Effect of radiotherapy on the hardness and surface roughness of two composite resins

The knowledge about the potential adverse effects of radiotherapy compared to dental composites is a useful information for the clinician's decision regarding adoption of repairs or replacement of dental restorations during oral cancer treatment. This study evaluated the effects of irradiation on microhardness and surface roughness of a microfilled and a packable composite resin. The microfilled composite resin demonstrated significantly lower microhardness and a smoother surface compared to the packable composite resin (p < 0.05). Although irradiation significantly reduced the microhardness for both composite resins (P < 0.05), increasing the x-ray doses did not cause an additional significant decrease in surface hardness (P > 0.05). Meanwhile, irradiation did not produce a significantly rougher surface (P > 0.05), but specimens submitted to abrasion exhibited a significant increase in surface roughness for both composite resins (P < 0.05). It was concluded that while irradiation can adversely affect the hardness of tested composite resins, it does not interfere with surface roughness.