Which restorative material causes the greatest wear of the opposing natural enamel?

Correct answer: A. Glazed porcelain

• A. CORRECT. PORCELAIN is by a wide margin the most abrasive to opposing enamel. Its hardness substantially exceeds that of enamel, and once the glaze is lost — through adjustment, wear or acid exposure — the exposed surface becomes a coarse abrasive that rapidly wears the opposing dentition. Adjusted ceramic that has not been repolished or reglazed is particularly destructive.
• B. Gold is the gentlest of all restorative materials on opposing enamel — one of the principal reasons it remains the ideal material for occlusal surfaces.
• C. Amalgam has a hardness close to that of enamel and is comparatively kind to the opposing dentition.
• D. Microfilled composite has small filler particles and is the least abrasive of the composites; it wears itself in preference to the opposing tooth.

Note: Ranking from kindest to harshest on opposing enamel: gold < amalgam < composite < porcelain < zirconia. Highly polished monolithic zirconia is gentler than its hardness suggests, but a roughened surface is aggressive. ALWAYS repolish adjusted ceramic.