Factors affecting the stability of maxillary extraction site closure

ABSTRACT Introduction: A side effect observed in cases treated with extractions is the instability of orthodontic space closure. Objective: The aim of this study was to investigate the influence of gingival invagination, presence of third molars and facial pattern, on the stability of orthodontic space-closure in the maxillary arch. Methods: Ninety-nine subjects (41 male and 58 female) with Class I malocclusion treated with four premolars extraction were evaluated. Extraction sites reopening and gingival invaginations were evaluated in scanned dental models in the posttreatment and 1-year posttreatment stages (mean age 16.1 years). Third molars presence was evaluated at 1-year posttreatment panoramic radiographs, and the facial pattern (SN.GoGn) was evaluated in the initial lateral headfilms. Multiple logistic regression analysis was used to estimate the influence of the aforementioned independent variables on the frequency of extraction space reopening. Results: Space reopening was observed in 20.20% of the subjects 1-year post-debonding. Gingival invaginations were present in 25.73% of quadrants after debonding and in 22.80% 1-year posttreatment. The mean pre-treatment SN.GoGn was 35.64 degrees (SD=5.26). No significant influence was observed of the three independent variables on the instability of extraction site closure. Conclusions: The presence of gingival invaginations, third molars and facial growth pattern do not seem to influence maxillary extraction sites reopening.

RESUMO Introdução: Um efeito colateral observado nos casos tratados com extrações é a instabilidade do fechamento ortodôntico do espaço. Objetivo: O objetivo do presente estudo foi investigar a influência da invaginação gengival, da presença de terceiros molares e do padrão facial na estabilidade do fechamento ortodôntico dos locais de extração na arcada superior. Métodos: Noventa e nove indivíduos (41 homens e 58 mulheres) com má oclusão de Classe I tratados com extração de quatro pré-molares foram avaliados. A reabertura dos locais de extração e as invaginações gengivais foram avaliadas nos modelos dentários digitalizados nos estágios pós-tratamento e um ano pós-tratamento (idade média de 16,1 anos). A presença dos terceiros molares foi avaliada em radiografias panorâmicas de um ano pós-tratamento, e o padrão facial (SN.GoGn) foi avaliado nas radiografias laterais iniciais. Análise de regressão logística múltipla foi utilizada para estimar a influência das variáveis independentes citadas na frequência de reabertura do espaço de extração. Resultados: A reabertura do espaço foi observada em 20,20% dos sujeitos um ano após a remoção do aparelho. Invaginações gengivais estiveram presentes em 25,73% dos quadrantes após a remoção do aparelho e em 22,80% após um ano pós-tratamento. O SN.GoGn pré-tratamento médio foi de 35,64 graus (DP = 5,26). Não foi observada influência significativa das três variáveis independentes sobre a instabilidade do fechamento do local de extração. Conclusões: A presença de invaginações gengivais, terceiros molares e padrão de crescimento facial não parece influenciar na reabertura dos locais de extração maxilar.

Cephalometric changes during aging in subjects with normal occlusion

Abstract Objective To assess craniofacial changes from early adulthood to the seventh decade of life in individuals with normal occlusion. Methodology The sample comprised lateral cephalograms of 21 subjects with normal occlusion (11 male, 10 female), taken at 17 (T1) and 61 years of age (T2). Anteroposterior and vertical maxillomandibular relationships, and dentoalveolar and soft tissue changes were analyzed. Interphase comparisons were performed using paired t-tests. Differences between sexes, and subgroups with and without tooth loss were evaluated using t-tests (p<0.05). Results Maxillary and mandibular anterior displacement, and facial and ramus height increased from T1 to T2. Maxillary molars showed significant mesial angulation. Maxillary and mandibular molars, and mandibular incisors developed vertically during the evaluation period. Soft tissue changes included a decrease of the nasolabial angle, upper and lower lip retrusion, decrease of upper lip thickness and increase of the lower lip and soft chin thickness. Maxillary incisor exposure by the upper lip decreased 3.6 mm in 40 years. Males presented counterclockwise rotation of the mandible, whereas females showed mandibular clockwise rotation and backward displacement of the chin. The group with tooth loss showed a greater increase of the posterior facial height and ramus height. Conclusion We observed aging changes in dentoskeletal structures and soft tissue, as well as sexual differences for craniofacial changes during the maturational process. Subjects with multiple tooth losses showed a greater increase in mandibular ramus height.