux disease. I think it's good for the patients to be aware of this. And some of these patients may need an evaluation from a gastroenterologic physician to confirm the diagnosis.

If you are interested in reading the study on how gastric reflux disease produce dental erosion, you can find it in the June, 2000 issue of _ Journal of Prosthetic Dentistry.

If you are interested in reading the study on how gastric reflux disease produce dental erosion, you can find it in the June, 2000 issue of The Journal of Prosthetic Dentistry.

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The frequency of congenitally missing lower second premolars is about 3 per cent. This means that the average orthodontic practice will see high number of patients presenting with this problem. In cases with significant anterior crowding, it is easy to remove the retained primary molar and additional premolars as required and treat the case as if it were premolar extraction case. In many cases, however the arch length is adequate and we are faced to the question of whether to extract the primary tooth and maintain the space for the missing premolar or to maintain the primary tooth as either and intramolar long-term replacement. How long can we expect to retain primary molar to last? Does the presence of some root resorption at the beginning of treatment predict its longevity? These are some of the questions Dr. Bjerklin and Dr. Bennett attempted to answer, in the recent publication entitled¡°The long-term survival of lower second primary molars in subjects with agenesis of the premolars.¡±This paper was published in the June 2000 issue of the European Journal of Orthodontics.

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The authors followed the group of 41 patients with congenitally absent second premolars. These 41 patients had total of 59 missing teeth. The subjects were first seen at the age of 11 to 12 years and reseen for follow-up every 2 years. The authors used bitewing radiographs to measure the position of retained primary tooth relative to the neighboring permanent teeth as well as the  classified the level of root resorption. The mean age of the last examination was approximately 21 years with the range of 14 to 32. Only 2 of 59 primary molars were exfoliated during the study. Additionally, 5 teeth were extracted. Some of which were to allow replacement with transplanted third molars. The authors found that root resorption of the primary teeth generally proceded at a slow rate. They also found that it was not possible to predict the probability of survival at an early age when treatment decision's needed to be made. It's slight trend for an increase in the measurement of infraocclusion occurred over time. In other words, some of these primary molars may become ankylosed. The authors found however that after the age of 20 years infraocclusion is not a problem for the survival of the primary teeth.

What does the studies told us then? This is follows. First, root resorption of retained primary molars generally occurs at a slow rate. Second, infraocclusion of ankylosis is not generally a problem for retention of primary molars specially after the age of 20, and third, prediction of longevity of retained primary molars not possible at age of 11 to 12 when treatment decisions are made. I would say that, in general, this study rend support to retaining primary teeth to replace congenitally missing permanent premolars but does not address tooth size issues.

To get more details regarding this well-done study, refer to the June 2000 European Journal of Orthodontics.

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Do you treat many patients who will have implants placed after orthodontics? If I were to be asked that question 10 years ago, I'm sure that the number of you answering 'yes' would have been very low. But today, many orthodontic patients, both young and old who were missing teeth, either through extraction or congenital absence will have implants placed now and also in the future. Implants are becoming integral part of restorative dentistry to replace missing teeth. But there's problems with implants. One of the biggest problem is esthetics. If you had patients who've been restored with implants. "Are you totally satisfied with the results?". I'm not talking about the color match of the ceramic restoration relative to the adjacent teeth. What I'm talking about is the gingival relationship. Are you always satisfied with the way the gingival margin appears around the implant crown? Does this change over time? What can one expect from a maxillary lateral incisor implant crown in terms of movement or migration of the gingival margin over time? Will the patients get gingival recession over period of time and will that expose the head of the implant or the threads on the implant?

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Some of those questions were addressed in an article that was published in the August 2000 issue of the International Journal of Oral and Maxillofacial Implants. The title of the article is "Gingival Recession Around the Implants: A 1-year Longitudinal Prospective Study". This paper was coauthored by Paula Small and Dannis Tarnow from the Department of Implant Dentistry at New York University College of Dentistry in Manhattan. The purpose of their study was to evaluate the changes in the gingival margin around implants that had been restored. The sample consisted of 65 implants. They've been placed in 11 different individuals or patients. In order to assess the movement of the gingival margin, the initial determination was made at the time that the abutment was placed on the implant. Then the gingival margin was assessed at intervals ranging up to 1 year. In addition, the determination of greatest movement of the gingival margin was also recorded.

Okay, what do you think happened? Does the gingival margin migrate at all? And if so, how much and when does this occur? Well, based upon the results of this study, the gingival margin does move, but not as significantly as you might think. When all of the data were assessed, the authors found that the greatest migration of the gingival margin occurred on the buccal or labial aspect of the implant. The gingival margin migrated apically all away from the incisal edge in 80% of the implants. Now, when do that occur? That was interesting. The authors found that the migration occurred within the first 3 months. After 3 months and up to 1 year, the movement of the gingival margin was minimal. So at least up to 1 year, the results looked pretty promising. Gingival margin migration around the crown occurs fairly soon after abutment placement or within the first 3 months. And futhermore, the amount is generally only about 1 mm. But this still doesn't answer the question of what happens long term. The authors realized that and suggested that the next study should make a longer term assessment of gingival margin integrity around implants. Perhaps over the long term, the results may not be as successful. We'll have to wait and see. In the mean time, if you're interested in reading this early evaluation of gingival margin migration around implants. You can find it at the August 2000 issue of the International Journal of Oral and Maxillofacial Implants.

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Are you satisfied with the stability of your orthognathic surgery cases? Are there any specific surgical cases that cause you difficulty when finishing? In my case, I'm extremely satisfied with most surgical cases and I had the opportunity to work with some wonderful surgeons. However, I still find it a challenge to finish some Class III mandibular setback cases because of skeletal relapse tendencies after surgery. Previous studies have shown that the mandibular setback is one of the least stable orthognathic procedures. Does the surgical technique used for the mandibular setback affect the stability? I found an article in the British Journal of Oral and Maxillofacial Surgery and titled "Evaluation of Skeletal Stability Following Surgical Correction of Mandibular Prognathism" which shed light on this question.

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This retrospective study compared 31 patients who had mandibular setback surgery by one of two surgical techniques. 16 patients had a vertical subsigmoid osteotomy, the other 15 patients had a bilateral sagittal split osteotomy. The sagittal split group had rigid fixation with screws and light elastics for 2 to 3 weeks. The vertical osteotomy group had the condylar segment left loose on the lateral surface of the ramus and the patients went intermaxillary fixation for 3 to 4 weeks. Statistical analysis of the two groups of patients before treatment showed no difference in the magnitude of mandibular prognathism. In addition, there was no difference between groups in the magnitude of surgical correction.

When the two groups of patients were examined 1 year after surgery, there were differences between the 2 groups. The sagittal split group showed an increase in ANB angle of 1.5°and a forward relapse of 2.5 mm. The changes in the vertical osteotomy group were near 0.

