title: Comparison between the in vitro surface transformations of AP40 and RKKP bioactive glasses.
abstract: Two bioactive silica-phosphate glasses, AP40 and RKKP, were compared in their behaviour in simulated biological environment. Their chemical composition is practically identical, except that RKKP contains small amounts of amphoteric network-former oxides Ta2O5 and La2O3 (composition in wt% for AP40: beta-Ca3(PO4)2 24.50, SiO2 44.30, CaO 18.60, Na2O 4.60, K2O 0.19, MgO 2.82, CaF2 4.99; RKKP: beta-Ca3(PO4)2 24.23, SiO2 43.82, CaO 18.40, Na2O 4.55, K2O 0.19, MgO 2.79, CaF2 4.94, Ta2O5 0.99, La2O3 0.09). Previous investigations showed a better performance in osteopenic bone for RKKP. To gain more insight into these differences in biological behaviour, the in vitro bioactivity of the glasses was studied by treatment with a continuously replenished Hanks' Balanced Salt Solution (HBSS). The glasses were examined before and after HBSS treatment for 20 and 40 days by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Energy Dispersion (EDX), Raman and IR vibrational spectroscopies. Some slight but notable differences between the two glasses were observed after HBSS treatment. IR and EDX analyses showed that deposits formed on both glasses were composed of a calcium deficient carbonate-apatite; however, the layer formed on RKKP glass was found to be slightly more calcium deficient and thinner. EDX analysis evidenced the presence of a small percentage of F- ions only in the layers formed on the RKKP samples. The differences disclosed, although slight, can contribute to the understanding of the different biological behaviour previously observed.
authors.affiliation: ISTEC-CNR, Via Granarolo 64, 48018, Faenza (Ravenna), Italy.
authors.forename: A
authors.initials: A
authors.lastname: Krajewski
authors.forename: A
authors.initials: A
authors.lastname: Ravaglioli
authors.forename: A
authors.initials: A
authors.lastname: Tinti
authors.forename: P
authors.initials: P
authors.lastname: Taddei
authors.forename: M
authors.initials: M
authors.lastname: Mazzocchi
authors.forename: R
authors.initials: R
authors.lastname: Martinetti
authors.forename: C
authors.initials: C
authors.lastname: Fagnano
authors.forename: M
authors.initials: M
authors.lastname: Fini
mesh_terms: D001672:Biocompatible Materials / Q000032:analysis / Q000737:chemistry* / Q000145:classification; D040761:Biomimetic Materials / Q000737:chemistry; D001826:Body Fluids / Q000737:chemistry*; D018786:Bone Substitutes / Q000032:analysis / Q000737:chemistry*; D002516:Ceramics / Q000032:analysis / Q000737:chemistry* / Q000145:classification; D005898:Glass / Q000737:chemistry*; D008422:Materials Testing; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; C031323:bio-vitroceramic AP40
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