The effect of maxillary first and mandibular second premolar extractions on the posterior Bolton ratio.

INTRODUCTION: The anterior and overall Bolton ratios and their application in orthodontics are widely known. However, little has been reported about the posterior Bolton ratio, how it is affected by the extraction of posterior teeth, and its application in orthodontic treatment planning. This study aimed to investigate how extracting maxillary first and mandibular second premolars affects the posterior Bolton ratio. METHODS: The sample included 55 patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios. The digitized models were subjected to virtual extraction of maxillary first premolars and mandibular second premolars and setup of posterior teeth in ideal occlusion. If space closure compromised occlusion, the teeth were moved to achieve ideal cusp-fossa or cusp-marginal ridge occlusion. The ideal setups were measured for residual interproximal spacing. Statistical analysis used R statistical software (version 2018; R Core Team, Vienna, Austria). RESULTS: The ideal nonextraction posterior Bolton ratio was determined from the sample to be 105.77 ± 1.99%. The ideal expected posterior Bolton ratio for maxillary first and mandibular second premolar extraction patients was 106.52 ± 2.52%. This significantly differed from the expected posterior Bolton ratio for the 4 first premolar extractions. Patients finished with an average of 1.28 mm net residual spacing between mandibular first premolars and first molars; 38.2% of patients finished with at least 1.5 mm of residual space, and 9.1% of patients finished with at least 2 mm of residual space. CONCLUSIONS: A patient with ideal anterior, posterior, and overall Bolton ratios treated with maxillary first and mandibular second premolar extractions to ideal occlusion will likely finish with some spacing in the mandibular dentition.

The effect of adenotonsillectomy and rapid maxillary expansion on the upper airway in pediatric obstructive sleep apnea: a randomized crossover-controlled trial.

STUDY OBJECTIVES: We aimed to determine the effects of adenotonsillectomy (AT) and rapid maxillary expansion (RME) on the apnea-hypopnea index (AHI) and compare volumetric changes in the upper airway (UA) arising from AT and RME. METHODS: Thirty-nine children who presented with maxillary constriction and grade III/IV tonsillar hypertrophy were randomized into two groups. One group underwent AT as the first treatment, and the other group underwent RME. Polysomnography (PSG) and cone-beam computed tomography (CBCT) were conducted before (T0) and 6 months after the first treatment (T1). In a crossover design, individuals with AHI>1 received the second treatment. Six months later, they underwent PSG and CBCT (T2). The influence of age, sex, tonsil and adenoid hypertrophy, initial AHI severity, initial volume of the UA, first treatment, and maxillary expansion amount was evaluated using linear regression analysis. Intra- and inter-group comparisons for AHI and inter-group comparisons of volumetric changes in each region of the UA were performed using a paired t-test and Wilcoxon test. RESULTS: The initial AHI severity and therapeutic sequence in which AT was the first treatment explained for 95.6% of AHI improvement. AT caused significant improvements in the AHI and volumetric increases in the buccopharynx and total UA areas compared to RME. CONCLUSIONS: The initial AHI severity and AT as the first treatment accounted for most of the AHI improvement. Most reductions in AHI were due to AT, which promoted more volumetric increases in UA areas than RME. RME may have a marginal effect on pediatric obstructive sleep apnea.

The effect of 4 first premolar extractions on the posterior Bolton ratio.

INTRODUCTION: Overall and anterior Bolton ratios have been well covered in the orthodontic literature; however, little has been reported on posterior Bolton ratios. Considering the frequency of premolar extractions in the specialty, it would be relevant to know how the posterior occlusion is affected by premolar extractions. This study aimed to investigate how the posterior Bolton ratio is affected by the extraction of the 4 first premolars. METHODS: Fifty-five patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios models were selected and digitized. Tooth widths were measured. Virtual extractions of 4 first premolars were performed, and a digital setup of anterior and remaining posterior teeth observing ideal occlusion relationships was executed. When space closure compromised the occlusion, preference was given to the latter. Residual interproximal spacing was digitally measured on the setups. Analysis of variance and linear regression tests were used to identify factors contributing to interproximal spacing. RESULTS: An average of 1.1 mm of net residual spacing between mandibular second premolars and first molars was observed. In 27% of the sample, at least 1.5 mm of residual space was found. In addition, 16% showed at least 2 mm of residual space. The ratio of the maxillary second premolars to the mandibular second premolars and the width of the maxillary second premolars best explain residual space (r = 0.554; r2 = 0.307). A regression equation for predicting residual space is offered. CONCLUSIONS: Ideal anterior, posterior, and overall Bolton ratios treated with extraction of 4 first premolars and ideal occlusion will likely finish with some spacing in the mandible.