So, according to this study done in the UK, the vertical osteotomy with intermaxillary fixation is more stable 1 year after surgery than the sagittal split procedure with rigid fixation. Considering the results of this study, you may want to discuss with your oral and maxillofacial surgeon the possibility of using a vertical ramus procedure when treating mandibular prognathism. It may make orthodontic finishing easier and the end result easier to maintain. The details of this study can be found in the August 2000 issue of the British Journal of Oral and Maxillofacial Surgery.

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Initial alignment of maxillary lateral incisors that are in lingual crossbite can be a challenge, especially if the patient has a deep overbite. A bracket placed on the labial surface will often interfere with the lower incisors preventing the rest of the teeth from occluding. Frequently we may plan to place a fixed or removable biteplane appliance to provide temporary occlusal support while allowing the lateral incisors to jump the crossbite. Not all patients tolerate biteplane well, especially adult patients. It is this specific situation that is addressed by Dr. Smith and colleagues in an article that appeared in the July 2000 issue of the Journal of Clinical Orthodontics. The article is titled "Alignment of blocked-out maxillary lateral incisors".

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The authors suggest that instead of placing the bracket on the facial surface of the lateral incisor that is in crossbite, that the standard labial bracket be bonded to the lingual surface initially. This avoids the occlusal interference and the shearing force that may tend to dislodge the bracket. If force is then applied by hooking in an elastic on the bracket wrapping at around the arch wire on the facial surface, and then hooking back on the bracket again. This provides a general force bringing the tooth towards the arch wire. The authors suggest using a 3.5 oz elastic but don't specify the size. I would guess about one quarter inch. They instruct the patient to change the elastic daily as they wear the class¥± elastics.

Once the tooth is moved out of crossbite, a bracket is placed on the facial surface and the tooth and root aligned in the conventional way. The authors demonstrate their technique by showing photographs of two cases. The lateral incisors were out of crossbite in 2 to 3 months. This technique has the advantage of being simple and avoiding the time, cost and uses of a biteplate appliance.

The authors don't describe how they deal with the occlusal trauma and interference that inevitably results as a tooth moves out of crossbite, but I would assume that the patient is instructed to chew carefully during this time. This technique also allows for a rapid tipping movement to correct the crossbite and relies on root uprighting later after the bracket interference has been resolved. I'm going to try this technique to see how it works for me. To get more details, see the description of this clinical technique in the July 2000 issue of the Journal of Clinical Orthodontics.

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Obstructive sleep apnea is a disorder characterized by recurrent upper airway obstruction during sleep, and is a significant health problem in the United States today. I suspect you remember of your family or one of patients has some form of obstructive sleep apnea. The most common and most effective treatment of obstructive sleep apnea is continuous positive airway pressure (or CPAP). Unfortunately, CPAP requires the ware of uncomfortable appliance during sleep, and for this reason and other reason is not very well tolerated by patients.

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Alternatives to CPAP treatment include weight-loss treatment, pharmacologic therapy and pharyngeal and maxillo-mandibular surgery, all of each has some various degrees of risk and success. And additional alternative is the use of oral appliances which repositioning mandible anteriorly. A this appliance is effective in treating obstructive sleep apnea, and if so, are the most effective for patients with severe or moderate obstructive sleep apnea.

A study title 'Effects of a mandibular repositioner on obstructive sleep apnea' by Yuehua Liu et al, which appeared in september 2000 issue of American Journal of  Orthodontics and Dentofacial Orthopedics, evaluated the use of mandibular repositioner which is an oral appliance to treat patients with obstructive sleep apnea. Twenty-two patients who had obstructive sleep apnea were fitted with mandibular repositioner designed to hold the mandible in anterior and inferior position. This appliance is similar to functional appliance with exception that has air holes between the upper and lower parts of the appliances to leave breathing. This appliances were worn for 6 months and at the end of this time, the patients were evaluated and cephalometric radiographs were taken.

Results of wareing the mandibular repositioning appliances are impressive. 82% of the subjects reported the decrease the snoring intensity, 73% underwent significant decrease in apneic episodes and 85 % reported subjective improvement in excessive daytime sleepiness.

When the patients were divided into 2 groups, based on the severity of their obstructive sleep apnea, mandibular repositioner resounded more effective in the group that have mild to moderate obstructive sleep apnea. However, 2 of these patients with respiratory disturbance of greater than 80 events/hour experienced a greater than 50% reduction in the respiratory distress index. More impressively, for 2 other patients with respiratory distress index is of greater than 50 events/hour, the apneic episodes completely stopped.

The bottom line of this article is that simple mandibular repositioning appliance which further have very few unfavorable side effects can be effective in treating some patients with obstructive sleep apnea. Unfortunately, at this time the ability to predict those patients for whom this appliance will be most effective appears to be weak. However, considering narrow risk and potential gains, it thinks reasonable to consider the use of this appliances for patients who suffer from obstructive sleep apnea.

You can find this article what contains many more details about obstructive sleep apnea in the september 2000 issue of American Journal of Orthodontics and Dentofacial Orthopedics.

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Let me ask you a question? Do you still cement band to teeth in your orthodontic patients. Today I think most orthodontists try to bond as many brackets to teeth as possible. But in adolescent patients especially, it is often difficult to bond bracket to the permanent molars, so many of us still place bands on the first and second molars. Ok, so a few want those who place band on molars.

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What kinds of cement do you use to secure the band? Today you have four choices. You could use the classic zinc phosphate cement or you could use glass-ionomer cement or you could possibly use a resin modified glass-ionomer cement or finally you could use the more recently developed polyacid-modified composite resin. Now, I'm sure some orthodontists listening this tape might not be sure what they actually use. What I mean by that is orthodontist typically know the brand name of the products but they may not be aware what type of cement they're actually using. Anyway he has to be using one of these four general types. So my question is those make it any different. Have any studies been to perform clinically test which of these four classes of cements provide the greatest shear-peel band strength for cementing orthodontic band to teeth? Of the answer to that question is yes.

A study was published in the August 2000 issue of the Angle Orthodontist compared these different cementing materials. It was a great study. The title of paper was "A comparison of shear-peel band strengths of different orthodontic cements". The paper was coauthored by Manish Aggrawal and two research colleagues from the University of Western Ontario in Canada. This was laboratory study. The authors gathered samples of 275 extracted molars. They were placed into different categories. First of all, bands were fit on each of the teeth and then they were cemented with either zinc phosphate, glass-ionomer, resin modified glass-ionomer or polyacid composite resin cement. Now in the paper the brand names of these cements were given but I'm not gonna provide with those on this tape and tell you why in just moment. In addition to testing this different cements, the authors also cemented band to moist teeth to determine if there be any differences between dry teeth or teeth are contaminated saliva prior to cementation of the band.

