Evaluation of tribological properties of new alumina/zirconia ceramics for dental restoration

There is great interest in the use of ceramics for dental restoration due aesthetic similarity to natural teeth. Dental applications also demand adequate mechanical and tribological properties. Namely, the restoration material must not wear out easily and must not lead to abnormal enamel wear of the antagonist tooth. In the present work ceramic composites were developed by slip casting of tailored Al2O3/Zr2O formulations containing ZrO2 in the form of submicrometric or of nanoparticles. After sintering sample surface was characterized by scanning electron microscopy and profilometry; hydrophilicity was evaluated using the sessile drop method. Wear behaviour was assessed by reciprocating pin-on-plate tests in artificial saliva, using molar and pre-molar human teeth as pins and samples of the produced materials as cusps. Commercial dental zirconia was used as reference material. High consolidation of composites was attained, with density values ranging from 95.8 %TD to 99.9 %TD. Samples containing submicrometric zirconia present uniform reinforcement distribution and small porosity. Samples containing nanomicrometric zirconia show irregular zirconia agglomerates with micrometric dimension and higher porosity. Wear measurements show that ceramic wear is not significant, while cusps wear is strongly dependent of the opposing ceramic surface counterface roughness and porosity. Attained results suggest that dental wear can be reduced if highly polished zirconia/alumina composites are used instead of zirconia.The authors acknowledge The Lab dental company for supplying the commercial zirconia used in the present work and some technical advice