Setting of commercial glass ionomer cement Fuji IX by 27Al and 19F MAS-NMR

Munhoz, Tais; Karpukhina, Natalia; Hill, Robert G.; Law, Robert V.; De Almeida, L.H.

doi:10.1016/j.jdent.2009.12.005

« Previous Next »Journal of Dentistry
Volume 38, Issue 4 , Pages 325-330, April 2010

Setting of commercial glass ionomer cement Fuji IX by ²⁷Al and ¹⁹F MAS-NMR

Tais Munhoz
- Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, UK
- Programa de Engenharia Metalurgica e de Materials, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
Natalia Karpukhina
- Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, UK
- Department of Chemistry, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, UK
- Institute of Dentistry, Unit of Dental Physical Sciences, Barts and The London School of Medicine and Dentistry, Mile End Road, London, E1 4NS, UK
- Corresponding author at: Institute of Dentistry, Unit of Dental Physical Sciences, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Mile End Road, London, E1 4NS, UK. Tel.: +44 02078827409; fax: +44 02078827979.
Robert G. Hill
- Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, UK
- Institute of Dentistry, Unit of Dental Physical Sciences, Barts and The London School of Medicine and Dentistry, Mile End Road, London, E1 4NS, UK
Robert V. Law
- Department of Chemistry, Imperial College London, South Kensington Campus, Exhibition Road, London, SW7 2AZ, UK
- Corresponding author. Tel.: +44 02075945860; fax: +44 02075945804.
L.H. De Almeida
- Programa de Engenharia Metalurgica e de Materials, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

Received 6 October 2009; received in revised form 18 December 2009; accepted 18 December 2009. published online 30 December 2009.

Abstract

Objectives

To investigate the long term setting reaction in the glass ionomer restorative, Fuji IX, by monitoring the structural evolution of aluminium and fluorine species using ²⁷Al and ¹⁹F MAS-NMR spectroscopy.

Methods

Fuji IX cements aged from 5min up to 3 months were prepared according to the manufacturer instructions from the commercial material. The ²⁷Al and ¹⁹F MAS-NMR studies were carried out on powders made after terminating the setting reaction.

Results

²⁷Al MAS-NMR results show conversion of aluminium from the glass phase, where it has coordination number four, Al(IV), into the cement matrix where it has a coordination number of six, Al(VI). At least two different Al(VI) species were detected at short ageing time cements. Assignment of these species is discussed and compared with the data from other sources. The possibility for a condensed aluminium species [Al₁₃(OH)₂₄(H₂O)₁₂]⁷⁺ to form is considered. The ratio of aluminium in the cement, Al(VI), to the remaining unreacted in glass has been evaluated by deconvolution of the spectra. Various theoretical ratios of aluminium species in the cement matrix to the unreacted ones remaining in glass have been estimated. The ¹⁹F MAS-NMR spectra are identical for the glass and cements at the early times and contain a dominant signal assigned to Al–F–Sr(n).

Conclusions

The data confirms that the conversion of aluminium is a diffusion-controlled process at early stage less than 1h and it is largely complete between 1 and 6h. The comparison with the experimental data shows that the majority of aluminium cations do not form tricarboxylates but are coordinated with one or two carboxylic groups and other ligands. Insufficient amount of water and excess of glass in this cement formulation affect glass degradation mechanism.

Keywords: Fuji IX, Glass ionomer/polyalkenoate cement, Setting, Ageing/aging, ²⁷Al, ¹⁹F MAS-NMR, Aluminium complex [Al₁₃(OH)₂₄(H₂O)₁₂]⁷⁺