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 γ‐irradiated cementum resembled those of γ‐irradiated enamel. Both spectra were characterized by the same line shapes and g values. The position of the extreme first derivate peaks can be described by g1 =2.0023 and g2= 1.9971 ± 0.0002, and are assignable to the CO33− center. The angular dependence of the cementum EPR spectra indicates a different arrangement of the hydroxyapatite microcrystals compared to that of enamel. A corresponding model of cementum microcrystal alignment has been proposed. The methodology presented can be utilized for studying the mineralization process of root cementum and other mineralized tissues.