When one of your rear teeth (molars) becomes decayed, especially when over half of the biting surface of the tooth is affected, an inlay or onlay may be a better option than a filling, which might compromise the strength or structural integrity of the tooth. Inlays and onlays are similar to fillings in that they fill the cavity left when the decay is removed, but they are stronger. Inlays typically are used when the cavity lies inside the cusp tips of the molar; onlays cover one or more cusps of the molar, and are used when the tooth requires more substantial reconstruction. Inlays and onlays are also often used when the patient wishes to replace metal or composite fillings with something more natural looking and appealing.
Each inlay or onlay is custom-made to fit the tooth, and can be constructed of different materials, depending on the cosmetic and cost concerns of the patient. Tooth-colored inlays and onlays are made of porcelain or other ceramics, or a plastic resin, and have a cosmetic advantage in that when completed they closely match the appearance of the original tooth. Gold inlays and onlays last longer and are more durable, but they are more difficult to craft and thus more expensive.
Advantages of dental inlays and onlays over fillings are that they are more aesthetic, they are stronger once permanently bonded to the tooth, they seal and protect the tooth against decay better than fillings, they are better suited to filling large cavities, and they are longer lasting. Disadvantages are that inlays and onlays are more expensive than amalgam or composite fillings (although generally less expensive than crowns), and that they can possibly fracture.
What can you expect if you get inlays or onlays?
Two dental appointments are usually required for an inlay or onlay. During the first visit the decay is removed (or the filling being replaced is removed) and an impression of the tooth is taken. A local anesthetic is used to numb the area while this is being done.
During the second visit the inlay or onlay, crafted from the impression, is inserted and cemented into place. The tooth is then polished to insure a proper bite, and to most closely resemble your other teeth. Once the inlay or onlay has been applied, you care for your inlays or onlays by brushing and flossing your teeth as usual. If you received porcelain or resin inlays or onlays, you should avoid biting hard objects, but because they are resistant to staining you do not have to avoid tea, coffee, colas, or red wine.