{'fraction_non_alphanumeric': 0.03423566878980892, 'fraction_numerical': 0.007961783439490446, 'mean_word_length': 4.819444444444445, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Apatite formation in composites of α-TCP and degradable polyesters

The objective of this study was to investigate the conversion of α-Ca3(PO4)2 (α-TCP) in composite bone cements based on a water-degradable polyester matrix as a function of the polymer formulation and the α-TCP filler content. Cross-linkable dimethacrylates of ε-caprolactone/D,L-lactide co-polymer or of ε-caprolactone/glycolide co-polymer were mixed with hydroxyethyl-methacrylate, a photo-initiator and α-TCP to obtain composites with a filler content of 80 or 40 wt% α-TCP. The disk shaped composite samples were set by visible light irradiation and immersed in HEPES at 37°C. At selected times the samples were removed from the solution and analysed with X-ray diffractometry and infrared spectroscopy. Conversion of α-TCP into calcium-deficient hydroxy-apatite (CDHAp) was observed for all composites, but the reaction was not completed after 8 weeks immersion. The conversion rate of α-TCP and the crystallinity of the formed apatite apparently were not affected by the type of polyester used, but significantly depended on the α-TCP content of the composites. An increase of the amount of α-TCP in the composite resulted in a slower formation of CDHAp with a higher crystallinity.