The effect of radiation exposure and storage time on the degree of conversion and flexural strength of different resin composites

Abstract

Abstract Background This study was conducted to evaluate the effect of radiation exposure and storage time on the degree of conversion (DC%) and flexural strength (FS) of three different resin composites. In total, 90 disk-shaped, and 360 rod-shaped composite specimens were prepared to evaluate the DC% and FS, respectively. Specimens were divided into 18 groups (DC%: n = 5 and FS: n = 20) according to the three experimental factors of the study: 1—Radiation (no-exposure and exposure), 2—Resin composite material (Herculite XRV Ultra, Z250 XT and Grandio), and 3—Storage time (24 h in distilled water, 3-m and 6-m in 70% ethanol). Fourier transform infrared spectrometer (FTIR) was used to determine the DC%. For FS, the specimens were subjected to a three-point bending test at 1 mm/min crosshead speed. Data were analyzed using three-way ANOVA/Tukey HSD test. Significant level was set at P = 0.05. Results For DC%, there was no significant difference between no-radiation exposure and radiation exposure (P > 0.05). Herculite XRV Ultra revealed the highest statistically significant DC% (P < 0.05). The 24-h storage time revealed the least significant DC% (P < 0.05). For FS, radiation exposure showed a statistically significant higher value compared to no-radiation exposure (P < 0.05). Herculite XRV Ultra showed the least FS value (P < 0.05). The 24-h storage time showed the highest significant value (P < 0.05). Conclusions Radiation exposure has no significant impact on the DC% of the different resin composites, but it has a significant positive effect on the FS. Storage time had a significant effect on both DC% and FS.