A narrative review by the Korean Academy of Periodontology on collagen matrices for peri-implant soft tissue augmentation.

This narrative review critically evaluates clinical and histological evidence on peri-implant soft tissue augmentation with xenogeneic collagen-based soft tissue substitutes. Particular attention is given to mucosal thickness (MT) and supracrestal tissue height (STH), with the goal of developing evidence-based clinical recommendations. A narrative literature review was conducted using preclinical and clinical studies that examined MT and STH augmentation around dental implants. The outcomes of interest were changes in MT, soft tissue contour, STH, peri-implant bone levels, keratinized tissue width, esthetic outcomes, histological findings, and patient-reported outcome measures. Because study design, surgical protocols, healing approaches, and outcome-assessment methods differed substantially across studies, the evidence was synthesized qualitatively. Several xenogeneic collagen-based soft tissue substitutes have been evaluated, but the amount and quality of evidence vary by material. Collagen-based substitutes generally increased MT, with the greatest dimensional change occurring during early healing and relative stability thereafter. Autogenous connective tissue grafts (CTGs) usually produced larger MT gains and showed greater predictability. Evidence for the use of substitutes to increase STH was sparse and methodologically heterogeneous, precluding firm conclusions. When esthetic outcomes and patient satisfaction were reported, findings were generally comparable between CTGs and collagen matrices. Collagen matrices were also associated with shorter surgical time and lower patient morbidity. CTGs remain the gold standard when the clinical goal is to maximize peri-implant MT and STH stability. Xenogeneic collagen-based soft tissue substitutes are clinically acceptable alternatives in selected cases. Further well-designed clinical trials using standardized outcome measures, especially for STH, are needed to clarify the role of collagen matrices in peri-implant soft tissue augmentation.