Evaluation of the clinical effect of restoring of the teeth with subgingivally involved defect conserved by crown lengthening surgery

Objective To evaluate the clinical effect of the crown lengthening surgery on the restoration of residual root and crown with subgingivally involved defect.Methods From May 2004 to June 2007,according to the subgingival depth of the defect,52 teeth from 48 patients with subgingivally involved defect were divided into two groups:minor defect group(28 teeth,depth 2.5 mm),major defect group(24 teeth,2.5 mm≤depth≤4.0 mm).All teeth were treated by the crown lengthening first and then underwent postcrown prosthesis at 6 weeks postoperatively.After following up for 6 months the preparative and postoperative data were reviewed and analyzed.Results The teeth sections of two groups were exposed well and the color of the gingival margin of two groups looked normal.The overall satisfying rate was 80.77%.The restoration of minor defect group without any teeth loose was better than that of major defect group with half teeth loose at degree I.Postoperative PD,PLI and SBI were better than those before operation.(P0.05).There were no differences on the periodontal index among the two groups(P0.05).Conclusion Crown lengthening surgery is a good method for the protection and restoration of residual root and crown,but should be used properly.