Inlays & Onlays
An inlay or an onlay is a filling made of cast gold alloy, lab processed composite or porcelain. Gold inlays are often used to replace worn out old fillings or as a more durable substitute for amalgam or direct composite filling. Onlays are usually used when a tooth needs the biting surface of the tooth covered, but a full crown is not needed.
Gold is the stongest material and has hardness and wear rates similar to the natural tooth structure, so is most suitable for persons with a heavy bite or grinding habit.
Most porcelains are harder than natural tooth structure but more brittle, and can be matched exactly to the natural tooth colour. Lab processed composite is also very natural looking, less brittle than porcelain and gentler on the opposing natural teeth.
Both inlays and onlays require at least two appointments to complete. At the first appointment the old filling is removed and the tooth prepared for the new restoration. Detailed impressions of the tooth and surrounding jaws are taken.
The laboratory uses these impressions to fabricate a custom filling to fit the tooth exactly. A temporary filling is placed to protect the tooth while the laboratory is making the inlay or onlay.
At the second appointment, the new inlay or onlay is tried in and any adjustments to the fit are made before it is cemented to the tooth with a permanent cement.