A synthetic peptide based on a natural salivary protein reduces demineralisation in model systems for dental caries and erosion

The salivary protein statherin is an inhibitor of spontaneous and secondary precipitation of hydroxyapatite (HAp). It is also detected in enamel pellicle. The N-terminal region of statherin is involved in its adsorption onto tooth surfaces, and, calcium binding. A peptide (StN21) was designed with a 21 amino acid sequence identical to the N-terminus of statherin. The aim was to measure the effect of StN21 on the rate of mineral loss in a model system for dental caries and erosion using HAp subjected to artificial carious and erosive conditions. StN21 was synthesised using Fmoc chemistry. A surface of each HAp block was exposed to solution containing StN21 at concentrations 9.4-376 μmol L^-1 (in phosphate buffer) for 24 h. Controls were HAp exposed to buffer only, and HAp exposed to lysozyme. Demineralising solution (0.1 mol L^-1 acetic acid, pH 4.5, 1.0 mmol L^-1 calcium and 0.6 mmol L^-1 phosphate) was circulated past the HAp blocks at 0.4 mL min ^-1 to mimic carious and erosive conditions. Scanning microradiography was used to measure the rate of mineral loss for demineralisation periods of 3 weeks. The rate of mineral loss of the samples exposed to StN21 was reduced by ∼40% compared to the controls, but no dependence on the concentration of StN21 was observed at the concentrations used. StN21 has been shown to be a potent and stable peptide that has potential as a preventive/therapeutic agent in the treatment of enamel erosion and dental caries.