Inlays
An inlay is a piece of ceramic that is later manufactured in a dental laboratory and inserted into the tooth. The inlay is usually used to treat cavities in the posterior region and replaces parts of the occlusal surface, but not the cusps of the tooth. The indication for inlays is to treat caries and to reconstruct the resulting tooth defect. An inlay is a precision-fit workpiece that is cemented into the tooth, as opposed to plastic filling material, which is placed into the tooth in a soft consistency using moulding aids and then hardens. An inlay can be made of different materials such as gold or ceramic. In our practice, we mainly use inlays made of individual tooth-coloured all-ceramics in cooperation with our dental laboratories.
Onlays
One speaks of an onlay when the cusps of a tooth that carry the chewing force are also covered. In this case, defective, weakened tooth walls are replaced by additionally coupling over those cusps of the tooth that carry the chewing force. It is a kind of larger inlay. The overlay also overcouples cusps of the tooth and replaces the entire occlusal surface. The partial crown also partially incorporates the tooth walls.
Partial Crowns
The partial crown is considered the most durable solution for medium to large tooth defects where sufficient healthy tooth structure is still present. In contrast to a complete crown, a partial crown does not cover the entire tooth, but replaces only parts of the dental crown. Precious metal alloys and all-ceramic materials can be used. Ceramics are an excellent material for partial crowns, not only from an esthetic point of view, but especially because of the possibility of adhesive cementation and thus stabilization of the remaining tooth structure.
The definitions are not always clear-cut, as the differences in size between the inlay, the onlay, the overlay and the partial crown are sometimes fluid.