Bioactive scaffolds mimicking natural dentin structure

Abstract

Organic scaffolds of poly(ethyl methacrylate-co-hydroxyethyl acrylate) [P(EMA-co-HEA)] 70/30 wt % ratio, with varying proportions of silica SiO(2) from 0 to 20 wt % and aligned tubular pores, were prepared using a fiber-templating fabrication method, with the aim of mimicking structure and properties of the mineralized tissue of natural dentin. Precursors of the copolymer and silica were simultaneously polymerized in a sol-gel process within the fiber template, which was eventually eliminated to generate homogeneously distributed parallel micrometer-sized pores in the material. Scaffolds of PEMA and PHEA were obtained by the same approach. The scaffolds were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and thermogravimetric analysis. The specific volume was determined by Archimedes' method and the porosity calculated from the geometry. The mechanical properties were analyzed in tensile and compressive modes. The bioactivity of the scaffolds with 15 wt % SiO(2) was tested by immersion in simulated body fluid (SBF) for 7 days followed by immersion in 2x SBF for 7 days. These scaffolds were afterwards characterized by SEM, energy dispersive spectroscopy, and compression assays. Percentages of silica above 10 wt % reinforced mechanically the copolymer, evidenced by the hindrance of the long range motions of the organic chains, altered shrinkage and swelling, and meanwhile conferred bioactivity to its surface. These tubular porous structures, which resemble natural dentin with regard to its structure and properties and induce the precipitation of apatite on their surfaces in vitro, are expected to facilitate the integration in the host mineralized tissue, to stimulate cell growth and to be useful as guiding scaffolds for in vivo dentin regeneration.