No universal dimension of the biologic width appears to exist .
BACKGROUND Consideration of the biologic width in restorative dentistry seems to be important for maintaining periodontal health .
OBJECTIVE To evaluate the dimensions of the biologic width in humans .
Surgical crown lengthening: evaluation of the biological width.
BACKGROUND Previous surgical crown lengthening studies have investigated positional changes of the free gingival margin but not the biological width . Histological studies utilizing animal models have shown that postoperative crestal resorption allowed reestablishment of the biological width . However , very little work has been done in humans . Therefore , the purpose of this study was to evaluate the positional changes of the periodontal tissues , particularly the biological width , following surgical crown lengthening in human subjects . METHODS Twenty-three ( 23 ) patients who needed surgical crown lengthening to gain retention necessary for prosthetic treatment and /or to access caries , tooth fracture , or previous prosthetic margins entered the study . The following parameters were obtained from line angles of treated teeth ( teeth requiring surgical crown lengthening ) and adjacent teeth with adjacent and non-adjacent sites : plaque and gingival indexes , free gingival margin , probing depth , attachment level , bone level , direct bone level , and biological width . During surgery , the bone level was reduced based on the future prosthetic margin and predetermined biological width ; flaps were placed at the bony crest . Patients were examined at baseline and at 3 and 6 months postoperatively . RESULTS Eighteen patients completed the study . Overall , the amount of bone resected was 1 to 5 mm . At 90 % of treated sites , > or = 3 mm of bone was removed . At 3 months , the apical displacement of the free gingival margin at non-adjacent , adjacent , and treated sites was 2.46 + /- 0.25 mm , 2.68 + /- 0.20 mm , and 3.07 + /- 0.16 mm , respectively . There was no significant change in the position of the free gingival margin from 3 to 6 months . The biological width at all sites was smaller at 3 and 6 months compared to baseline ( P<0.05 ) except for the treated sites , which were not significantly different from baseline at 6 months . CONCLUSIONS During surgical crown lengthening , the bone level was lowered for placement of the prosthetic margin and reestablishment of the biological width . The biological width , at treated sites , was reestablished to its original vertical dimension by 6 months . In addition , a consistent 3 mm gain of coronal tooth structure was observed at the 3- and 6-month examinations
No universal dimension of the biologic width appears to exist .
BACKGROUND Consideration of the biologic width in restorative dentistry seems to be important for maintaining periodontal health .
OBJECTIVE To evaluate the dimensions of the biologic width in humans .