Inlays are similar to fillings but the entire work lies within the cusps (bumps) on the chewing surface of the tooth. Onlays involve more surface area, covering one or more cusps. Onlays are sometimes called partial crowns.
Benefits of Dental Inlays and Onlays:
Increase the strength of a tooth with respect to fillings
Alternative to an crown when teeth damage is not extensive
Porcelain inlays/onlays does not change colour over time