What Is Crown Lengthening?

There are two conditions where dental crown lengthening surgery is required; “gummy smile” correction (cosmetic crown lengthening) and below gum line tooth restorations (functional crown lengthening):

Cosmetic crown lengthening

Cosmetic crown lengthening is done to remove an overgrowth of gum tissue that causes a condition known as “gummy” smile where teeth appear to be too short. The excessive gum tissue is removed to restore the proper length of the tooth’s crown (visible part of tooth).

‘Gummy smile’, is a condition where too much gingival (gum) tissue is visible when a person speaks or smiles. Almost 7% of men and 14% of women have some degree of ‘gummy smile’ due to several reasons such as a short upper lip, a large upper jaw or short upper front teeth.

Cosmetic crown lengthening repositions the gum line for one or several teeth to follow the contours of the face, improving the aesthetic appearance of the smile. Other treatments of ‘gummy smile’ include orthodontic treatment, jaw surgery and lip repositioning.

Crown lengthening aka ‘gum recontouring’ is a cosmetic dental treatment that can not only improve appearance but can also help prevent gum disease by making teeth easier to keep clean.

Functional crown lengthening

Functional crown lengthening is performed when there is not enough of the tooth exposed above the gum line to fit a filling or a prosthetic restoration (crown or bridge) on a decayed or broken tooth.

The most common situations that require crown lengthening are when a tooth is decayed or broken below the gum line or there is not enough tooth structure to anchor a restoration, such as a crown or bridge, in cases of gingival hyperplasia, not fully erupted teeth, malocclusion or severely worn teeth due to bruxism. It is also needed when a crown or filling fails and there is tooth decay underneath it close to the gum line. Crown lengthening adjusts the gum and bone level to allow room for the dentist to reach the decay and expose sufficient tooth to anchor the restoration.

In many cases when crown lengthening is required, it involves bone removal to provide the necessary space between the bone and the restoration in order to prevent future damage to gum and bone near the restoration.

Gums need at least 2 mm of tooth structure above the supporting bone to attach to properly. Good bonding of gums on teeth prevents food debris and dental plaque from trapping under the gums and causing gum disease. Dentists may have to perform crown lengthening before restoring a tooth to provide this minimum space.

The crown lengthening surgery can often be completed in a single visit under local anaesthesia. More visits may be needed if the procedure involves several teeth in different mouth quadrants. A professional tooth cleaning is usually recommended before the surgery. Any existing temporary crown will be removed from the tooth prior to the procedure.

The dentist initially makes an incision around the tooth that needs crown lengthening, to remove the excess gum tissue. The adjacent teeth are usually also involved in the procedure, especially in cosmetic crown lengthening procedures, in order to provide a smoother gum contour. The gum line must be shaped in a way that the smile will look natural and even.

The gum tissue is carefully pulled away from the tooth to expose the tooth root and the alveolar bone. In case the procedure is performed in preparation of a restoration, the dentist will check if there will be adequate space between the bone tissue and the restoration. If the distance is less than 2mm, the dentist will remove some of the bone. Bone removal is rarely needed for cosmetic crown lengthening.

The dentist will stitch the reshaped gums back in place to complete the gum surgery. A periodontal dressing is placed to protect the surgical site.

Cosmetic crown lengthening surgery is normally simpler and faster to heal than functional ones, because it usually does not involve the removal of bone tissue but only of gum tissue.

The stitches (if used) are removed after 7-10 days and a follow-up visit is scheduled four to six weeks later to check healing progress. Healing period may vary depending on the severity of the surgery. For extensive surgeries the wound will heal in about 2 months, but the gums may continue to shrink for 3-4 months after the crown lengthening surgery until they are considered completely healed.

If the procedure is performed in preparation of a restoration, a temporary crown may be placed immediately or some days after gum surgery, but the permanent dental crown must be placed only after the gums have settled in their final new position. If the restoration is placed earlier, it is possible that the gums may shrink more making the edges of the crown to become distinguishable above the gums.

The possible complications of crown lengthening surgery include:

• Bleeding / Swelling: Some bleeding and swelling may be expected especially if the procedure involves several teeth. You may apply some light pressure to reduce bleeding. Ice packs placed outside the mouth in the affected area can help with the swelling.
• Pain: the dentist will prescribe a pain reliever to ease the pain. Severe pain is not expected.
• Infection: As in any other surgery, infections are a risk. Dentists usually suggest the use of an antimicrobial mouthwash containing chlorhexidine for some days in order to prevent infections. Proper oral hygiene after the crown lengthening surgery is also important for preventing infections. (avoid to brush directly on the surgical site for several days in order not to disturb the periodontal dressing). You should call or visit your periodontist if you have:
  • bleeding that doesn't stop.
  • severe pain not manageable by pain medication.
  • excessive swelling, discharge from the surgical area or any other sign of infection.
  • the periodontal dressing becomes loose or is displaced.
  • swollen lymph nodes beneath the lower jaw or in the neck
• Esthetics: After a functional crown lengthening procedure, the treated tooth may look longer than the teeth next to it. For this reason the gum position of the adjacent teeth should also be corrected during the initial procedure or later to create a naturally looking gum line.
• Sensitivity: Exposing a larger part of the tooth may result in exposing part of the tooth root which is not covered by enamel. Exposed cementum or dentine may cause tooth sensitivity to hot and cold. Sensitivity can be treated by either placing the permanent crown or by using special varnishes for sensitive teeth treatment.
• Loosening of tooth: removing bone around the tooth roots may result in the tooth to become loose. Another implication of bone removal is that if the tooth is later lost for any reason, it is harder to replace it with a dental implant due to the reduced bone structure.
• Functional failure: If a functional crown lengthening fails to provide the required minimum distance between restoration and bone, this can cause chronic pain, gum inflammation and gradual loss of alveolar bone.

Regardless of the initial reason for crown lengthening, either esthetic or functional, it can offer you a better looking smile and improved dental health.