Thickness of the alveolar process in the anterior region of the maxilla and mandible of patients with antero-posterior discrepancy

Made available in DSpace on 2019-09-12T16:25:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2005O presente estudo teve como objetivo avaliar a espessura do processo alveolar da região anterior da maxila e mandíbula em pacientes portadores de discrepâncias ântero-posteriores. Após a seleção de telerradiografias laterais de cinqüenta e dois pacientes entre idades de sete e 13 anos, mediu-se a espessura do processo alveolar da região anterior da maxila e mandíbula. Todos os pacientes apresentavam o ângulo do plano mandibular entre vinte e trinta graus e discrepância óssea ântero-posterior entre maxila e mandíbula. Após a análise estatística (teste qui-quadrado) observou-se que não houve dependência entre a espessura do processo alveolar da maxila e mandíbula e a idade do paciente. Todavia houve dependência entre o tipo de má oclusão e a espessura de osso vestibular na região anterior da maxila. Os pacientes portadores de má oclusão de Classe III apresentaram maior porcentagem de redução de osso vestibular da região anterior da maxila quando comparados aos pacientes Classe II. Os pacientes com tendência ao crescimento vertical apresentaram a dimensão reduzida de osso lingual da maxila e osso vestibular da mandíbula.The purpose of the present study was to assess the thickness of the alveolar process on the anterior region of maxilla and mandible of patients with antero-posterior discrepancy. The thickness of the alveolar process on the anterior regions of maxilla and mandible was measured by lateral cephalograms from fifty two patients with ages between seven to thirteen years. All the patients included on this study had the mandibular plan angle between 20 and 30 degrees and antero-posterior bone discrepancy between maxilla and mandible. The statistical analysis (Chi-square test) revealed independence between the thickness of the maxilla and mandible alveolar process and the patient age. However, a statistical dependence was found between the type of the malocclusion and the thickness of the buccal bone on anterior region of maxilla. The patients with Class III malocclusion showed a higher percentage of buccal bone reduction on the anterior region of maxilla when compaired with Classe II patients. The patients with trend to vertical growing had a reduced dimension of the maxilla lingual bone and mandible buccal region.[Claro, Cristiane Aparecida de Assis] Universidade de São Paulo, BrazilClaro, Cristiane Aparecida de Assis; Chagas, Rosana Villela; Almeida, Gerval de] Universidade de Taubat

Comparative photoelastic study of dental and skeletal anchorages in the canine retraction

OBJECTIVE: To compare dental and skeletal anchorages in mandibular canine retraction by means of a stress distribution analysis. METHODS: A photoelastic model was produced from second molar to canine, without the first premolar, and mandibular canine retraction was simulated by a rubber band tied to two types of anchorage: dental anchorage, in the first molar attached to adjacent teeth, and skeletal anchorage with a hook simulating the mini-implant. The forces were applied 10 times and observed in a circular polariscope. The stresses located in the mandibular canine were recorded in 7 regions. The Mann-Whitney test was employed to compare the stress in each region and between both anchorage systems. The stresses in the mandibular canine periradicular regions were compared by the Kruskal-Wallis test. RESULTS: Stresses were similar in the cervical region and the middle third. In the apical third, the stresses associated with skeletal anchorage were higher than the stresses associated with dental anchorage. The results of the Kruskal-Wallis test showed that the highest stresses were identified in the cervical-distal, apical-distal, and apex regions with the use of dental anchorage, and in the apical-distal, apical-mesial, cervical-distal, and apex regions with the use of skeletal anchorage. CONCLUSIONS: The use of skeletal anchorage in canine retraction caused greater stress in the apical third than the use of dental anchorage, which indicates an intrusive component resulting from the direction of the force due to the position of the mini-implant and the bracket hook of the canine

Influência da perda óssea e da inclinação do incisivo na distribuição de tensões perirradiculares decorrentes da simulação de forças oclusais

