Prospective Clinical and Radiographic Study of Alveolar Ridge Preservation Combining Freeze-Dried Bone Allograft With Two Xenogeneic Collagen Matrices

Background: Tooth extractions are followed by significant dimensional changes in the alveolar crest that may preclude implant placement. This randomized, controlled, prospective compares the preservation of soft and hard tissue dimensional changes after alveolar ridge preservation (ARP) using two membranes consisting of collagen matrix (CM) or extracellular matrix (ECM) as barriers over freeze-dried bone allograft (FDBA). Methods: Standardized clinical and radiographic measurements of soft and hard tissues were recorded by means of a stent before and 4 months after ARP. The surgery entailed sulcular incisions with minimal flap elevation and repositioning without advancement. Results: Of 11 patients in the CM group and 12 in the ECM group who completed the study, gingival thickness (GT) increased from 0.1 to 0.2 mm for both groups along with a 0.5-mm decrease in the width of keratinized tissue after healing. Reductions in ridge width were most pronounced on the coronal aspect, 1.8 mm for CM and 2.0 mm for ECM, whereas vertical reduction was most pronounced on the buccal aspect, 0.7 to 1.0 mm. Differences between groups were not statistically significant. However, significant correlation for changes in GT (P = 0.001) and crestal bone width (P = 0.002) with preoperative buccal plate thickness (BPT) was observed. Conclusions: Both xenogeneic collagen matrices combined with FDBA were effective in maintaining soft tissues and minimizing ridge resorption in all dimensions after ARP. BPT was an important determinant for amount of change in crestal GT and ridge width.