What are Inlays and Onlays?

What Are Inlays and Onlays?

Inlays and onlays are two types of dental restorations used to repair teeth that are moderately damaged or decayed. A more conservative treatment approach than dental crowns, inlays and onlays do not completely cover the damaged tooth. Instead, they are used to fill in only the damaged portion of the tooth, leaving more of the underlying tooth intact and minimizing irritation to the adjacent gum tissue. Used in much the same way to repair damage on the bite surface of a tooth, inlays are designed to fit within the cusps of the tooth while onlays wrap around and fit over the cusps themselves.

Custom crafted to fit the tooth they are intended to repair, inlays and onlays can be made from metal, porcelain or composite resin. Because of their natural tooth-like color, porcelain or composite inlays and onlays are often used as replacements for metal fillings in patients who are particularly concerned about the appearance of their teeth.

Inlays and onlays are usually applied over the course of two dental appointments. At your first visit, your tooth will be prepared for the inlay or onlay and an impression will be taken from which the final restoration will be made. You will be fitted with a temporary restoration that will stay in place until your permanent replacement is ready. Your second visit will involve the final bonding of your permanent inlay or onlay to your tooth’s surface.

Who Needs Them?

Since inlays and onlays can be used for both treatment and replacement purposes, there are two groups of candidates for this type of tooth restoration.

First, individuals with highly noticeable metal fillings may wish to consider inlays or onlays as replacements in order to enhance the appearance of their teeth. Because both porcelain and composite resin are extremely natural-looking (and are available in several shades to match your tooth color), restorations made from these materials are less noticeable and can improve your appearance overall.

Furthermore, many dentists now recommend replacing amalgam fillings with a composite or porcelain alternative for reasons that go beyond just cosmetic concerns. First, amalgam can expand and contract, causing the tooth to either become more susceptible to breakage as it expands, or allowing harmful bacteria to enter the tooth and cause further decay as it contracts. Second, there is some concern in the dental community about the long-term safety of amalgam (mercury) fillings. The American Dental Association acknowledges these concerns, but reports that “the major U.S. and international scientific and health bodies, including the National Institutes of Health, the U.S. Public Health Service, the Centers for Disease Control and Prevention, the Food and Drug Administration and the World Health Organization, among others have been satisfied that dental amalgam is a safe, reliable and effective restorative material.” Still, some notable dental care providers like Hal Huggins, whose criticisms of amalgam fillings were featured on 60 Minutes, insist that the mercury in amalgam fillings is absorbed by the body and can contribute to serious neurological problems. If you are concerned about possible complications related to your metal fillings, inlays or onlays made of porcelain or composite can be effective replacements.

More routinely, inlays and onlays are used to repair mild to moderate tooth decay and damage and to prevent further decay by sealing the tooth permanently. Individuals with moderately severe cracks, chips or cavities are good candidates for inlays or onlays.

Benefits

Inlays and onlays allow your dentist to preserve more of your natural tooth. While crowns require extensive tooth preparation that can traumatize the root and surrounding gum tissue, inlays and onlays involve only surface preparation.

Inlays and onlays also add strength to the teeth. According to André V. Ritter, DDS in the Journal of Esthetic and Restorative Dentistry, whereas traditional fillings can weaken the tooth and make it more prone to breakage, inlays and onlays provide added durability and improved bite strength. In fact, many dentists who perform this type of restoration claim that teeth restored with inlays or onlays are able to withstand up to 75% more chewing force. Unlike metal fillings, porcelain and composite inlays and onlays do not expand or contract. So, they offer a more effective, longer-term solution for tooth decay.

Risks

Few risks are associated with the placement of inlays and onlays. Because little preparation is involved, the risks of a reaction to local anesthesia are minimized. In a few cases, patients experienced allergic reactions to the materials used in inlays and onlays. If this happens, an alternative material may be used.

The Bottom Line

Whether you are concerned about aesthetics, are worried about the potential health effects of metal fillings, or simply prefer a more conservative treatment approach, inlays and onlays offer an attractive, highly effective solution for restoring mildly to moderately decayed or damaged teeth. More durable than fillings and free from the uncertainties surrounding amalgam fillings, inlays and onlays are a win-win for the health and appearance of your smile.

The information in the article is not intended to substitute for the medical expertise and advice of your healthcare provider. We encourage you to discuss any decisions about treatment or care with an appropriate healthcare provider.