Ok, what do you think happened? Each of these bands were peeled out by using an instron testing machine. So the first, deband each of these cements was calculated, then the cements were compared. All right let me give you the data. First of all, it's might be expected if the teeth were moistened prior to banding, the strength of cement decreased substantially. So another words if teeth contaminated with saliva prior to place the band, the strength of cement is extremely in affective. So the surface be needed dried. Ok were the dried surface how did these different cements compared. The weakest was traditional zinc phosphate cement. It's shear-peel band strength was significantly less than the other cements. Here is the good news. The glass-ionomer cement, the resin modified glass-ionomer cement and polyacid composite resin were all equivocal. In another words there was not significant difference between these three cements. That's why I didn't give you brand names. As long as using one of the newer cement either glass-ionomer cement, resin modified glass-ionomer or polyacid composite resin and you're cementing to dried teeth, you are on the right track. If you are still using zinc phosphate cement, there is a better way shear-peel band strength is much better with the newer cements. If you're interested reviewing study on the strength traditional and newer orthodontic cements, you can find this information in the August 2000 issue of the Angle Orthodontist.

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I find dealing with children that have a thumbsucking habit, to be one of the most rewarding yet challenging tasks in my practice. What is your method of dealing with these patients when they are present your office? Do you immediately fabricate an intraoral appliance to try to discourage the habit? Dr. Skinazi from Paris France, recently published an article in the August 2000, Journal of Clinical Orthodontics entitled "A psychological approach to thumbsucking,¡±that had a different perspective. Dr. Skinazi believes that most thumb habits can be successfully extinguished with the use of simple psychological techniques rather than the use of appliances.

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Here is what he recommends. First, the orthodontist must create a dialogue with the child that involves 3 things. The first is non-accusatory awareness. This is where the orthodontist and the patient acknowledge the problem, without placing blame on the child. The author suggests language such as, "It's not so much that you suck your thumb, it's more that your thumb comes into your mouth all by itself." Second, the dialogue must also include an offer to help on the part of the orthodontist such as, "I think you can be the boss. If you want, I can help.¡±The final part of this initial dialogue is to offer encouragement such as in any case, "We can take care of the problem, but I'm sure that you can do it by yourself." After this initial dialogue and challenge, the patient is given one week to work on the problem and then returns to see the orthodontist. The author finds that most patients' will are had success controlling the habit during waking hours, but ask for help at night. The author's second stage then is introduced the¡°Thumb Home.¡±The thumb home is a fabric pocket that is attached to the patient's pajamas and provides an alternative comfortable home for the thumb rather than the patient's mouth. The patient is given very specific instructions of how to give the thumb an order before bedtime, by stating 3 times directly to the thumb,¡°Thumb, you will not come into my mouth¡± and then placing it into the "Thumb Home.¡±The orthodontist sees the patient back in 2 weeks and states that in the great majority of cases, the habit has been extinguished. The big advantage of this technique is that it also gives the patient a wonderful feeling of accomplishment and control. This is far more rewarding to the child and the orthodontist than appliance treatment. It makes orthodontist supportive friend rather than the mean enemy.

The article contains many more examples of specific language that can be use to solicit the child's cooperation, and I would recommend reading the entire article in the August issue of the Journal of Clinical Orthodontics. Remember, proper use of psychology can allow you to extinguish the majority of thumb habits, without having to result to appliances, while at the same time giving a great boost that child's self-esteem.

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What method do you employ to provide traction force to an impacted canine? Do you use elastomeric thread to a rigid arch wire in order to maintain arch form and help avoid unwanted vertical effects? Do you use flexible piggy back arch wires? How about cantilever arms from the molars to eliminate forces on the adjacent teeth? I had met that foremost routine cases. I usually use the elastomeric thread even though I know the forces level is hard to gauge and that it decays rapidly. I use it because it is simple, and easy for the patients to clean and in most of the cases eventually gets the job done. If you are looking for a different idea for putting in more predictable force on an impacted tooth, in a way that a still simple and easy to reactivate, you may want to check the September issue of the Journal of Clinical Orthodontics.

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Dr. Christine Hauser and colleagues from New York University present an alternative method for providing traction force to an impacted canine in an article titled "Eruption of impacted canines with an Australian helical arch wire". The authors wanted a technique that help to maintain the position of adjacent teeth where providing a predictable force level to the impacted tooth. The technique they described uses a 0.016" Special Plus Australian wire. Three helices are typically placed on the wire one helix next to each adjacent tooth and one in the middle of the canine space, which is where the impacted tooth is connected.

The article shows the table the different possible helix configurations and the associated force levels with activations, for one half to one and a half millimeters. A deflection or activation of one millimeter generally provides one hundred fifty to two hundred grams of traction force. This force level of one hundred fifty to two hundred grams is just recommended during the time the canine is impacted and a reduced level of sixty to one hundred fifty grams is suggest, once the canine has penetrated the tissue. The direction of the force vector to the impacted tooth can be changed by changing the mesiodistal location of the middle helix. A stainless steel ligature is placed from the middle helix to the chain on the impacted tooth and the ligature tightened to deflect the wire about one millimeter. The ligature is tightened periodically to maintain the force and keep the impacted tooth moving. A case report had shown which demonstrated the clinical use of this technique. A thirty-year-old male had shown that very slow progress with an impacted maxillary right canine. Use of conventional elastic thread and piggy back arch wires is doing little to move the tooth into the arch. But the placement of Australian wire created rapid and predictable movement.

In summary, this article shows an alternative technique for providing traction to an impacted canine using helices bent into an Australian stainless steel wire. The force to the impacted tooth can be controlled by monitoring and measuring of the deflection of the middle helix. Just see the pictures may help you to understand this clinical technique. See the September 2000 issue of the Journal of Clinical Orthodontics.

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As more and more orthodontic offices gather and store the records in digital formats, it becomes easier to use these records for prediction of treatment outcomes. The most popular use is in combined orthodontic-orthognathic surgery cases were we are tried to  help patient understand likely difference in the treatment outcomes. For instance, if I have an adult Cl. II patient with mandibular deficiency, I would like the patient understand the differences that could be expected in the post-treatment appearance, if we did mandibular advancement surgery as compared to orthodontic treatment alone with extraction of two upper premolars. Having a visual way to help the patients few the expected differences is very helpful. How well did the software program in our variable predict soft-tissue outcome of orthognathic surgery.

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A recent research project done at of University of Iowa helps understand benefits and limitations of these types of software. Dr. Tod Curtis was leader author of paper that appeared in the September 2000 issue of the Journal of Clinical Orthodontics entitled "Accuracy of a Computerized Method of Predicting Soft-Tissue Changes from Orthognathic Surgery." The software used in this study was Orthodontic Treatment Planner or OTP. Like all programs these types, this software takes pre-treatment lateral cephalogram and lateral photograph and links some together. The orthodontist then produces the expected hard tissue changes in tooth and jaw position, and the software generates the expected changes in facial appearance. The authors used protocols were 28 patients that at already completed their treatment or identified on the records obtained. The researcher, then enter the pre-treatment ceph and photo as we do for a new patient. Then the actual hard tissue changes at occur during treatment with these patients. We duplicated software at OTP allowed to generate predict post-treatment lateral photographic image. This predicted image was then compared to the actual post treatment image of patient.

