Estimating molar-incisor-hypomineralization among 8-year-olds based on 15-year public oral health practice-based data.

Background: A wide range in the prevalence of molar-incisor-hypomineralization (MIH) has been reported. Population-based studies are recommended. However, such studies are expensive and time-consuming.Objectives: To estimate the magnitude of MIH condition among 8-year-olds based on routine oral health examinations and to associate first permanent molar (FPM) affection with that of other permanent teeth over time.Materials and methods: This retrospective study, with cross-sectional and longitudinal components, was based on electronic oral health records; all 8-year-olds examined between 2002 and 2016 were included.Results: The average estimated prevalence of MIH was 8.3%; yearly range was 4.8-15.9%. The mean number of affected teeth was 1.4; 62% had one affected tooth. One-surface defects were the most frequent (66%). Asymmetric distribution of affected teeth was observed. In follow-up, 10.7%, 8.4%, and 11.2% had at least one affected permanent canine, premolar, or second permanent molar, respectively. The proportion of children with other MIH-affected permanent teeth was higher in the group with ≥2 MIH-affected teeth than in group with one affected FPM at the age of 8.Conclusions: The average prevalence of MIH 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. Further screening of children with MIH is recommended to improve individually tailored early preventive and restorative dental care.