Influence of Polymerization Mode on Degree of Conversion and Micropush-out Bond Strength of Resin Core Systems Using Different Adhesive Systems

Abstract

The aim of this study was to evaluate the influence of different polymerization modes on degree of conversion and micropush-out bond strength of dual-polymerized resin core systems to dentin by using two different adhesive systems. Two resin core systems, Rebilda DC and Build-It FR, were used in combination with total-etch (Adper Scotchbond Multi-Purpose) and self-etch (Clearfil SE Bond) adhesive systems. After treatment of dentin surfaces, resin core systems were applied into the cavities and subjected to different polymerization modes as follows: (1) chemical polymerization; (2) dual polymerization with standard mode of LED (Elipar FreeLight 2 LED); or (3) dual polymerization with exponential mode of LED. The cavities (n=10 per group) were tested in a universal testing machine. Degree of monomer conversion (DC%) was determined by Fourier transform infrared spectroscopy (n=5 cavities per group). ANOVA revealed that resin core (p = 0.002), adhesive system (p < 0.001), and polymerization mode (p < 0.001) had significant effects on bond strength values. The degree of conversion for resin cores decreased significantly (p < 0.001) when only chemical polymerization was employed.