Acellular dermal matrix allograft versus free gingival graft: a histological evaluation and split-mouth randomized clinical trial

Objectives: This split-mouth controlled randomized clinical trial evaluated clinical and histological results of acellular dermal matrix allograft (ADM) compared to autogenous free gingival graft (FGG) for keratinized tissue augmentation.

Material and methods: Twenty-five patients with the absence or deficiency of keratinized tissue (50 sites) were treated with FGG (control group) and ADM (test group). Clinical parameters included keratinized tissue width (KTW) (primary outcome), soft tissue thickness (TT), recession depth (RD), probing depth (PD), and clinical attachment level (CAL). Esthetic perception was evaluated by patients and by a calibrated periodontist using visual analog scale (VAS). Histological analysis included biopsies of five different patients from both test and control sites for each evaluation period (n = 25). The analysis included percentage of connective tissue components, epithelial luminal to basal surface ratio, tissue maturation, and presence of elastic fibers. Data were evaluated by ANOVA complemented by Tukey's tests (p < 0.05).

Results: After 6 months, PD and CAL demonstrated no differences between groups. ADM presented higher RD compared to FGG in all periods. Mean tissue shrinkage for control and test groups was 12.41 versus 55.7%. TT was inferior for ADM group compared to FGG. Esthetics perception by professional evaluation showed superior results for ADM. Histomorphometric analysis demonstrated higher percentage of cellularity, blood vessels, and epithelial luminal to basal surface ratio for FGG group. ADM group presented higher percentage of collagen fibers and inflammatory infiltrate.

Conclusions: Both treatments resulted in improvement of clinical parameters, except for RD. ADM group presented more tissue shrinkage and delayed healing, confirmed histologically, but superior professional esthetic perception.

Clinical relevance: This study added important clinical and histological data to contribute in the decision-making process between indication of FGG or ADM.