So, how do OTP do it predicting images? I would say only pair. The good news was that 50% of soft tissue landmarks were predictive within 1mm of the actual post-treatment position. This is very good. The bad news is the other 50% were greater than 1mm from the actual post treatment position, and almost one in ten were  3mm greater from the actual location. This is not so good. The other disappoint thing is that the hardest landmark to predict what thing like the lower lip that are very important to the treatment differences we are trying to demonstrate.

The result of this study confirm many of other studies in that predict accuracy of software were like OTP is variable and the lower lip is one of most difficult areas to predict. To see more details about this study and about the OTP software, refer to the complete article in the September 2000 issue of the Journal of Clinical Orthodontics.

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Let me describe a clinical situation and then ask you a couple of questions. Suppose  planning treatment for 25-year-old male with a class III malocclusions. The treatment plans were involved non extraction orthodontic therapy and mandibular osteotomy to move the mandible posteriorly to correct a class III malocclusion. The patient is very interested in treatment but his concern because he has a anteriorly displaced disc on the right side and he has pain in the temporomandibular joint for about past five years. Here is the concerns, when the mandibular surgery is accomplished and mandible is setback. There are 2 options for fixation. One is transosseous wiring or used to call loose fixation, the other is to use miniplates or screws which we now not call rigid internal fixation.

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Now for my questions, which of these types of fixation would be best for this patient's temporomandibular joint symptoms? If rigid fixation is accomplished, were the torque or twisting of the condyle cause worse temporomandibular symptoms? All of there be no differences. Those questions will be discussed in the study was published in the August 2000 issue of Clinical Orthodontic Reseach. Now the title of the article is "Effects of wire and miniplate fixation on TMJ symptoms following orthognathic surgery". This study was coauthored by Dr. Kobayashi and serveral reseach colleagues from Niigata University in Japan. The purpose of their paper was to retrospectively evaluate 150 patients who had had mandibular prognathism corrected bi-sagittal split osteotomy. 100 these individuals had loose or interosseous wiring for fixation, the other 50 individuals had rigid fixation with miniplates and screws. The temporomandibular joints of all individuals were examined clinically for pain, sounds, movements, and of course limitations before orthodontics and then after orthognathic surgery and finally at least one year after the surgery had been completed. Ok! What would you think of the author's found? Will rigid internal fixation cause worse temporomandibular joint symptoms. The answer of that question is No. In both groups prior to surgery about 20% the individuals had TMJ signs and symptoms such as clicking and/or pain. So, there was no differences in the incidence of TMJ signs and symptoms between the two experimental groups. When the propriate statistical analysis would show you differences in postoperative changes of the symptoms between the groups. There were no statistically significant differences.

So in conclusion, if a patient present for bilateral sagittal split osteotomy, to reduce mandibular prognathism, based upon this study it makes no differences at all, if the patient has a wire fixation or rigid fixation.

The incidence of TMD or temporomandibular joint  symptoms after surgery will equivocal in both the experimental groups. This is important information for orthodontist to know when treating these types of patients. If you're interesting in reviewing the study you can find it in the August 2000 issue of Clinical Orthodontic Research.

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Let me describe a clinical situation and then I will ask you a couple of questions. Suppose you're examining a 15-year-old female. She has a Class I malocclusion with mild crowding. Now the reason she was referred to you is because she has popping of the right temporomandibular joint and in addition she has some muscle pain on the same side. She is concerned that her occlusion isn't treated, her temporomandibular symptoms could get worse with time. Now her mother accompanies her to the examination. What would tell them? What will happen to her temporomandibular symptoms? or their incidence over the next 20 years? When she is an adult, will she have the same symptoms? Will they fluctuate? Will the symtoms get a lot worse or will the symptoms tend to decrease?

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In the really, all of the those are important questions or issues for us orthodontists who see young population that often has at least one or possibly two signs of TMD during the teenage years. Knowing the answers to those questions is important in evaluating these young patients and determining the need for treatment. All of these questions were answered in the study that was published in the fall, 2000 issue of The Journal of Orofacial Pain.

The purpose of this study was to evaluate the long term developement and analyze possible connections between TMD signs and symptoms overall 20 year period. The authors of this study were Thomas Magnusson and Gunnar Carlson from the University of G teborg in Sweden. This was a very interesting study. It represents the best in research. And that's because it was a long-term longitudinal evaluation of young patients who had initially been examined at 15 years of age. The original sample consisted of over 125 subjects. These individuals were examined for any type of TMD or TMJ dysfunction. The actually from part of doctoral offices of the senior author 20 years ago. Then these individuals were reevaluated at 5, 10, and now finally at 20 years after the initial examination. So the long term evaluation, these subjects were 35 years of age. The response late to getting the subjects back for investigation was phenomenal. 92 percents of the subjects were reexamined 20 years later. Now when these individuals were reevaluated, the same methods of assessing their occlusion or their temporomandibular function were accomplished. The amount of opening, pain on opening, joint noises, occlusions, habits, and many other aspects were evaluated at both of the time intervals.

What do you think the researchers found? What happens to TMD symptoms over time? All these researchers uncovered some very interesting trends. First of all and by the way most importantly, the authors showed that at age 35, only 3 individuals are the entire sample had moderate or severe signs of clinical dysfunction. This means the incidence was less than 3 percents. Rarely did any of these younger patients end that put severe problems at age of 35. That's good news. The second most important finding according to these researchers was the substantial fluctuation in TMD signs and symptoms over the observation period. In other words, these subjects may have had some signs and symptoms at one time that disappeared at another time So, in another words, the symptoms simpley didn't get worse with time, but vary significantly. In fact, two thirds of the entire sample at 35 years of age said that they had never or only occasionally had headaches and as you probably what would be expected, problems with the mouth opening in pain, that occurred during chewing were much more common among women than among men.

So what's the bottom line. Well I think it's what we probably would be expect to see. The incidence of TMD at 15 and 35 was actually similar at about some where around 13%. But this study showed that the signs and symptoms in a 15 year old rarely progress, and cause severe or even and moderate TMD at age of 35. So if you are interested in reading the study, you can find it in the fall, 2000 issue of The Journal of Orofacial Pain.

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Has this ever happened to you? You are just about to examine a 43-year-old male patient. In your initial conversation with this individual, he seems like a very nice person. After you ask a few preliminary questions, you are ready to examine the patient's teeth and look at the oral cavities. The patient appears well dressed and well groomed. But when you get close to the patient to begin to evaluate the teeth, you smell his breath. It's awful! In fact its so bad that you hope this patient doesn't have malocclusion, because you dread the thought of treating this individual. In fact you thinking to yourself, only a few times in your career can you remember this degree of halitosis. When you examine this patient, you realize that he has no periodontal disease, he's not a smoker and he has clean teeth. What's causing the breath odor? Is it possible to eliminate this problem? What could you suggest to the patient to eliminate the halitosis? Those questions were discussed in the study that was published in the October, 2000 issue of the Journal of Dental Research.

