Comparative evaluation of flexural strength of heat polymerized polymethyl methacrylate (PMMA) denture base material reinforced with different percentages of silanized zirconium silicate nanoparticles – An in vitro study

Abstract

PMMA has been the material most frequently utilized to create complete dentures. Due to its biocompatibility, stability in the oral environment, favourable operating properties, processing ease, it has become the material of choice. However, it is still far from ideal in terms of meeting the mechanical criteria of the denture base material due to some limitations such weak mechanical strength, low fatigue strength, brittleness, etc. Zirconia has a physical characteristic called as transformation toughening, which accounts for its high flexural strength and fracture toughness. Zirconia's biocompatibility has also been thoroughly investigated. Inorganic nanoparticles being added to PMMA to enhance its characteristics has received a lot of interest.To evaluate and compare the flexural strength of heat polymerized polymethyl methacrylate (PMMA) denture base material reinforced with different percentages of silanized zirconium silicate nanoparticles.Metal dies were fabricated to prepare moulds for the fabrication of heat polymerized PMMA denture base material specimens. Three brass metal dies of dimension 65 mm in length, 10 mm in width, and 3 mm in height (65×10×3) were fabricated. These specimens were reinforced with different percentages of silanized zirconium silicate nanoparticles. The polymerized specimens were carefully removed and specimens with defects were discarded. Finishing of the specimens was done using sandpaper and the finished specimens were stored in distilled water for 1 week at room temperature.When flexural strength was compared between Group 1 (control) and Group 2 (1.5%) (silanized zirconium silicate nanoparticle) (p = 0.004), there was a significant statistical difference (p <0.05). Additionally, Group 2 (1.5% silanized zirconium silicate nanoparticle) and Group 6 (4% silanized zirconium silicate nanoparticle) showed a statistically significant difference (p <0.05) (p = 0.029). However, there was no discernible statistically significant difference (p >0.05) between the remaining Groups.Specimens with reinforcement increased the flexural strength. Reinforcement with 1.5% of silanized zirconium silicate nanoparticles showed statistically significant increase in flexural strength.