Influence of delayed irradiation through different thickness of indirect restoration on curing characteristics of dual-cured resin cements

Abstract

The aim of this in vitro study will be to evaluate the effect of delayed irradiation on the kinetics of polymerization and flexural strength of dual-cured resin cements polymerized under different thickness of ceramic restoration. Two experimental formulations of dual-cured resin cements (Type I - based on camphorquinone/amine system or Type II - based on diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide [TPO]) will be prepared and polymerized under different thickness of ceramic (without ceramic; 2 mm or 4 mm), submitted to four irradiation modes (without photoactivation; immediate photoactivation for 40 seconds; immediate photoactivation for 10 seconds - 150 mW/cm2 + 60 seconds wait for chemistry cure + 30 seconds of photoactivation - 1000 mW/cm2; and delayed photoactivation of 5 minutes and after application of light activation for 40 seconds - 1000 mW/cm2). Polymerization kinetics will be monitored by Fourier-transform near infrared spectroscopy (FT-NIRS) in the resin cements, while flexural strength property will be determined by a universal testing machine. Data will be subjected to statistical normality tests and specific tests to verify the significance between means (p<.05). (AU)