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

Abstract

To test whether implant placement with simultaneous guided bone regeneration (GBR) differs from implant placement without GBR regarding the change in marginal mucosal contour. In 28 patients, single implants were placed >4months 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 3months before abutment connection, at 6months immediately after crown insertion, at 1year, and at 3years. 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. From baseline to 6months, horizontal contour change at the level 1 and 2mm apical to the mucosal margin measured 0.65±0.74mm and 0.55±0.56mm at sites without GBR, and 1.92±0.87mm and 1.76±0.70mm at sites with GBR (P<0.05). In the period from baseline to 1year, the corresponding values amounted to 0.81±0.67mm and 0.60±0.55mm in the group without GBR, and to 1.81±0.86mm and 1.37±0.62mm in the group with GBR (P<0.05). From baseline to 6months, mucosal margin moved 0.16±0.49mm in the coronal direction in the group without GBR and 0.82±0.65mm in the group with GBR (P<0.05). In the period from baseline to 1year, vertical change of mucosal margin amounted to 0.64±0.54mm in the group without GBR and to 1.17±0.53mm in the GBR group (P<0.05). From 1 to 3years, the mucosal contours remained stable. 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.