Background: Molar Incisor Hypomineralisation (MIH) is systemic in origin, and affects one to four permanent first molars. It frequently affects the incisors also. Its aetiology remains unknown, with some evidence suggesting association with childhood diseases during the first four years of life, the use of antibiotics (amoxicillin, a macrolide), and exposure to dioxins.
Methods: Four sets of monozygotic twins had MIH. In each of the four cases described, precipitating environmental factors could be identified. This ranged from prolonged use of antibiotics, to early childhood illnesses, prenatal maternal ill health, and long duration of breast feeding. The possibility of genes in the aetiology of MIH is further strengthened by the observation in this study, that all the monozygotic twin pairs identified with MIH during public oral health screening exercises, had the lesion.
Conclusion: The aetiology of MIH may be due to early childhood illnesses and the use of amoxicillin. Also, the possible role of genetic disposition needs to be further investigated.