Enamel thickness of maxillary canines evaluated with microcomputed tomography scans.

INTRODUCTION: Enameloplasty of maxillary canines is often needed for aesthetic substitution in patients with congenitally missing lateral incisors. The exact enamel thicknesses for the various canine surfaces are unknown because previous studies failed to employ accurate measurement tools to report and compare detailed enamel thicknesses for each surface at various crown heights. METHODS: Thirty-two extracted maxillary canines were collected and scanned in a microcomputed tomography scanner. The scans were imported into a custom-written MATLAB software (version 9.2; MathWorks, Natick, Mass) and the enamel thickness on the mesial, distal, labial, fossa, cingulum, and incisal edge of each tooth was computed, obtaining the mean value from slices at 0.1 mm intervals. The overall mean enamel thickness for each surface was also calculated, and these values were compared using paired t tests. Incisal wear stage and incisal enamel thickness that was measured were compared using Spearman rank correlation coefficient. RESULTS: The mean enamel thickness was significantly thinner at the gingival level when compared with the incisal for all surfaces that were analyzed (1-tailed, P <0.001). The mean enamel coverage at the mesial was significantly thinner than the distal when measured gingival to the widest mesiodistal area. The mean enamel coverage of the cingulum was particularly thin and therefore requires extreme care in reshaping it. Incisal edge enamel thickness was highly negatively correlated with the wear stage of the scoring system that was used (1-tailed, P <0.001). CONCLUSIONS: The enamel coverage of the maxillary canine varies depending on the tooth surface and the incisogingival measurement location.

Long-term stability of maxillary and mandibular arch dimensions when using rapid palatal expansion and edgewise mechanotherapy in growing patients.

OBJECTIVE: The purpose of this study was to assess the long-term stability of rapid palatal expansion (RPE) followed by full fixed edgewise appliances. METHODS: This study included 67 patients treated using Haas-type RPE and non-extraction edgewise appliance therapy at a single orthodontic practice. Serial dental casts were obtained at three different time points: pretreatment (T1), after expansion and fixed appliance therapy (T2), and at long-term recall (T3). The mean duration of the T1-T2 and T2-T3 periods was 4.8 ± 3.5 years and 11.0 ± 5.4 years, respectively. The dental casts were digitized, and the computed measurements were compared with untreated reference data. RESULTS: The majority of treatment-related increases in the maxillary and mandibular arch measurements were statistically significant (p < 0.05) and greater than expected for the untreated controls. Although many measurements decreased postretention (T2-T3), the net gains persisted for all of the measurements evaluated. CONCLUSIONS: The use of RPE therapy followed by full fixed edgewise appliances is an effective method for increasing maxillary and mandibular arch width dimensions in growing patients.

Three-dimensional evaluation of craniofacial characteristics related to mandibular asymmetries in skeletal Class I patients.

INTRODUCTION: Our objective was to analyze the characteristics that affect skeletal Class I adults with mandibular asymmetries using cone-beam computerized tomography. METHODS: The sample included cone-beam computerized tomography images of 120 subjects. Asymmetry was determined by the deviation of gnathion from the midsagittal plane and classified as relative symmetry, moderate asymmetry, or severe asymmetry. Maxillary and mandibular measurements were made, and the differences between the contralateral side and the deviated side were evaluated, as well as the differences between the categories of asymmetry. RESULTS: For patients with moderate asymmetry, there were significant differences between the contralateral and deviated sides for some measuments in the transverse and vertical planes. For those with severe asymmetry, statistically significant differences were found between the sides for all measurements, except for the measuments that evaluated the position of the mandibular condyle in the transverse and sagittal directions. Furthermore, a strong correlation was found in patients with severe asymmetry, between the deviation of the mandibular dental midline and the lateral displacement of gnathion. CONCLUSIONS: Patients with relative symmetry had a bilateral balance, whereas those with moderate and severe asymmetries showed several skeletal imbalances. A great deviation of the mandibular dental midline may indicate severe skeletal asymmetry in Class I adults.

