When more than half of the tooth’s biting surface is damaged, one treatment option is an onlay.

What Are Onlays?

Onlays can be made of porcelain, gold, or composite resin. These conservative restorations replace the missing portion of the tooth and are bonded onto the remaining tooth structure.

Traditionally, gold has been the material of choice for onlays. In recent years, however, porcelain and composite resin have become increasingly popular because they match the natural color of your teeth.

How Are They Applied?

Onlays require two appointments. During the first visit, the filling being replaced, or the damaged or decayed area of the tooth, is removed. The tooth is then prepared for the onlay. An impression of the tooth is taken and sent to a lab for fabrication. A temporary filling is placed on the tooth.
At the lab, porcelain or composite resin, which is processed under heat and pressure to increase its strength, is fabricated using the model of your tooth to reproduce the tooth’s natural shape and contour.
At the second appointment, the temporary filling is removed. The doctor seats the onlay, and if the fit is satisfactory, the onlay will be bonded to the tooth with a strong resin and polished to a smooth natural finish.


Traditional amalgam fillings can reduce the strength of a natural tooth. As an alternative, onlays are bonded directly onto the tooth using special high-strength resins that can actually increase the strength of a tooth. Onlays can last more than a decade. 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.