[Evaluation of the clinical effect of the teeth with subgingivally involved defect conserved by crown lengthening surgery].

Purpose: To evaluate the clinical effect of the teeth with subgingivally involved defect which were conserved by crown lengthening surgery.

Methods: 62 teeth, with defect subgingivally from 1.5 mm to 4 mm, mobility degree(MD)
Results: The overall effective rate was 83.9%. PD and SBI demonstrated a significant improvement (P<0.01), but MD showed an increasing trend after operation (P<0.01). No significant difference about MD of anterior teeth in two groups was found before operation (P>0.05), but a significant increase about MD occurred in the major defect group one year after restoration (P<0.01), and there was significant correlation between MD of each stage after operation and PD of pre-operation in anterior teeth (r=0.489, 0.526, 0.531, P<0.01).

Conclusions: According to the biological width principle, crown lengthening surgery may conserve these teeth with subgingivally involved defect, and has a good, long-time clinical effect. But MD showed an increasing trend after operation and significant cor.