The effects of UV-irradiation on ESR-dosimetry of tooth enamel

Tooth enamel has been shown to be an excellent dosimeter material for retro spective dosimetry. A complication is that it is sensitive to ultraviolet l ight (UV), creating a signal that interferes with the dosimetric signal. Ir radiation of tooth enamel by UV-light induces a mixture of stable and unsta ble free radicals. The unstable radicals disappear in about three weeks. St able radicals are created both at the dosimetric peak and at the same g-val ue as the native peak. The stable peak coinciding with the native peak show s saturation behavior both for UVA/B- and UVC-light. The signal intensity f rom the sun is roughly estimated to induce a signal comparable to 15 mGy/h from 60 kV Xrays. The blue lamps used by dentists when hardening plastic re pairs contain a narrow tail in the UVA/B-region, and it is shown here that these lamps also contribute to the stable peak coincident with the native p eak. The contribution to the dosimetry peak, though negligible, at least fo r the irradiation times is used in this work. Most of the problems with UVA /B-induced signal contributions can probably be avoided by not using front teeth and teeth close to plastic repairs. (C) 2000 Elsevier Science Ltd. Al l rights reserved.