Magister Scientiae Dentium - MSc(Dent) / Aim: The aim of this study was to assess the effect of retraction of anterior teeth on pharyngeal airway dimensions, after orthodontic treatment of bimaxillary protrusion cases by means of the extraction of four premolars. Method: A total of 88 lateral cephalometric radiograph pairs, consisting of a pre-treatment and post-treatment radiograph taken for orthodontic treatment of bimaxillary protrusion by means of extraction of four premolars, was used. The pharyngeal airway space, measured across three different levels, as well as the length of the maxilla and mandible were assessed for changes from pre-treatment to post-treatment. Pearson’s correlation coefficient was used to determine the degree to which the change in pharyngeal airway space was associated with the change in maxilla or mandible length. Results: The pre-treatment average pharyngeal airway space measurements were recorded as 15.23mm for the Superior Pharyngeal Airway Space, 11.63mm for the Middle Pharyngeal Airway Space and 13.56mm for the Inferior Pharyngeal Airway Space. The average reduction in the pharyngeal airway space was noted as 1.21mm, 1.64mm and 2.23mm respectively. All with statistically significant P values of <0.001.

Introduction: This study aimed to compare the third molars angulation and eruption status in Class I and II malocclusions in orthodontic treatment with and without first premolar extractions. Methods: The sample was comprised by 96 patients divided into four groups: Group 1 Class I malocclusion treated with first premolars extraction; Class I malocclusion treated without extractions; Group 3 Class II malocclusion treated with first premolars extraction; Group 4 Class II malocclusion treated without extractions. Panoramic radiographs were used to evaluate third molars mesiodistal angulations at T1, T2 and at T3. Third molar eruption status was assessed in dental casts. Intergroup angulations and eruption status comparisons were performed using ANCOVA followed by Tukey tests and Kruskal-wallis test, respectively. Results: Significantly greater mesial angulation and percentage of erupted right maxillary third molars were found in Class I extraction group. Significantly greater distal angulation and percentage of erupted right mandibular third molars were found in Class II extraction group. Conclusion: Class I and II extraction treatment exhibited more favorable angulations and greater number of erupted third molars than nonextraction treatment. Regardless the treatment performed third molars showed a more uprighted position in each malocclusion type. / Introdução: Este estudo comparou as angulações mesiodistais e o grau de irrompimento dos terceiros molares nas más oclusões de Classe I e II no tratamento ortodôntico com e sem extrações dos primeiros pré-molares. Métodos: Foram avaliados 96 pacientes divididos em quatro grupos. Grupo 1, indivíduos com má oclusão de Classe I tratada com extrações dos primeiros pré-molares. Grupo 2, má oclusão de Classe I tratada sem extrações. Grupo 3 indivíduos com má oclusão de Classe II tratada com extração dos primeiros pré-molares. Grupo 4 má oclusão de Classe II tratada sem extrações. As angulações mesiodistais dos terceiros molares foram avaliadas em radiografias panorâmicas e o grau de irrompimento em modelos de estudo. Para comparar as angulações e o grau de irrompimento entre os grupos, utilizou-se o teste ANCOVA seguido do teste Tukey e o teste de Kruskal-wallis, respectivamente. Resultados: O grupo 1 apresentou significativamente maior angulação mesial do terceiro molar superior direito assim como uma porcentagem maior de molares irrompidos. O grupo 2 apresentou significativamente maior angulação distal do terceiro molar inferior direito e uma porcentagem maior de molares irrompidos. Conclusão: Os tratamentos de Classe I e II com extrações apresentaram angulações mais favoráveis e uma porcentagem maior de terceiros molares irrompidos do que os tratamentos sem extrações. Independentemente do tratamento realizado, os terceiros molares apresentaram uma posição mais vertical.

Magister Scientiae Dentium - MSc(Dent) (Orthodontics) / Orthodontic treatment has the ability to improve the aesthetics and the function of patients. In order to create space, orthodontic treatment often requires removal of teeth. The most common teeth removed for orthodontic treatment are the premolars. It has become popular to remove second premolars in certain cases where the soft tissue profile should not be altered. The Damon self-ligating orthodontic system is renowned for not requiring dental extractions in the majority of cases. The effect of extractions on the soft tissue profile of patients, in conjunction with using the Damon system, has therefore not been researched. It is important to understand the effect that orthodontic treatment and extractions can have on the soft tissue profile of patients. This effect can accurately be determined by making use of the soft tissue cephalometric analysis, developed by Dr Reed A. Holdaway in 1983.