Protection and acid resistivity of bioactive-glasses, arginine and calcium silicate

Mahmoodi, Behrad, Wood, Robert and Cook, Richard (2018) Protection and acid resistivity of bioactive-glasses, arginine and calcium silicate. International Association of Dental Research: IADR, The Excel, London, United Kingdom. 25 - 28 Jul 2018.

Abstract

Objectives: The purpose of this study was to evaluate the acid resistivity, tribological protection and remineralisation offered by five toothpastes containing Calcium-Sodium-Phosphosilicate (Novamin®), Chloro-Calcium-Phospho-Silicate (BioMinC®), Fluoro-Calcium-Phospho-Silicate (BioMinF®), Arginine (Pro-Argin®), and Calcium Silicate (Regenerate®) using nanomechanical characterisation in a hydrated state and Raman microscopy. Materials and methods: 50 Bovine dentine discs were divided into 5 toothpaste groups. Discs were brushed twice daily for two minutes over 7 days and stored in artificial saliva after every brushing cycle. Scanning electron microscopy was used to demonstrate layer formation after 7 days of simulated brushing. 20 indents were performed on each disc pre and post brushing using a 5μm radius spherical diamond to a maximum load of 10mN. 5 discs were chosen at random from each group for the citric acid challenge. Dentin discs were immersed into 15ml of 1 wt% citric acid (pH 3.2) for 2 minutes. Nanoindentation were repeated after the acid challenge to evaluate the resistance of the hydroxyapatite like layers. The other 5 discs were initially characterised by Raman spectroscopy followed by multi-pass wear test using the above tip and 300mN load. Results: After brushing the layers formed by all 5 toothpaste significantly increased the hardness and modulus (p<0.05). Regenerate® produced the hardest layer followed by Pro-Argin® which was significantly more acid resistant than other 4 layers. There was no significant difference between the mechanics and acid resistivity of layers formed by Novamin®, BioMinC®, BioMinF®, Raman measurements showed increase in phosphate peak intensity after brushing. The increase in intensities followed the same trend as mechanical properties. Conclusion: Although Regenerate toothpaste produced the hardest layer after brushing it did not perform well under acid challenge. The layer formed by Pro-Argin® had the highest hardness and demonstrated the best acid resistance out of the five pastes, and may offer the best protection to the dental tissue.

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Contributors

Author: Robert Wood

Author: Richard Cook

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