Orthodontic treatment of a patient with maxillary lateral incisors with dens invaginatus: 6-year follow-up.

INTRODUCTION: Dens invaginatus is an anomaly of dental development in which calcified tissues, such as enamel and dentin, are invaginated into the pulp cavity. This morphologic alteration is more frequent in maxillary permanent lateral incisors and makes them more susceptible to carious lesions and pulp alterations. METHODS: This case report describes a patient with maxillary lateral incisors affected by dens invaginatus. The maxillary right lateral incisor had already undergone endodontic treatment, and the maxillary left one had a periapical lesion. Additionally, the patient had a Class II Division 1 malocclusion, with anterior open bite, posterior crossbite, and an impacted mandibular left second molar. RESULTS: The orthodontic treatment involved extraction of the maxillary lateral incisors and 2 mandibular premolars, resulting in proper overjet and overbite with good arch coordination and occlusal stability. CONCLUSIONS: Treatment results were stable, as evaluated in a 6-year posttreatment follow-up.

Cephalometric evaluation of adult anterior open bite non-extraction treatment with Invisalign.

OBJECTIVE: The purpose of this study was to evaluate, by means of cephalometric appraisal, the vertical effects of non-extraction treatment of adult anterior open bite with clear aligners (Invisalign system, Align Technology, Santa Clara, CA, USA). METHODS: Lateral cephalograms of 30 adult patients with anterior open bite treated using Invisalign (22 females, 8 males; mean age at start of treatment: 28 years and 10 months; mean anterior open bite at start of treatment: 1.8 mm) were analyzed. Pre- and post-treatment cephalograms were traced to compare the following vertical measurements: SN to maxillary occlusal plane (SN-MxOP), SN to mandibular occlusal plane (SN-MnOP), mandibular plane to mandibular occlusal plane (MP-MnOP), SN to mandibular plane (SN-MP), SN to palatal plane (SN-PP), SN to gonion-gnathion plane (SN-GoGn), upper 1 tip to palatal plane (U1-PP), lower 1 tip to mandibular plane (L1-MP), mesiobuccal cusp of upper 6 to palatal plane (U6-PP), mesiobuccal cusp of lower 6 to mandibular plane (L6-MP), lower anterior facial height (LAFH), and overbite (OB). Paired t-tests and descriptive statistics were utilized to analyze the data and assess any significant changes resulting from treatment. RESULTS: Statistically significant differences were found in overall treatment changes for SN-MxOP, SN-MnOP, MP-MnOP, SN-MP, SN-GoGn, L1-MP, L6-MP, LAFH, and OB. CONCLUSIONS: The Invisalign system is a viable therapeutic modality for non-extraction treatment of adult anterior mild open bites. Bite closure was mainly achieved by a combination of counterclockwise rotation of the mandibular plane, lower molar intrusion and lower incisor extrusion.

Cephalometric evaluation of adult anterior open bite non-extraction treatment with Invisalign

ABSTRACT Objective: The purpose of this study was to evaluate, by means of cephalometric appraisal, the vertical effects of non-extraction treatment of adult anterior open bite with clear aligners (Invisalign system, Align Technology, Santa Clara, CA, USA). Methods: Lateral cephalograms of 30 adult patients with anterior open bite treated using Invisalign (22 females, 8 males; mean age at start of treatment: 28 years and 10 months; mean anterior open bite at start of treatment: 1.8 mm) were analyzed. Pre- and post-treatment cephalograms were traced to compare the following vertical measurements: SN to maxillary occlusal plane (SN-MxOP), SN to mandibular occlusal plane (SN-MnOP), mandibular plane to mandibular occlusal plane (MP-MnOP), SN to mandibular plane (SN-MP), SN to palatal plane (SN-PP), SN to gonion-gnathion plane (SN-GoGn), upper 1 tip to palatal plane (U1-PP), lower 1 tip to mandibular plane (L1-MP), mesiobuccal cusp of upper 6 to palatal plane (U6-PP), mesiobuccal cusp of lower 6 to mandibular plane (L6-MP), lower anterior facial height (LAFH), and overbite (OB). Paired t-tests and descriptive statistics were utilized to analyze the data and assess any significant changes resulting from treatment. Results: Statistically significant differences were found in overall treatment changes for SN-MxOP, SN-MnOP, MP-MnOP, SN-MP, SN-GoGn, L1-MP, L6-MP, LAFH, and OB. Conclusions: The Invisalign system is a viable therapeutic modality for non-extraction treatment of adult anterior mild open bites. Bite closure was mainly achieved by a combination of counterclockwise rotation of the mandibular plane, lower molar intrusion and lower incisor extrusion.