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The title of the article is "Morning Breath Odor, Influence of Treatments on Sulfur Gases". This study was co-authored by Dr. Suarez and three other research colleagues from the university of Minnesota in Minneapolis. Now the purpose of their investigation was to measure the breath concentrations of various sulfur gases in subjects after they were just awaken from a night sleep. Then secondly they determine the effects of various types of remedies or interventions on the concentration of these sulfur gases over the next 8 hrs. In order to accomplish this subjective the authors enlisted 8 healthy adult volunteers. They ranged in age from 25 up to 50 years. All of the subjects were free of dental caries and none of them had periodontal disease. So generally they had pretty healthy mouth. First of all after waking in the morning, each of the subjects collected two oral gas samples. Then six different interventions or possible remedies for mouth malordor were tested. Then gas samples were again taken at 15 minutes, 30 minutes and then hourly over the next 8 hrs. During the time of this experiment, of course, the individuals were not allowed to eat food, but only to drink water.

Now let me explain these six interventions that we used. These include, first of all, no treatment, second, brushing the teeth with the fluoride containing toothpaste, third, only brushing the tongue with tooth the brush and water for one minute, four, rinsing the mouth with 5mL of 3% hydrogen peroxide for 1 minute, number five, consumption of the subjects standard breakfast for example either cereal or toast and milk, and finally number six, ingestion of two BreathAssure capsules. These are commercially available, well known to promote treatment of bad breath, by the way, these tablets contain parsley oil, seed oil, and sunflower oil.

Okay, what do you think these researchers found? Is it possible to eliminate mouth odor, and if so, how? Let me give you the bottom line. First of all, the reason for the bad breath is the presence of three different types of sulfur gases in the mouth. Now I know the actual names of these are pretty important to you, but the most prominent is hydrogen sulfide, which is present in the greatest concentrations and is really what causes the odor. Now let me tell you which two treatments have no affect on mouth odor. One is brushing the teeth with the fluoride toothpaste and the other is ingestion of BreathAssure tablets, these two interventions have absolutely no influence on sulfur gases. What worked a little bit better intended to improve or decrease sulfur gases  was either eating breakfast or brushing the tongue with water but the best method to reducing the sulfur gases was to rinse with hydrogen peroxide. These researchers found that rinsing for 1 minute with 3% hydrogen peroxide significantly reduced the sulfur gas concentration and was even better it lasted for 8 hours.

So back to the 43 year old patient with bad breath, if this patient has malocclusion and you want to treat the patient but you don't want to smell the bad breath. You might suggest to this individual that rinsing with 3% hydrogen peroxide either before he comes to see you or at his orthodontic appointment may be a good method to reduce the sulfur concentration and improve this patient's breath. If you are interested in reading this article, you will find it in October 2000 issue of the Journal of Dental Research.

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When we think of skeletal transverse constriction, we usually think of the maxilla. Rapid maxillary expansion in growing patients or surgically assisted rapid maxillary expansion in adults are commonly used to correct transverse discrepancies in the maxilla. Transverse constriction of the mandible is a less common problem and presence more of a challenge. Patients with constricted mandibles often present with significant crowding and bilateral buccal crossbite. An article title "Long-term skelectal and dental effects of mandibular symphyseal distraction osteogenesis" by Marinho Del Santo, Jr, et al which appeared November 2000 American Journal of Orthodontics and Dentofacial Orthopedics.

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The authors evaluated the use of the distraction osteogenesis to expand the mandible in 20 Hispanic nonsyndromic patients who ranged from 13 to 37 years of age. The procedure that was used involve placing a Hyrex appliance in the mandible attached to the first premolars and molars. A circumferential osteotomy cut was made in the anterior symphysis area and a Hyrex appliance with activated 2 mm at the time of surgery. After an average latency period of 8 days, the distraction device was activated 1 mm per day. The average expansion achieved was approximately 8 mm.

Lateral and P-A cephalometric radiographs as well as panoramic radiographs were used to evaluate changes presurgically, immediately following expansion and long term at average 1.3 years postsurgery. When they evaluate the patients postexpansion, the authors found that intercanine width increased a little over 3 mm and intermolar width increased slightly more than 2 mm an average. In an interesting finding they noted that the mandibular incisors were flared significantly and that proclination of the mandibular incisors with significantly greater for the patients who did not have predistraction orthodontic appliances in place. Unfortunately the authors did not speculate as to the cause of the mandibular incisor flaring. However, I couldn't helpful wonder its the placement of a Hyrex appliance in the mandible cause the tongues to be significantly displaced thereby placing pressure on the lower incisors.

The long-term evaluation of the changes that were achieved appear to be stable. However I should know that while the average long-term results were at 1 year 3 months the range was from 6 months which was not really long term to 31 months. The intraoral radiographs of one of the cases are presented in the article and show severely constricted mandibular arch with anterior crowding and lingual inclination of the posterior teeth. The bottom line of this study is that the choice of a tooth-bone distraction appliance can be used to transversely expand the mandible. However, I suspect that this type of treatment would be indicated for very limited number of patients. I say this because I have successfully treated a number of patients with bilateral buccal crossbite by simply uprighting the mandibular posterior teeth which are usually lingually inclined. Also tooth extraction or reproximation seems much more conservative means for resolving crowding. I would also question the likelihood of the patients tolerating a Hyrex appliance in the mandible very well.

Possible the development of smaller more efficient appliances in the future will make this more patient friendly procedure. You can find this article in November 2000 issue of the American Jounal of Orthodontics and Dentofacial Orthopedics.

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I suspect back that there was no one listening to me who isn't concerned about relapse occurring after the completion of active treatment. What do you do in your practice? Do you reduce the likelihood heard of relapse, recrowding particularly of the anterior teeth? I suspect you routinely use some form of retention either fixed or removable, motivate your patients to wear the retainers and hope to the best. In the late 1960's John Edwards described the use of a circumferential supracrestal fiberotomy to reduce rotational relapse. Are circumferential supracrestal fiberotomies effective in reducing relapse short-term that is up to 1 year-post treatment. This question was addressed in a study titled "Short-term effects of fiberotomy on relapse of anterior crowding" by Tulin Taner et al. which appeared in the December 2000 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

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In this study, the authors evaluated 23 patients treated with fixed appliances. All of whom were treated to an optimal occlusion. 11 of these patients received circumferential supracrestal fiberotomies on the maxillary and mandibular anterior teeth 1 week prior to debonding. The other 12 patients served as the controls. Dental casts were taken at the initiation of active treatment, at the completion of active treatment, 6 months and 1 year after active treatment. And these models were used to evaluate crowding relapse.  At both the 6 months and 1 year-post treatment evaluations, there was a significant increase in the irregularity in the control group for both the maxillary and mandibular anterior teeth and the difference was striking. At the end of treatment in both groups, the irregularity index values were close to zero. For the group which received the circumferential supracrestal fiberotomies, the percentages of the mean relapse for the mandibular anterior teeth were 0.6 % and 1.5 % at the 6 month and 1 year intervals respectively. For the maxillary teeth, they were 0.8 % and 1.0 %, these were obviously very minimal amounts of relapse. In the control group, however, the percentages of mean relapse for the maxillary anterior teeth were 14.1 % at 6 months and 25.0 % at 1 year, and in the mandible, 38 % at 6 months and 63 % at 1 year. The bottom line is that in the control group that did not received the fiberotomies, there were significant increases in the irregularity index for both the maxillary and mandibular arches, while brought in the group that received the circumferential supracrestal fiberotomies, minimal changes in the irregularity index were observed.

