Inlay is an indirect restoration (filling) consisting of a solid substance fitted to a cavity in a tooth and cemented into place. It can be fabricated from gold, porcelain or other ceramic material. In some instance, when an composite filling fails to achieve in preventing the recurrence of a decay or the tooth fractured even after a composite treatment, then an inlay is the next option f choice. It is polished that to such a super-fine line of contact that recurrent decay will be all impossible.
Onlays, similar to inlays, is an indirect restoration which incorporates a cusp or cusps by covering the missing cups of the tooth. It is designed to restore the chewing surface and some of the surface along sides of the teeth that are located in the back of the mouth. In this technique it will allow the conservation of the tooth structure when the only alternative is to totally eliminate the cusp.