Inlays and onlays are indirect dental restorations that reinforce an existing tooth that is too damaged to support a filling, but not damaged enough to require a crown. An inlay is placed on the chewing surface between the bumps (cusps) of a tooth, whereas an onlay covers one or more of the cusps.

Prior to an inlay or onlay procedure, local anesthesia is injected into the patient’s mouth to numb the area to be treated. Tooth decay or old fillings are then removed from the tooth and the area may be reshaped to ensure a good fit. An impression is taken of the area and a mold sent to a dental laboratory, where the custom inlay or onlay is created. A patient is fitted with a temporary inlay or onlay while waiting for the permanent one to be completed. The entire process may take two or more visits to the dentist.

Sometimes an inlay or onlay may be permanently affixed during a single visit. In these cases, restorative material is shaped into the prepared tooth, then removed and hardened in a special oven in the dentist’s office, after which it is cemented or bonded into the tooth.

Inlays and onlays offer better strength and durability than fillings, and cost less than crowns. Inlay and onlay procedures are usually completed without complications, although patients may experience some minor pain or discomfort immediately afterward. In some cases, the cement used to affix the inlay or onlay to the tooth may wash out or become contaminated with saliva during application. Patients should consult their dentist if the inlay or onlay becomes loose, cracks or falls out.

Teeth with inlays and onlays should receive the same type of oral hygiene as natural teeth, including brushing, flossing and regular dental examinations.