Mechanical and antimicrobial properties of hard denture relining material with surface pre-reacted glass-ionomer filler

PURPOSE: We evaluated the effects of the particle size and content of surface pre-reacted glass-ionomer (S-PRG) filler on the mechanical properties and antimicrobial efficacy of a hard denture relining material. METHODS: S-PRG microfiller (0.8-1 μm; 5, 10, and 20 wt%) and nanofiller (0.3-0.5 μm; 2.5, 5, and 10 wt%) were incorporated into a Shofu denture liner. The control group did not contain S-PRG fillers. The surface morphology (scanning electron microscopy), roughness (confocal scanning laser microscopy; Shapiro-Wilk's test followed by Dunnett or Steel's test), ion release after 24 h immersion in ultrapure water (fluoride, aluminum, borate, sodium, silicate, strontium ions; Shapiro-Wilk's test followed by one-way ANOVA with Tukey's test or Kruskal-Wallis and Dunn's tests), three-point flexural strength (Weibull analysis), shear bond strength after 24 h water immersion or 10,000 thermal cycles (linear mixed-effects model), and antimicrobial activity against Candida albicans (confocal microscopy, Shapiro-Wilk's test followed by Dunnett's or Steel's test) were analyzed and compared. The significance level was set at α = 0.05. RESULTS: Although a higher S-PRG filler content reduced the flexural and bond strengths, it increased the surface roughness and ion release. Groups treated with 10 wt% nanofiller or 20 wt% microfiller displayed significantly inhibited C. albicans adhesion. The nanofiller-containing groups maintained flexural strength comparable to that of the control. CONCLUSIONS: The incorporation of 10 wt% S-PRG nanofiller provided the best balance between antimicrobial efficacy and mechanical performance, indicating that this formulation may be clinically acceptable for use in hard denture relining materials.