Occlusal contact area (OCA) wear of two new composite restoratives

The occlusal contact area wear resistance of two new composite restoratives (Z250 and P60) was investigated and compared with two existing materials (Silux and Z100) using a reciprocal compression-sliding test apparatus. Six wear specimens were made for each material and subjected to wear testing at 20 MPa with artificial saliva as lubricant. Wear depth (microm) was measured using profilometry every 20, 000 cycles up to 120 000 cycles. Results were analysed using ANOVA/Scheffe's test (P < 0.05) and Pearson's correlation. The effects of cyclic loading on wear and counter-body loss were material dependent. Silux had the lowest wear at all cyclic intervals. At 20 000 and 40 000 cycles, Silux had significantly less wear than all the other composites evaluated, and Z100 had significantly less wear than Z250 and P60. After 60 000 cycles, significant differences in wear was observed only between Silux and the other composites. Correlation between number of cycles and wear/counter-body loss, and between wear and counter-body were significant and positive. The microfilled composite Silux had significantly better OCA wear resistance than the minifilled composites Z100, Z250 and P60.