WEAR OF HUMAN ENAMEL OPPOSING MONOLITHIC ZIRCONIA, GLASS CERAMIC AND RESIN COMPOSITE

Abstract

Objective The purpose of this study was to investigate wear of human enamel when opposed to dental ceramics (monolithic zirconia, glass ceramic) and resin composite. Materials and methods Twenty-four test specimens (antagonists) – 6 each of monolithic zirconia, glass-ceramic, resin composite, and enamel – were prepared into cylindrical rods. Enamel specimens were prepared from 24 extracted human permanent molars. Using a pin-on-disc wear tester, enamel specimens were abraded against each type of antagonist under a constant load of 25 N, at 20 rpm for 4,800 cycles. Maximum depth of wear (Dmax), mean depth of wear (Da), and mean surface roughness (Ra) of enamel specimens were measured with a profilometer. All data were statistically analyzed using one-way ANOVA, followed by Tukey’s test (α = 0.05). A paired t-test was used to compare Ra of enamel at baseline and after testing. SEM pictures were used for evaluating wear qualitatively of both enamel and antagonists. Results There were no significant differences in enamel wear depth (Dmax, Da) between monolithic zirconia (2.17 ± 0.80, 1.83 ± 0.75 μm) and resin composite (1.70 ± 0.92, 1.37 ± 0.81 μm), and between glass-ceramic (8.54 ± 2.31, 7.32 ± 2.06 μm) and enamel (10.72 ± 6.31, 8.81 ± 5.16 μm). Significant differences were found when enamel wear depth by monolithic zirconia and resin composite were compared with those by glass-ceramic and enamel (P < 0.001). Ra of enamel specimens increased significantly after wear tests with monolithic zirconia, glass-ceramic and enamel (P < 0.05), however no difference was found among these materials. Conclusions. Within the limitations of this study, monolithic zirconia and resin composite caused less wear depth to human enamel compared to glass-ceramic and enamel. All test materials except resin composite similarly increased enamel surface roughness after wear testing.