Assessment of Flexural Strength and Cytotoxicity of Heat Cure Denture Base Resin Modified with Titanium Dioxide Nanoparticles: An In Vitro Study

Abstract

To assess the effect of titanium dioxide nanoparticles (NPs) on flexural strength and cytotoxicity of heat-cured polymethyl methacrylate (PMMA) resins. Sixty-four rectangular and 12 circular specimens were fabricated from metal dies to test flexural strength and cytotoxicity, respectively. The rectangular specimens were grouped into four (16 specimens each)-control group (Group 1), Group 2 with 3% TiO2, Group 3 with 5% TiO2, and Group 4 with 7% TiO2. They were tested for flexural strength using universal testing machine. The circular specimens were grouped into two (six specimens each)-control group and the test group which included the group which showed a highest flexural strength. They were tested for cytotoxicity using MTT assay. The analysis of variance (ANOVA) test was used to analyze the mean flexural strength of each group and Tukey's post hoc test, for pairwise group comparison (p <0.05). An independent sample t-test was used to analyze the cytotoxicity between the groups (p <0.05). The study showed that there was a significant decrease in the flexural strength from the control group (mean: 298.95), which reduced as the concentration of TiO2 increased. However, the toxicity reduced considerably from 24 hours to 7 days in both groups while the test group showed better cell viability (%) than the control group. The flexural strength of heat cure acrylic resin (modified and unmodified) was much higher than the recommended flexural strength for these resins. On adding TiO2 NPs, flexural strength decreased when compared to the control group. However, with 3% TiO2 NPs, there was no significant decrease in flexural strength as compared to conventional resins. TiO2 NP-modified heat cure acrylic resin showed less toxicity on day 1 and even lesser toxicity after 7 days indicating that it is biocompatible. TiO2 NPs incorporated at 3% concentration in denture base resin had less cytotoxicity and adequate flexural strength, to be used as a promising alternative to conventional denture base resin.