As I mentioned earlier, the differences were truly impressive. The only question I had about this study was related to the mean time for active treatment, which was 23 months for the circumferential supracrestal fiberotomy group and 16 months for the control group. With the patients who received the fiberotomies averaging approximately 7 more months of active treatment. I couldn't help of wonder if the increasibility of the fiberotomy group was in part due to the longer period of active treatment, because the differences were so striking. I feel confident that the primary cause of the difference was the fiberotomies, however, it would be nice to see similar periods of active treatment for both groups. It will also be interesting to see if these results hold up over a longer post treatment period. These article appeared in the December 2000 issue of the American Journal of Orthodontics and Dentofacial Orthpedics.

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Imagine a patient referred to you for retraction and alignment of upper incisors prior to undergoing prosthetic restoration of the posterior teeth. When you are examining this patient, you realize that they have no teeth distal to the upper first premolars and the vertical dimension is collapsed due to the lack of posterior support.

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How do you provide anchorage for retraction of the upper incisors when there are no posterior teeth? If you were worked closely with restorative colleague, it may be possible to place traditional dental implants that could be use for orthodontic anchorage now and then for prosthetic support later. The drawback to this approach is that it requires very precise prediction of the final position of the teeth, so you know where to place the implants initially. It also involves expense and healing time of traditional and osseous implants.

Dr. James Gray and Dr. Robert Smith recently published a case report article in the November 2000 issue of the Journal of Clinical Orthodontics that may give us another option in this type of situation. The article is titled "Transitional Implants for Orthodontic Anchorage." The key to the technique described in this article is a unique dental implant called Modular Transitional Implant or MTI.

This implant was designed to support temporary prosthesis during the healing time of the traditional implant and then to be removed. It is a small diameter implant, only 1.8 mm and its all in one piece, no separate abutment is needed. The implant is placed by drilling of a small pilot hole right through the tissue under local anesthesia. No soft tissue flap or sutures are required.

The implant is screwed into the pilot hole and then attach to the teeth orthodontic appliance. The authors believed that immediate loading with orthodontic force level is possible. The case report shows these implants used successfully to retract anterior teeth in the situation we described earlier where no posterior anchorage is available. The MTI implants were placed in the alveolus distal to the last tooth on each side and used its anchorage. The implants were able to be unscrewed and removed when no longer needed. The authors did relate this problem that they had with these implants, when used to support the temporary prosthesis.

Ten MTI implants failed that were subjected to occlusal loading forces and rotational forces for support of temporary prosthesis. For this reason, they believed that it is important to place the MTI implants in a way that they are not subjected to rotation and where they are not loaded with the occlusal forces.

Next time you have a patient with the need for additional anchorage that cannot be provided with traditional way, you may consider trying the MTI implants. They are easy to place and can be loaded immediately with orthodontic forces. But need to be sheltered from heavy occlusal and rotational forces. Refer to the article by Dr. Gray and Dr. Smith in the November Journal of Clinical Orthodontics for photographs of the implants and to see how they were used to provide an innovated solution for their patient.

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Let me describe situation that you could face in your future. A ten-year-old boy comes to your office with the crowded Class I malocclusion and the history of maxillary central incisor that had been traumatically lost two years previously. The crowding is severe enough to require the extraction of 4 premolars and the main problem that you have is trying to figure out what to do for the missing permanent central incisor. I believe most orthodontists would probably hold space for the incisor and place a prosthetic tooth on the archwire during treatment and on the retainer during retention and then wait until the end of growth. At that time, a maxillary central incisor implant would probably be placed. In a situation like this, I believe most orthodontists in the United States would not consider the possibility of transplanting one of extracted premolars into central incisor area. However, in Europe and particularly in scandinavia the autotransplantation of the permanent teeth is much more common practice. In an article titled¡°Autotransplantation of Premolars to Replace Maxillary Incisors: A Comparison With Natural Incisors¡±by EM Czochrowska et al. which appeared in the December, 2000 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

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The authors evaluated 40 patients who had a total of 45 premolars transplanted to replace maxillary incisors. The mean age at the time of surgery was 11 years, and the mean observation period was 4 years post-treatment. Most of the patients in the study had lost incisors due to traumatic injuries. When the authors evaluated these patients 4 years later after the premolars had been transplanted to the incisor area reshaped and restored with either composite restorations or porcelain laminate veneers. What do they find? Basically they found that the autotransplantation procedures were very successful. At the 4 year follow-up examination, all transplanted teeth were present in a normally appearing alveolar process and signs of ankylosis were present in only one of the transplanted teeth. The most obvious difference between the transplanted teeth and adjacent control teeth was partial pulp obliteration that occurred in all the transplanted teeth and which was not observed in the intact natural incisors. Two transplanted premolars had undergone treatment because of signs of inflammatory root resorption, and the interproximal papillae next to the transplanted premolars generally were well preserved or slightly hyperplastic. In only 4 cases that the papillae not extend all the way to the contact point between the transplanted tooth and the controled central incisor.

The photographs from a number of cases were presented in the article and the esthetics of recontoured premolars appears to be excellent. The authors emphasized that only premolars with partially formed roots were included in this study. This is important because researchers had shown that the autotransplantation of premolars with fully formed roots reduces the success rates. The obliteration of the pulp which was seen in the transplanted teeth was usually restricted to the area of the root that had developed prior to transplantation and based on previous studies appears to have no significant effect on the long-term success of the autotransplantation. The bottom line of this study is that for most variable investigated, there were no clinically important differences between the transplanted teeth and the adjacent natural incisors. The authors emphasize that an important side effect of the autotransplantation is the potential for bone induction and reestablishment of the normal alveolar process after traumatic bone loss. They further note that even if the transplant should fail at a later stage, an intact recipient area may be preserved by the transplant and could subsequently be used to accommodate an implant. While the results of this study are impressive I believe it is important to know that the autotransplantation of premolars requires a very sensitive and highly technical surgical technique in order to be successful. The method of autotransplantation of immature premolars was developed at the University of Oslo in Norway where this study was performed. I suspect that the lack of experience of most oral and maxillofacial surgeons in the United States with autotransplantation is one of the reasons that we don't see similar success rates and are more likely to use implants for permanent incisor replacement

I look forward to seeing the results of the follow-up longer terms studies of the same patients. You can find this interesting article in the December, 2000 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

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Sometimes adolescent patients presented with severely retruded mandibular incisors or large ANB difference that require the mandibular incisors be in a protrusive position in order to compensate for the large ANB difference. What do you think would happen to the periodontal status of mandibular incisors that are severely protruded. By severely protruded I mean approximately 4 mms at the incisal edge or approximately a 10 degree increase in the IMPA angle. If we evaluate the patients who have undergone significant mandibular incisor protrusion during adolescent at a longer follow up post-treatment time. Would they demonstrate greater periodontal disease? These questions were addressed in an article titled "Periodontal Status of Mandibular Incisors After Pronounced Orthodontic Advancement During Adolescence: A Follow-Up Evaluation" by John Artun and Domini Grobety which appeared in the January 2001 issue of The American Journal of Orthodontics and Dentofacial Orthopedics.

