Production and characterization of glass-ceramic materials for potential use in dental applications: thermal and mechanical properties, microstructure, and in vitro bioactivity

Multicomponent silicate glasses and their corresponding glass-ceramic derivatives were prepared and tested for potential applications in dentistry. The glasses were produced via a melting-quenching process, ground and sieved to obtain fine-grained powders that were pressed in the form of small cylinders and thermally treated to obtain sintered glass-ceramic samples. X-ray diffraction investigations were carried out on the materials before and after sintering to detect the presence of crystalline phases. Thermal analyses, mechanical characterizations (assessment of bending strength, Young’s modulus, Vickers hardness, fracture toughness), and in vitro bioactivity tests in simulated body fluid were performed. On the basis of the acquired results, different potential applications in the dental field were discussed for the proposed glass-ceramics. The use of such materials can be suggested for either restorative dentistry or dental implantology, mainly depending on their peculiar bioactive and mechanical properties. At the end of the work, the feasibility of a novel full-ceramic bilayered implant was explored and discussed. This implant, comprising a highly bioactive layer expected to promote osteointegration and another one mimicking the features of tooth enamel, can have an interesting potential for whole tooth substitution

Sol-gel synthesis of spherical monodispersed bioactive glass nanoparticles co-doped with boron and copper

In this work, an optimized sol-gel process for the synthesis of spherical and monodispersed bioactive glass nanoparticles doped with boron and copper was developed, by investigating different synthesis parameters. The obtained glasses were characterized in terms of morphology, composition, dispersibility, structure and in vitro reactivity. The performed characterizations demonstrated that shape, dimension and dispersion can be tailored by acting on the timing of the addition of the catalyst and on the synthesis process, in particular the centrifugation step. The optimized glass particles showed a spherical shape, good ions incorporation and good dispersion. In vitro bioactivity test demonstrated that the boron and copper addition did not interfere with the glass ability to induce the precipitation of hydroxyapatite. The shape, dispersion, bioactive behavior and content of boron and copper of these novel bioactive glass particles make them very promising for both hard and soft tissue engineering applications

Bioactive glasses: from parent 45S5 composition to scaffold-assisted tissue-healing therapies

Nowadays, bioactive glasses (BGs) are mainly used to improve and support the healing process of osseous defects deriving from traumatic events, tumor removal, congenital pathologies, implant revisions, or infections. In the past, several approaches have been proposed in the replacement of extensive bone defects, each one with its own advantages and drawbacks. As a result, the need for synthetic bone grafts is still a remarkable clinical challenge since more than 1 million bone-graft surgical operations are annually performed worldwide. Moreover, recent studies show the effectiveness of BGs in the regeneration of soft tissues, too. Often, surgical criteria do not match the engineering ones and, thus, a compromise is required for getting closer to an ideal outcome in terms of good regeneration, mechanical support, and biocompatibility in contact with living tissues. The aim of the present review is providing a general overview of BGs, with particular reference to their use in clinics over the last decades and the latest synthesis/processing methods. Recent advances in the use of BGs in tissue engineering are outlined, where the use of porous scaffolds is gaining growing importance thanks to the new possibilities given by technological progress extended to both manufacturing processes and functionalization techniques

Bioactive glass-derived trabecular coating: a smart solution for enhancing osteointegration of prosthetic elements

In this work, the use of foam-like glass-ceramic scaffolds as trabecular coatings on ceramic prosthetic devices to enhance implant osteointegration is proposed. The feasibility of this innovative device was explored in a simplified, flat geometry: glass-ceramic scaffolds, prepared by polymeric sponge replication and mimicking the trabecular architecture of cancellous bone, were joined to alumina square substrates by a dense glass coating (interlayer). The role played by different formulations of starting glasses was examined, with particular care to the effect on the mechanical properties and bioactivity of the final coating. Microindentations at the coating/substrate interface and tensile tests were performed to evaluate the bonding strength between the sample's components. In vitro bioactive behaviour was assessed by soaking in simulated body fluid and evaluating the apatite formation on the surface and inside the pores of the trabecular coating. The concepts disclosed in the present study can have a significant impact in the field of implantable devices, suggesting a valuable alternative to traditional, often invasive bone-prosthesis fixatio

Mesoporous bioactive glass as a multifunctional system for bone regeneration and controlled drug release

Purpose: Coupling the potential for bone regeneration and the ability for in situ controlled drug release in a single device is a challenging field of research in bone tissue engineering; in an attempt to pursue this aim, mesoporous bioactive glass (MBG) membranes belonging to the SiO2-P2O5-CaO ternary system were produced and characterized. Methods: The glass was synthesized via a sol-gel route coupled with an evaporation-induced self-assembly process by using a non-ionic block co-polymer as a mesostructure former. MBG structure and morphology, as well as mesopores size and shape, were investigated by x-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption measurements. In vitro bioactivity was investigated by soaking MBG membranes in simulated body fluid (SBF) for different time frames. Ibuprofen was encapsulated into MBG pores and drug release kinetics in SBF were assessed. Biological tests by using SAOS-2 cells were performed to assess the material cytocompatibility. Results: The material revealed significant ability to induce hydroxyapatite formation on its surface (bioactivity). Drug release kinetics in SBF are very similar to those obtained for mesoporous silica having mesopore size comparable to that of the prepared MBG (∼5 nm). No evidence of cell viability depression was detected during in vitro culture, which demonstrates the good biological compatibility of the material. Conclusions: The easiness of tailoring and shaping, the highly bioactive and biocompatible behavior, and the drug uptake/release ability of the prepared materials may suggest their use as "smart" multifunctional grafts for bone reconstructive surgery