RESUMO Objetivo: o objetivo desse estudo foi realizar uma avaliação cefalométrica dos efeitos verticais do tratamento sem extração de mordidas abertas anteriores em adultos com o uso de alinhadores (sistema Invisalign, Align Technology, Santa Clara, CA, EUA). Métodos: foram analisados cefalogramas laterais de 30 pacientes adultos com mordida aberta anterior, tratados com o sistema Invisalign (22 do sexo feminino, 8 do sexo masculino, com idade média ao início do tratamento de 28 anos e 10 meses, e mordida aberta anterior média igual a 1,8mm). Os cefalogramas pré- e pós-tratamento foram traçados e as seguintes medidas verticais foram avaliadas: SN ao plano oclusal maxilar (SN-MxOP), SN ao plano oclusal mandibular (SN-MnOP), plano mandibular ao plano oclusal mandibular (MP-MnOP), SN ao plano mandibular (SN-MP), SN ao plano palatino (SN-PP), SN ao plano gônio-gnátio (SN-GoGn), incisivo central superior ao plano palatino (U1-PP), incisivo central inferior ao plano mandibular (L1-MP), cúspide mesiovestibular do molar superior ao plano palatino (U6-PP), cúspide mesiovestibular do molar inferior ao plano mandibular (L6-MP), altura facial anterior inferior (AFAI) e sobremordida (OB). Testes t pareados e estatística descritiva foram utilizados para analisar os dados e as alterações significativas resultantes do tratamento. Resultados: foram encontradas diferenças estatisticamente significativas durante o tratamento para SN-MxOP, SN-MnOP, MP-MnOP, SN-MP, SN-GoGn, L1-MP, L6-MP, AFAI e OB. Conclusões: o sistema Invisalign é uma modalidade terapêutica viável para o tratamento sem extração de mordidas abertas anteriores em pacientes adultos. O fechamento da mordida foi obtido principalmente por uma combinação de rotação do plano mandibular no sentido anti-horário, intrusão molar inferior e extrusão do incisivo inferior.

Quantitative assessment of the effectiveness of phase 1 orthodontic treatment using the American Board of Orthodontics Discrepancy Index.

INTRODUCTION: This retrospective study included a sample of 300 randomly selected patients from the archived records of Saint Louis University's graduate orthodontic clinic, St. Louis, Mo, from 1990 to 2012. The objective of this study was to quantify the changes obtained in phase 1 of orthodontic treatment and determine how much improvement, if any, has occurred before the initiation of the second phase. METHODS: For the purpose of this study, prephase 1 and prephase 2 records of 300 subjects were gathered. All were measured using the American Board of Ortodontics Discrepancy Index (DI), and a score was given for each phase. The difference of the 2 scores indicated the quantitative change of the complexity of the treatment. Paired t tests were used to compare the scores. Additionally, the sample was categorized into 3 groups according to the Angle classifications, and the same statistics were used to identify significant changes between the 2 scores. Analysis of variance was applied to compare the 3 groups and determine which had the most change. Percentages of change were calculated for the significant scores. RESULTS: The total DI score overall and the scores of all 3 groups were significantly reduced from before to after phase 1. Overall, 42% improvement was observed. The Class I group showed 49.3% improvement, the Class II group 34.5% and the Class III group 58.5%. Most components of the DI improved significantly, but a few showed negative changes. CONCLUSIONS: Significant reductions of DI scores were observed in the total sample and in all Angle classification groups. This indicates that early treatment reduces the complexity of the malocclusions. Only 2 components of the DI showed statistically significant negative changes.

