Cheese molars (MIH) can be recognized not only by their colour abnormalities but also by the enamel breakdown. Clinical management of those teeth may become challenging by the chronic hypersensitivity, that makes various steps during treatment, such as pain control or light curing of any type of composite restorations, difficult or even impossible, despite profound local anaesthesia. The aim of this study is to determine the relationship between colour of the defect and loss of ename in the affected teeth. A correlation between colour of the defect and risk of enamel breakdown could enable early prognosis leading to preventive measures in order to delay or even avoid completely any breakdown of the enamel. Children diagnosed with MIH on their first permanent molars of different severity are matched to children with sound molars. They are identified by the annual school dental check-up and are invited to take part in the study. The children will be invited to the university dental clinic via letter for the first appointment. Upon parental consent, the teeth will be photographed and scanned on the first appointment. Three follo-up appointments will be organised in order to take pictures and scan again the teeth. The baselne scan of the tetth will be compared to the scans of the subsequent appointments in order to measure the level of enamel breakdown and correlate it to the colour of the defect.