The part of the tooth that is seen above the gum is called the clinical crown. When not enough of the clinical crown is showing, the gum must be moved up the root to expose more tooth. This is called crown lengthening.
There are three situations in which crown lengthening is commonly performed: (1) to improve esthetics, (2) to allow the dentist better access to decay, and (3) to increase retention of the final crown.
A second indication for crown lengthening is to access decay.
Below is an example of how the procedure works to enhance the esthetics of a smile.
A second common use of crown lengthening is to access decay. If the dentist is unable to reach decay that is deep under the gum, the tooth will be lost. As a rule, simply trimming back the gum is not sufficient, for the bone would be exposed. Rather, the periodontist must reflect a flap (See Flap Surgery), trim back the bone to allow for access to the decay, and then suture the gum back at the lower level. Sufficient bone must be removed to allow room below the decay for the gum to reattach to the tooth.
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| Decay far under gum | Flap reflected to access decay |
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| Bone trimmed for access to decay and to allow room for gum to reattach |
Gum replaced with decay visible for dentist to restore with filling or crown |
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| Following removal of decay, there is inadequate tooth structure |
Following crown lengthening, note increase tooth structure above bone |
Most crown lengthening procedures are very straightforward, and there is little or no post-operative discomfort. Sutures and dressing are removed after about 2 weeks.
If a crown is to be placed in a cosmetic area, the restorative dentist should wait 6-8 weeks following crown lengthening before taking final impressions. This ensures that the gum, which shrinks slightly as it re-attaches to the tooth during healing, is in its final position. If the margin of the crown is placed at the gum level before final healing, and additional shrinkage occurs, the results may be unsightly. A temporary crown can be placed two weeks after surgery if the patient desires to cover the exposed root during this healing period.
The third indication for crown lengthening is to increase retention of the final prosthesis. Following removal of severe decay or due to severe tooth wear, sometimes there is inadequate tooth structure to firmly retain a crown. Crown lengthening exposes more of the clinical tooth, providing more tooth structure for the prosthesis to hold on to.
