A long-term study on the setting reaction of glass ionomer cements by 27Al MAS-NMR spectroscopy

Zainuddin, Norhazlin; Karpukhina, Natalia; Hill, Robert G.; Law, Robert V.

doi:10.1016/j.dental.2008.07.008

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Volume 25, Issue 3 , Pages 290-295, March 2009

A long-term study on the setting reaction of glass ionomer cements by ²⁷Al MAS-NMR spectroscopy

Norhazlin Zainuddin
- Department of Materials, Imperial College, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
Natalia Karpukhina
- Department of Materials, Imperial College, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
Robert G. Hill
- Department of Materials, Imperial College, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
- Corresponding author. Tel.: +44 2075945860; fax: +44 2075945804.
Robert V. Law
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
- Corresponding author. Tel.: +44 2075945860; fax: +44 2075945804.

Received 19 March 2008; accepted 18 July 2008.

Abstract

Objectives

The main objective is the characterization of the setting reaction in glass ionomer cements (GICs) based on experimental glasses using the ²⁷Al magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy in order to understand the crosslinking process during the setting reaction.

Methods

Three types of GICs which are based on fluoro-alumino-silicate glasses (LG125, ART10, and LG26Sr) were studied using ²⁷Al MAS-NMR to monitor the setting reaction of the cements.

Results

The result showed clearly the formation of six coordinate, aluminium Al(VI), that crosslink the carboxyl groups in the PAA. The deconvolution study was performed to quantify the amount of each Al species in the cements. The finding showed that composition of original glass has a substantial effect on the setting behavior of the cements.

Significance

Our data demonstrate that the setting reaction of GICs can be followed by ²⁷Al MAS-NMR spectroscopy discovering the conversion of Al(IV) to Al(VI). Considerable amount of the five coordinate aluminium, Al(V), species was found in the cements aged up to one year. The presence of phosphorus has a strong influence on the setting reaction. The formation of Al–O–P species was postulated to be present in the cement.

Keywords: Glass polyalkenoate cement, Glass ionomer cement, ²⁷Al MAS-NMR spectroscopy, Dental materials, Biomaterials