Contour changes after guided bone regeneration of large non-contained mandibular buccal bone defects using deproteinized bovine bone mineral and a porcine-derived collagen membrane: an experimental in vivo investigation

The objective of this study was to evaluate soft tissue contour changes after three different regenerative therapies in chronic ridge defects. Buccal bone defects were created in the mandible of nine beagle dogs. Augmentation procedures were performed 3 months later using a bone replacement graft (BRG), resorbable collagen membrane (MBG), or a combination of both procedures (CBG). Silicone impressions were taken before tooth extraction (T1), before the augmentation procedure (T2), and 3 months after the regenerative surgeries (T3). Casts were optically scanned and stereolithography files were superimposed to analyze the horizontal changes in ridge contours. After defect creation, most part of the horizontal changes occurred 4 and 6 mm below the gingival margin. In the mesial defect (D1) at T3, the mean horizontal gain in MBG amounted to 0.47 +/- 0.34 mm, 0.79 +/- 0.67 mm in the BRG, and 0.87 +/- 0.69 mm for the CBG. In the middle defect (D2), the mean changes for the MBG were 0.11 +/- 0.31, 1.01 +/- 0.91 for the BRG, and 0.98 +/- 0.49 for the CBG. The mean changes in the distal defect (D3) amounted to 0.24 +/- 0.72 for the MBG, 1.04 +/- 0.92 for the BRG, and 0.86 +/- 0.56 for the CBG. The differences reached significance in all defects for the comparison MBG-BRG and MBG-CBG, while similar parameters were observed for the comparison BRG-CBG. BRG and CBG were equally effective and superior to MBG in increasing the horizontal tissue contours. The augmentation seldom reached the values before extraction. Scaffolding materials are needed for contour augmentation when using resorbable collagen membranes.