Clinical Evaluation of Absorbable Gradient Membrane vs. Free Gingival Grafts for Periodontal Soft-Tissue Augmentation: A Randomised Controlled Clinical Trial

Abstract

Aim: To assess a new material in comparison with free gingival graft (FGG) for increasing the width of keratinised tissue (KT). Material and Methods: Forty-six participants were randomly allocated to the absorbable gradient membrane (AGM) or the FGG group. This trial used inter-patient comparison to establish the non-inferiority of AGM compared to FGG. The primary outcome (KT) was examined from baseline to 3 years after surgery. Secondary outcomes included the plaque index (PI), bleeding index (BI), gingival recession (GR), probing depth (PD), immunoglobulin E (IgE) level, postoperative pain, aesthetics and patient satisfaction. Results: The width of KT in the AGM group was non-inferior to that of the FGG group at all short-term follow-ups (1, 3 and 6 months), with a pre-defined margin of 1 mm. However, this non-inferiority disappeared by 3 years after operation. From 6 months to 3 years, the GR associated with FGG significantly decreased, while that associated with AGM showed no significant change between adjacent time points. No significant differences were observed in PI, BI, PD or IgE levels between the groups. AGM required shorter surgery times and secured better aesthetic outcomes than FGG. Conclusion: AGM showed short-term non-inferiority to FGG for KT augmentation. However, the non-inferiority was not sustained at 3 years. Trial Registration: The study was registered with the China Clinical Trial Center under ChiCTR2000034683. Informed consent was obtained from all participants.