Morihiro Yasuda

Susceptibility of calcium-deficient hydroxyapatite-collagen composite to irradiation

Abstract We investigated the susceptibility of a human tooth and synthetic calcium-deficient hydroxyapatite compounds to irradiation. The ESR signal intensities at nearly g =2 in a human tooth (enamel, dentine) and synthetic calcium-deficient hydroxyapatite compounds, i.e., calcium-deficient hydroxyapatite (DAp), DAp-collagen composites (cp-Dap, cu-DAp), and stoichiometric hydroxyapatite (HAp) after X-ray irradiation were proportional to the absorbed dose in the range from 6 to 39 Gy. These ESR signal intensities at nearly g =2 decreased when the X-ray irradiated samples were soaked in the simulated body fluid. This fact suggests that the surface layer contained a high density of ESR active species in all samples dissolved in the simulated body fluid. Furthermore, the fading of these ESR signal intensities was observed in all of the samples. Regarding the dosimeter utilizing such biomaterials as a tooth, care must be sufficiently given to the storage conditions of the irradiated samples, especially for exact evaluation in the low-dose region.