20/03/2024
🔴Amelogenesis imperfecta is a group of clinically and genetically heterogeneous disorders that affect the development of enamel and result in abnormalities of the amount, composition, and/or structure of enamel. These disorders are caused by mutations in a variety of genes that are important for enamel formation. The enamel may be hypoplastic, hypomature, or hypocalcified. Mutations in several genes, including ENAM, AMEL, DLX3, and P63, are known to cause isolated or syndromic amelogenesis imperfecta.
🔴__ Amelogenesis Imperfecta is a hereditary developmental disorder of enamel formation in the absence of a systemic involvement. Affected teeth have abnormal color (yellow, brown, or gray), are more susceptible to dental caries (cavities), tooth attrition, calculus apposition, and gingival hyperplasia, and are often accompanied by anterior open bite.
🔵AI is classified into three patterns depending on which stage is affected: hypoplastic, hypocalcified, and hypomaturation. (1) Hypoplastic AI teeth result from inadequate secretion of the enamel matrix, which is still normally mineralized. Therefore, affected teeth have inadequate amount of enamel and commonly show multiple scattered pits on the surface of the enamel. (2) Hypocalcified AI teeth are initially formed with proper amount of enamel, but due to absence calcification, they show lower density, which is easily found in radiographs, and their enamel are soft and easily lost. (3) Hypomaturation AI teeth are also initially formed with proper amount of enamel, which is calcified to a certain extent, but undergo defective maturation of the crystal structure of the enamel, resulting in soft enamel that is easy to chip.
* Mutations in several extracellular matrix (ECM) protein coding genes or ECM modifying enzyme coding genes have been associated with AI, such as the amelogenin, X-linked (AMELX), enamelin (ENAM), matrix metallopeptidase 20 (MMP20), and kallikrein related peptidase 4 (KLK-4) (Lagerström et al., 1991; Rajpar et al., 2001; Kim et al., 2005; Hart et al., 2004).
