Effect of remineralisation on the mechanical properties and tribological behaviour of human tooth dentine

With ageing and pathological factors, dentine exposure becomes more and more commonplace in the clinic. The mechanical properties of dentine are far less than those of enamel. Once exposed, dentine exhibits a weak wear-resistance and then results in many oral diseases. Therefore, it is necessary to study effective measures to improve the wear-resistance of dentine. In this study, the effect of remineralisation on the mechanical properties and tribological behaviour of human dentine was studied in vitro using nano-indentation/scratch technique. Remineralisation treatment was conducted by immersing dentine specimens in casein phosphopeptides–amorphous calcium phosphate–asparagine-serine-serine solution for 7 days after 24 h pre-treatment in polydopamine solution. Results show that after the remineralisation treatment, dentine surface is covered with a layer of dense hydroxyapatite (HA) crystals with high crystallinity and preferential orientation, and dentinal tubules are occluded. Surface hardness and elastic modulus of dentine increase by 35 and 78%, respectively, and the wear volume decreases by 86%. The crystals that occlude the dentine tubules do not fall off on the worn surface. In sum, remineralisation enhances the mechanical properties and anti-wear performance of dentine surface by forming a hard covering consisting of dense HA crystals, which is a potential measure to prevent excessive tooth wear by dentine exposure.