Relationship between body mass and dental and skeletal development in children and adolescents.

INTRODUCTION: The purpose of this investigation was to determine whether a relationship exists between body mass and dental and skeletal development in children and adolescents. A sample of 197 orthodontic patients (82 boys, 115 girls) was selected. Ethnicity was recorded, and body mass index (BMI) was calculated according to the standard equation from the Centers for Disease Control and Prevention, and then a BMI percentile according to sex and age was obtained. The panoramic radiographs were used to calculate the dental ages with an index. The chronologic ages were subtracted from the calculated dental ages to determine a "dental age difference" for each subject. The lateral cephalogram radiographs were analyzed for skeletal development using the cervical vertebral maturation stage method. RESULTS: The white population (60%) had an average BMI percentile of 53.6 and was statistically different from the Hispanic/black population (40%), which had an average percentile of 64.3. There were no significant differences for boys and girls for the BMI percentile and dental age difference, or for the BMI percentile and cervical vertebral stages. The multiple regression model showed that BMI percentile and ethnicity were statistically significant explanatory variables for the dental age difference. CONCLUSIONS: A relationship exists between body mass and dental and skeletal development. BMI percentile, dental age difference, and cervical vertebral stage are weakly correlated. No significant differences existed between boys and girls in any variables. BMI percentile and ethnicity are weak predictors of the discrepancy between dental age and chronologic age.

Long-term stability of rapid palatal expansion in the mixed dentition vs the permanent dentition.

INTRODUCTION: Palatal expansion has been a popular and proven technique for transverse discrepancies used in orthodontics for decades. The short-term effectiveness of the technique is understood, yet questions remain regarding the long-term stability, with much debate surrounding the optimum treatment timing to initiate expansion for the most beneficial and stable results, especially with regard to mixed dentition treatment. The purpose of this study was to determine the long-term stability of palatal expansion performed in the mixed dentition vs the permanent dentition. METHODS: Fifty-four subjects were grouped as follows: 24 in the mixed dentition and 30 in the permanent dentition at the start of treatment. All patients had been treated with the Haas type of palatal expansion appliance followed by nonextraction fixed edgewise mechanics. Digitized dental casts were evaluated at 3 times: before treatment (T1), after treatment (T2), and at the long-term retention (T3). Intermolar widths were computed by subtracting measurements between time points, and comparisons between the groups were made to determine expansion and stability differences. RESULTS: Significant intermolar width increases were observed from T1 to T2 with significant relapses from T2 to T3, and an overall net gain remained at T3 in each group. No significant differences were found for relapse between the mixed and permanent dentitions. CONCLUSIONS: There are no differences for the long-term intermolar width stability in patients treated with palatal expansion in the mixed dentition vs the permanent dentition.

Posttreatment evaluation of maxillary canine positions in 15-year-old subjects.

INTRODUCTION: Esthetic improvement is a primary reason that people seek orthodontic treatment. The maxillary canine is considered by many to have great importance for both function and esthetics. Limited information is available about the position of the maxillary canine in relation to skeletal landmarks and whether the position can influence esthetic perceptions. The purposes of this study were to evaluate the normal maxillary canine position in relation to skeletal landmarks, to determine posttreatment 3-dimensional maxillary canine position with cone-beam computed tomography images, and to see whether maxillary canine position influences esthetic perceptions. METHODS: The Bolton standard template was used as the control sample, and the maxillary canine position was determined by implementing a Cartesian coordinate system. The right and left maxillary canines of 96 treated patients (48 boys, 48 girls; 15 years old) were analyzed by digitization of the cone-beam computed tomography volumes. The subjects' posttreatment smile photographs were ranked and quantified by 9 orthodontic residents who completed a Q-sort. Correlations were determined between canine positions and esthetic outcomes. RESULTS: The only difference between the right and left canine positions was the anteroposterior position of the root apex. Statistically significant sex differences were found for the superoinferior position of the right and left canine cusp tips, the mediolateral right and left canine root apices, and the mediolateral left canine cusp tips. No correlation was determined between the maxillary canine position and the esthetic perception. CONCLUSIONS: The maxillary canine position in relation to skeletal landmarks was determined and does not appear to significantly impact the esthetic perception, according to this study.

