Maria Perpétua Mota Freitas

Objective: The present study aims at using cone beam computed tomography (CBCT) to analyze the maxillomandibular characteristics present in adults with mandibular asymmetries and different sagittal jaw relationships. Methods: 360 patients were selected and divided into three groups (Class I, Class II, and Class III), with 120 individuals per group. The groups were then subdivided according to the intensity of lateral deviation of the gnathion point, into: 1) relative symmetry, 2) moderate asymmetry, and 3) severe asymmetry. Three planes of reference were established in the CBCT images and several measurements were taken to compare the bilateral skeletal differences between the intensities of asymmetry for the different sagittal jaw relationships. Results: When the groups were compared by the intensity of asymmetry, significant differences among patients with relative symmetry and moderate to severe asymmetry were found. This was especially noticed for severe asymmetry, suggesting that the deviation of the chin did not constitute the only morphological alteration for these patients, especially because a series of measurements showed significant bilateral differences. When comparing sagittal jaw relationships, the only significant finding was the vertical positioning of the gonion between Class II and III patients with severe asymmetry. Conclusions: When comparing the three sagittal jaw relationships with the same intensity of asymmetry, most maxillofacial aspects were quite similar. The only difference was found for patients with severe asymmetry, as the individuals with Class II showed greater bilateral difference in the vertical positioning of the gonion, when compared to patients with Class III.

Objectives: To estimate the prevalence of mandibular asymmetries in orthodontic and orthognathic surgery patients and to investigate demographic and skeletal factors associated with this disharmony. Materials and Methods: Cone-beam computed tomography images of 1178 individuals aged 19 through 60 years with complete dentitions were analyzed. Outcomes were classified as relative mandibular symmetry, moderate asymmetry, and severe asymmetry. Factors recorded included sex, age, side of mandibular deviation, sagittal jaw relationship, vertical skeletal pattern, angle of the cranial base, and maxillary asymmetry. Ordinal logistic regression was used to estimate simple and adjusted odds ratios (OR) for the individuals with moderate and severe mandibular asymmetry, as well as 95% confidence intervals. Results: Prevalence values of 55.2%, 27.2%, and 17.6% were observed for relative mandibular symmetry, moderate asymmetry, and severe asymmetry, respectively. An independent association with the side of mandibular deviation and the presence of maxillary asymmetry was observed, both for subjects with moderate mandibular asymmetry (left side: OR = 1.50; 95% CI: 1.01–2.24 / maxillary asymmetry: OR = 2.07; 95% CI: 1.11–3.76) and for those with severe asymmetry (left side: OR = 2.09; 95% CI: 1.27–3.44 / maxillary asymmetry: OR = 4.93; 95% CI: 2.64–9.20). Conclusions: Moderate and severe mandibular asymmetries were present in 44.8% of the sample, being associated with the side of mandibular deviation and with maxillary asymmetry.

Introduction: The T-loop as designed by Burstone is a space closure spring used in the rational application of orthodontic biomechanics. Despite the diversity of studies, there is still no consensus on the optimal parametric characteristics for its conformation. Objective: This study aimed at reviewing the literature on the force systems released by different conformations of the T-loop, according to the type of anchorage and the main characteristics and factors that influence them. Results: Comparing the studies, the need for standardization was perceived in the methodology to shape the loops, regarding the variables that influence the force system. Most of the experimental studies with this loop do not report the vertical movement, nor the steps and angles that occur in the brackets. Clinical studies have obtained more variable results in relation to vertical acting forces, considering the influence of chewing. Conclusion: There is great potential for future studies with this type of loop, especially using nickel-titanium alloys, in order to achieve a pure translational movement without friction, with optimal and constant levels of force.

Objective: To investigate the association between malocclusion/dentofacial anomalies and traumatic dental injuries (TDI) in adolescents. Materials and Methods: The sample of this cross-sectional study comprised 509 adolescents aged 11 to 14 years enrolled at public schools in the city of Osório, southern Brazil. Parents answered a structured questionnaire addressing demographic and socioeconomic characteristics. An examiner who had undergone a training and calibration exercise recorded malocclusion/dentofacial anomalies (Dental Aesthetic Index, DAI), TDI (Andreasen), and dental caries (World Health Organisation). Statistical analyses (SPSS software) involved Poisson regression with robust variance. Results: The prevalence of TDI was 11.6%, and the prevalence of defined, severe, and handicapping malocclusion was 24.0%, 21.6%, and 22.0%, respectively. The multivariate analysis demonstrated that the probability of TDI was approximately twofold higher among adolescents with severe malocclusion (prevalence ratio [PR] 2.22; 95% confidence interval [CI] 1.14–4.31) and handicapping malocclusion (PR 1.95; 95% CI 1.01–3.85) in comparison to those with normal occlusion or minor malocclusion. Defined malocclusion was not significantly associated with the outcome. Among the dentofacial anomalies evaluated, the probability of TDI was nearly twofold higher among adolescents with overjet greater than 3 mm (PR 1.96; 95% CI 1.14–3.37) and 2.2-fold higher among those with an abnormal molar relationship (PR 2.24; 95% CI 1.17–4.32), after controlling for confounding variables. Conclusions: Severe and handicapping malocclusion, accentuated overjet, and abnormal molar relationship were strongly associated with the occurrence of TDI. Future studies should investigate whether the treatment of these conditions can help reduce the occurrence of TDI in adolescents.

The aim of this study was to evaluate the characteristics affecting different intensities of mandibular asymmetry in skeletal Class II adults using three-dimensional images. This study is clinically relevant since it allows professionals to evaluate the morphological components related to these deformities and more carefully obtain correct diagnosis and treatment plan for such patients.

Article Citation: Maria Perpétua Mota Freitas (2017) Letters From Our Readers. The Angle Orthodontist: May 2017, Vol. 87, No. 3, pp. 485-485. https://doi.org/10.2319/0003-3219-87.3.485

BACKGROUND This study aimed to estimate the prevalence of mandibular asymmetry and investigate some associated factors. METHODS Tomographic images of 952 individuals aged from 18 to 75 years old were analyzed. The investigated outcome was mandibular asymmetry. The explanatory variables included gender, age, absence of posterior teeth, and sagittal jaw relationship of the individuals. Statistical analyses included the chi-squared and the Poisson regression with robust variance. RESULTS Mandibular asymmetry was present in 17.4% of the sample (95% confidence interval 15.2-20.0). In the bivariate analysis, there was an association between the variables age and sagittal jaw relationship with mandibular asymmetry (P = 0.026 and P = 0.018, respectively). However, in the adjusted regression model, the association with age was not maintained, occurring only an association between sagittal jaw relationship and mandibular asymmetry (P = 0.045), with significant difference between individuals with skeletal Class II and skeletal Class III (P = 0.013). CONCLUSION Mandibular asymmetry was not independently associated with sex, age, or absence of posterior teeth. The only verified independent association was between mandibular asymmetry and sagittal jaw relationship.

Key words: Facial asymmetry; Tooth loss; Epidemiology; Orthodontics