Influence of activated bentonite nanoclay/TiO2 on antibiofilm and mechanical properties of PMMA denture base nanocomposite

Abstract

Objectives . This study aimed to evaluate the effects of bentonite nanoclay (B) and titanium-activated bentonite nanocomposite (BT) on reducing Candida albicans adherence to heat-polymerized acrylic denture base resin and to assess the mechanical properties of the modified acrylic, focusing on surface hardness and flexural strength. Methods . A total of 182 heat-polymerized acrylic resin specimens were fabricated, including a control group and 12 study groups (n = 7). The study groups incorporated bentonite nanoclay (B) or titanium-bentonite nanocomposite (BT) at six concentrations: 0.5, 1, 1.5, 2, 2.5, and 3 wt%. Antibiofilm activity was evaluated using a crystal violet (CV) staining assay. Flexural strength and surface hardness were measured via a three-point bending and Shore D microhardness test. Nanocomposite characterization was performed using XRD, FTIR, SEM, EDS analysis, and (AFM). Antibiofilm data were analyzed using the Kruskal–Wallis test and mechanical data with one-way ANOVA ( α = 0.05). Results . All groups exhibited significantly better antibiofilm activity than the control (4.07 ± 0.11), with BT 1.5% (1.41 ± 0.27) and B 1.5% (1.81 ± 0.40) being the most effective. Flexural strength was significantly lower in all groups compared to the control (90.57 ± 3.78), decreasing with increased B and BT concentrations, but remained above the minimum 65 MPa for denture bases. BT samples at 2.5% and 3% showed non-significant improvements in hardness compared with the control. Conclusions . At 1.5%, bentonite significantly enhanced antibiofilm activity without greatly reducing hardness, whereas Ti-bentonite offered superior performance in both antifungal and mechanical properties, making it a promising material for denture bases. Clinical significance . Incorporating Ti-bentonite nanocomposites into acrylic denture bases may reduce Candida albicans. adhesion while preserving adequate mechanical properties. This reduction in fungal colonization on the denture surface can potentially enhance denture hygiene, prevent oral inflammation, and reduce the risk of denture-related infections such as candidiasis and denture stomatitis.

Keywords

• bentonite nanoclay
• Ti-bentonite nanocomposite
• PMMA
• antibiofilm
• crystal violet staining assay