Efficacy of Xenogeneic Collagen Matrix to Augment Peri-implant Soft Tissue Thickness Compared with Autogenous Connective Tissue Graft: A Systematic Review and Meta-Analysis

Purpose: Several approaches for increasing peri-implant mucosal thickness have been proposed, including autogenous, allogeneic, and xenogeneic grafts. The objective of this meta-analysis was to analyze whether xenogeneic matrices are viable alternatives to autogenous soft tissue grafts in peri-implant soft tissue augmentation. Materials and Methods: A systematic search was performed to select randomized clinical trials that compared connective tissue grafts and xenogeneic collagen matrices. The primary outcomes were the mucosal thickness and keratinized mucosa changes, while the secondary outcomes were patient morbidity, painkiller consumption, and surgical time required for the procedure. Results: Seven randomized clinical trials were included for the final evaluation with a total number of 218 implant sites (108 in the connective tissue graft group, 110 in the collagen matrix group) with 3 to 12 months (mean: 6 months) followup period. Results showed mucosal thickness increase in both buccal and crestal sites, but it did not yield statistical significance. The keratinized mucosa gain difference was only -0.06 mm (95% CI [-30.0, 0.18]) between the treatments. The postsurgical discomfort, increased consumption of painkillers, and reduction of treatment time (15.46 minutes less) differed significantly in favor of the collagen matrix group. Conclusion: Within the limits of this study, it can be concluded that collagen matrix and connective tissue graft are equivalent in peri-implant soft tissue augmentation. Keywords: collagen matrix, connective tissue, dental implants, keratinized tissue, meta-analysis, soft tissue management