An inlay is similar to a filling and is used inside the cusp tips of the tooth. An onlay is a more substantial reconstruction, similar to the inlay but extending out over one or more of the cusps of the tooth. Inlays and onlays can be made of porcelain, gold, or composite resin. Porcelain inlays mimic enamel's translucency and color, making them attractive choices for patients. Gold alloy inlays and onlays possess greater durability and better resist tarnishing and corrosion.