Molar incisor hypomineralization (MIH) is a structural developmental disorder of the enamel that classically affects the permanent first molars and possibly also the incisors. It is characterized by poor quality of mineralization of the enamel, which leads to white, yellow, or brown discoloration of the affected teeth. Disturbed areas are vulnerable to posteruptive breakdowns, and hypersensitivity may also occur. Children with MIH should therefore be closely monitored. Keywords: MIH, diagnosis, MIH-TNI, Würzburg concept, therapy