WEAR OF HUMAN ENAMEL OPPOSING ULTRA-TRANSLUCENT ZIRCONIA WITH TWO SURFACE FINISHING PROCEDURES

Abstract

ABSTRACT Introduction: With the advancement of material technology, CAD-CAM zirconia restorations have become increasingly popular. Their influence on the opposing tooth surface wear requires further investigation to ensure clinical occlusal stability. Objectives: to determine wear behavior and surface roughness of enamel when opposed by ultra-translucent monolithic zirconia (UTMZ) with two surface finishing procedures (glazed or polished). Materials and Methods: This in vitro study consisted of three groups; Group A: enamel opposing glazed ultra-translucent zirconia, Group B: enamel opposing polished ultra-translucent zirconia, and Group C: enamel opposing enamel as a control group. A modified custom-made tooth brushing machine was used for chewing simulation. The zirconia specimens and the enamel antagonists were subjected to 120,000 cycles with vertical load 49N. The amount of wear was determined based on percentage of weight loss. Qualitative and quantitative analysis of the specimens’ surfaces ware carried out using 3D laser scanning microscope. Data were analyzed with a 1-way ANOVA and Games-Howell post hoc tests (α=0.05) Results: Enamel surface wear was significantly affected by the opposing surface after chewing simulation, with antagonist natural enamel causing the greatest wear and polished UTMZ the least. There was a significant increase in the surface roughness of both the zirconia specimens and the enamel antagonists after wear test. Conclusion: Within the limitations of this study, polished UTMZ was shown to be more wear friendly to the antagonist enamel than both the glazed UTMZ and natural enamel. Increase in the surface roughness leads to an increase in the amount of antagonist wear.