Surgical crown lengthening: evaluation of the biological width. Placement of the preparation line and periodontal health--a prospective 2-year clinical study. Biological width formation to immediate implants placed at different level in relation to the crestal bone: an experimental study in dogs. Culture of human gingival fibroblasts on a biodegradable scaffold and evaluation of its effect on attached gingiva: a randomized, controlled pilot study.
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 The aim of this prospect i ve clinical 2-year study was to determine whether the placement of the proximal margins of crowns within the zone of the biologic width results in periodontal alterations . In 41 patients , 116 prepared teeth as well as 82 unrestored , healthy contralateral teeth were examined . The following indices were determined before as well as 3 , 6 , 12 , and 24 months after preparation :  hygiene index , papillary bleeding index ( PBI ) , and probing depth .  After preparation , the distance between the restoration margins and the alveolar crest was measured with a modified periodontal probe on both proximal aspects of each tooth . These values were classified into 3 groups : I = < or = 1 mm between crown margin and alveolar crest , II = 1 to 2 mm , and III = > 2 mm . In addition , radiographs were taken directly after cementation of each restoration and after 12 and 24 months . The hygiene index did not significantly vary during the investigation , but PBI increased in all groups . The highest PBI increase was found in group I ; in this group , the most significant increase was found between 3 and 6 months after preparation . The mean probing depth only increased in group I during the first 3 months after preparation on the mesial aspects . Only minor changes were found on the distal aspects of the teeth in group I and on all aspects in groups II and III . No alterations of the bone levels were diagnosed on the radiographs . These results indicate that the location of the restoration margins within the zone of the biologic width may impair the periodontal health of restored teeth PURPOSE / AIM Evaluate differences in bone remodeling , soft tissue reactions and biological width formation around immediate implants placed at different level in relation to the crestal bone in beagle dogs . MATERIAL AND METHODS The m and ibular second , third and fourth premolars of six beagle dogs were extracted , and three implants were placed in the right side of each dog . Healing abutments were adjusted ( n = 18 ) . After 4 weeks , the procedure was repeated on the left side of the m and ible ( n = 18 ) . R and omly , three implants were placed at crestal level ( control group ) , and three implants were placed 2 mm subcrestally ( test group ) in relation to the crestal bone in each animal . The dogs were sacrificed after 8 weeks from the first surgical procedure , and biopsies were obtained . Sample s were processed for ground sectioning . Histometric analysis was carried out to compare buccal and lingual bone resorption , soft tissue behavior and biological width formation in both groups . RESULTS Crestal bone resorption was higher in the test group when considering the difference of 2 mms ( IS-B = 2.05 ± 0.36 mm , control ; 1.75 ( + 2 ) ± 0.38 mm , test ) . However , the dimensions of the biological width were similar for both groups ( PM-C = 3.34 ± 0.53 mm , control ; 3.13 ± 0.55 mm , test ) . CONCLUSIONS The alterations that occurred in the peri-implant soft tissues may be related to the hard tissue remodeling , showing similar quantitative findings in the biological width formation in both groups . Even though the subcrestal placement might reduce the distance from the implant shoulder to the first bone-to-implant contact and reestablish the biological width dimension in a most coronal position , it might not have any effect on minimizing the marginal bone loss BACKGROUND An adequate width of attached gingiva is necessary to maintain healthy periodontium , especially in orthodontics or restorative treatments in periodontics . The purpose of this study was to evaluate the width of attached gingiva after clinical application of a cultured gingival graft compared to a periosteal fenestration technique . METHODS This study was conducted on nine patients ( 18 sites ) with insufficient attached gingiva adjacent to at least two teeth in contralateral quadrants of the same jaw . A small portion ( approximately 3 x 2 x 1 mm ) of attached gingiva ( epithelial + connective tissue ) was removed with a surgical blade . After culture of gingival fibroblasts , 2 x 10(5 ) cells in 250 microl nutritional medium were added to 250 microl collagen gel . One tooth in each patient was r and omized to receive a periosteal fenestration technique for gingival augmentation ( control ) or a tissue-engineered mucosal graft ( test ) . Clinical parameters measured at baseline and 3 months included width of keratinized tissue , probing depth , and width of attached gingiva . RESULTS An increased amount of keratinized tissue was seen at all treated sites after 3 months . The mean increased amount of attached gingiva was 2.8 mm at test sites and 2 mm at control sites ; this difference was significant ( P < 0.05 ) . CONCLUSION Based on the results of this investigation , the tissue-engineered mucosal graft is safe and capable of generating keratinized tissue
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 .