Inlays are fillings that are placed inside the cavity of the tooth. These fillings are created outside the mouth, usually from durable materials like ceramic or composite, and then fitted into the tooth by the dentist. The process involves taking an accurate impression of the tooth, which ensures that the inlay will fit perfectly into the cavity created by the decay, preserving most of the natural structure of the tooth.

Onlays, on the other hand, are broader and also cover one or more cusps of the tooth. They are used when the damage is greater, requiring coverage over the surface of the tooth in addition to the interior. Onlays are useful for restoring the functionality and aesthetics of the tooth, avoiding the need for a full crown, which can be more invasive.

Both types of fillings are made from materials such as ceramic, resin, or porcelain, which offer an aesthetic and durable solution for tooth repair. Inlays and onlays help maintain the natural structure of the tooth, providing a more conservative alternative compared to dental crowns. These procedures are often quick, and with proper care, the fillings can last for many years, contributing to overall oral health.