Optical properties and kinetics of conversion of dental composites made with alternative photoinitiator systems and cured with different light curing units

Abstract

Objectives: The aim of this study is to evaluate the effect of the photoinitiator system and the light curing unit on the optical properties (OP) and kinetics of conversion (KC) of experimental dental resin composites. Materials and Methods: Six experimental dental resin composites will be produced with the same organic matrix (29 wt% Bis-GMA, 32.5 wt% UDMA, 32.5 wt% Bis-EMA, 6 wt% TEGDMA) and filler content (13 wt% 0.04 mm fumed silica and 52 wt% 0.7 mm BaBSiO2) and alternative the photoinitiator systems: (1) CQ+DMAEMA; (2) CQ+EDMAB; (3) CQ+DMPOH; (4) BAPO; (5) TPO; (6) CQ+Sesamin. To assess the KC, a FT-IR spectrometer (Nicolet Nexus 6700, Thermo Scientific, Waltham, MA, USA) will be used to measure the peak area corresponding to the vinyl stretching absorption in the near-IR spectrum (6165 cm-1) during one minute continuous irradiation with two light curing units (A) Radii (SDI, Bayswater, Victoria, Australia) or Bluephase G2 (Ivoclar Vivadent, Schaan, Liechtenstein). The OP will be evaluated by measuring color using a chromameter (CR221, Konica Minolta, Tokyo, Japan) and translucency change during curing using a calibrated sensor (Resin Calibrator, Bluelight Analytics, Halifax, Nova Scotia, Canada) before, during and after light curing. Statistics: Data will be submitted to one or two-way ANOVA and Tukey's test (±=0.05) to compare the effects of the different photoinitiators on the optical properties before and after curing, and the maximum curing rate. (AU)