Plant-Derived Modifiers for Antimicrobial Soft Denture Liners: A Review

This review examines strategies to enhance the antifungal properties of commercial soft lining materials (SLMs) through modification with plant-derived oils, extracts, and powders. These natural bioactive compounds act via multiple mechanisms, including disruption of fungal cell membranes, inhibition of biofilm formation, and interference with Candida albicans metabolism, the pathogen causing denture-associated candidiasis. Their incorporation into SLM provides localized antifungal activity at the denture-mucosa interface. The review highlights Aloe vera (aloe), Azadirachta indica (neem), Ocimum basilicum (basil), Melaleuca alternifolia (tea tree), Cocos nucifera (coconut), Allium sativum (garlic), Thymus vulgaris (thyme), and chitosan as notable sources of phytotherapeutics that consistently inhibit C. albicans growth. In addition to antimicrobial effects, studies assessed both intrinsic (hardness, tensile strength, tear strength) and interfacial (bond strength) mechanical properties, as well as surface roughness. Most formulations maintained acceptable mechanical performance and improved surface smoothness. Key limitations include rapid leaching of active compounds, variability in testing methods, and insufficient in vivo and cytotoxicity data. Future research should prioritize the high-quality purification of natural extracts, the isolation of well-defined bioactive compounds, and the design of systems enabling selective and sustained release of these agents, ensuring reproducibility, enhanced stability, and clinical reliability of next-generation bioactive SLMs.