Progression of Molar Incisor Hypomineralization: A Longitudinal Study

Objectives: Molar Incisor Hypomineralization (MIH) is a qualitative enamel defect of systemic origin. The affected enamel could be porous and brittle, resulting in a post-eruptive breakdown and increased risk for dental caries. Longitudinal studies of MIH are still lacking. Our longitudinal study aimed to characterize the progression of MIH lesions over 5 years.
Methods: This study was conducted in 860 children who participated in the Prospective Cohort Study in Thai Children (PCTC) in Khon Kaen, Thailand. Children with MIH were followed from 6-7 years to 12-13 years of age. Two calibrated dentists performed dental caries examination according to the World Health Organization criteria. MIH was evaluated by two other calibrated dentists using the European Academy of Paediatric Dentistry criteria.
Results: The analysis included 43 children with MIH who completed all examinations at 8 time points over 5-6 years. At baseline, demarcated opacities were present in 74 molar teeth. With an average follow-up duration of 5.0 years (SD=0.7), 49% of the lesions remained unchanged, 31% had post-eruptive enamel breakdown (PEB), 11% had restoration, and 10% were extracted. Majority of the enamel breakdown occurred during the first 2 years after tooth eruption. At baseline, PEB was present in 21 molars. After an average follow-up of 5.3 years (SD=0.8), 29% of the teeth were extracted, and most extractions were performed within 3 years after the first diagnosis. Dental caries occurred in 72% of the teeth with PEB after 1 year. Atypical restoration was present in 2 molars at baseline and remained in the same status until the end of follow-up.
Conclusions: MIH defects became more severe with increasing age. Because the MIH lesions could progress rapidly during the first 3 years after eruption, a close monitor is recommended to prevent tooth extraction.