IADR Abstract Archives

EPR Properties of Carbonated Hydroxyapatite Synthesized through Calcium Phosphate Cements

Objectives: To investigate the reproducibility and stability of radiation-induced Electron Paramagnetic Resonance (EPR) properties of carbonated hydroxyapatite (CHA) cements and assess the feasibility of using these materials as EPR calibration references and, potentially, as dosimeters.
Methods: CHA discs (3.5 mm D × 3 mm H) were prepared by mixing a cement powder (tetracalcium phosphate, dicalcium phosphate anhydrous, and sodium bicarbonate) with a cement liquid (0.5 mol/L disodium hydrogen phosphate) at a powder-to-liquid ratio of 5:2. The hardened discs were analyzed for phase composition (X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR)) and for carbonate and sodium contents. The CHA discs were gamma-ray irradiated at doses in the range of 10-3-102 kGy. The EPR spectra of the irradiated discs were collected on a Bruker ELEXSYS E500 EPR spectrometer.
Results: XRD results showed that all samples consisted only of a low-crystalline apatite. The discs contained 0.92% sodium and 1.86% carbonate. FTIR analyses revealed two peaks at 1415 cm-1 and 1454 cm-1, indicating that B-type CHA was formed in all cases. EPR spectra showed characteristic axial peaks of CO-2 free radicals (g=1.9976, g=2.0030). Peak-to-peak intensities of CHA discs that received 10 kGy irradiation were highly reproducible (37.80±0.89; n=3) and indicated the identical and homogeneous composition of all specimens. Peak-to-peak intensities immediately after irradiation and at various time points post-irradiation were not statistically different (p>0.05), indicating no detectable deterioration of the signals following irradiation. The CHA exhibited EPR signals proportional to the irradiation dose.
Conclusions: Irradiated CHA cement samples exhibited distinct, reproducible and stable EPR signals. These materials have the potential for use as EPR calibration references and as bio-dosimeters.
IADR/AADR/CADR General Session
2020 IADR/AADR/CADR General Session (Washington, D.C., USA)
Washington, D.C., USA
2020
0863
  • Karim, Eaman  ( American Dental Association Foundation , Gaithersburg , Maryland , United States )
  • Cumberland, Lonnie  ( National Institutes of Standards and Technology , Gaithersburg , Maryland , United States )
  • Takagi, Shozo  ( American Dental Association Foundation , Gaithersburg , Maryland , United States )
  • Frukhtbeyn, Stanislav  ( American Dental Association Foundation , Gaithersburg , Maryland , United States )
  • Pazos, Ileana  ( National Institutes of Standards and Technology , Gaithersburg , Maryland , United States )
  • Chow, Laurence  ( American Dental Association Foundation , Gaithersburg , Maryland , United States )
  • American Dental Association (ADA), American Dental Association Foundation (ADAF), and National Institute of Standards and Technology (NIST)
    NONE.
    Poster Session
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