Amelogenesis Imperfecta- A Review

NTRODUCTION Amelogenesis Imperfecta (AI) is a developmental disorder of genomic origin, associated with abnormal enamel formation. Although AI is considered as a single disease entity, it actually represents a group of heterogeneous conditions, with diverse structural defects of enamel resulting in a range of clinical phenotypes. 1 It is characterized by clinical and genetic heterogeneity in the absence of systemic abnormalities or diseases. AI is also known by varied names such as hereditary enamel dysplasia, hereditary brown enamel, and hereditary brown opalescent teeth. 2 The prevalence varies from 1:700 to 1:14 000, according to the populations studied. 3 During the secretory stage of enamel formation, enamel matrix proteins amelogenin, enamelin and ameloblastin secreted by ameloblasts play key roles in the growth of enamel crystal. Reports have shown that mutations in the amelogenin gene (AMELX), and enamelin gene (ENAM), is implicated in the pathogenesis of the dominant forms of AI. In I ABSTRACT: Dental enamel is the epithelial derived hard tissue covering the crowns of teeth it is most highly mineralized and hardest tissue of the body. Dental enamel is acellular and has no physiological means of repair outside of that provided by saliva. Amelogenesis imperfect (AI) is a disorder which affects the enamel structurally as well as clinically of all or nearly all the teeth in a more or less equal manner. The enamel may be hypoplastic, hypomineralized or both. AI is a group of inherited defects of dental enamel formation that show both clinical and genetic heterogeneity. Enamel findings in AI are highly variable, ranging from deficient enamel formation to defects in the mineral and protein content. AI exists in isolation or associated with other abnormalities in syndromes. It may show autosomal dominant, autosomal recessive, sex-linked and sporadic inheritance patterns. In families with an X-linked form it has been shown that the disorder may result from mutations in the amelogenin gene, AMELX. The enamelin gene, ENAM, is implicated in the pathogenesis of the dominant forms of AI. Autosomal recessive AI has been reported in families with known consanguinity. Diagnosis is based on the family history, pedigree plotting and meticulous clinical observation.