When over 1/2 of the tooth’s biting surface is damaged a dentist will often use an inlay or onlay.
What are inlays and onlays?
Inlays and onlays can be made of porcelain, gold, or composite resin. These pieces are bonded to the damaged area of the tooth. An inlay, which is similar to a filling, 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.
Traditional fillings can reduce the strength of a natural tooth by up to 50%. As an alternative, inlays and onlays, being bonded directly onto the tooth using special high-strength resins, can actually increase the strength of a tooth by up to 75%. As a result, they can last from 10 to 30 years. In some cases, where the damage to the tooth is not extensive enough to merit an entire crown, onlays can provide a very good alternative.