Evaluation of Flexural Strength of Heat Cure PMMA Denture Base Material Reinforced with Various Concentrations of Zirconium Oxide Nanoparticle: An In-vitro Study

Abstract

Objective: The aim of this study was to investigate the effect of zirconium oxide (ZrO2) nanoparticle dispersion on the flexural property of heat-cure polymethylmethacrylate denture base material. 
 Methods: Eighty specimens were divided into 10 groups of eight specimens; Group 1 unreinforced acrylic, group 2: treated with ethanol alcohol, Groups 3,4,5 and 6 reinforced acrylic specimens with 1, 3, 5, and 7 wt% of untreated zirconium oxide nanoparticle (u- ZrO2) and Groups 7,8,9 and 10 reinforced acrylic specimens with treated and sonicated zirconium oxide nanoparticle in ethanol alcohol (t-ZrO2). X-ray diffraction test (XRD) was used to study the dispersion quality of the tested specimens, and universal testing machine was used to evaluate flexural strength and flexural modulus. SPSS software program used to compare groups results statistically.
 Results: The results revealed significant decrease in flexural strength with u-ZrO2 nanoparticle addition in different concentration groups (p<0.05), while with t-ZrO2 nanoparticle addition, above 3 wt% statistically significant decrease was noted as compared to the conventional group. However, the flexural modulus increased with increasing the both of u-ZrO2 and t-ZrO2 nanoparticles addition. XRD results showed better dispersion quality of the t-ZrO2 than u-ZrO2 throughout the acrylic resin denture base material.
 Conclusions: Flexural strength decreased inversely with increasing u-ZrO2 concentration, while it decreases significantly above 3 wt% of t-ZrO2 nanoparticle concentration. The flexural modulus increased with increasing both of u-ZrO2 and t-ZrO2 nanoparticles. Reduced nanoparticle’s cluster size of t-ZrO2 allows more nanofiller to be incorporated to denture base materials with less adverse effect on the mechanical properties.