CRYSTALLITE ARRANGEMENT OF HYDROXYAPATITE MICROCRYSTALS IN HUMAN TOOTH CEMENTUM AS REVEALED BY ELECTRON-PARAMAGNETIC-RESONANCE (EPR)

Human dental cementum was analyzed by electron paramagnetic resonance (EPR). The measured EPR powder spectra of gamma-irradiated cementum re sembled those of gamma-irradiated enamel. Both spectra were characteri zed by the same line shapes and g values. The position of the extreme first derivate peaks can be described by g(1) = 2.0023 and g(2) = 1.99 71 +/- 0.0002, and are assignable to the CO33--center. The angular dep endence of the cementum EPR spectra indicates a different arrangement of the hydroxyapatite microcrystals compared to that of enamel. A corr esponding model of cementum microcrystal alignment has been proposed. The methodology presented can be utilized for studying the mineralizat ion process of root cementum and other mineralized tissues.