Comparative analysis of load/deflection ratios of conventional and heat-activated rectangular NiTi wires

OBJECTIVE: This study compared the load-deflection ratios between 0.019 x 0.025-in rectangular orthodontic wires using 5 conventional preformed nickel-titanium (NiTi) and 5 heat-activated NiTi archwires from four different manufacturers (Abzil, Morelli, 3M Unitek and Ormco), totaling 40 archwires. The archwires were placed in typodonts without tooth # 11 and tested using a universal testing machine connected to a computer. RESULTS: The comparisons of mean load-deflection values of conventional NiTi wires revealed that the lowest mean-deflection ratio was found for 3M Unitek, followed by Ormco, Morelli and Abzil. Regarding the heat-activated wires, the lowest load-deflection ratio was found for Ormco, followed by 3M Unitek, Abzil, and Morelli. CONCLUSION: The comparison of mean load-deflection ratios revealed that the heat-activated wires had lowest mean load-deflection ratios, and this trend was seen during all the study. However, at 2-mm deflection, mean load-deflection ratios for heat-activated Morelli and conventional 3M Unitek wires were very similar, and this difference was not statistically significant.

Are torque values of preadjusted brackets precise?

OBJECTIVE: The aim of the present study was to verify the torque precision of metallic brackets with MBT prescription using the canine brackets as the representative sample of six commercial brands. MATERIAL AND METHODS: Twenty maxillary and 20 mandibular canine brackets of one of the following commercial brands were selected: 3M Unitek, Abzil, American Orthodontics, TP Orthodontics, Morelli and Ortho Organizers. The torque angle, established by reference points and lines, was measured by an operator using an optical microscope coupled to a computer. The values were compared to those established by the MBT prescription. RESULTS: The results showed that for the maxillary canine brackets, only the Morelli torque (-3.33º) presented statistically significant difference from the proposed values (-7º). For the mandibular canines, American Orthodontics (-6.34º) and Ortho Organizers (-6.25º) presented statistically significant differences from the standards (-6º). Comparing the brands, Morelli presented statistically significant differences in comparison with all the other brands for maxillary canine brackets. For the mandibular canine brackets, there was no statistically significant difference between the brands. CONCLUSIONS: There are significant variations in torque values of some of the brackets assessed, which would clinically compromise the buccolingual positioning of the tooth at the end of orthodontic treatment.

Avaliação cefalométrica de componentes mandibulares em jovens portadores de má-oclusão classe II esquelética / Cephalometric evaluation mandibular components in young individuals with class II skeletal malocclusion

Este trabalho avalia o relacionamento ântero-posterior da mandíbula com a base do crânio (SNB, Nperp-P), o comprimento efetivo da mandíbula (Co-Gn)e a altura ântero-inferiorda face (Ena-Me), em jovens com rná-oclusão Classe II esquelética que apresentam ANB maior que 4,00 e Nperp-AP maior que 5,0 mm. A amostra foi composta por 80 telerradiografiascraniofaciais de perfil de 80 jovens brasileiros, leucodermas, divididos igualmente quanto ao gênero, com idade média de 12 anos e 11 meses. As medidas Nperp-P e SNB indicaram apresença de retrognatismo mandibular, com diferença estatisticamente significante entre o grupo avaliado e a norma populacional para as medidas Nperp-P para o gênero masculinoe Nperp-P e SNB para o feminino. A grandeza cefalométrica Co-Gn apresentou valor médio normal para o gênero feminino e normal ou aumentado para o gênero masculino e a medidaEna-Me apresentou valor aumentado para o gênero feminino e dentro da normalidade para o gênero masculino. Essas duas grandezas, apesar de alteradas, não apresentaram significância estatística. Concluiu-se que os componentes cefalométricos mandibulares foram determinantesna composição da má-oclusão Classe II esquelética.

In this study were eva/uated the effective length of mandible (Co-Gn), their antero-posterior relationship to the cranial base (SNB, Nperp-P), and the lower anterior facial height (Ena-Me), in young individuais withskeletal Class II malocclusion, that presented anANB higher than 4° and Nperp-AP higher than 5.0 mm . The study sample consisted of 80 cephalometric x-rays of white young individuais, equally divided according to the gender, with an age range of 12 to 13 years and 11 months. The measure Nperp-P and SNB, indicatedmandibular retrognatism, with statistically significant difference between evaluated group andpopulation norm for the measure Nperp-P for male gender and SNB and Nperp-P for female gender. The cephalometric measure Co-Gn presented normal value for female gender, and normal ar increased for male gender, and the cephalometric measure Ena-Me presented increased value for female gender and normal value for male gender. These two measure, even ir changed, don't presented stastistical significant. The results suggested that mandibular components were determinating on the composition of Class 11skeletal malocclusion.

Avaliação da rotação do primeiro molar superior em más-oclusões classes I e II, divisão 1 / Evaluation of the first upper molar rotation in classes I and II, division 1 malocclusions

Este estudo teve como objetivo analisar e comparar a rotação do primeiro molarpermanente superior em pacientes portadores de más-oclusões de Classes I e II, Divisão 1 de Angle, além de verificar uma possível relação entre a rotação molar e a severidade da má -oclusão de Classe II. Para tanto, foram selecionados sistematicamente 60 pares de modelos, procedentes da Clinica de Ortodontia HM Dentistas Associados Ltda., de Porto Alegre, de indivíduos não tratados ortodonticamente, de ambos os gêneros, sendo 30 portadores demá-oclusão de Classe I, denominado grupo 1 e 30 de Classe II, Divisão 1, denominado grupo 2. O grupo 2 foi dividido em subgrupos, conforme o grau de severidade. Por meio de umaanálise dos modelos, que foram escaneados e avaliados em um programa de computador, foram mensurados três ângulos e uma medida linear. Os resultados foram determinados ecomparados estatisticamente para verificar a diferença da rotação do primeiro molar entre os grupos, assim como correlacionar a quantidade dessa rotação com a severidade da má-oclusãode Classe II. Concluiu-se que, na amostra analisada, houve rotação mesiopalatina do primeiro molar superior em ambas as más-oclusões e não ocorreu diferença estatisticamentesignificante entre os dois grupos. Também não se evidenciou relação entre a quantidade da rotação do molar e a severidade da má-oclusão de Classe II.

This article aims to analyze and compare the rotation of the first permanentmolar excess in samples of malocclusion of Classes I and II malocclusion, Division 1, Angle, besides see a possible link between the rotation moles and severity of the Class II. For both, was randomly selected 60 pairs of models, from the clinic of HM orthodontic dentistsassociated Ltda., Porto Alegre, untreated people of both sexes, with 30 malocclusion of Class I, called group 1; 30, Class II, Division 1, known as Group 2, which was divided into subgroups, as the degree of severity. The survey was developed by an analysis of patterns,which were scanned and evaluated through a computer program, for the measurement of three angles and a linear measure. The results were determined and compared betweengroups to try to link changes in the rotation of moles between the group of malocclusion group of Classes I and li, as well as to highlight the severity of the rotation of the upper first molar is related to the severity of Class li. It was concluded that there is mesiopalatal rotation of the upper first molar in both malocclusions, and there is no statistically significant difference between the two groups. Also there was no relationship evidenced between rotation and severity of Class II.