A crown is sometimes required when the filling in a tooth is too big which could place the tooth at risk of fracture. Also when a tooth has had root canal treatment a crown is recommended. A crown can be all porcelain (optimum cosmetic results) or porcelain fused to metal.
If an implant is not feasible in replacing a missing tooth, a bridge is the next alternative. For a bridge, the teeth on either side of the missing tooth are crowned and the two crowns are connected together with a crown sitting over the gums where the tooth used to be.
Placing a crown or a bridge involves two appointment which after the first one which usually is 1-2 hours long, you will leave the office with a provisional restoration which will protect your teeth during the time we are waiting for the final restoration to be returned by the dental laboratory where your final porcelain or porcelain fused to metal restoration is fabricated. After about 3 weeks, your second visit is usually a very short one which does not require you getting numb.
During that visit, your temporary restoration will be replaced by the final permanent restoration.