Clinical and histological evaluation of the use of acellular dermal matrix (ADM) membrane in peri-implant vertical soft tissue augmentation: A controlled clinical trial

The aim of this study was to clinically and histologically evaluate the efficacy of using acellular dermal matrix (ADM) for peri-implant vertical soft tissue augmentation at implant placement.Twenty patients were enrolled in this study. According to the initial thickness of vertical soft tissue, patients were assigned into the ADM group (≤2 mm) or the control group (2 mm) prior to implant surgery +ADM grafting or implant surgery alone. Second-stage surgery was carried out 3 months later, and a small piece of ridge membrane was harvested for histological and immunohistochemical evaluation. Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF)-BB in peri-implant crevicular fluid (PICF) were also assessed 1 week, 1 month, and 5 months after second-stage surgery. Clinical parameters were recorded to evaluate peri-implant health at 1 week and 3 months after implant restoration.All 20 implants healed uneventfully and successfully. Soft tissue thicknesses were comparable in the two groups at second-stage surgery (3.20 ± 0.42 mm vs. 3.50 ± 0.58 mm). In the ADM group, the mean increase in soft tissue thickness was 1.85 ± 0.34 mm. Histological and immunohistochemical outcomes showed no differences between the two groups. VEGF and PDGF-BB levels in PICF were significantly lower in the ADM group 1 week after second-stage surgery (p .01), yet they decreased in both groups later. The difference between the groups had disappeared by 5 months after second-stage surgery. The clinical peri-implant parameters were good and stable by the end of the study (3 months after restoration).Our results suggested that using ADM at implant placement was effective in increasing the thickness of peri-implant vertical soft tissue and achieved comparable clinical and histological performance to the control group. However, the incremental soft tissue showed inferior angiogenic ability in the early stage of wound healing.