Made available in DSpace on 2019-09-11T20:58:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2018Resumo Introdução Adultos com sequelas de doenças periodontais tendem a apresentar perda óssea, com consequente vestibularização dos incisivos superiores. Objetivo A influência da perda óssea e da inclinação do incisivo superior na distribuição de tensões devido a forças mastigatórias simuladas foram avaliadas nesse estudo. Material e método Modelos em resina epóxi foram confeccionados em três condições (sem perda óssea e com perda óssea de 5mm e 8mm). Aumentos na inclinação vestibular do incisivo superior de 10° e 20° foram obtidos com um bloco metálico chanfrado. Cargas de 100N foram aplicadas cinco vezes em cada condição usando uma máquina de ensaio universal. Os modelos foram observados e filmados com um polariscópio circular. Ordens de franjas isocromáticas (tensões) nas faces vestibular, lingual e apical foram registradas. A concordância dos dados foi avaliada pelo teste kappa ponderado e os resultados foram 0,89 e 0,82 para intra e interexaminadores, respectivamente. Resultado Os resultados dos testes de Kruskal-Wallis e SNK indicaram maiores tensões (2,0) com aumento da inclinação vestibular na face vestibular; maiores tensões (2,67) com aumento da perda óssea; maior tensão com a associação de perda óssea e inclinação vestibular (3,6); e as maiores tensões tenderam a concentrar-se na face vestibular, exceto em casos de inclinação normal e sem perda óssea (0,45). Conclusão Concluiu-se que aumentos tanto da inclinação vestibular dos incisivos superiores quanto da perda óssea aumentam as tensões perirradiculares, e a combinação desses fatores aumenta ainda mais as tensões devido às forças mastigatórias, com a maior concentração na face vestibular.Abstract Introduction Adults with sequelae of periodontal disease tend to have bone loss, with consequent flaring of the maxillary incisors. Objective The influence of bone loss and the inclination of the maxillary incisor in the distribution of stresses due to simulated bite forces was studied. Material and method Models in epoxy resin were made in three conditions (without bone loss and with bone loss of 5mm and 8mm). Increases in the labial inclination of the maxillary incisor of 10° and 20° were obtained with a beveled metallic block. Loads of 100N were applied five times in each condition using a universal test machine. The models were observed and filmed with a circular polariscope. Orders of isochromatic fringes (stresses) on the labial, lingual, and apex surfaces were recorded. The agreement of the data was evaluated using the weighted kappa test, and the results were 0.89 and 0.82 for intra- and inter-examiners, respectively. Result The results of the Kruskal–Wallis and SNK tests indicated higher stresses (2.0) with increased labial inclination in the labial surface; higher stresses (2.67) with increased bone loss; higher greater stresses with the association of bone loss and labial-inclination (3.6); and the highest stresses tended to concentrate on the labial surfaces, except in cases of normal inclination and without bone loss (0.45). Conclusion It was concluded that increases in both the labial inclination of the maxillary incisors and bone loss increase periradicular stresses, and the combination of these factors further increases the stresses due to bite forces, with the highest concentration on the labial side.[CLARO, Ana Paula Rosifini Alves] Universidade Estadual Paulista, BrazilRODRIGUES, Samuel; CORTELLI, José Roberto; CHAGAS, Rosana Villela; CONCÍLIO, Lais Regiane da Silva; ARCAS, Luciana Paula Benicio; CLARO, Cristiane Aparecida de Assis] Universidade de Taubaté, Brazi

Influence of bone loss and inclination of incisor on periradicular stresses due to simulated bite force

Abstract Introduction Adults with sequelae of periodontal disease tend to have bone loss, with consequent flaring of the maxillary incisors. Objective The influence of bone loss and the inclination of the maxillary incisor in the distribution of stresses due to simulated bite forces was studied. Material and method Models in epoxy resin were made in three conditions (without bone loss and with bone loss of 5mm and 8mm). Increases in the labial inclination of the maxillary incisor of 10° and 20° were obtained with a beveled metallic block. Loads of 100N were applied five times in each condition using a universal test machine. The models were observed and filmed with a circular polariscope. Orders of isochromatic fringes (stresses) on the labial, lingual, and apex surfaces were recorded. The agreement of the data was evaluated using the weighted kappa test, and the results were 0.89 and 0.82 for intra- and inter-examiners, respectively. Result The results of the Kruskal–Wallis and SNK tests indicated higher stresses (2.0) with increased labial inclination in the labial surface; higher stresses (2.67) with increased bone loss; higher greater stresses with the association of bone loss and labial-inclination (3.6); and the highest stresses tended to concentrate on the labial surfaces, except in cases of normal inclination and without bone loss (0.45). Conclusion It was concluded that increases in both the labial inclination of the maxillary incisors and bone loss increase periradicular stresses, and the combination of these factors further increases the stresses due to bite forces, with the highest concentration on the labial side