Risk factors in the occurrence of molar-incisor hypomineralization amongst a group of Iraqi children.

BACKGROUND.  Despite the worldwide increasing interest in the prevalence studies of molar-incisor hypomineralization (MIH), there is still insufficient evidence to verify the aetiological factors of this condition. AIMS.  To investigate risk factors involved in the development of MIH in a group of school-aged Iraqi children. DESIGN.  Seven- to nine-year-old school children (823 of 1000 eligible, response rate of 82.3%) had their first permanent molars and incisors evaluated using the European Academy of Paediatric Dentistry evaluation criteria for MIH. Mothers completed a medical history questionnaire-based interview performed in the schools by a trained examiner. RESULTS.  For children with MIH, 6% reported no relevant medical history; the remaining 94% reported various medical conditions putatively associated with MIH compared with 70% for the non-affected group. Post-natal medical conditions (33.3%) were most frequently reported. When data were split into the possible risk effect groups, maternal psychological stress (OR, 3.24), frequent exposure to ultrasonic scans during the last gestational trimester (OR, 2.51) and birth order as a fourth sibling or later (OR, 3.17 and 5.73, respectively) were previously unreported significant risk factors and postulated as contributing to, or causing the defect. CONCLUSIONS.  Children with MIH had experienced a greater number of medical conditions than their unaffected peers with no single health event identified as a risk factor.