Evidence of annealing-induced transformation of CO2- radicals in irradiated tooth enamel

Results of EPR study on the series of γγ-irradiated and thermally treated tooth enamel plates are presented and discussed. The analysis of EPR lineshape variation shows that the thermal annealing causes the transformation of orthorhombic CO2- radicals into axial ones. Possible models of this transformation are discussed in details. Conclusion is made that the most plausible explanation of the radicals transformation can obtained under condition that both types of CO2- radicals are located in identical structural positions, namely in a position B (substitution of phosphorus by carbon).