Evaluation of marginal alveolar bone in the anterior mandible with pretreatment and posttreatment computed tomography in nonextraction patients.

INTRODUCTION: Our objectives were to evaluate marginal alveolar bone height in the anterior mandible after orthodontic treatment and to assess any correlations between morphologic and treatment changes. METHODS: We used 57 pretreatment and posttreatment cone-beam computed tomography images (17 male and 40 female subjects; 22 Class I, 35 Class II; average age, 18.7 ± 10.8 years; average treatment time, 22.7 ± 7.3 months) to measure cortical bone thickness, ridge thickness, distance from the apex to the labial cortical bone, and the distance from the cementoenamel junction to the marginal bone crest. Changes in the cementoenamel junction to the marginal bone crest distance were correlated with pretreatment measurements and treatment changes. RESULTS: Although there were great variations, the average facial and lingual vertical bone losses were 1.16 ± 2.26 and 1.33 ± 2.50 mm, respectively. The incisor-mandibular plane angle changes were also highly variable, averaging 2.4°. CONCLUSIONS: Orthodontic treatment causes changes in alveolar bone height and cortical bone thickness around the mandibular incisors. Although pretreatment cortical bone thickness, ridge width thickness, and specific tooth movements all play roles in what happens to the bone during treatment, incisor inclination was not correlated with alveolar bone height changes.

Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis.

INTRODUCTION: The aim of this study was to analyze stress distribution and displacement of the craniofacial structures resulting from bone-borne rapid maxillary expanders with and without surgical assistance using finite element analysis. METHODS: Five designs of rapid maxillary expanders were made: a tooth-borne hyrax expander (type A); a bone-borne expander (type B); and 3 bone-borne surgically assisted modalities: separation of the midpalatal suture (type C), added separation of the pterygomaxillary sutures (type D), and added LeFort I corticotomy (type E). The geometric nonlinear theory was applied to evaluate the Von Mises stress distribution and displacement. RESULTS: The surgical types C, D, and E demonstrated more transverse movement than did the nonsurgical types A and B. The amounts of expansion were greater in the posterior teeth in types A and B, but in types C, D, and E, the amounts of expansion were greater in the anterior teeth. At the midpalatal suture, the nonsurgical types showed more anterior expansion than did the posterior region, and higher stresses than with the surgical types. Type B showed the highest stresses at the infraorbital margin, anterior and posterior nasal spines, maxillary tuberosity, and pterygoid plate and hamulus. CONCLUSIONS: The 3 surgical models showed similar amounts of stress and displacement along the teeth, midpalatal sutures, and craniofacial sutures. Therefore, when using a bone-borne rapid maxillary expander in an adult, it is recommended to assist it with midpalatal suture separation, which requires minimal surgical intervention.

Apicotomy: surgical management of maxillary dilacerated or ankylosed canines.

This clinical article reports a technique, apicotomy, for managing dilacerated or ankylosed canines. The records of 3 patients successfully treated with apicotomy are presented. Orthodontists observe clinically significant incidences of impacted maxillary canines in their daily practices. Several procedures have been described to bring an ankylosed, impacted tooth into occlusion. Luxation is the most widely used solution, but there are risks involved with that approach, and the success rate is low. Surgical repositioning has also been used, but morbidity is high, and the aggressiveness of the procedure might also contraindicate it. Ankylosis might be related to the anatomic position of the canine's root apex and its adjacent anatomic structures. Apicotomy is a guided fracture of a canine root apex, followed by its orthodontic traction. It is a conservative surgical alternative for treating impacted canines with dilacerations or apical root ankylosis.

Evaluation of skeletal and dental asymmetries in Angle Class II subdivision malocclusions with cone-beam computed tomography.

