Gamma Irradiation Studies I. Dental Grafts

Abstract

The development of nanoceramics-polymer composites and bioactive materials such as calcium phosphates and bioglasses and ceramics especially hydroxyapatite (HAp) and β-tricalcium phosphate (TCP) for bone regeneration has been carried out for bone regeneration. Due to their resorption in the body and direct contact with tissues, it is necessary to sterilize the dental graft before administration to the patient. Three different dental graft materials including TCP, bioglass, and equine bone tissue (G1, G2, and G3, respectively) were studied in this study. The effects of γ irradiation were evaluated with different analytical methods (organoleptic analysis, FTIR, DSC, TGA, and SEM) and microbiological analysis (sterility, pyrogenity, and sterility assurance level (SAL) determination). The physicochemical results indicated that G1 is the most γ stable (optimum) dental graft material for γ radiation sterilization with minimum changes in chemical and physical properties in comparison with other two dental graft materials. G3, was the most sensitive dental graft material according to organoleptic investigations, TGA and SEM analysis. Another aspect of this study was, to investigate the effect of ethylene oxide (EtO) sterilization on optimum dental graft material, G1 and the comparison of two sterilization methods with analytical and microbiological examinations. The resorption times and resorption characteristics of γ sterilized dental graft material (G1G) and EtO sterilized one (G1E) were evaluated on New Zealand rabbits for 12 weeks. Histological studies showed that TCP containing dental graft material, G1, did not induce inflammation in bone and soft tissue. Resorption and bone formation of G1G was faster than G1E. Total resorption time of G1 was 12 weeks for both sterilization groups. The analytical, microbiological and in vivo results suggest that the dental graft G1 can be sterilized with γ radiation safely with validated doses lower than medical γ sterilization dose, 25 kGy.