OBJETIVO: avaliar as diversas cores de ligaduras elásticas do tipo modular da marca Morelli. METODOLOGIA: estas ligaduras foram estiradas em cilindros de aço inoxidável com diâmetro aproximado de um braquete de incisivo central superior, imersas em saliva artificial a 37ºC e tiveram suas forças medidas em uma máquina de ensaios de tração, antes da colocação nos estiletes (0h) e após 24 horas de imersão em saliva artificial. Os resultados foram obtidos através de um computador que opera conectado à máquina de tração e foram submetidos a testes estatísticos (ANOVA e Tuckey) com p<0,05. RESULTADOS E CONCLUSÕES: as médias das forças obtidas foram: md=0,3792KgF para 0h e md=0,1286KgF para 24h e o desvio padrão do percentual de degradação da força foi de 66,07% ± 2,31%. Diante dos resultados, pode-se concluir que existe uma diferença significativa entre as forças geradas em 0h e 24h. Em 0h, mesmo antes da ação do tempo e da imersão em saliva artificial, já existem diferenças significativas entre algumas cores, com valores mais altos (md=0,4024KgF) para a pérola e mais baixos (md=0,3511KgF) para a verde clara. Em 24h, também foram constatadas diferenças significativas, sendo que a distribuição das cores por grupos foi diferente da observada em 0h. As cores verde clara, vermelha, amarela e branca tiveram menor percentual de degradação da força, sendo a verde clara com melhor desempenho (62,60%). Já as cores pérola, prata e cinza demonstraram maior percentual, sendo a pérola com pior desempenho (69,23%).
Objective: This clinical study was conducted in order to evaluate force decay over time of latex and non-latex orthodontic intraoral elastics. Methods: Patients (n = 15) were evaluated using latex and non-latex elastics in the periods of : 0, 1, 3, 12 and 24 hours. The rubber bands were transferred to the testing machine (EMIC DL-500 MF), and force values were recorded after stretching the elastic to a length of 25mm. Paired t test was applied and analysis of variance (ANOVA) was used to evaluate the variation of force generated. LSD (Fisher’s least significant difference) post-hoc test was thus employed. Results: As regards the initial forces (zero time), the values of force for non-latex elastic were slightly higher than for the latex elastic. In the subsequent times, the forces generated by the latex elastic showed higher values. Regarding the material degradation, at the end of 24 hours the highest percentage was observed for non-latex elastic. Conclusions:The latex elastics had a more stable behavior during the studied period, compared with non-latex.
The evaluation of the bone maturation is very important for the orthodontic diagnostic and treatment plan and many places of the body can be utilized for this goal. The aim of this study was to verify the correlation between hand-wrist and cervical maturation stages of skeletal maturation. Lateral cephalometrics and hand wrist radiographs were made. The Hassel and Farm method was used for the cervical vertebras and Singer simplified method for the hand wrist radiographs. About 60 patients formed the sample with ages ranging between 7 and 14 years. From this total, 30 were male and 30 female. Spearman’s (r1) and Kendall’s (r2) coefficients were used to establish the correlation among the 6 stages presented by the two methods. The male group’s results were r1= 0.680 and r2= 0.656, the female group’s were r1= 0.666 and r2= 0.634 and the whole sample’s were r1= 0.743 and r2= 0.696. All the results showed a high correlation, statistically significant (p≤ 0.001). There was a significant correlation among maturation stages presented by both methods. The radiograph evaluation of the cervical vertebras is an alternative parameter which is practical and completes the range of information that can be obtained from cephalometric radiographs and it can, circumstantially, replace other method for evaluation, further on decreasing the additional x-ray exposition.
Aim: This study was conducted in order to evaluate and compare the behavior of latex and non-latex elastics, as the loss of strength over time in vitro. Methods: The study evaluated 15 of each elastic material for the pre-selected times: 0, 1, 3, 12 and 24 hours. The rubber bands were transferred to the testing machine (EMIC DL-500 MF). The force values were recorded after stretching the elastic to a length of 25mm. Independent t-test was applied. Analysis of variance (ANOVA) was used to check the variation of the forces generated between those determined times. To identify between which times the difference was present, Tukey post-hoc test was accomplished. Results: As regards the initial forces (zero time), the values of force for non-latex elastic were slightly higher than the latex elastic. In subsequent times, the forces generated by the latex elastic showed higher values. Regarding the material degradation, at the end of 24 hours the highest percentage was observed for non-latex elastic. Conclusion: The latex elastic had a more stable behavior during the studied period compared with non-latex.
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