This is a prospective, multi-centre clinical study to evaluate the safety and performance of the Calcivis Caries Activity Imaging System. Dentists will identify tooth surfaces as either sound (inactive) or unsound (active caries lesion present) according to ICDAS staging (International Caries Detection and Assessment System). Images of the tooth surface will be taken with the Calcivis System immediately before and after application of a disclosing solution containing a bioluminescent protein. Presence or absence of elevated luminescence on the images will indicate activity / inactivity of the presence or absence of active demineralisation on the tooth surfaces.