Inlays and Onlays are metal or ceramic restorations used when a molar or premolar is too damaged to support a normal filling, but not damaged so severely that it needs a crown. The inlay or onlay fits into the prepared tooth much like a puzzle piece and are intended to rebuild a large area of chewing surface of a tooth. In contrast, a filling is a paste like material which is placed in a small cavity in the tooth and undergoes hardening when exposed to a blue light. Inlays and onlays are manufactured in the laboratory using an impression made by the dentist of a prepared tooth. Our in-house laboratorytechnicians use this impression to make the inlay or onlay out of high strength metal or ceramic. This is then cemented to the tooth. As they are made in the laboratory, we have an excellent copy of the anatomy of the tooth. Large fillings tend to shrink over time on exposure to the moisture in the mouth, but inlays and onlays are much more stable and durable. At Acharya Dental, we recommend inlays and onlays instead of large fillings, especially when the filling also involves the side of the tooth. This is because the region between two teeth, or the “contact point” between two teeth, is the area where food frequently gets stuck, leading to gum irritation and cavities.
Inlays and onlays are not as extensive as crowns which cover most of the tooth. An Inlay is placed on the chewing surface between the cusps of the tooth, while an onlay covers one or more cusps. Onlays, which are sometimes called partial crowns, may be used if more that half of the biting surface of the tooth is decayed or otherwise in need of repair. Onlays can frequently prevent the need for root canal treatment by sealing the tooth properly and preventing further decay.
Inlays and onlays also cost less than a typical crown, and have great long term results. The only situation where an inlay or an onlay is not used is when a tooth has undergone root canal treatment, since these teeth need to be covered completely by a crown to ensure proper function and esthetics.