Why do crowns or bridges come off or keep coming off?
The most common reason a crown or bridge keeps coming off is lack of sufficient retention for the crown or bridge. The most common reason for lack of sufficient retention is lack of adequate tooth structure above the gum for a crown or bridge to hold onto. A minimum of 2 millimeters of tooth structure (without decay) above the gum all the way around the tooth is needed for adequate retention. If there is a lack of adequate tooth structure above the gums, the crown will come off occasionally. Gum treatment called crown lengthening is commonly used and can in most cases create the adequate tooth structure above the gum that is needed for long term retention. In some cases, orthodontic treatment can also be used to expose more tooth structure above the gums. Other less common reasons for lack of retention are how the teeth are prepared above the gum line and how the crown or bridge fits on the supporting natural tooth. If the space between the tooth structure and the edge of the crown or