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In this study, the authors compared the group of 30 adolescent patients who were treated with reverse headgear to the mandibular dentition to a match group of 21 patients who had essentially no advancement of the mandibular incisors. The patients who wear the reverse headgear to the mandibular dentition had the mandibular incisal edges protruded an average of 4 mms with approximately at 10 degree increase in the IMPA angle. The upper end of the range of advancement for these patients was 7 and a half mms at the incisal edge and 23 degrees increase in the IMPA angle. Both groups of patients were evaluated at an average of approximately 8 years post-treatment. Study models, color slides and periodontal examinations were used to evaluate the periodontal condition of the mandibular incisors long term. I think you may find the results of the long term evaluation somewhat surprising in that the authors found no significant differences between the patients in the two groups and the amount of recession, the width of attached gingiva, the length of supracrestal connective tissue attachment, the probing pocket depth, the gingival bleeding index or the visible plaque index of the mandibular incisors.

The bottom line of this study is that adolescent orthodontic patients with dentoalveolar retrusion may be treated with pronounced advancement of the mandibular incisors without increasing the risk of periodontal recession. There are few aspects of this study that I think are important to note. First, this study was done at an adolescent patients who averaged approximately 10 years of age. Second, the group of patients whose mandibular incisors were significantly protruded started treatment with retruded mandibular incisors. Although the incisors were advanced extensively during treatment, the actual position of the incisors was not anterior to that found in the controlled subjects at the end of treatment. I found the results of this study very interesting. In that they suggest that it may be possible to gain significant arch length in adolescent patients by protruding the mandibular incisors without risking recession. It will be really interesting to see a similar study performed on adults.

You can find the study in the January 2001 issue of The American Journal of Orthodontics and Dentofacial Orthopedics.

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Achieving clinical excellence in orthodontics is no accident and sometimes it takes time to save time. These two thoughts were driven home when I read an article titled "bracket positioning and resets; 5 steps to align crowns and roots consistently" by Sean Carlson and Earl Johnson which appeared in the January 2001 issue of The American Journal of Orthodontics and Dentofacial Orthopedics.

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Despite all the work and research that has been done to develop precision preadjusted or straight wire orthodontic appliances. The results achieved by these appliances are totally dependent on proper bracket positioning. Unfortunately for all of us, proper bracket positioning doesn't always accure. What do you do in your practice to deal with poorly placed brackets? In this article, the authors describe a 5 step process that they routinely use to prevent, identify and correct poor bracket position.

Step 1 involves initial bracket positioning. In this step, they first check the contour of the bracket base to make sure as follows contour of the tooth surface and they evaluate the rotational position of each bracket from the occlusal. They then determine the vertical position of each bracket by using well fitted molar bends as bench marks and finally determine the desire slot angulation by using periapical radiographs to evaluate root position. In the article, there are excellent photographs that clearly illustrate proper bracket positioning.

The goal of step 2 is to completely express the predescribed bracket position through complete leveling and aligning. A full size wire is completely engaged in each bracket before moving to step 3 which is the reset evaluation. The authors who use in 18 slot appliance recommend in 18 square sentalloy archwire. Only by placing a full archwire in allowing sufficient time for the arch wire to completely express itself can bracket positioning be accurately evaluated.

Step 3 which is a reset evaluation involves both a clinical and radiographic examination. The authors note that for most patients these reset evaluation can take place within the first 6 months of active treatment. During this appointment they evaluated any misplaced brackets and take additional radiographs to evaluate root position. In the article they present a sample form that is used to indicate corrections that need to be made and which facilitates bracket positioning during the next appointment.

During step 4 which is the reset appointment this prescription form which was completed at the previous visit is used to replace any brackets or bends that are incorrectly positioned. After recementation and bonding the same 18 square sentalloy archwire is fully engaged.  

The rest of 5th step in this process involves the reevaluating occlusal relationships after the replace 18 square wires has had time to fully experss itself.

The authors believe that infirmity the 5 step protocol reduces the treatment time and achieves superior results. They also note that while this process doesn't completely eliminate the need for wire bends during finishing, it does significantly reduce their number and complexity. The only thing that I would do in addition to at the authors suggested is to take a quick snap set up impressions during step 2 to help identify poorly positioned brackets after the initial full archwire has had time to express itself. This is an excellent article which contains numerous diagrams related to proper bracket positioning. You can find it in the January 2001 issue of The American Journal of Orthdontics and Dentofacial Orthopedics.

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In the previous review I suggested that achieving clinical excellence is not an accident and discussed the five-step procedure to achieve more accurate bracket positioning. Achieving excellent facial and smile esthetics is also not an accident. An article titled "Macroesthetic Elements of Smile Design" by Jeff Morley and Jimmy Eubank. It's appeared on the January 2001 issue of the Journal of the American Dental Association.

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Discuss is a number of important characteristics and relationships that result in on esthetic smile. While the article is primarily directed at restorative dentist or focused on esthetic dentistry, many of the principles of an esthetic smile are directly related to orthodontic treatment. The authors suggest that the starting point of an esthetic treatment plan is the facial midline. While there is general agreement that the midline between the maxillary central incisors should be coincidental with the facial midline, asymmetry of facial features such as the eyes and nose can make the facial midline difficult to identify. Probably, the easiest way to identify the facial midline is to identify the most inferior point in the center of cupid's bow on the maxillary lip. The contour of the embrasures between incisal edges of the maxillary anterior teeth can significantly affects smile esthetics. The size and volume of the incisor embrasures increase at the dentition progresses away from the midline. The article contains at excellent picture of proper incisor embrasure form and provides an excellent guide for orthodontist to use when they're esthetically reshaping the maxillary anterior teeth at the end of treatment.

