Amalgam onlay restoration

This article discusses a conservative class II amalgam cavity preparation that is similar to a cast onlay preparation except for the absence of the lingual and facial bevels. When extensive decay is removed and undermined cusps are present, onlays from amalgam support tooth structure and prevent fractures. To achieve this, cusps must be reduced to provide for a sufficient bulk of amalgam. The described technique can be applied to class II cavity preparations with weak cusps, class I cavity preparations when the remaining cavity provides adequate retention, and to endodontically treated teeth for which finances do not permit cast restorations.