In Vitro Evaluation of Surface Roughness and Microhardness of Restorative Materials Submitted to Erosive Challenges

The aim of this study was to evaluate the effect of different acidic solutions on the microhardness and surface roughness of restorative materials. The 120 specimens of restorative materials (Fuji II LC, Vitremer, Supreme XT, and Supreme XT + Biscover LV) were randomly divided into three groups according to the immersion media: hydrochloric acid, soft drink, or distilled water. Over a period of five weeks, the groups were immersed in the solutions, which were changed weekly. Data were tested using analysis of variance and the Fisher protected least significant difference test (p < 0.05). The results showed that the glass ionomer materials showed the highest surface roughness values (Fuji II LC: 0.111 +/- 0.014 mu m before and 0.139 +/- 0.016 mu m after immersion; Vitremer: 0.177 +/- 0.012 mu m before and 0.084 +/- 0.012 mu m after immersion), whereas the lowest values were found for the resin sealed with Biscover LV before (0.047 +/- 0.011 mu m) and after exposure in distilled water (0.043 +/- 0.007 mu m), soft drink (0.040 +/- 0.005 mu m), and hydrochloric acid (0.045 +/- 0.005 mu m). The Supreme XT showed the highest microhardness values before (44.96 +/- 2.51 KHN) and after the aging process (41.26 +/- 1.22 KHN in water, 35.96 +/- 0.81 KHN in soft drink, and 34.74 +/- 0.97 KHN in HCl), with significant differences from the other materials (p < 0.0001). The lowest microhardness values were found for glass ionomer materials. The solutions used in this study decreased the microhardness of all studied materials, whereas the sealed surface suffered minor changes in microhardness and surface roughness after exposure to acidic solutions.