Separation of the contributions from gamma- and UV-radiation to the EPR spectra of tooth enamel plates.

Anisotropy of EPR spectra of tooth enamel plates irradiated with gamma-rays and UV light has been studied. UV-irradiated enamel plates exhibit a stronger anisotropy than gamma-irradiated plates. Investigation of samples cut out of different teeth and irradiated to different doses showed that the value of anisotropy is characteristic of each type of irradiation; it equals to approximately 0.35 for gamma- rays and 0.50 for UV light. It is suggested that the difference in the anisotropy values can be attributed to different relative amounts of oriented and disordered radicals produced by the two types of radiation. This can be used for separating gamma- and UV-contributions to the total EPR signal of a tooth exposed to both types of radiation.