Hydroxyapatite – this is the substance from which our teeth are made of. It is the main active ingredient in Kinder Karex and was copied from nature. Hydroxyapatite repairs minor defects on the enamel every time the teeth are brushed, minimises the build-up of bacteria and thus provides effective protection against caries. In addition, BioHAP releases calcium to protect children teeth from acid attacks. Calcium promotes the repair (remineralisation) of microfine defects in teeth. The formula of the Kinder Karex toothpaste was developed specifically for children. The mild flavour was chosen by children for children.