Comparative Effect of Glass Fiber and Nano-Filler Addition on Denture Repair Strength

Purpose: To evaluate and compare the effects of glass fiber (GF), Zirconium oxide nanoparticles (nano-ZrO₂), and silicon dioxide nanoparticles (nano-SiO₂) addition on the flexural strength and impact strength of repaired denture base material. Materials and Methods: Heat-polymerized acrylic resin specimens were fabricated. All specimens were sectioned centrally and beveled creating 2.5 mm repair gap except for 10 controls. Specimen grouping (n = 10/group) was done according to filler concentration of 0%, 0.25%, 0.5%, and 0.75% of auto-polymerized acrylic powder. Modified resin was mixed, packed in the repair gap, polymerized, finished and polished. Three-point bending test and Charpy type impact testing were done. Data were analyzed using one-way-ANOVA and Post-Hoc Tukey test (α = 0.05). Results: All additives significantly increased flexural strength and impact strength (p < 0.05). Within the modified subgroups, no significant differences were found for GF. Significant increase for nano-ZrO₂ and significant decrease for nano-SiO₂ as the concentration of additive increased were noted for both flexural strength and impact strength. Highest flexural strength was found with 0.75%-nano-ZrO₂ (69.59 ± 2.52MPa) and the lowest was found with 0.75%-nano-SiO₂ (53.82 ± 3.10MPa). The 0.25%-nano-SiO₂ showed the highest impact strength value (2.54 ± 0.21 kJ/m²) while the lowest impact strength value was seen with 0.75%-nano-SiO₂ (1.54 ± 0.17 kJ/m²). Conclusion: Nano-filler effect was concentration dependent and its addition to repair resin increased the flexural and impact strengths. The incorporation of 0.75%-ZrO₂ or 0.25%-SiO₂ into repair resin proved to be a promising technique to enhance repair strength and avoid repeated fractures.