Effect of functionalized titanium dioxide nanotubes on the bond strength, hardness, and antifungal properties of an interim soft denture liner.

STATEMENT OF PROBLEM: The adhesive bonding of interim soft denture liners to acrylic resin denture bases may be limited, with progressive changes in hardness over time and susceptibility to microbial colonization, potentially compromising clinical performance.

PURPOSE: The purpose of this in vitro study was to evaluate the effects of incorporating functionalized and nonfunctionalized TiO₂ nanotubes into an interim soft denture liner on the tensile bond strength (TBS), Shore A hardness (SAH), and antifungal behavior against Candida albicans.

MATERIAL AND

METHODS

TiO₂ nanotubes were synthesized, functionalized with methacrylic acid, and incorporated into a tissue conditioner (Viscogel; Dentsply Sirona) at 1 wt%. Three groups were prepared: control (no nanotubes), nonfunctionalized TiO₂ (nTiO₂), and functionalized TiO₂ (nTiO₂-MA). The TBS was evaluated according to the International Organization for Standardization (ISO) 10139-2:2016 standard using acrylic resin specimens (n=10/group). SAH was measured at 2 hours, 1 day, 3 days, and 7 days following the ISO 10139-1:2018 standard. Antifungal activity against C albicans ATCC 10231 was assessed qualitatively on separately prepared disk specimens. Statistical analysis was performed using 1-way ANOVA for TBS data and 2-way repeated-measures ANOVA for SAH data (α=.05), with additional robust analyses performed when required.

RESULTS

The nTiO₂-MA group showed significantly higher TBS values than the control group (P=.008), while nonfunctionalized nanotubes showed no significant effect (P=.251). All groups exhibited a significant increase in SAH values over time (P<.001), with no significant differences between groups (P=.247). A significant Time × Group interaction (P=.001) indicated differences in hardness progression. No measurable inhibitory antifungal effect against C albicans was observed for the disk-based formulations.

CONCLUSIONS

Functionalized TiO₂ nanotubes improved TBS without adversely affecting short-term hardness. However, no inhibitory antifungal effect was demonstrated under the experimental conditions.