The prevalence of Molar-Incisor Hypomineralisation (MIH) in Wainuiomata children.

OBJECTIVES: The aim of this study was to determine the prevalence of Molar-Incisor Hypomineralisation (MIH) in Wainuiomata children and describe differences in prevalence among Maori, Pacific Island and New Zealand European ethnic groups. DESIGN: Cross-sectional survey of developmental defects of enamel in a random sample of children attending primary school in Wainuiomata, Wellington. METHOD: Study information and consent forms were sent to 850 7-to-10-year-old schoolchildren. Using the modified Developmental Defects of Enamel index, a single paediatric dentist examined students in the classroom. Dental caries experience was recorded as decayed, missing or filled primary and permanent teeth. RESULTS: Examinations were conducted on 522 children (participation rate 61.4%). The mean age of the children was 8.2 years (range 7 to 10 years). MIH prevalence was 14.9%. The prevalence ofhypomineralisation ofany tooth was 15.3%, and that for hypoplasia was 4.0%. There was no statistically significant ethnic difference in MIH prevalence. The mean DMFT was 0.16 (SD, 0.54) in those without a developmental defect, 0.54 (SD, 1.12) in those with hypomineralisation and 1.85 (SD, 1.85) in those with hypoplasia (p < 0.01). CONCLUSIONS: Approximately one in seven Wainuiomata children have MIH. Ethnicity is not a modifying factor in the occurrence of developmental defects of enamel. The presence of hypomineralisation and/or hypoplasia was associated with significantly greater caries experience in the permanent dentition.