Inlays and onlays are similar to crowns but are less destructive to the remaining tooth structure. Inlays replace tooth structure within the cusp tips, onlays incl. covering one or more cusp tips.
When decay is quite significant fillings can weaken the remaining tooth structure. Inlays and onlays are indirect restorations made in the laboratory that do not weaken the structure of the tooth. They also spread the forces of biting evenly throughout the tooth.
They can be made from a combination of materials incl. gold, ceramic or zirconia.