Dentinogenesis imperfecta

Dentinogenesis imperfecta is an inherited disorder of tooth development that causes teeth to be discolored, translucent, and weaker than normal. This condition can affect both primary and permanent teeth, making them prone to rapid wear, breakage, and loss.

Overview

Dentinogenesis imperfecta is a disorder that affects tooth development, resulting in teeth that are discolored (most often a blue-gray or yellow-brown color) and translucent. Because the teeth are weaker than normal, they are highly susceptible to rapid wear, breakage, and loss. These dental problems can affect both primary (baby) teeth and permanent teeth.

Researchers have classified three types of dentinogenesis imperfecta, which present with similar dental abnormalities:

• Type I: Occurs in individuals who also have osteogenesis imperfecta, a genetic condition characterized by brittle bones that break easily.
• Type II: Typically occurs in people without other inherited disorders. A few older individuals with this type have also experienced progressive high-frequency hearing loss, though it is not yet known if the hearing loss is directly related to the dental condition.
• Type III: Typically occurs in people without other inherited disorders.

Some researchers suggest that dentinogenesis imperfecta type II and type III, along with a condition called dentin dysplasia type II, are actually variations of a single disorder. While the signs and symptoms of dentin dysplasia type II closely resemble those of dentinogenesis imperfecta, it affects primary teeth much more severely than permanent teeth.

Frequency

Dentinogenesis imperfecta is estimated to affect approximately 1 in 6,000 to 8,000 people.

Causes

Mutations in the DSPP gene have been identified as the cause of dentinogenesis imperfecta type II and type III, as well as dentin dysplasia type II. In contrast, dentinogenesis imperfecta type I occurs as part of osteogenesis imperfecta, which is caused by mutations in other genes (most commonly COL1A1 or COL1A2).

The DSPP gene provides instructions for producing two proteins that are essential for normal tooth development. These proteins are critical to the formation of dentin, the bone-like substance that makes up the protective middle layer of each tooth. Mutations in the DSPP gene alter these proteins, resulting in the production of abnormally soft dentin. Teeth with this defective dentin are weak, discolored, and highly prone to decay and breakage. It remains unclear whether DSPP gene mutations are linked to the hearing loss observed in some older individuals with type II.

Genes Associated with Dentinogenesis Imperfecta

• DSPP

Inheritance

This condition is inherited in a pattern where one copy of the altered gene in each cell is sufficient to cause the disorder.

Other Names for This Condition

• DGI
• Hereditary opalescent dentin