Porcelain Inlays and Porcelain onlays can be made of laboratory cast porcelain or gold. These pieces are bonded to the damaged area of the tooth. A porcelain inlay, which is similar to a filling, is used inside the cusp tips of the tooth. A porcelain onlay is similar to the porcelain inlay but extends out over one or more of the cusps of the tooth to provide more strength to weakened teeth. Porcelain inlays and porcelain onlays allow for less tooth removal than a porcelain crown or PFM crown (porcelain fused to metal) while providing the same strength.