Porcelain inlays or onlays are filings permanently cemented into place over a tooth in order to make the tooth stronger by holding it together. Porcelain inlays or onlays are used when the tooth’s structure is insufficient to support a filling but the tooth doe not require a full crown.

Also called indirect fillings, porcelain inlays and onlays are made in a dental lab rather than being molded to shape in the patient’s mouth. Inlays fit into the space remaining after the decay of an old filling or cavity has been removed, while onlays sit on the tooth and build up its shape.

The advantages of inlays and onlays are that they are more durable than fillings.  With good home care, porcelain inlays and onlays can last up to 30 years. And where fillings can reduce the strength of a tooth by as much as 50%, inlays and onlays can actually increase toot strength by as much as 75%.

Though inlays and onlays can be made from a variety of materials including gold, and tooth-colored composite resin, porcelain inlays and onlays provide the best esthetic appearance. The disadvantage of is that it is more brittle and consequently more likely to break than gold. Porcelain has also been known to accelerate wear on the opposing tooth when biting, which gold does not.

Porcelain inlays or outlays require two visits to a cosmetic dentist, one to remove the decay around the old filling or cavity and take an impression of the tooth, and the second to fit the porcelain inlay or onlay, which has been made in a dental laboratory using the impression taken, into place.