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Wear of opposing teeth by posterior composite resins--evaluation of newly developed wear test methods.

In the present study, enamel wear against indirect composite resins was evaluated using two newly designed wear test methods: a rotating sliding wear test and a buff wear test. For the composite resins investigated in this study, their surface morphologies were examined using a scanning probe microscope after buff-polishing. After the wear tests, enamel was worn down by hard fillers that protruded from the abraded resin matrices. Notably, enamel wear was induced by composite materials with a Vickers hardness number (VHN) greater than 45 and that the amount of enamel wear increased with increasing hardness of the composite material. Therefore, 45 VHN was the critical hardness value for composite resins at which antagonistic enamel wear would occur. Besides, the D-value obtained from the buff wear test indicated not only the relative wear resistance of the composite resin itself, but also its potential risk to induce antagonistic enamel wear.