Assessment of first molars sagittal and rotational position in Class II, division 1 malocclusion

OBJECTIVE: This study assessed the anterior-posterior positioning of the upper and lower first molars, and the degree of rotation of the upper first molars in individuals with Class II, division 1, malocclusion. METHODS: Asymmetry I, an accurate device, was used to assess sixty sets of dental casts from 27 females and 33 males, aged between 12 and 21 years old, with bilateral Class II, division 1. The sagittal position of the molars was determined by positioning the casts onto the device, considering the midpalatal suture as a symmetry reference, and then measuring the distance between the mesial marginal ridge of the most distal molar and the mesial marginal ridge of its counterpart. With regard to the degree of rotation of the upper molar, the distance between landmarks on the mesial marginal ridge was measured. Chi-square test with a 5% significance level was used to verify the variation in molars position. Student's t test at 5% significance was used for statistical analysis. RESULTS: A great number of lower molars mesially positioned was registered, and the comparison between the right and left sides also demonstrated a higher number of mesially positioned molars on the right side of both arches. The average rotation of the molars was found to be 0.76 mm and 0.93 mm for the right and left sides, respectively. CONCLUSION: No statistically significant difference was detected between the mean values of molars mesialization regardless of the side and arch. Molars rotation, measured in millimeters, represented ¼ of Class II.OBJETIVO: esse estudo avaliou o posicionamento anteroposterior dos primeiros molares superiores (1º MS) e inferiores, e o grau de rotação dos 1º MS, em indivíduos com má oclusão de Classe II, divisão 1. MÉTODOS: mensuraram-se, em aparelho de precisão Assimetria I, 60 pares de modelos, de 27 indivíduos do sexo feminino e 33 do masculino, entre 12 e 21 anos de idade, com má oclusão de Classe II, divisão 1. Utilizando a sutura palatina mediana como referência de eixo de simetria, os modelos foram posicionados no aparelho para mensuração da distância entre a crista marginal mesial do molar mais distal e a crista marginal mesial do molar do lado oposto, a fim de verificar o posicionamento sagital dos molares. Em relação à giroversão, mediu-se a distância entre pontos na crista marginal mesial. O teste qui-quadrado a 5% foi utilizado para verificar a variação de posicionamento dos molares, por arcos e por lado. O teste t de Student a 5% foi utilizado para comparar esses valores. RESULTADOS: houve maior número de molares inferiores mesializados e, comparando os lados, maior número de molares mesializados no lado direito em ambas as arcadas. As rotações médias dos molares foram de 0,76mm do lado direito e 0,93mm do esquerdo. CONCLUSÃO: não houve diferença estatisticamente significativa entre os valores médios das mesializações dos molares quanto a lado ou arco. Quando observada isoladamente, a rotação dos molares, quantificada em milímetros, representou uma situação de ¼ de Classe II.10611

Evaluation of the dental arch asymmetry in natural normal occlusion and Class II malocclusion individuals

OBJECTIVE: To verify the presence and degree of asymmetry of dental arches in Brazilian individuals with natural normal occlusion and Class II, Divisions 1 and 2 malocclusions. METHODS: The study evaluated the symmetry of the maxillary and mandibular dental arches of 180 pairs of dental casts, divided into: Group I = 60 pairs of natural normal occlusion individuals; Group II = 60 pairs of Class II, Division 1 malocclusion individuals; and Group III = 60 pairs of Class II, Division 2 malocclusion individuals. A device was used to measure dental midline deviation and the canine tip in the dental arches (in degrees). It was also verified the distance of the upper canines from the palatal suture, intercanine distance, and anteroposterior upper and lower first molar position. RESULTS: Dental arches of individuals from all groups presented asymmetry, regardless of the presence of malocclusion. Group I showed a lower asymmetry degree in relation to Groups II and III. The asymmetry in Groups II and III was similar. CONCLUSION: The dental arches of individuals with natural normal occlusion and with Class II, Division 1 and Division 2 malocclusions showed asymmetry. The asymmetry degree was higher in the mandibular dental arches than in the maxillary dental arches in all 3 evaluated groups

Assessment of first molars sagittal and rotational position in Class II, division 1 malocclusion

OBJECTIVE: This study assessed the anterior-posterior positioning of the upper and lower first molars, and the degree of rotation of the upper first molars in individuals with Class II, division 1, malocclusion. METHODS: Asymmetry I, an accurate device, was used to assess sixty sets of dental casts from 27 females and 33 males, aged between 12 and 21 years old, with bilateral Class II, division 1. The sagittal position of the molars was determined by positioning the casts onto the device, considering the midpalatal suture as a symmetry reference, and then measuring the distance between the mesial marginal ridge of the most distal molar and the mesial marginal ridge of its counterpart. With regard to the degree of rotation of the upper molar, the distance between landmarks on the mesial marginal ridge was measured. Chi-square test with a 5% significance level was used to verify the variation in molars position. Student's t test at 5% significance was used for statistical analysis. RESULTS: A great number of lower molars mesially positioned was registered, and the comparison between the right and left sides also demonstrated a higher number of mesially positioned molars on the right side of both arches. The average rotation of the molars was found to be 0.76 mm and 0.93 mm for the right and left sides, respectively. CONCLUSION: No statistically significant difference was detected between the mean values of molars mesialization regardless of the side and arch. Molars rotation, measured in millimeters, represented ¼ of Class II.OBJETIVO: esse estudo avaliou o posicionamento anteroposterior dos primeiros molares superiores (1º MS) e inferiores, e o grau de rotação dos 1º MS, em indivíduos com má oclusão de Classe II, divisão 1. MÉTODOS: mensuraram-se, em aparelho de precisão Assimetria I, 60 pares de modelos, de 27 indivíduos do sexo feminino e 33 do masculino, entre 12 e 21 anos de idade, com má oclusão de Classe II, divisão 1. Utilizando a sutura palatina mediana como referência de eixo de simetria, os modelos foram posicionados no aparelho para mensuração da distância entre a crista marginal mesial do molar mais distal e a crista marginal mesial do molar do lado oposto, a fim de verificar o posicionamento sagital dos molares. Em relação à giroversão, mediu-se a distância entre pontos na crista marginal mesial. O teste qui-quadrado a 5% foi utilizado para verificar a variação de posicionamento dos molares, por arcos e por lado. O teste t de Student a 5% foi utilizado para comparar esses valores. RESULTADOS: houve maior número de molares inferiores mesializados e, comparando os lados, maior número de molares mesializados no lado direito em ambas as arcadas. As rotações médias dos molares foram de 0,76mm do lado direito e 0,93mm do esquerdo. CONCLUSÃO: não houve diferença estatisticamente significativa entre os valores médios das mesializações dos molares quanto a lado ou arco. Quando observada isoladamente, a rotação dos molares, quantificada em milímetros, representou uma situação de ¼ de Classe II