Evaluation of Water Sorption of Various Heat-Curing Acrylic Resins and the Effect of Aqueous Environment on its Fracture Toughness

Abstract

Background: Water sorption is one of the concern regarding acrylic resin denture base materials since it might affect the dimensional stability of the prosthesis, furthermore the absorbed water may dramatically compromise the physical and mechanical properties. Methods: Three different commercial denture base materials (heat-curing acrylic resin) available in local markets were used (Vertex, Ivoclarw and Luxacryl) to evaluate water sorption and the effect of dry and wet environment on the fracture toughness of these materi-als. Water sorption test was carried out according to international organization for standardization (ISO) Specification 1567-2000. The fracture toughness was determined using single edge notch bending test (SEN-B) according to ISO 13586:2000. Results: Water sorption in term of percentage was highest for Ivoclar (0.78% of its weight) and lowest for Luxacryl (0.68% of its weight). Statistical analysis with two-way Analysis of Variance (ANOVA) test showed a significant difference between different acrylic material groups, and be-tween different water immersion times (p<0.0001). For fracture toughness, it has been found that the Ivoclar samples displayed the highest fracture toughness after 28 days of immersion in distilled water at room tem-perature. Statistical analysis with two-way ANOVA test showed a significant difference for fracture toughness between different acrylic material groups (P<0.04). Conclusion: in general, fracture toughness of denture base materials was highly-changed after immersion in water.