Dental inlays, onlays and overlays are designed to repair larger cavities or root canal treated teeth; they are made in a laboratory to fit exactly into the cavity and bonded into place by the dentist.
If you leave your tooth to be attacked by bacteria for long enough, a piece of the tooth may break or cave in on itself, but the tooth will still have a functional outer structure to warrant extraction or the use of a dental crown. But the decay may be extensive enough that a standard filling will not nurture the tooth back to health. In these cases, a dental inlay or dental onlay is needed.
The difference between an inlay and an onlay is the relative size and position of the prosthesis. An inlay is used when the wall of the tooth and possibly one or two cusps have become missing, while an onlay is used when the top of the tooth has been eaten away by tooth decay, or a piece of it is missing as a result of trauma.
You will need an inlay if a large piece of the tooth on one tooth surface is missing. If the cavity is on a tooth surface that cannot be readily filled, then it is likely that an inlay will be necessary. An overlay becomes essential when the tooth is structurally sound, but an entire tooth surface is gone, or a corner of the tooth or an whole cusp of it is missing, but a crown would make the tooth too tall.
Inlays and onlays can be differentiated based on what kind of materials they are made out of. Traditionally the inlays and onlays are made out of porcelain, just like dental crowns, and these prosthetics look like little pieces of a dental crown. But inlays and onlays can be made of precious metals like gold or silver, and smaller inlays can be made out of the composite resin used for tooth fillings.
At our dental clinic in London, we provide dental inlays and onlays, and we can make prostheses out of tooth-coloured porcelain, composite or precious metal as well. The process involves two trips to the dentist. During the first one, your tooth will be cleaned, and a temporary inlay may be given. An impression of your tooth will also be made, and the permanent dental inlay or onlay will be made for you.