Antifungal Activity and Time-Dependent Polymethyl Methacrylate Surface Response to Fruit-Peel Fermentation-Derived Denture-Cleansing Formulations

Fermentation-derived fruit-peel formulations have potential as alternative denture cleansers, but their development requires evidence that they can provide antifungal activity without compromising denture-base materials during repeated use. Objectives: To evaluate the antifungal activity of six-month-fermented mixed pineapple–orange and papaya-based effective eco-produce formulations (M-EEP and P-EEP, respectively) against Candida albicans and determine their time-dependent effects on heat-polymerised polymethyl methacrylate (PMMA) surface roughness and topography. Methods: Antifungal activity against Candida albicans was assessed using broth microdilution to determine the minimum inhibitory concentration and minimum fungicidal concentration. A peroxide-based denture cleanser (PDC) served as the commercial reference. PMMA specimens were allocated to PDC, M-EEP, P-EEP or distilled water (n = 7). Arithmetic mean roughness (Ra) and root mean square roughness (Rq) were measured at baseline, 7, 14, 28 and 90 days using atomic force microscopy. Surface topography was evaluated qualitatively, and longitudinal data were analysed using generalised estimating equations. Results: Both EEP formulations inhibited visible fungal growth when tested as prepared and prevented colony recovery after subculture, demonstrating fungicidal activity. Significant time and medium x time effects were observed for Ra and Rq (p < 0.05). M-EEP showed no significant within-group roughness change, whereas P-EEP and PDC showed early reductions that were not sustained by day 90. No medium produced progressive roughening, and all Ra values remained below the commonly cited 0.2 µm plaque-retentive threshold. Conclusions: Six-month-fermented EEP formulations demonstrated antifungal activity against planktonic Candida albicans ATCC 10231 without progressive increases in mean PMMA surface roughness, thereby addressing both biological efficacy and material compatibility within the same experimental framework.