engleski

Study of radiation induced radicals in HAP and β-TCP based bone graft materials by EPR spectroscopy

Calcium phosphates such as beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HAP) are frequently used as dental implants due to proven excellent biocompatibility. Because of their resorption in the body and direct contact with tissues, in order to inactivate bacteria, fungal spores and viruses, they are usually sterilized by γ-irradiation. However, literature provides little information about effects of γ-irradiation on the formation and stability of the free radicals in the bone graft materials during and after sterilization procedure. In this study EPR (electron paramagnetic resonance) spectroscopy was used to investigate HAP and -TCP based dental implants present on the market. Eight dental graft materials present on the market were investigated: Bioresorb® Macropore, Poresorb®-TCP, Easy-Graft™ and Cerasorb® synthetic β-tricalcium phosphates, Easy-Graft™ crystal and Ossceram® two phase synthetic CaP consisting of 60% HAP and 40% β-TCP, and Dexabone® and Bio-Oss® bone graft material of bovine origin. EPR study show that this is the only technique for characterization of free radicals with can simultaneously determine not only the presence and content, but also the position and the structure of free radicals formed by γ-sterilization in the investigated materials, as well as the paramagnetic substitutions incorporated in the materials during the synthesis (such as Mn2+, Fe3+ or Cr2+). Additionally, EPR provides information on stability of irradiation-induced radicals ( , trapped H-atoms, etc.) and processes for reducing them. Results show that EPR should be considered as a valuable technique in improving the quality of bone graft materials, which must be sterile, and to offer the high quality, efficacy and reliable materials to the patients.

dental implants; EPR; radicals; biocompatibility

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