The study showed that the average prevalence of MIH among children of 8 years in Helsinki was comparable to that reported elsewhere. The number of MIH-affected teeth at early mixed dentition predicts the affection of other permanent teeth over time, mainly that of permanent canines. An irrelevant number of children had MIH-affected second primary molars. Further screening of children with MIH-affected teeth is recommended to improve individually tailored early preventive and restorative dental care. In this way, an early intervention will facilitate management of further clinical dental problems of MIH-affected teeth and improve oral health-related quality of life of children with this condition.