Crown lengthening (or crown exposure) is required when your tooth needs a new crown or other restoration. The edge of that restoration is deep below the gum tissue and not accessible by your dentist. It is also usually too close to the bone or below the bone level.
The procedure involves adjusting the level of the supporting tissues around the tooth in question to create a new gum-to-tooth relationship. This allows your dentist to predictably reach the edge of the restoration, ensuring a proper fit to the new crown or filling. It should also provide enough tooth structure so the new restoration will not come loose in the future. This allows you to clean the edge of the restoration when you brush and floss to prevent decay and gum disease. The procedure takes approximately one hour.