Prevalence, clinical characteristics, and associated factors of molar-incisor hypomineralisation among schoolchildren: a cross-sectional study in the Vietnamese Northern provinces

This study aimed to analyse the prevalence, clinical status of Molar-incisor hypomineralisation (MIH), and associated factors in schoolchildren from Northern provinces in Vietnam. A cross-sectional study was performed in 2024 among 1834 7- to 11-year-old schoolchildren across three provinces. MIH and enamel defects were diagnosed using the European Academy of Paediatric Dentistry criteria. Clinical dental examinations were undertaken, and parental questionnaires collected relevant background information. The overall MIH prevalence was 12.7% (95% CI 11.2-14.3%). The lower left first permanent molar was the most affected tooth. For incisors, the upper right central incisor was most involved. Common clinical presentations included white or creamy demarcated opacities, lesions involving less than one-third of the tooth surface, and severe lesions. Except for age, there were no significant relationships between MIH and gender, geography, or most prenatal, perinatal, and postnatal factors. Postnatal pneumonia was significantly associated with MIH (OR = 1.49; 95% CI 1.000035-2.24). Hypomineralised second primary molars (HSPM) were observed in 7.1% of children (95% CI 5.96-8.36%) and increased the risk of MIH significantly (OR = 8.48; 95% CI 5.81-12.39). This study provided population-based data on MIH in Vietnam and contextualized it within global findings, highlighting the importance of early diagnosis and management, while acknowledging recent translational perspectives under the broader concept of molar hypomineralisation (MH).