There are times when a tooth suffers damage (from decay, for example) that is too extensive to be treated with a simple filling — but not extensive enough to need a full-coverage crown. In these cases, the best option for restoring the tooth may be an inlay or onlay.

What are Dental Inlay and Onlay?

Inlays and Onlays also called indirect fillings, are made from gold, porcelain or composite materials and fill decayed or damaged teeth. Dental fillings are molded into place during an office visit; however, inlays and onlays are created in a dental laboratory and bonded into place by your dentist. The filling is called an “inlay” when the material is bonded within the center of a tooth; it is called an “onlay” when the filling includes one or more points of the tooth or covers the biting surface. Inlays and onlays preserve as much healthy tooth as possible and are an alternative to crowns.

Dental Inlays

Typically used when the cavity is too large for a simple filling. The inlays can be made of a tooth-colored material such as ceramic/porcelain or special dental composite. Defective or unsightly “fillings” can be replaced by tooth-colored inlays and bonded to the tooth. This bonding process may actually improve the strength of the tooth and help seal the inlay to the tooth.

Dental Onlays

Onlays also fit inside the tooth, but extend onto the chewing surface of a back tooth to replace one or more cusps. In the past, onlays were made only of gold, but like inlays, more and more patients request a tooth-colored onlay. Making the onlay of ceramic/porcelain allows the restoration to be bonded to the tooth.

How Dental Inlay and Onlay work?

Getting an inlay or onlay is very much like what you would experience having a crown placed, with one important distinction: less of your natural tooth structure will need to be removed by drilling when you receive an inlay or onlay. When you get a crown, the tooth needs to undergo significant reshaping so that it will fit inside its new covering. Since dentistry's goal is to preserve as much of your natural tooth structure as possible, inlays and onlays may be recommended instead of crowns when a tooth can be restored with this more conservative type of treatment.

There are benefits to inlays and onlays in comparison to metal fillings:

• Inlays and onlays are durable — they’re made from tough, hard-wearing materials which last up to 30 years.
• They help to strengthen teeth by up to 75 percent, unlike traditional metal fillings which can actually reduce the strength of the teeth by up to 50 percent.
• Inlays and onlays prolong tooth life and prevent the need for more dental treatment in the future.