Tooth-coloured inlays and onlays are restorations placed usually on the chewing surfaces of the back teeth. An inlay fits within the confines of the teeth. An onlay covers the entire chewing surface of the tooth. These can be made of either plastic resin or porcelain. The procedure involves removing decayed tooth structure or old fillings, preparing the tooth cavity, taking an impression of the cavity to fabricate a custom-fit inlay or onlay. Two visits are required to complete the treatment.