Critical-sized bone defects have, in many cases, posed challenges to the current gold standard treatments. Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics; however, the difficulty in producing porous scaffolds made of bioactive glasses has limited their extensive use in bone regeneration. On the other hand, calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. This paper gives an overview of the recent developments in the field of bioactive nanoparticles, with a focus on nanohydroxyapatite and bioactive glasses for bone repair and regeneration. First, a brief overview of the chemical structure and common methods used to produce synthetic nanohydroxyapatite and bioactive glasses has been presented. The main body of the paper covers the physical and biological properties of these biomaterials, as well as their composites with biodegradable polymers used in bone regeneration. A summary of existing challenges and some recommendations for future directions have been brought in the concluding section of this paper.

To cite this version:Eric Wers, Hassane Oudadesse. Thermal behaviour and excess entropy of bioactive glasses and Zn-doped glasses.. Journal of Thermal Analysis and Calorimetry, Springer Verlag, 2013, pp.1-8. of pure bioactive glass elaborated with different amounts of CaO, Na 2 O in pure glass and with different amounts of introduced Zn in glass (ranging from 0.1 to 10 in wt%), were studied. The excess entropy was calculated for different compounds. Glasses were prepared by the melting process. The thermal behaviour of obtained bioactive glasses was determined using differential thermal analysis. Therefore, the glass transition (T g ), the crystallization (T c ) and the melting temperatures (T f ) were revealed. Moreover, according to Dietzel formula, the thermal stability (TS) of the studied bioactive glasses has been calculated. The first results concerning the impact of different oxides, revealed a decrease of the TS, T g , T c and T f when the SiO 2 /CaO increases and revealed an increase of these thermal characteristics when the SiO 2 /Na 2 O and CaO/Na 2 O ratios increase. Introducing Zn into the bioactive glasses induces a decrease of T f and an increase of TS. Contrary to crystals, prepared glasses have entropy different to zero at T = 0 K and vary versus T f . The excess entropy of pure glasses and Zn-doped glasses were calculated. The significant variations were registered.

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