Abstract
Abstract This study determined the influence of photoinitiator concentration on polymerization characteristics of experimental composites photoactivated by different methods. Composites based on BisGMA/TEGDMA and 65% of filler were prepared with the concentration of camphorquinone/amine C1-0.5%, C2-1%, C3-1.5%, and photocured using 4 methods: High-intensity (HI), Low-intensity (LI), Soft-start (SS) and Pulse-delay (PD). Were determined the degree of conversion (DC), depth of cure (DCure) and crosslink density (CLD). Data were submitted to ANOVA and Tukey’s test (p < 0.05). DC and DCure revealed that there were no differences among the photoactivation methods. C3 and C2 showed higher DC than C1. The CLD evaluation revealed considerable differences among the photoactivation methods. Photoinitiator concentration is a determinant factor in the polymerization characteristics of composites. Composite with low photoinitiator concentration show decreased DC and DCure, when compared with the composites with higher concentrations. Photoactivation methods had no effect on the DC and DCure. However, photoactivation methods showed differences when CLD was tested for composites with higher concentration of photoinitiators.
Highlights
Increasing the conversion of double bonds during the photopolymerization is critical for the optimization of mechanical properties [1,2], biocompatibility [3,4] and color stability [5] of light-activated dental resins
There are limits on the amount of amine used by the tendency to internal discoloration of the resin
Considering that the aim of this study was to determine the influence of photoinitiator concentration on polymerization characteristics of experimental composites photoactivated by different methods
Summary
Increasing the conversion of double bonds during the photopolymerization is critical for the optimization of mechanical properties [1,2], biocompatibility [3,4] and color stability [5] of light-activated dental resins Photopolymerization implies both in the increase of molecular weight by monomer to polymer conversion, as well as cross-linking of developing or preexisting macromolecules [6]. There are limits on the amount of amine used by the tendency to internal discoloration of the resin In addition to these problems, a high quantity of initiator induces quick and high generation of free radicals, what could result in reduction of the reaction ability of the monomers due to the surrounding polymer network, and polymers with relatively lower molecular weight are formed. This, in turn, places practical limits on the concentration of photoinitiators, and limits the degree of polymerization and depth of cure that can be attained [7,8,9,10,11]
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