Chemical and mechanical properties of experimental dental composites as a function of formulation and postcuring thermal treatment

Abstract

This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elasticmodulus of experimental composites. Six composites were analyzed at BisGMA: TEGDMAmolar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70wt%.The degree of conversionwas analyzed by Fourier transforminfrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170∘C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey’s test (𝛼 = 5%).The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties.The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA: TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.