What Is It?
This common procedure involves the removal of gum tissue, bone or both, to expose more of a tooth's structure.

What It's Used For
It is usually required when gum levels are of uneven height or decay has advanced beyond the gum level. Crown lengthening is done when a tooth needs to be restored, but there is not enough tooth structure above the gum line to support a filling or a crown.
This can happen when a tooth breaks off at the gum line, or a crown or filling falls out of a tooth that has extensive decay underneath. If your dentist wants to repair the tooth using a crown or a large filling, he or she may need to expose more of the tooth by removing some soft tissue or bone.
In rare cases, a condition called gummy smile — when an unusually large amount of gum tissue shows around the upper teeth — can be treated using crown lengthening.

How It's Done
This procedure is done under local anesthesia. The amount of time it takes varies depending on the number of teeth that require treatment. Although your problem may involve only one tooth, crown-lengthening surgery typically includes neighboring teeth so that the tissues can be reshaped gradually. If only soft tissue is removed, the procedure probably will take less time than if both soft tissue and bone are removed. The periodontist will make incisions to "flap" the gums away from the teeth. This provides access to the roots of the teeth and the surrounding bone. In some cases, by simply removing a little gum tissue when the incisions are made, enough tooth structure will be exposed for your dentist to place a crown of filling.
After the soft tissue and bone have been removed, the incisions are sutured. This will cause more of the tooth or teeth to be exposed. Some dentists use a periodontal dressing to cover the incisions.