Crown lengthening (crown exposure) procedure is required when the edge of the new crown is significantly below the gum tissue. In same cases, the new crown edge is very close to the jawbone or even below the bone.
The crown lengthening procedure removes and reshapes the gum tissue and bone around the tooth. As a result, the edge of the crown is at or above the gum line. This procedure ensures proper fit of the crown to the tooth and provides enough tooth structure so the new crown will not become loose in the future.
The following diagrams are illustration of the Crown Lengthening Procedure.