ABSTRACT
OBJETIVO: comparar a posição rotacional do primeiro molar permanente superior entre a oclusão normal e a má oclusão de Classe II, Divisão 1, de Angle. MÉTODOS: a amostra de oclusão normal consistiu de 60 pares de modelos de pacientes com média de idade de 15,1 anos, denominada Grupo 1. A amostra de Classe II, Divisão 1, consistiu de 120 pares de modelos de gesso de pacientes não tratados, com média de idade de 15,5 anos, denominada Grupo 2. Os modelos superiores foram escaneados e a posição dos molares superiores foi avaliada por três medidas angulares e uma linear, denominadas indicadores 1, 2, 3 e 4, respectivamente. A rotação mesiopalatina dos primeiros molares superiores era evidenciada pelo aumento dos valores dos indicadores 1 e 4 e diminuição dos valores dos indicadores 2 e 3. A comparação entre os grupos foi realizada pelo teste t de Student nas medidas de distribuição normal e Mann-Whitney para distribuição anormal com intervalos de confiança de 95 por cento. RESULTADOS: diferenças estatisticamente significativas foram encontradas entre os grupos 1 e 2, para todos os indicadores dos lados direito e esquerdo. CONCLUSÃO: concluiu-se que a má oclusão de Classe II Divisão 1 apresenta maior rotação mesiopalatina dos primeiros molares superiores.
OBJECTIVE: The purpose of this study was to evaluate and compare the rotational position of maxillary first permanent molars (U6) in subjects in the permanent dentition presenting normal occlusion and Class II, division 1 malocclusion. METHODS: Casts of 60 subjects with normal occlusion (Group 1, mean age 15.1 years) and 120 with untreated Class II, division 1 malocclusion (Group 2, mean age 15.5 years) were evaluated. The maxillary dental casts were scanned and the position of maxillary molars was analyzed using three angular measurements and one linear measurement, named indicators 1, 2, 3 and 4, respectively. The mesiopalatal rotation of maxillary first molars was evidenced by an increase in the values of indicators 1 and 4 and decrease in the indicators 2 and 3. Comparisons between groups were performed using Student´s t test for measurements with normal distribution and by the Mann-Whitney test for non-normal distribution, at p<0.05. RESULTS: Statistically significant differences were found between Groups 1 and 2 for all indicators, on both right and left sides. CONCLUSION: It was concluded that individuals with Class II, division 1 malocclusion present greater mesiopalatal rotation of the maxillary first molars.
Subject(s)
Humans , Male , Female , Adolescent , Dental Occlusion , Molar/abnormalities , Malocclusion, Angle Class II/therapy , Orthodontics/methodsABSTRACT
Dr. Youn-Sic Chun and coworkers invented the new machine for getting information about the relative effectiveness of the orthodontic appliances and we named it Calorific machine. The author and colleagues used this machine to compare with tooth moving mechanism by 3 types of the insertion method of precision-TPA for derotating the posterior teeth. We measured the distance of tooth movement and found out the rotational center on the occlusal X-ray film and the tooth movement on the occlusogram and then processed paired t-test by SAS program. The results were as follow : 1. In the intermolar width, the mesial insertion method showed the loss of distance, and the other methods(-distal insertion method, mesial expansion method-) showed the increase of distance. 2. In the arch length, the distal insertion method was exhibited as most recommandable way for increasing the arch length. 3. The rotation center of the mesial insertion method for derotating the molar, was located between mesial pit and central pit of the lower 2nd molar. and, in the distal insertion method, it was located between distal pit and distolingual cusp, and in the mesial expansion method was located at distal pit.