Modification of conventional glass-ionomer cements with N-vinylpyrrolidone containing polyacids, nano-hydroxy and fluoroapatite to improve mechanical properties

Moshaverinia, Alireza; Ansari, Sahar; Movasaghi, Zanyar; Billington, Richard W.; Darr, Jawwad A.; Rehman, Ihtesham U.

doi:10.1016/j.dental.2008.03.008

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Volume 24, Issue 10 , Pages 1381-1390, October 2008

Modification of conventional glass-ionomer cements with N-vinylpyrrolidone containing polyacids, nano-hydroxy and fluoroapatite to improve mechanical properties

Alireza Moshaverinia
- Department of Materials, Interdisciplinary Research Centre in Biomedical Materials, Queen Mary University of London, Mile End Road, London E1 4NS, UK
Sahar Ansari
- Department of Materials, Interdisciplinary Research Centre in Biomedical Materials, Queen Mary University of London, Mile End Road, London E1 4NS, UK
Zanyar Movasaghi
- Department of Materials, Interdisciplinary Research Centre in Biomedical Materials, Queen Mary University of London, Mile End Road, London E1 4NS, UK
Richard W. Billington
- Department of Biomaterial in Relation to Dentistry, Queen Mary University of London, Mile End Road, London E1 4NS, UK
Jawwad A. Darr
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK
Ihtesham U. Rehman
- Department of Materials, Interdisciplinary Research Centre in Biomedical Materials, Queen Mary University of London, Mile End Road, London E1 4NS, UK
- Corresponding author: Tel.: +44 20 7882 5502; fax: +44 20 8983 1799.

Received 27 March 2007; received in revised form 22 February 2008; accepted 4 March 2008.

Abstract

Objective

The objective of this study was to enhance the mechanical strength of glass-ionomer cements, while preserving their unique clinical properties.

Methods

Copolymers incorporating several different segments including N-vinylpyrrolidone (NVP) in different molar ratios were synthesized. The synthesized polymers were copolymers of acrylic acid and NVP with side chains containing itaconic acid. In addition, nano-hydroxyapatite and fluoroapatite were synthesized using an ethanol-based sol–gel technique. The synthesized polymers were used in glass-ionomer cement formulations (Fuji II commercial GIC) and the synthesized nanoceramic particles (nano-hydroxy or fluoroapatite) were also incorporated into commercial glass-ionomer powder, respectively. The synthesized materials were characterized using FTIR and Raman spectroscopy and scanning electron microscopy. Compressive, diametral tensile and biaxial flexural strengths of the modified glass-ionomer cements were evaluated.

Results

After 24h setting, the NVP modified glass-ionomer cements exhibited higher compressive strength (163–167MPa), higher diametral tensile strength (DTS) (13–17MPa) and much higher biaxial flexural strength (23–26MPa) in comparison to Fuji II GIC (160MPa in CS, 12MPa in DTS and 15MPa in biaxial flexural strength). The nano-hydroxyapatite/fluoroapatite added cements also exhibited higher CS (177–179MPa), higher DTS (19–20MPa) and much higher biaxial flexural strength (28–30MPa) as compared to the control group. The highest values for CS, DTS and BFS were found for NVP-nanoceramic powder modified cements (184MPa for CS, 22MPa for DTS and 33MPa for BFS) which were statistically higher than control group.

Conclusion

It was concluded that, both NVP modified and nano-HA/FA added glass-ionomer cements are promising restorative dental materials with improved mechanical properties.

Keywords: Glass-ionomer cements, N-Vinylpyrrolidone, Nano-hydroxyapatite, Nanofluoroapatite, Free radical polymerization, Sol–gel technique, Synthesis, Mechanical properties, Reinforcement