Effect of Gamma Radiation on Properties of a Calcium Phosphate-Calcium Sulfate Composite Cement

Abstract

The present study investigates £-radiation effect on structure and selected properties of a tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)/calcium sulfate hemihydrate (CSH) cement immersed in Hanks' solution. The results indicate that, at a dosage of 25 kGy, the working and setting times of the cement paste derived from £-ray-sterilized TTCP/DCPA/CSH powder did not change significantly. At 50 kGy or higher, however, both significantly decreased. A dose of 25 kGy caused the 1-d compressive strength of the cement to decrease by 15%. Further increases in £-ray dose did not further change the strength. After immersion for 1 day, the pH values of all non-sterilized and sterilized samples were in the range of 7.68.0. The XRD patterns of non-sterilized and sterilized powders were substantially similar. After immersion for 1 day, TTCP phase was still distinguishable, while CSH peaks were largely diminished and apatite phase became dominant. The non-sterilized sample had a significantly higher apatite conversion ratio than those of £-ray-sterilized samples. The average 1-d porosity values of all sterilized and non-sterilized samples were similar (3133%). The £-ray-sterilized cement samples had coralline type morphology with numerous tiny apatite crystals and micropores. Compared to the sterilized samples, the non-sterilized cement showed a smoother and denser morphology.

Sterilization effects on the handling and degradation properties of calcium phosphate cements containing poly (D,L‐lactic‐co‐glycolic acid) porogens and carboxymethyl cellulose

“…69 Chen et al investigated the effect of gamma irradiation on calcium phosphate-sulfate composite cements and determined that non-irradiated cements had a~10% higher apatite conversion ratio compared to irradiated cements in the range of 25-100 kGy. 56 This can also explain why the phase transformation appears to be diminished for CPCs irradiated at a higher dose in our study.…”

“…The irradiation of CPC particles has also been shown to inhibit the degree of phase transformation for apatite‐forming CPCs, and can induce the formation of undesired free radicals on the particles surface . Chen et al investigated the effect of gamma irradiation on calcium phosphate‐sulfate composite cements and determined that non‐irradiated cements had a ~10% higher apatite conversion ratio compared to irradiated cements in the range of 25–100 kGy .…”

“…Among the different methods available for sterilizing bone substitutes, gamma irradiation has proven to be the most common method to sterilize CPCs due to its reliability and safety, with doses typically ranging between 10 and 35 kGy . However, it is known that polysaccharides, such as CMC, degrade through the cleavage of glycosidic bonds present along the backbone of the polymer chain once exposed to ionic irradiation, thereby reducing the molecular weight .…”

“…14,21,22,26 Among the different methods available for sterilizing bone substitutes, gamma irradiation has proven to be the most common method to sterilize CPCs due to its reliability and safety, with doses typically ranging between 10 and 35 kGy. 30,31,55,56 However, it is known that polysaccharides, such as CMC, degrade through the cleavage of glycosidic bonds present along the backbone of the polymer chain once exposed to ionic irradiation, thereby reducing the molecular weight. 30,31,34,[57][58][59][60] This phenomenon, coupled with the formation of free radicals during the irradiation process, is known to accelerate the degradation kinetics of CMC and PLGA as well as reduce the viscosifying properties of CMC.…”