Effect of Therapeutic Radiation on Degree of Conversion, Flexural Strength and Microhardness of Three Resin Composite Materials

Abstract

This study was conducted to evaluate the effect of radiation exposure and aging time on the degree of conversion (DC%), flexural strength (FS), micro-hardness (MH) and surface topography (ST) of three different resin composites. In total, 360 rod-shaped resin composite specimens were prepared to evaluate FS and 90 disc-shaped resin composite specimens were prepared for evaluation of each of DC% and MH. In addition, 36 disc-shaped resin composite specimens were prepared for ST examination. Specimens were divided into 18 groups (DC%: n=5, FS: n=20 and MH: n=5, ST: n=2) according to the three experimental factors of the study; 1- Radiation exposure (no-radiation exposure and radiation exposure), 2- Resin composite (Herculite XRV Ultra, Z250 XT and Grandio), and 3- Aging time (24-h in distilled water, 3-m and 6-m in 70% ethanol). Fourier-Transform Infrared Spectrometer (FT-IR) was used to determine the DC %. For FS, specimens were subjected to a three-point bending test at 1 mm/min crosshead speed. Vickers Micro-hardness tester was used for testing MH. The ST for each resin composite material was evaluated using the Scanning Electron Microscope (SEM). Data were analysed using 3-Way ANOVA/Tukey HSD test. Significant level was set at P=0.05. DC% results showed that, there was no significant difference between no-radiation exposure and radiation exposure. Herculite XRV Ultra revealed the highest statistically significant DC%. The 24-h aging time revealed the least significant DC