Evaluation of degradation of force of esthetic elastomeric chains

Abstract

Introduction Elastomers are considered important allies to orthodontic treatment and due to the aesthetic demand, aesthetic elastomers are increasingly used in adult patients. Objective The aim of this experimental in vitro study was to evaluate the degradation of force of esthetic elastomeric chains, of three different sizes: short, medium and long. Material and method For evaluating the degradation of force, 90 elastomeric chain segments were used, divided into 9 Groups (n=10), as follows: Morelli short elastomer, Morelli medium, Morelli long, Orthometric short, Orthometric medium, Orthometric long, American Orthodontic short, American Orthodontic medium and American Orthodontic long. Acrylic plates with pins were used to provide stretching of the elastomeric chains. The initial stretching force of the elastomeric chain was 150 grams, measured by a tensiometer. After this, they were prestretched to 50% of their original length, measured in an Instron 4411 Universal test machine, and placed on the seating pin on the plate. The plate was immersed in artificial saliva at 37 °C in a plastic receptacle, and removed for measurement after a time interval of 21 days. For statistical analysis, the methodology of mixed models for repeated measures in time and Tukey-Kramer test were used. Degradation of the forces was analyzed by 2-way analysis of variance (ANOVA) and the Tukey test. Result All the elastomeric chains showed statistically significant reduction in force (p<0.05). The American Orthodontic elastomeric chains showed higher reduction in force values, irrespective of the elastic size (p<0.05). Conclusion The three commercial brands studied underwent significant reduction in the quantity of force released; the American Orthodontic brand of elastomer showed the highest value of degradation in force.

Dinâmica Sazonal Da Assembleia De Aves Da Mata De Brejo Do Jardim Botânico Municipal De Bauru, São Paulo

“…Outros estudos que utilizaram o mesmo método amostral (e. g. Sementili-Cardoso et al, 2019) abrangeram áreas amostrais mais extensas e esforços mais longos; consequentemente, a riqueza de aves é expressivamente maior. Por fim, os demais estudos levantados (e. g. Medolago et al, 2006;Lucindo, 2007;Cavarzere e Moraes, 2011;Cavarzere, 2013;Moraes, 2016) possuem características amostrais distintas, o que reflete na diferença encontrada nos padrões de riqueza. Tabela 1.…”