R-NH+Ra-[ (CH2)u-NH+Rb]v-Rc (I) wherein R is a saturated or unsaturated straight-chain hydrocarbon residue of 10 to 20 carbon atoms, v is an integer from 0 to 1, u is an integer from 2 to 3 and Ra, Rb and Rc are independently selected from hydrogen and -CH2CH2OH. The composition is preferably a mouthrinse. These compositions are tested in the treatment or prevention of erosive tooth demin-eralisation caused by food acids.