Effect of demineralising agents on organic and inorganic components of dentine

There is a requirement to ensure that in-vitro studies that use demineralised human dentine models are reliable and clinically relevant. The literature reports several strategies for these studies with a lack of consensus on the mode of action of the different demineralising acids on human dentine. This in-vitro study aims to characterise the effect of clinically-relevant acids on human dentine, using standardised substrates and complementary analytical techniques. The study focuses on an analysis of the mineral content and the integrity of the collagen following partial demineralisation. Samples of human dentine were exposed to a range of acids commonly encountered in the oral cavity. Characterisation of the mineral content used Vickers micro-hardness, Energy dispersive spectroscopy and X-ray fluorescence. Characterisation of the collagen integrity was undertaken by means of Scanning electron microscopy and Hydroxyproline assay. The following conclusions were reached: (i) Each demineralising agent tested had a unique effect on the mineral levels; (ii) Chelating agents, strong acids and weak acids affect the mineral and organic phases of dentine in significantly different ways with no correlation between them; (iii) The demineralising agents caused some degree of collagen denaturation, citric acid causing the most damage. Overall, there is no clear link between the type of demineralising agent and the effect on the organic and inorganic dentine. The choice of demineralising agent should be aligned to the experiment objectives so that the selected dentine (caries or erosion) model is fit for purpose