As we continue our discussion of Aesthetic Crown Lengthening it becomes apparent that we need to be able to identify and measure both the amount of attached gingival and the position of the alveolar crest. The above would also be true if we were planning the crown lengthening for retention.
To measure the attached gingival one needs to identify three landmarks: the free gingival margin, the base of the sulcus and the mucogingival junction. To determine the amount of attached gingival one measures the distance from the free gingival margin to the mucogingival junction and then subtracts the value for the depth of the sulcus.
It is important to note that there is no relationship between the mucogingival junction and the crest of bone. The mucogingival junction exists on the facial of all teeth, but not all teeth have alveolar bone on the facial. It is not uncommon for a dehiscence to exist on the facial of anterior teeth and the mesial root of first molars. As long as there is no recession, everything is perfectly healthy, and we will never know.
It is also necessary for us to be able to identify the position of the crest of bone. To do this, we employ a procedure called “sounding.” To sound the bone, we place a periodontal probe into the sulcus and then push, with sufficient force, through the pocket epithelium and connective tissue below until our probe stops by hitting the crest of bone. It is important to angle the probe toward the tooth rather than holding it as parallel as possible, as one would do during regular periodontal probing. In this way, if the crest of bone is thin, it avoids the problem of slipping past the crest and continuing far down the tooth through the connective tissue and alveolar mucosa and getting a false reading. Of course, the patient must be anesthetized to do this.
As mentioned before, there is a long-standing debate about how much attached gingiva is necessary. The consensus in the literature seems to be that around a natural tooth, at least one millimeter should be present.
Once these two measurements have been made, one can then make a decision about which surgical procedure to employ: gingivectomy or full thickness flap. In the next post, I will talk about the diagnostic reasons for needing aesthetic crown lengthening. Proper diagnosis leads to proper treatment. It is important to understand why the teeth are too short.