While I was familiar with the esthetic importance of incisor embrasures, I was not familiar with the term connector space. These are the spaces in which the anterior teeth appear to touch,  I should know that there is a distinction between connector space and contact point. The connector space is a larger, broader area that is defined as the zone in which two adjacent teeth appear to touch. The connector space should decrease as you progress distally from the central incisors. All orthodontists are familiar with the importance of inclination of the maxillary incisors and this was emphasized in the article with well. Tooth reveal is a term that is used to describe the amount of tooth structure or gingiva that shows in various views and lip positions. The authors suggest that when a patient repeat the letter "M" and allows his lips to gently apart, younger patients should reveal between 2 and 4 mm of maxillary incisal edge.

In this article the authors also discuss the relationship of the maxillary incisors to a favorite refer to as the intercommissure line. This is a line that is drawn through the corners of the mouth when the patient's mouth is in the broad smile position. Approximately 75 to 100 percent of the maxillary teeth should show below this line to have a youthful esthetic smile. Also the plane of the incisal edges of the maxillary anterior teeth should have a convex appearance that approximates and harmonizes with the contour of the lower lip.

There are additional guidelines in this article that relate more directly to restorative dentistry. I believe will be helpful for any orthodontists to read this article not only because with make you more contracts of some of the certain changes that you can make to approve smile esthetics of your patients but also because of provide a basis for you to evaluate restorative treatment that your patients are receiving. You can find this article in the January 2001 issue of the Journal of the American Dental Association.

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How Comfortable do you feel localizing structures radiographically using the buccal object rule? This technique, of course apply two films taken of the same structures at different angles. The structure that appears to move opposite to tube head, it's known to be the more buccal object. It sounds simple but in practice isn't all that clear at times. A recent report that I read, founded, test panel of dentists was wrong 58% of the time in determining whether the inferior alveolar canal was buccal or lingual to tooth roots using the buccal object rule. The exciting news was a new technique that was being investigated was much better at localization. The article I own summarized for you appeared in the Febrary 2001 issue of Oral surgery, Oral medicine and Oral pathology and this entitled "Array-Projection Geometry and Depth Discrimination with Tuned-Aperature Computed Tomography for Assessing the Relationship between Tooth Roots and the Inferior Alveolar Canal."

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Let me try to describe to you how this new radiographic technique works. Tuned aperture computed tomography or TACT is a simplified CT scan. Instead of using and expensive scaner that takes a continuous series of images around the body. TACT takes a series of images using standard radiographic tube heads. In this investigation, the TACT series use nine exposures. The authors also compare how the nine exposures should best be taken along a horizontal plane, along a vertical plane, in a circular, a conical array or an X-shaped pattern. After all, nine images are taken, special software is used to create tomographic slices from these nine images. And this series of slices is used aid localization. This study use the model of the mandible to study the localization of the inferior alveolar canal relative to the tooth root. But it could just as well have been used to localize an impacted teeth. The authors then have panel of twelve dentists localized canal has being buccal or lingual to the tooth root, and further ask them estimated distance from the tooth to the nerve. The test panel use the different TACT arrange and also the standard buccal object rule.

What were the results. I told you at the beginning the dentists were wrong 58% of the time using the buccal object rule. This means they would been correct more often if they simply cost coin. The impressive thing was that the same group of dentists was correct everytime when using the TACT technique with a conical, or X-shaped arrays. The distance estimation was also much better using the TACT technique. How this is apply orthodontics? First, it may prove to be a reliable system for localizing impacted teeth and for looking at root position in orthodontics patients. Secondly, most exciting to me this technique could be developed into a sort of 3-D cephalometer that could provide real 3-Dimensional skeletal data for our diagnosis and treatment planning at a reasonable cost and with low patient radiation. To read more about this new radiographic technique, CD article by Dr. Morant colleagues from the university of Louisville in the february 2001.

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Have you ever treated the patient with obstructive sleep apnea who required jaw surgery to correct the problem. Suppose you just be referred the patient by the oral and maxillofacial surgeon in your community. The patient comes in for an examination appointment with a referral letter. In the letter the surgeon state the patient who is 45 -year old male has severe obstuctive sleep apnea. Recent sleep studies were done on is patient on the local hospital and because of those the position recommended bimaxillary surgery to advance the maxilla and the mandible to open his airway. The patient is referred to you to provide the orthodontic treatment. So you examine the patient. He has a class I occlusion. He only has mild crowding of his teeth and certainly or require the extraction of any teeth to correct alignment. The only problem is that the patient has a resonable good facial profile now.

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In the letter, the surgeon is recommending an advancement of the maxilla and the mandible at about 7 mm to open the airway. Here is your concern. If the patient looks cceptible in profile you now, will we look like after maxilla and mandible advanced 7 mm. Is it possible to predict the change? What happen to the tip of nose when the maxilla is moved forward that far. You know orthodontist we may at some point participate on the team that renders this type of surgical treatment for the patients with obstructive sleep apnea. So I was very interested in an article that I found in the February 2001 issue of the Journal of Oromaxillofacial Surgery that discussed this topic in detail. The article was titled "Soft Tissue Changes of the Upper Lip associated with Maxillary Advancement in Obstructive Sleep Apnea Patients."

It answers all of the questions I just posed regarding this type of procedure. The sample for this study consisted of 15 adult patients who had severe obstructive sleep apnea. Other modalities had been attempted on all of these patients to cure their apnea, but all attempts had failed. So each of these patients were to have both maxillary and mandibular advancement surgery to open the airway. The average amount of advancement for this group was large. It was 8 mm.

So the purpose of this study was to determine what amount the lip and the nose move forward as the maxilla was move forward to this degree. In order to answer this questions, pretreatment and posttreatment cephalometric radiographs were made on each of these patients. The patients were evaluated up to 8 months after the surgery. At that time the lip movement and the tip of nose movement were compared and related to the amount of maxilla movement.

Ok! let's look at the results. What we wanna know is the percentages. If the maxilla is moved forward 8 mm, what percentage of that would upper lip move in response. In this study the average ratio was 80%. That is, the upper lip moved forward 80% of the amount of maxillary movement. But wait a minute! What is the patient had thick lips rather than normal lips? That question also was addressed. The authors actually separated the samples into patient with thick lips compared to normal. On evaluated the difference, there were no significant difference is in the proportion of lip to maxillary movement. Ah! but how about the tip of nose? How much that moved forward proportional to the maxilla? In this study the average movement forward of the tip of nose was about 15% of the movement of the maxilla.

Ok! last question, would these patients look like after the surgery. Unfortunately, photographs were not shown in the article. I would love to see the pre and posttreatment photographs of these individuals to be able to judge for myself the static impact of moving the upper lip forward that amount.

Anyway this was very interesting study. As an orthodontist,  you may have to treat the patient someday who has obstructive sleep apnea so severe that is life-threatening and may require maxillary and mandibular advancement surgery to open the airway. Now at least, you can predict the change. You know that if the maxilla has moved forward 8mms, the upper lip moved forward about 80% and the tip of nose would moved forward about 15% percent of the total. If you're interesting in reviewing in this article, you can find it in the February 2001 issue of the Journal of Oromaxillofacial Surgery.