OBJECTIVETo investigate the effect of different surface treatment of zirconia and to find the best way to reduce the wear of its antagonist.

METHODSTwenty-five plates(5 mm×10 mm×15 mm) made of zirconia were divided into five equal groups. Group A was only ground, group B was ground and polished, group C was ground and polished then polished by prophylaxis paste, group D was ground and glazed, group E was ground, polishsed, and then reglazed. Five central incisors were embedded in autopolymerizing acrylic resin with a size of 5 mm×10 mm×15 mm as the control group F. Thirty upper premolars buccal cusps were prepared as the antagonist. Cusps were embedded in autopolymerizing acrylic resin with a shape of circular column whose diameter were 3.1 mm. The wear test was performed in the universal micro-tribotester in artificial saliva. The roughness of each group was measured with rough meter before the wear test. The volume loss of the antagonist was measured using a 3D scanner. The wear surface was observed with scanning electron microscopy to determine the wear characteristics. Data were analyzed using one-way analysis of variance.

RESULTSEach group of surface roughness and mass loss of antagonist showed significant statistical difference (P<0.05). Antagonist of group D showed the maximum volume loss([0.905±0.018] mm3). Antagonist of control group showed the least volume loss([0.235±0.017] mm3). Antagonist of group C showed less volume loss than antagonist of control group did([0.413±0.017] mm3). Wear type of enamel of control group and the antagonist of the groups in which the samples were polished with prophylaxis paste was fatigue wear, and the other groups showed abrasive and adhesive wear.

CONCLUSIONSIn the surface treatment methods of zirconia, polishing is better than glazing. Ground and polishing and then polishing with prophylaxis paste can decrease the wear of the antagonist.