compared to a restoration, due to the need for a dental laboratory Lengthier process as two appointment required i.e. increased chair time for patient Over time, they can present complications such as marginal leakage and staining by foods Tricky to ensure the absence of undercuts in the tooth preparation stage & highly technique sensitive Composite or ceramic inlays have a lower strength than materials such as a gold Risk of loss of vitality with tooth removal Last longer than restorations but may need replacement Ceramics can be brittle Repair of inlay is difficult Onlays When decay or fracture incorporate areas of a tooth that make amalgam or composite restorations inadequate, such as cuspal fracture or remaining tooth structure that undermines perimeter walls of a tooth, an onlay might be indicated. Similar to an inlay, an onlay is an indirect restoration which incorporates a cusp or cusps by covering or onlaying the missing cusps. All of the benefits of an inlay are present in the onlay restoration. The onlay allows for conservation of tooth structure when the only alternative is to totally eliminate cusps and perimeter walls for restoration with a crown. Just as inlays, onlays are fabricated outside of the mouth and are typically made out of gold or porcelain. Gold restorations have been around for many years and have an excellent track record. In recent years, newer types of porcelains have been developed that seem to rival the longevity of gold. If the onlay or inlay is made in a dental laboratory, a temporary is fabricated while the restoration is custom-made for the patient. A return visit is then required to fit the final prosthesis. Inlays and onlays may also be fabricated out of porcelain and delivered the same day utilizing techniques and technologies relating to CAD/CAM dentistry. A systemic review found that the most common cause of onlay failure is ceramic fracture, followed by ceramic de-bonding from the tooth structure, and the occurrence of secondary caries which is seen as a discolouration at the margins of the restoration. High failure rates were associated with teeth that had previous root canal treatment, and with patients who exhibit para-functional habits such as bruxism, or teeth clenching. Indications Inlays/onlays are indicated when teeth are weakened and extensively restored. There are no obvious contrast between the two. Inlays are usually indicated when there has been repeated breach in the integrity of a