Prevalence and association of molar-incisor hypomineralisation and dental caries in 7-9-year-old children in Kaifeng, China

The aim of the present cross-sectional study was to analyze the prevalence of Molar-Incisor Hypomineralisation (MIH) and its association with dental caries among 7-9-year-old children in Kaifeng, China. A cross-sectional study was conducted from 2023 to 2025, in which a sample of 2,296 schoolchildren aged 7 to 9 years in Kaifeng was enrolled. The European Academy of Paediatric Dentistry (EAPD) criteria were applied to assess MIH, while dental caries was defined in accordance with the standards of the Fourth National Oral Health Epidemiological Survey. The investigation focused on the prevalence of MIH and dental caries, as well as the association between them. The prevalence of MIH was 13.50% in 7-9-year-old children of Kaifeng. There were no significant differences in sex between MIH and non-MIH children. A significant association was found between dental caries in the first permanent molars (FPMs) and MIH. Children affected by MIH exhibited a 5.3 times higher likelihood of developing dental caries in FPMs compared to those without MIH. There was no significant association between the occurrence of dental caries in primary teeth and MIH. The prevalence of MIH in 7-9-year-old children of Kaifeng was similar to the global average prevalence. Children with MIH were more likely to experience dental caries in the FPMs. MIH was strongly associated with an increased prevalence of dental caries, and the severity of MIH appeared to correlate with a higher caries risk.