Effect of silanized silica, calciumhydroxyapatite and modified clay on strength and hardness of dental composites/nanocomposites

Abstract

The ultimate aim of this work was to enhance the mechanical strength of dental resin by monomer intercalation into clay galleries to obtain dental nanocomposites. However, to obtain suitable hardness and compatibility to human bone tissue, silane treated silica and calciumhydroxyapatite (CHA) were also employed. The optimum contents of silanized silica and CHA were 60 and 15% wt, respectively. Diametral Tensile Strength (DTS) of CHA filled dentalc composites show higher value than those of silanized even at lower content. From SEM micrographs of fracture surfaces of CHA filld dental composites, plastic deformation was found on the resin matrix and inside of the filler holes. In the other words, CHA-filler have better adhesion than silanized silica. The acrylate polymer-octadecyltrimethylamine modified clay exfoliated nanocomposites at 1 %wt was obtained showing strong reinforcement and large expansion of silicate layer distance evidenced by X-ray diffraction. With increasing clay content, DTS was reduced corresponding to lowering layer distance to bring about intercalated type nanocomposites.