Increasing Diagnosis of Enamel Hypomineralisation in a Sample of More Than 70 000 Children in the City of Zurich: Repeated Cross-Sectional Prevalence Analyses and a Retrospective Longitudinal Cohort Analysis

Abstract

Background

The prevalence of molar-incisor hypomineralisation (MIH) has garnered increasing attention, with a likely association to hypomineralised second primary molars (HSPM).

Aim

To elucidate the prevalence of MIH and its association with HSPM.

Design

This retrospective observational study combined repeated cross-sectional analyses with a retrospective longitudinal cohort analysis of over 70 000 children (851 685 observations) attending public schools in Zurich, Switzerland (2005–2019). Hypomineralised lesions in second primary and first permanent molars were assessed. Prevalence rates and sex differences were calculated using annual age-specific cross-sectional samples. Logistic and log-binomial regressions complemented by machine learning algorithms explored the longitudinal association between HSPM and MIH in children with records both at ages 5–7 and ≥ 8.

Results

HSPM prevalence in five-year-olds increased from 5% to 13% between 2005 and 2019. Hypomineralised permanent first molars in eight-year-olds increased from 12% to 21%. Children with HSPM were approximately twice as likely to develop hypomineralised permanent molars (OR = 2.3; 95% CI: 2.1–2.5; PR = 1.9; 95% CI: 1.7–2.0).

Conclusion

This large dataset confirms increasing HSPM and MIH diagnosis in Zurich between 2005 and 2019 and supports HSPM as a useful clinical indicator for elevated MIH risk. Limitations include study retrospectivity and potential examiner variability.