Li, Qiu, Hurt, Andrew P. and Coleman, Nichola (2019) The application of 29Si NMR spectroscopy to the analysis of calcium silicate-based cement using Biodentine™ as an example. Journal of Functional Biomaterials, 10 (2):25. ISSN 2079-4983 (Print), 2079-4983 (Online) (doi:10.3390/jfb10020025)

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Abstract

Biodentine is one of the most successful and widely studied among the second generation of calcium silicate-based endodontic cements. Despite its popularity, the setting reactions of this cement system are not currently well understood. In particular, very little is known about the formation and structure of the major calcium silicate hydrate (C-S-H) gel phase as it is difficult to obtain information on this poorly crystalline material by the traditional techniques of powder X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). In this study, the hydration reactions of Biodentine™ are monitored by XRD, FTIR, isothermal conduction calorimetry, and for the first time, 29Si magic angle spinning nuclear magnetic resonance spectroscopy (29Si MAS NMR) is used to investigate the structures of the anhydrous calcium silicate phases and the early C-S-H gel product. XRD analysis indicated that the anhydrous powder comprises 73.8 wt% triclinic tricalcium silicate, 4.45 wt% monoclinic β-dicalcium silicate, 16.6 wt% calcite and 5.15 wt% zirconium oxide. Calorimetry confirmed that the induction period for hydration is short and that the setting reactions are rapid with a maximum heat evolution of 28.4 mW g−1 at 42 min. A progressive shift in the FTIR peak maximum from 905 to 995 cm-1 for the O-Si-O stretching vibrations accompanies the formation of the C-S-H gel during 1 week. The extent of hydration was determined by 29Si MAS NMR to be 87.0, 88.8 and 93.7% at 6 h, 1 day and 1 week, respectively, which is significantly higher than that of MTA. The mean silicate chain length (MCL) of the C-S-H gel was also estimated by this technique to be 3.7 at 6 h and 1 day, and to have increased to 4.1 after 1 week. The rapid hydration kinetics of Biodentine, arising from the predominance of the tricalcium silicate phase, small particle size, and ‘filler effect’ of calcite and zirconium oxide, is a favourable characteristic of an endodontic cement, and the high values of MCL are thought to promote the durability of the cement matrix.

Item Type:	Article
Additional Information:	This Open Access article is a part of the special issue of "Journal of Functional Biomaterials", titled "Endodontic Biomaterials". *** © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Uncontrolled Keywords:	Biodentine; calcium silicate cement; endodontic bioceramic; cement hydration; magic angle spinning nuclear magnetic resonance spectroscopy; X-ray diffraction; Fourier transform infrared spectroscopy; calorimetry; nitrogen gas sorption analysis
Subjects:	Q Science > QD Chemistry
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Science (SCI)
Last Modified:	19 Jun 2020 17:21
URI:	http://gala.gre.ac.uk/id/eprint/24521

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