Gamma dose response of synthetic A-type carbonated apatite in comparison with the response of tooth enamel

Synthetic A-type carbonated apatite samples were irradiated at room tempera ture with Co-60 gamma rays. Their ESR spectra consist of the lines of CO2- and CO3- radicals of orthorhombic and axial symmetry. The measurements carr ied out immediately after sample irradiation showed that CO2- species are p roduced by decomposition of CO3- radicals. Intensity of the CO2- lines in t he synthetic and enamel samples increases during the first 400 and 200 h af ter irradiation, respectively. The dependence of the EPR signal on the dose varies with carbonate content of the sample. The dose response curve for t ooth enamel is steeper for the synthetic material. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.