Degradation of the surface of a metasilicate glass due to atmosphere moisture

Ziemath, Ervino C.

doi:10.1590/s0100-40421998000300021

Cited by 13 publications

(7 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, the review papers cited above tend to deliberately omit the several disadvantages of high alkali-containing BGs [67,68,69,70,72,73,76,77,275]. Such high alkali content bioactive glasses are usually also hygroscopic [276], which is a serious drawback for applications in bioactive glass/polymer composites, affecting the stability, degradation, and mechanical performance of the composite materials. The presence of [OH − ] ions on the surface of the glass powders promotes crystallisation.…”

Section: Bioactive Glasses and Glass-ceramicsmentioning

confidence: 99%

Bioactive Glasses and Glass-Ceramics for Healthcare Applications in Bone Regeneration and Tissue Engineering

et al. 2018

View full text Add to dashboard Cite

The discovery of bioactive glasses (BGs) in the late 1960s by Larry Hench et al. was driven by the need for implant materials with an ability to bond to living tissues, which were intended to replace inert metal and plastic implants that were not well tolerated by the body. Among a number of tested compositions, the one that later became designated by the well-known trademark of 45S5 Bioglass® excelled in its ability to bond to bone and soft tissues. Bonding to living tissues was mediated through the formation of an interfacial bone-like hydroxyapatite layer when the bioglass was put in contact with biological fluids in vivo. This feature represented a remarkable milestone, and has inspired many other investigations aiming at further exploring the in vitro and in vivo performances of this and other related BG compositions. This paradigmatic example of a target-oriented research is certainly one of the most valuable contributions that one can learn from Larry Hench. Such a goal-oriented approach needs to be continuously stimulated, aiming at finding out better performing materials to overcome the limitations of the existing ones, including the 45S5 Bioglass®. Its well-known that its main limitations include: (i) the high pH environment that is created by its high sodium content could turn it cytotoxic; (ii) and the poor sintering ability makes the fabrication of porous three-dimensional (3D) scaffolds difficult. All of these relevant features strongly depend on a number of interrelated factors that need to be well compromised. The selected chemical composition strongly determines the glass structure, the biocompatibility, the degradation rate, and the ease of processing (scaffolds fabrication and sintering). This manuscript presents a first general appraisal of the scientific output in the interrelated areas of bioactive glasses and glass-ceramics, scaffolds, implant coatings, and tissue engineering. Then, it gives an overview of the critical issues that need to be considered when developing bioactive glasses for healthcare applications. The aim is to provide knowledge-based tools towards guiding young researchers in the design of new bioactive glass compositions, taking into account the desired functional properties.

show abstract

Section: Bioactive Glasses and Glass-ceramicsmentioning

confidence: 99%

Bioactive Glasses and Glass-Ceramics for Healthcare Applications in Bone Regeneration and Tissue Engineering

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Bioactive glasses traditionally contain large amounts of sodium oxide (e.g., 24.4 mol% in Bioglass ® 45S5), and according to Hench's original mechanism of bioactivity, sodium is a critical component for glass degradation and apatite formation . However, high sodium oxide content bioactive glasses have disadvantages, particularly for applications in bioactive glass/polymer composites: high sodium content usually makes the bioactive glass phase hygroscopic, and thereby affects stability, degradation, and mechanical performance of the composite materials. This reduces the applicability of conventional high sodium oxide content bioactive glasses as fillers in composites.…”

Section: Introductionmentioning

confidence: 99%

Sodium is not essential for high bioactivity of glasses

Chen

Brauer

et al. 2017

Int J of Appl Glass Sci

View full text Add to dashboard Cite

This study aims to demonstrate that excellent bioactivity of glass can be achieved without the presence of an alkali metal component in glass composition.In vitro bioactivity of two sodium-free glasses based on the quaternary system SiO 2 -P 2 O 5 -CaOCaF 2 with 0 and 4.5 mol% CaF 2 content was investigated and compared with the sodium containing glasses with equivalent amount of CaF 2 . The formation of apatite after immersion in Tris buffer was followed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 31 P and 19 F solid state MAS-NMR. The dissolution study was completed by ion release measurements in Tris buffer.The results show that sodium free bioactive glasses formed apatite at 3 hours of immersion in Tris buffer, which is as fast as the corresponding sodium containing composition. This signifies that sodium is not an essential component in bioactive glasses and it is possible to make equally degradable bioactive glasses with or without sodium. The results presented here also emphasize the central role of the glass compositions design which is based on understanding of structural role of components and/or predicting the network connectivity of glasses.

show abstract

“…These results demonstrate that atmospheric water and CO 2 strongly interact with gels. Such interactions were also reported in the case of sodo-calcic glasses exposed to atmosphere during few months in which a 1380 cm − 1 centered hump in the infrared spectra was observed [26]. This may be a serious limitation to the use of such material but storage under argon atmosphere may be enough to prevent such problem.…”

Section: Discussionmentioning

confidence: 53%