Comparative Evaluation of the Antimicrobial Property of Nano Titanium Dioxide and Nano Titanium Dioxide Infused with Punica granatum in Heat-polymerised Denture Base Resin: An in vitro Study

Abstract

Background: Edentulism remains a major global public-health burden, commonly rehabilitated using heat-polymerised polymethyl methacrylate (PMMA) complete dentures. Microbial colonisation of the porous PMMA surface predisposes to denture stomatitis, and incorporating inorganic nanoparticles together with organic phytotherapeutic agents represents a contemporary strategy for engineering antimicrobial denture-base biomaterials. Objectives: To fabricate and comparatively evaluate the antimicrobial efficacy of heat-polymerised PMMA modified with nano titanium dioxide (TiO2) alone and with nano-TiO2 infused with Punica granatum (pomegranate) peel extract against Streptococcus mutans. Materials and Methods: Twenty standardised disc specimens (10 × 2 mm, ISO 1567) were divided into two groups (n = 10 per group): Group A, PMMA reinforced with 1.5 wt% nano TiO2; and Group B, PMMA reinforced with 1.5 wt% nano TiO2 infused with 20% Punica granatum extract. Antimicrobial performance was assessed by the zone-of-inhibition assay on blood agar inoculated with S. mutans following a 7-day aerobic incubation at 37 °C. Data were analysed with IBM SPSS using the Shapiro-Wilk test, Levene's test, and an independent-samples t-test (p < 0.05). Results: Group B exhibited a significantly larger net zone of inhibition (mean 7.19 +/- 0.82 mm) than Group A (mean 2.38 +/- 0.55 mm). The independent-samples t-test confirmed a highly significant difference (t = -15.52, df = 18, p < 0.0001). Conclusion: The addition of Punica granatum peel extract markedly enhanced the antimicrobial performance of nano-TiO2-modified heat-cured PMMA, indicating the potential of this light-independent antimicrobial modification for denture-base resin. As this in vitro study did not include an unmodified PMMA control or a Punica granatum-only group, true synergy between the two agents cannot be confirmed from the present data, and this preliminary finding should be interpreted with appropriate caution.