When the cavities become bigger in size and there is extensive loss of tooth structure, the filling of choice is inlay. It's a partial cover for any tooth made of different materials like metals or ceramic or composite and is made outside the oral cavity.
By book definition it's an intracoronal dental restoration, made outside the oral cavity to conform to the prepared cavity, which restores some of the occlusal surface of a tooth, but does not restore any cusp tips. It is retained by luting cement. (American College of Prosthodontics; The Glossary of Prosthodontic Terms).
It's bigger in size as compared to inlay and covers more surfaces of tooth. It is also made of metal alloys like Gold and other materials (Ceramic and composite)
By book definition it's a dental restoration made outside the oral cavity that covers one or more cusp tips and adjoining occlusal surfaces, but not the entire external surface. It is retained by luting cement. (American College of Prosthodontics; The Glossary of Prosthodontic Terms)
The natural colour ceramic ensures continuity with the rest of teeth. They are strong and durable.
They require two visits to the dentist i.e. in first visit the tooth is prepared and measurements are made by taking rubber base impressions; following which temporization is done. In next appointment the prepared inlay/onlay is cemented on tooth with help of dental adhesives.