Dental composites reinforced with hydroxyapatite: Mechanical behavior and absorption/elution characteristics

The purpose of this study was to analyze the behavior in water as well as t he mechanical and surface properties of experimental composites designed fo r dental restoration. Studied materials were composed of a visible-light-cu red monomer mixture as a matrix (bisphenol-alpha -glycidyl methacrylate wit h triethyleneglycol dimethacrylate or hydroxyethyl methacrylate) and either micrometric or nanometric hydroxyapatite (HA) particles as a reinforcing f iller. The surface of the filler particles was modified by using different coupling agents (citric, hydroxysuccinic, acrylic, or methacrylic acid). Th e hydrolytic stability of the evaluated materials was studied through eluti on-in-water and water-uptake tests. Mechanical and surface properties were examined through the results of flexural, hardness, and surface roughness t ests. Means and standard deviations were calculated for each variable. Anal ysis of variance and multiple comparison tests were performed. Materials co ntaining bisphenol-alpha -glycidyl methacrylate: triethyleneglycol dimethac rylate and micrometric-HA coated with citrate, acrylate, or methacrylate di splayed the most favorable results. Improvements should be obtained by incr easing the total filler amount, and by the introduction of nanometric-HA fi ller into a micrometric-HA reinforced composite resin system. (C) 2001 John Wiley & Sons, Inc. J Biomed Mater Res 56: 297-305, 2001.