INTRODUCTION: The purpose of this study was to determine whether Angle Class II subdivision malocclusions have skeletal or dental asymmetries between the Class II and Class I sides. METHODS: A sample of 54 untreated Angle Class II subdivision patients with pretreatment photos and cone-beam computed tomography (CBCT) scans was used. The photos were used to identify the Class II subdivision malocclusion and to record the amount of crowding per quadrant. Landmarks were plotted on each CBCT volume so that direct 3-dimensional measurements could be made to compare the positions and dimensions of the skeletal and dental structures on the Class II side vs the Class I side. RESULTS: Significant differences were found for 2 skeletal measurements: the position of the maxilla relative to the cranial base, and the mandibular dimension from the mandibular foramen to the mental foramen. Statistically significant dental differences were found for the position of the mandibular first molars and canines in relation to the maxilla and the mandible. Statistically significant differences were found for the maxillary first molars and canines in relation to the mandible. CONCLUSIONS: There were significant skeletal and dental differences between the Class I and Class II sides. The dental asymmetries accounted for about two thirds of the total asymmetry.

Evaluation of immediate soft tissue changes after rapid maxillary expansion

OBJECTIVE: To evaluate immediate soft tissue changes following rapid maxillary expansion (RME) in growing patients, using cone beam computed tomography (CBCT). METHODS: Twenty-three consecutive patients (10 male, 13 female) treated by RME were selected. Patients were scanned using CBCT prior to placement of the rapid maxillary expander (T0), then immediately following full activation of the appliance (T1). Defined landmarks were then located on the pre- and post-treatment orientated images. Change in landmark position from pre- to post-treatment was then measured. In addition to landmarks, 10 direct measures were made to determine distance change without regard to direction to measure soft tissue change of the lips. RESULTS: Significant transverse expansion was measured on most soft tissue landmark locations. All the measures made showed significant change in the lip position with a lengthening of the vertical dimension of the upper lip, and a generalized decrease of anterior-posterior thickness of both the upper and lower lips. CONCLUSIONS: Significant changes in the soft tissue do occur with RME treatment. There is a transverse widening of the midface, and a thinning of the lips.

OBJETIVO: avaliar as mudanças imediatas no tecido mole após a expansão rápida da maxila (ERM) em pacientes em fase de crescimento, usando tomografia computadorizada de feixe cônico (TCFC). MÉTODOS: vinte e três pacientes (10 do sexo masculino e 13 do feminino) tratados com ERM foram selecionados. Os pacientes foram escaneados por TCFC antes da implantação do expansor maxilar (T0) e imediatamente após a completa ativação do aparelho (T1). Pontos cefalométricos definidos foram localizados nas imagens pré- e pós-tratamento. As mudanças de posição desses pontos do pré- para o pós-tratamento foram, então, analisadas. Adicionalmente aos pontos, 10 medições diretas foram realizadas para determinar a mudança nas distâncias - independentemente da direção - nos tecidos moles dos lábios. RESULTADOS: uma expansão transversal significativa foi notada na maioria dos pontos demarcados em tecido mole. Todas as medições apresentaram mudança significativa na posição labial, com um aumento da dimensão vertical do lábio superior e uma redução generalizada da espessura anteroposterior dos lábios inferior e superior. CONCLUSÃO: de fato, mudanças significativas do tecido mole ocorrem no tratamento com ERM. Há um alargamento transversal do terço médio da face e um afinamento dos lábios.

Attitudes, awareness, and barriers toward evidence-based practice in orthodontics.

INTRODUCTION: The purpose of this study was to evaluate the attitudes, awareness, and barriers toward evidence-based practice. METHODS: A survey consisting of 35 questions pertaining to the use of scientific evidence in orthodontics was sent to 4771 members of the American Association of Orthodontists in the United States. Each respondent's age, attainment of a master's degree, and whether he or she was currently involved with teaching were ascertained. To minimize bias, the survey questions were phrased as an examination of the use of scientific literature in orthodontics. RESULTS: A total of 1517 surveys were received (response rate, 32%). Most respondents had positive attitudes toward, but a poor understanding of, evidence-based practice. The major barrier identified was ambiguous and conflicting research. Younger orthodontists were more aware, had a greater understanding, and perceived more barriers than did older orthodontists. Orthodontists involved in teaching were more aware, had a greater understanding, and reported fewer barriers than those not involved with teaching. Those with master's degrees had a greater understanding of evidence-based practice than those without degrees. CONCLUSIONS: Educational initiatives are needed to increase the understanding and use of evidence-based practice in orthodontics.