An onlay is a laboratory fabricated prosthetic that fits inside and over a portion of a tooth, looking much like a puzzle piece; onlays should last as long as a crown, when properly placed and cared for, also looking exactly like a natural tooth when completed.
There is no metal in today's onlays, as the zirconia, alumina and pressed porcelain is very strong and mimics the look of your existing teeth.
Onlays are used when a filling is going to be too large, causing the potential for fracture. Onlays are also used if a patient does not want to replace a larger filling as often, as onlays are made with a more durable material and are bonded to the tooth for a long service life. When onlays are done properly, and with proper continued homecare that includes daily brushing and flossing, an onlay should last 15-30 years.
Onlays look exactly like real teeth, in many cases even better, as they look like they are brand new teeth; all a single color with perfect cusps, fossae and contours. Onlays can close spaces between teeth, where food gets impacted, they can also restore a brighter smile to mouths that have large amalgam (AKA: mercury) fillings.
Onlays are precision oriented; precision takes a bit of time, so expect your appointment to not be rushed and be done correctly the first time. Dr. Hoffman is a perfectionist when it comes to creating the proper onlay preparation.
This is because part of making an onlay look and feel correct involves a dental laboratory, who performs their work based on principles of material science. Onlay preparations must have certain reductions and shapes (AKA: Internal and external Morphology) in certain specific locations, which allow the materials to possess the proper strength to last the full life-expectancy, also for the shade and shape of the onlay to properly mimic a natural tooth.
Onlays do not get cavities, but the margin, or area where the onlay meets the tooth can get cavities. Actually, this area is the area that most commonly fails on an onlay tooth. There are two ways to combat this phenomenon: 1. Have the onlay fit correctly at the time of placement 2. Make sure proper flossing and brushing is done around the onlay nightly.
Onlays take 2 visits to complete. The first visit is the actual removal of the damage and/or cavities and the preparation of the tooth for the onlay. This is also where the impression is taken for the lab, and when your temporary onlay is fabricated. The second visit is to permanently deliver your new onlay; this visit only takes about 30-minutes or so. Before your new onlay is permanently delivered to you, all parties must be completely happy. You must be happy with the color (shade), shape and bite, and Dr. Hoffman must be happy with the x-ray, the margins, the interproximal contacts, and the bite. Once everyone thinks things are "perfect", Dr. Hoffman will ask your permission to permanently deliver your new onlay.