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Published online by Cambridge University Press: 15 February 2011
Calcium phosphates are widely used as implantable materials in both dental andorthopaedic applications. Seven different bone substitutes (BS), including Interpore CorallineHAP, Cortical Bio-Oss, Endobon, Cancellous Bio-Oss, Dense HAP (hydroxyapatite), Collagraftgranules, and Porous HAP, have been evaluated using the Dual Constant Composition (DCC)kinetics methods. DCC measurements of the kinetics of dissolution and re-mineralization of theBS materials offer considerable advantages for the characterization of minor calcium-containingsurface species due to the insensitivity of conventional physical chemical methods such as X-raydiffraction and ESCA. Each sample was pre-conditioned (PC) in 0.15 M NaCl prior to the DCCkinetics procedures. The fastest dissolving material, Collagraft granules, showed a dissolution ratemore than two orders of magnitude larger than Dense HAP. Interestingly, the relativesupersaturation with respect to HAP (σ) following PC was normally negative, whereas withplasma sprayed HAP coated implants, these a values were as high as 20. Surface impurities mayplay a major role following in vivo implantation, since resorption is probably a major reparativemechanism. It is therefore essential to understand the dissolution behavior. Moreover, in a remineralizationmode, trace surface phases may determine the phase and morphology of the newlydeposited bone mineral.