[Clinical aesthetic effectiveness of restoring the subgingival residual crowns of anterior teeth with crown lengthening surgery]. Twenty-five patients with 28 subgingival residual crowns were treated by root canal therapy, crown lengthening surgery, and restored with post- core crown after 8 weeks.  For subgingival residual crowns of anterior teeth, crown lengthening surgery can conserve the biological width, and produce enough height of ferrule. 
Crown Lengthening Surgery
Twenty-five patients with 28 subgingival residual crowns were treated by root canal therapy, crown lengthening surgery, and restored with post- core crown after 8 weeks. 
Post-core Crown