What Is the Difference Between Fillings, Inlays, and Onlays?

April 25, 2017 88finch 0

Most people know that fillings are used to treat cavities, but they are unaware of the two other options: dental inlays and onlays. Depending on the extent of the decay, your dentist could recommend any one of these treatments.


Fillings are suitable for small- and medium-sized cavities. They come in a range of materials, including gold, amalgam, ceramic, and composite resin. Modern fillings are strong enough to protect even your back teeth from wearing down.


For larger cavities, but where decay is still confined to within the cusps (the raised parts of the tooth), your dentist will likely suggest an inlay. These are stronger than fillings and made from porcelain or gold. Inlays are also a common solution for replacing old fillings.

Unlike fillings, the process to receive an inlay requires two visits to the clinic, as your dentist will need to send an impression of your tooth to a laboratory. You may receive a temporary filling while you wait for the inlay.


An onlay is much the same as an inlay but treats teeth with more extensive decay. It can cover one or more of the cusps or even the entire surface of the tooth. The dental onlay procedure is exactly the same as for an inlay. However, as an onlay covers more of the tooth, it is often quite visible. For this reason, most people prefer to opt for porcelain over gold. When your onlay is made from porcelain, your dentist will choose a material in the exact shade as your tooth.

The dental onlay cost is also slightly higher than the cost of an inlay.