Evaluation of degree of conversion and hardness of dental composites photoactivated with different light guide tips

• Autor(a) principal: Galvão, Marília Regalado [UNESP]
• Data de Publicação: 2013
• Outros Autores: Caldas, Sergei Godeiro Fernandes Rabelo [UNESP], Bagnato, Vanderlei Salvador, Rastelli, Alessandra Nara de Souza [UNESP], Andrade, Marcelo Ferrarezi de [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3571515/; http://hdl.handle.net/11449/74878
• topic: Composite resins; Hardness; Polymerization

Objective: The aim of this study was to evaluate the degree of conversion and hardness of different composite resins, photo-activated for 40 s with two different light guide tips, fiber optic and polymer. Methods: Five specimens were made for each group evaluated. The percentage of unreacted carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1. The Vickers hardness measurements were performed in a universal testing machine. A 50 gf load was used and the indenter with a dwell time of 30 seconds. The degree of conversion and hardness mean values were analyzed separately by ANOVA and Tukey's test, with a significance level set at 5%. Results: The mean values of degree of conversion for the polymer and fiber optic light guide tip were statistically different (P<.001). The hardness mean values were statistically different among the light guide tips (P<.001), but also there was difference between top and bottom surfaces (P<.001). Conclusions: The results showed that the resins photo-activated with the fiber optic light guide tip promoted higher values for degree of conversion and hardness.