Glass - Back to the Future!



Presenting Author:
Altair Contreras Jaimes
<a.contreras@sheffield.ac.uk>

article posted 27 June 2016


Altair Contreras Jaimes is a final year PhD Student at the University of Sheffield Dentistry School working on aluminium free bioactive glasses for use as cements in bone related applications in collaboration with Regener8. She has an MSc. in Bioengineering from The University of Nottingham and an MEng. Degree in Metallurgical Engineering from Universidad Central de Venezuela. The Bioengineering & Health Technologies Research Group focuses on regeneration therapies for bone and soft tissue and computer modelling for craniofacial prosthetics applications






Degradable bioactive glasses for development of aluminium free bone cements

Altair Contreras Jaimes*, Paul V. Hatton, Ian M. Brook & Cheryl A. Miller
Bioengineering & Health Technologies Research Group, School of Clinical Dentistry, University of Sheffield, UK


Glass ionomer cements (GICs) have been traditionally used in dentistry as luting and restorative materials. Their low exothermic setting reaction and ability to bond to bone have extended their applications to other areas such as middle ear surgery. However, the aluminium contained in the glass had been classified as a neurotoxin and linked to Alzheimerís disease when the material was exposed to the nervous system. Moreover, aluminium had been reported to induce bone mineralisation defects.

Recent research has been targeted towards the substitution of the Al2O3 component in the parent glass, since Al salt complexes are linked to the cement setting and its stability in aqueous media. Ions such as Zn, Mg, Ge and Fe have resulted in different drawbacks such as reduced hydrolytic stability of the cements, poor in vitro performance and glass crystallisation during melting. However, compositions such as Bioglass®, with known osteoinductive and osteoconductive properties had been overlooked as a potential degradable glass for cement formation. Therefore, in this research a series of glasses based on the Bioglass® composition were produced with compositions ranging within the bone bonding area described by Hench for the SiO2-Na2O-CaO-P2O5 glass system (Hench, 2006).

The glasses were produced by a melt quench route and the frit was ball milled to obtain particles sizes < 45µm. The glass powders were characterised by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. Cements with varying powder liquid (P/L) ratios, setting modifier content (H3PO4 sol) and 10.7% of poly (acrylic acid) were evaluated. Mass change after immersion in deionised water was measured in order to establish possible correlations between the glass compositions and the stability of the cements in water. Setting cements were successfully produced; showing the potential of these Bioglass® based cement formulations to be used in bone related applications.

Acknowledgements
This work was supported by the Medical Technologies Innovation and Knowledge Centre, funded by the EPSRC, BBSRC and the Technology Strategy Board under grant number EP/G032483/1.

References
Hench, L. L. 2006. The story of Bioglass (R). Journal of Materials Science-Materials in Medicine, 17, 967-978.