Objective: To observe the results of surgical crown lengthening procedure and the factors which affected the success of the surgery.
Methods: Crown lengthening surgery was performed on 27 teeth. The distance between margin of tooth and bone crest (MT-B) was obtained greater than 4 mm during the surgeries on 10 teeth which were considered as satisfying group. The other 17 teeth were as temporized group with MT-B < or = 3 mm. The position of the tooth margin was evaluated before surgery, immediately after suturing, and at 4 - 6 weeks after surgery. The occlusal force and tooth mobility were measured immediately after restoration, at 3 and 6 months after surgery.
Results: MT-B was obtained > or = 4 mm and all margins and sites of the teeth were exposed in satisfying group (10/10). At least 1 site with MT-B < 3 mm in temporized group in which there still were 11 sites (16%) in 5 teeth (29%) with subgingival tooth margin at 4 - 6 weeks after surgery. There were more teeth showing increased mobility in temporized group (12/17) than in satisfying group (1/10) after surgery (P < 0.05). The occlusal force of the teeth after surgery and restoration in temporized group was significantly lower than that of their counterpart teeth (P < 0.01), but it was not the case in satisfying group (P > 0.05).
Conclusions: It is suggested that ideal exposure of tooth margin could be obtained if 4 mm from tooth margin to alveolar crest could be created during the crown lengthening surgery. The teeth both with 4 - 5 mm subgingival margin sites and factors limiting surgical performance are not the suitable indications for the surgical crown lengthening.