Provided is a kit suitable for remineralising treatment of a tooth of a subject, and in particular for treating dentine hypersensitivity. The kit comprises a first composition (120) for applying to a tooth, and a separate second composition (140) for applying to the same tooth. The first composition comprises a first cationic component including a first free or peptide-coupled amino acid having a basic side group which is protonated, and thereby cationic, when at a pH of 6-8. The first cationic component is at least partially charge-balanced by a first anionic component (130) comprising at least one of a phosphate anion, a hydrogen phosphate anion, a dihydrogen phosphate anion, a carbonate anion and a bicarbonate anion. The second composition comprises a second anionic component including a second free or peptide-coupled amino acid having an acidic side group which is deprotonated, and thereby anionic, when at a pH of 6-8. The second anionic component is at least partially charge-balanced by a second cationic component (150) comprising a calcium cation.
