A porcelain onlay is fabricated to fit your tooth precisely and is bonded tightly in place to strengthen and protect the damaged tooth. Like a crown, an onlay covers and protects the tooth's biting surface. Where a crown covers the entire tooth, an onlay fits inside the tooth cusps and covers only the biting surfaces. Because an onlay is fabricated in a dental laboratory, it takes two or more appointments to restore a tooth with a porcelain onlay.
We want the entire procedure to be comfortable for you, so the first thing we do is make sure your mouth is thoroughly numb. Depending on the size of the filling and which tooth we're working on, we may use a rubber dam. A rubber dam is a small, flexible rubber sheet that isolates the teeth we're working on and prevents anything from falling to the back of your throat. Then we use the handpiece to remove the decay and shape the tooth.
The next step is to take impressions of your teeth, which we then use to make models on which the dental laboratory will fabricate your porcelain onlay. Sometimes we put a small piece of string in the space between the tooth and the gum. We use the string to gently push the gum away from the tooth so that we can get a more complete impression. When we're finished, we place a temporary onlay in your tooth, which you'll wear until your next appointment when we place the permanent onlay.
During the next visit, we remove the temporary onlay and make sure that your new porcelain onlay fits properly. We check the fit and your bite, and when everything looks good, we cement or bond your new porcelain onlay in place.