Inlays and Onlays

By Danine M. Fresch, DDS

Inlays and onlays are valuable for restoring teeth that are severely decayed or worn. Typically, they are applied to the chewing surfaces on the back teeth.

What Is the Difference Between an Inlay and an Onlay?

An inlay is used more like a filling for restoring normal tooth structure. It is best if the surface is small and only involves the chewing surface and surfaces between the teeth.

An onlay is similar to an inlay but treats larger areas, covering the entire chewing surface of a tooth. Onlays are recommended for larger tooth restorations and when chewing surfaces require long-term protection.

What Are Inlays and Onlays Made of?

Since both are used in areas of heavy chewing and grinding, they must be made from durable materials. They can be made from porcelain or composite resin chosen to match the color of your teeth, or a mixture of metals called an alloy. Alloys can be a mixture of metals like gold and palladium or nickel and chromium.

What Are the Treatment Procedures for Inlays and Onlays?

The tooth is first prepared by removing portions of decay or damage. The remaining tooth structure is shaped in preparation for the inlay or onlay. An impression of the tooth is made along with opposing teeth and the bite. From this, a plaster model is formed that is used for a custom fit matching the contours of the tooth.

Since both inlays and onlays are custom-made, a second appointment is needed for checking the fit and cementing the inlay or onlay permanently. At that appointment, any adjustments to the bite will be made. A final polishing adds the final touch to this restorative treatment.