Effects of processing techniques of monolithic lithium disilicate ceramic on wear resistance against zirconia antagonist

Abstract

Background: The durability of the materials used in the prosthesis is a determining factor for the success of the rehabilitation.

Objectives: The aim of the study was to evaluate the wear resistance of monolithic lithium disilicate ceramics processed by heat pressing and computer-aided design/computer-aided manufacturing (CAD/CAM) methods, with a leucite-reinforced feldspathic ceramic processed by CAD/CAM serving as a control group.

Material and methods: Monolithic lithium disilicate ceramic samples, processed as CAD/CAM milled blocks or heat-pressed ingots, were tested against flat zirconia antagonists. A CAD/CAM leucite-reinforced feldspathic ceramic was used as the control specimen. Conical specimens were made for each group and subjected to thermomechanical cycling with a flat zirconia antagonist. The roughness of the conical and flat specimens was evaluated before and after thermomechanical cycling. The height loss in the conical specimens was also assessed. The data concerning height loss was analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc test. The data obtained from the roughness analysis of the conical and flat samples was evaluated using a linear model of repeated measures and Bonferroni complementary test.

Results: A significant difference was observed in the extent of height loss among the ceramics under consideration. Amber® Mill (AMM) exhibited a lesser extent of height loss in comparison to Rosetta® SP (RSP) (p = 0.010) and Rosetta® BM (RBM) (p = 0.005), yet it demonstrated congruence with Rosetta® SM (RSM) (p = 0.525). Additionally, a significant difference was noted between the initial and final roughness values for both the conical (p = 0.017) and flat (p < 0.05) samples, with the final roughness values being lower than the initial values.

Conclusions: The attrition between ceramic surfaces and zirconia led to a decrease in superficial roughness (Sa). In the context of lithium disilicate ceramics, milled ceramics demonstrated superior performance in terms of wear behavior. The tested feldspathic ceramic exhibited a lower wear resistance compared to the milled lithium disilicate ceramics; however, its wear behavior was similar to that of the heat-pressed lithium disilicate ceramic.

Keywords: computer-aided design; dental materials; dental porcelain; dental restoration wear; lithium disilicate.