Comparative study on wear behaviors of interproximal tooth enamel against CAD/CAM ceramic materials at interproximal contact zone

OBJECTIVES: This study investigated the fretting and sliding wear behavior of interproximal enamel (IE) against four CAD/CAM ceramic materials including polymer-infiltrated ceramic network (PICN), lithium disilicate (LS), zirconia-reinforced lithium silicate (ZLS), and monolithic zirconia (MZ) were evaluated. METHODS: Flat specimens were analyzed for microstructure, nanoindentation results. Spherical specimens underwent fretting and sliding wear tests against IE in a ball-on-plate configuration. Wear volume, morphology, and elemental changes on the wear scars of IE were assessed using white light interferometry, SEM, and EDX. RESULTS: Under both fretting and sliding conditions, MZ and ZLS (with the highest elastic modulus and hardness) induced the greatest enamel wear volume through abrasive wear and fatigue wear. LS and PICN, whose mechanical properties are closer to those of enamel, resulted in significantly milder wear. However, in sliding tests, LS caused notable wear likely due to particle exfoliation, whereas PICN consistently produced only mild abrasive wear. Surface polishing substantially reduced the wear severity of IE caused by LS, MZ and ZLS, but its effect was minimal for PICN. CONCLUSION: MZ and ZLS caused more severe enamel wear, with their damage significantly mitigated by polishing. In contrast, PICN and LS exhibited superior compatibility with IE, resulting in milder wear, although LS caused notable damage under sliding conditions due to three-body wear associated with ceramic particle exfoliation. Polishing effectively reducing antagonist IE wear caused by LS but offering limited benefit for PICN.