Crown lengthening is a routine surgical procedure, which remodels the contour of the gum line. Cavities can decay teeth below the gumline, making a crown restoration sit too close to the bone. Teeth can also break below the gumline. Crown lengthening changes the amount of tooth you se by lowering the gumline. After a healing period of several weeks crown lengthening provides access to the tooth so that a proper impression can be made for a crown restoration.