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Bioactive glasses have played a very important role in the development of new materials for bone tissue regeneration. The development of new synthesis and manufacturing methods allows the preparation of bioactive glasses with new chemical compositions, nanoscaled features, customized morphologies, and pore architectures. The composition of glasses can be designed at the atomic-molecular level to ensure bioactivity and beneficial effects including capabilities for enhancing osteogenesis and vascularization or to exert bactericide action. Moreover, the glasses can be prepared as mesoporous bioactive glasses, exhibiting ordered arrangements of nanometric pores. Through the control of the microstructure, glasses can be prepared to achieve suitable interactions with living cells. Finally, the scaffolds obtained with bioactive glasses must display interconnected pores over 100 μm to make possible bone cell ingrowths and angiogenesis. In this article, the advances in the field of bioactive glasses through the control of the chemical, nanometer scale, microstructural properties, and architectural features are presented and discussed. A detailed control of these four levels of matter organization will allow optimizing the biological response of bioactive glasses when used in bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Bioactive glasses play an important role for the bone defects treatment. Forty years ago, it was discovered the first bioactive glass, Bioglass®, obtained by melting and used in Orthopedics and Dentistry. Twenty years ago, another family of bioactive glasses obtained by solgel processing was reported. Solgel glasses exhibit high textural properties and quicker bioactive response than melt glasses. However, their presence in the market is scarce which could be explained considering that the improvements they bring do not justify the costs of their translation to product. In the last decade, so-called template glasses exhibiting greater bioactivity than solgel glasses were described. These glasses display high pore volume and ordered mesopore structure, which makes them optimal candidates for hosting biologically active substances. For these characteristics, template glasses are being considered ideal candidates for the scaffolds manufacture used in bone engineering. This article shows the main features of three families of bioactive glasses and the importance of their nanostructure in the bioactivity. We demonstrate here that glasses with identical composition may exhibit very different properties, specifically bioactivity, as a function of their nanostructure. This fact demonstrates the importance of controlling this nanostructure in the design of new bioactive materials for bone regeneration. [ABSTRACT FROM AUTHOR]