Electron spin resonance characterization of human tooth enamel response to proton, neutron, and ultraviolet radiation

Janine Faith Katanic, Purdue University

Abstract

In this research, Continuous Wave (CW) Electron Spin Resonance (ESR) techniques and advanced pulsed ESR techniques were used to examine the response of human tooth enamel to different types of radiation and to investigate the characteristics of the radiation-induced free radicals created in tooth enamel. An examination of the response of tooth enamel to proton, neutron, and ultraviolet (UV) radiation was conducted using CW-ESR techniques. Pulsed ESR methodologies were used to examine the spatial properties of free radicals created in tooth enamel irradiated by gamma, proton, and UV radiation. The CW-ESR determined dose response of tooth enamel irradiated by 2.0 MeV protons indicated a linear dose response until approximately 2,000 Gy after which the dose response appeared to plateau. No conclusive CW-ESR determined dose response was detected for tooth enamel irradiated with either 1.02 MeV neutrons or 14.0 MeV neutrons. An examination of the relationship between tooth position in the mouth and the CW-ESR signal produced by UV radiation from sunlight indicated that front teeth should be avoided and that it is important to take tooth type, and therefore position in the mouth, into account when tooth enamel is used for radiation biodosimetry. A well-defined UV source was used to irradiate tooth enamel in order to conduct an examination of the CW-ESR signal produced. Tooth enamel irradiated by several different UV wavelengths, power levels, and total energies emitted indicated a CW-ESR signal intensity dependence on total dose, dose rate, and UV wavelength. Pulsed ESR methodologies indicated that the numbers of free radicals per cluster, the cluster radii, and the local concentrations of radicals were clearly different for gamma, proton, and UV-irradiated tooth enamel even though the predominant radical species trapped in each case was CO2−. These results indicated that pulsed ESR techniques are capable of providing information that could be used to help identify the type of radiation to which tooth enamel has been exposed.

Degree

Ph.D.

Advisors

Zimbrick, Purdue University.

Subject Area

Radiation|Biophysics

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