Evaluation of the Clinical Effect of Crown Lengthening Surgery on Residual Root

Objective To evaluate the clinical effect of crown lengthening surgery on residual root with subgingivally involved defect.Methods 29 residual roots with subgingivally involved detect within 3mm were divided into two groups:group A(13 teeth,tooth root≥1.5 cm ),group B(16 teeth,1.2 cm≤tooth root1.5 cm).All teeth were treated by the crown lengthening first and restored 6 weeks after surgery.The parameters of probing depth(PD),sulcus bleeding index(SBI) and tooth mobility degree(MD) were reviewed and analyzed before surgery,6 weeks after surgery,1 and 3 months after restoration.Results Periodontal conditions of the teeth were well and the overall effective rate was 86.21%.Postoperative PD and SBI were better than those preoperatively(P0.05).But there were not differences among the two groups (P0.05).There were more teeth showing increased mobility in group A than in group B after surgery.Conclusions Crown lengthening surgery has good clinical effect for the protection and restoration of residual root,but the indication must be selected properly.