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Dentinogenesis imperfecta is a disorder of tooth development. This condition causes the teeth to be discolored (most often a blue-gray or yellow-brown color) and translucent. Teeth are also weaker than normal, making them prone to rapid wear, breakage, and loss. These problems can affect both primary (baby) teeth and permanent teeth.
Researchers have described three types of dentinogenesis imperfecta with similar dental abnormalities. Type I occurs in people who have osteogenesis imperfecta, a genetic condition in which bones are brittle and easily broken. Dentinogenesis imperfecta type II and type III usually occur in people without other inherited disorders. A few families with type II have progressive hearing loss in addition to dental abnormalities. Type III was first identified in a population in Brandywine, Maryland. Some researchers believe that dentinogenesis imperfecta type II and type III, along with a similar condition called dentin dysplasia type II, are actually forms of a single disorder.
Dentinogenesis imperfecta affects an estimated 1 in 6,000 to 8,000 people.
Mutations in the DSPP gene cause dentinogenesis imperfecta.
Mutations in the DSPP gene have been identified in people with type II and type III dentinogenesis imperfecta. Mutations in this gene are also responsible for dentin dysplasia type II. Dentinogenesis imperfecta type I occurs as part of osteogenesis imperfecta, which is caused by mutations in one of several other genes.
The DSPP gene provides instructions for making three proteins that are essential for normal tooth development. These proteins are involved in the formation of dentin, which is a bone-like substance that makes up the protective middle layer of each tooth. DSPP mutations alter the proteins made from the gene, leading to the production of abnormally soft dentin. Teeth with defective dentin are discolored, weak, and more likely to decay and break. It is unclear how DSPP mutations are related to hearing loss in some families with dentinogenesis imperfecta type II.
This condition is inherited in an autosomal dominant pattern.