Antifungal Efficacy and Surface Properties of Conventional and 3D-Printed Denture Base Materials Modified with Titanium Tetrafluoride (TiF4): In Vitro Study

Background: Candida albicans adhesion to denture base materials is a primary contributor to denture stomatitis. To address this issue, numerous studies have explored the incorporation of various additives into denture base resins to enhance their antifungal properties. Titanium tetrafluoride (TiF4) is an inorganic fluoride compound that has proven antimicrobial properties but has not yet been tested with denture materials. This study aimed to evaluate the effect of TiF4 addition into different denture base materials on antifungal activity, surface roughness, hardness, and color properties. Methodology: A total of 200 disc-shaped specimens were prepared-100 heat-polymerized acrylic resins and 100 3D-printed NextDent resins. Four different concentrations of TiF4 were incorporated: 1 wt%, 2 wt%, 3 wt%, and 4 wt% for both resins, while one group of each resin remained unmodified as a control. All specimens were subjected to thermal cycling for 5000 cycles, and four tests were conducted: Candida albicans adherence, surface roughness, hardness, and color change. A scanning electron microscope (SEM) was used to prove Candida albicans colonies' adhesion on the specimens' surfaces, and Fourier-transformed infrared (FTIR) analysis was performed to show the presence of TiF4 in the resin material; data were analyzed using one-way ANOVA followed by a post hoc test (alpha = 0.05). Results: TiF4 significantly reduced the Candida albicans adhesion to heat-polymerized specimens (p < 0.001). Compared to the control group, the incorporation of TiF4 resulted in a substantial reduction in C. albicans colony counts, with reductions of approximately 97.6% in 1HP, 97.2% in 2HP, 97.4% in 3HP, and complete inhibition (100%) in 4HP. However, there was no significant difference between the 3D-printed ones (p = 0.913). Surface roughness, hardness, and color change of heat-polymerized groups were not significantly affected by TiF4 (p > 0.05) except the color of the group treated with 4% (p < 0.05). For the 3D-printed groups, no significant differences were detected between the groups regarding candida count, hardness was significantly increased at 2% TiF4 compared to the control (p = 0.002), and roughness was least with 4% TiF4, while the color varied significantly between the groups (p < 0.001). Conclusions: TiF4 addition decreased Candida albicans adhesion to heat-polymerized denture base materials but showed no antifungal effect on the 3D-printed resin. While roughness remained low in 3D-printed groups at higher concentrations. Hardness was not significantly altered in the heat-polymerized resin, whereas it increased significantly in the modified 3D-printed resin. Color stability was compromised at higher TiF4 concentrations, particularly in the 3D-printed groups. The type of denture base material and TiF4 concentration both influenced antifungal activity and denture surface properties.