Guided bone regeneration and abutment connection augment the buccal soft tissue contour: 3-year results of a prospective comparative clinical study.

AIM: To test whether implant placement with simultaneous guided bone regeneration (GBR) differs from implant placement without GBR regarding the change in marginal mucosal contour. MATERIALS AND METHODS: In 28 patients, single implants were placed >4 months after tooth extraction. Eighteen implants were completely surrounded by native bone, and no bone augmentation was performed. At 10 implant sites, bone defects and thin bone plates were grafted with deproteinized bovine-derived bone mineral and covered with collagen membrane. Impressions were taken prior to implant placement (baseline), at 3 months before abutment connection, at 6 months immediately after crown insertion, at 1 year, and at 3 years. Models were optically scanned and 3D images were superimposed for the evaluation of mucosal contour changes at the mid-buccal aspect. The nonparametric Mann-Whitney U-test was applied to detect differences. RESULTS: From baseline to 6 months, horizontal contour change at the level 1 and 2 mm apical to the mucosal margin measured 0.65 +/- 0.74 mm and 0.55 +/- 0.56 mm at sites without GBR, and 1.92 +/- 0.87 mm and 1.76 +/- 0.70 mm at sites with GBR (P < 0.05). In the period from baseline to 1 year, the corresponding values amounted to 0.81 +/- 0.67 mm and 0.60 +/- 0.55 mm in the group without GBR, and to 1.81 +/- 0.86 mm and 1.37 +/- 0.62 mm in the group with GBR (P < 0.05). From baseline to 6 months, mucosal margin moved 0.16 +/- 0.49 mm in the coronal direction in the group without GBR and 0.82 +/- 0.65 mm in the group with GBR (P < 0.05). In the period from baseline to 1 year, vertical change of mucosal margin amounted to 0.64 +/- 0.54 mm in the group without GBR and to 1.17 +/- 0.53 mm in the GBR group (P < 0.05). From 1 to 3 years, the mucosal contours remained stable. CONCLUSIONS: Implant placement with simultaneous GBR resulted in more gain of buccal soft tissue contour in comparison with implant placement without GBR. Abutment connection increased the contour of the marginal mucosa at the augmented and the nonaugmented sites. GBR procedure contributed more to the contour gain than did the abutment connection. The augmented and the nonaugmented ridges exhibited stable peri-implant mucosal contour over a 3-year period.