Effect of Reinforcement of High-Impact Acrylic Resin With Zirconia on Some Physical and Mechanical Properties

OBJECTIVES: To evaluate the effect of reinforcing high-impact acrylic resin (Metrocryl HI)with zirconia powder in two different concentrations on the transverse strength, impact strength,surface hardness, water sorption and solubility. MATERIALS AND METHODS: Fifteenspecimens were prepared for each test, five from Metrocryl HI resin as control, five others wereprepared from the 5% zirconia-modified Metrocryl HI resin, and another five specimens wereprepared from the 15% zirconia-modified Metrocryl HI resin. Transverse strength was assessedwith a 3-point bending test using a screw-driven testing machine. For the impact strength, a Charpytester was used. Surface hardness testing was conducted using Vickers tester. The water sorptionand solubility test was performed according to International Standards Organization specificationNo. 1567 for denture base polymers. Micro-structural examination of two specimens, onerepresenting each ZrO2 concentration group, was carried out using scanning electron microscopy.RESULTS: As determined by ANOVA and Bonferroni multiple comparison tests, the additionof zirconia resulted in a highly significant increase in transverse strength of high-impact acrylicresin (P 0.05). Although a significant increase in water sorption was demonstrated (P< 0.05), still its meanvalue lies within the specification limits. CONCLUSIONS: Reinforcement of high-impact acrylicresin with zirconia powder increases its transverse strength significantly.