
INLAYS, ONLAYS, CROWNS
Inlays and onlays are considered “indirect” restorations. Like crowns, they are made in the lab versus “direct” restorations or fillings which are done same day in the mouth. This is a two-appointment process: one to drill your teeth, take the mold, and make a temporary restoration and the second is to cement it. The cementation process involves placing materials that will strongly bond to the tooth structure, the same way a tooth-coloured filling is bonded to the tooth.
Each of these options would be recommended over just a regular filling when the filling is very large and long term success of the restoration will be improved by one of these indirect restorations.
Inlay
An inlay is a type of dental restoration that is used to repair a tooth that has been damaged by decay, cracks or, trauma. An inlay is made from a solid material, such as ceramic or composite resin, and is designed to fit within the cusps (raised areas) of the tooth. Inlays are typically used to repair teeth that have moderate to severe damage, but are not so extensively damaged that a crown (also called a "cap") is required.

Onlay
An onlay is similar to an inlay, but it is larger and covers more of the tooth surface. Onlays are used to repair teeth that have more extensive damage from cavities or cracks, but are not so severely damaged that they need to be completely covered by a crown. Onlays are typically made from the same materials as inlays, such as ceramic or composite resin.

Difference Between Inlays, Onlays, and Crowns
Inlays and onlays are more conservative treatment options compared to conventional crowns. Less natural tooth structure is removed in the process. By preserving as much natural tooth structure as possible, we can regain much of the normal function and prevent cracks from forming. With advances in bonding materials, inlays and onlays can be just as strong and last a very long time.
Each situation is different as multiple factors need to be considered. We will discuss all of this with you before recommending what is best for you.