Enamel wear opposing different surface conditions of different CAD/CAM ceramics

Objective: The aim of this study was to evaluate bovine enamel wear opposed to four different ceramic substrates (CEREC) in the glazed and polished conditions. Method and Materials: Sixty-three ceramic (IPS Empress CAD, Paradigm C, Vitablocs Mark II) and fourteen composite resin (MZ100) styli were prepared. Ceramics were subdivided into three surface conditions (n = 7), unpolished, polished, and glazed, and the composite resin (n = 7) into unpolished and polished. All styli were used as wear antagonists opposing bovine enamel blocks (8 mm × 9 mm) in an oral wear simulator. Wear tests were conducted at 30 N abrasion and 70 N attrition forces applied at 1.7 Hz for 5,000 simulated mastication cycles. Abrasion and attrition wear were evaluated using an automatic profilometer. Statistical analyses were conducted using Tukey's B rank order test, P = .05. Results: For bovine enamel opposing glazed Vitablocs, abrasion and attrition wear showed a volume loss significantly higher than bovine enamel opposing polished Vitablocs (P .05). For attrition wear, bovine enamel opposing glazed Vitablocs and untreated Paradigm C showed a volume loss higher than bovine enamel opposing the other ceramic conditions. Conclusion: Abrasion and attrition wear of bovine enamel opposing antagonist ceramic was affected according to the ceramic surface condition and the ceramic material. Antagonistic wear against the studied ceramic materials and conditions exhibited wear rates within the range of normal enamel. In addition, the glaze layer presented as a protection, exhibiting fewer cracks and less loss of material on the ceramic surface. Keywords: abrasion wear, attrition wear, bovine enamel, ceramic antagonist, composite resin antagonist