Amelogenesis imperfecta

Amelogenesis imperfecta is a group of disorders of tooth development. In people with this condition, tooth enamel does not form properly. Tooth enamel is the hard, white material that is mainly made of mineral crystals and forms the protective outer layer of each tooth. People with amelogenesis imperfecta may have teeth that appear (erupt) later than normal, and their teeth may be unusually small, discolored, pitted, or grooved. Affected individuals can also have misalignment of the top and bottom teeth (malocclusion). Because of these teeth problems, people with amelogenesis imperfecta often have difficulty eating, sensitivity to certain foods and drinks, and pain when brushing their teeth. Their teeth are also prone to rapid wear, frequent cavities, and breakage. Other dental abnormalities are also possible. These problems can affect both primary (baby) teeth and permanent (adult) teeth.

Because amelogenesis imperfecta causes changes in a person's appearance, the condition can profoundly affect quality of life and self-esteem if not treated. In some people, the condition can lead to avoidance of social activities, anxiety, and other emotional or psychological issues.

Researchers have described at least four forms of amelogenesis imperfecta: hypoplastic (also referred to as type I), hypomaturation (type II), hypocalcified (type III), and hypomaturation and hypocalcified with taurodontism (type IV). These types are generally distinguished by their specific enamel abnormalities. The hypoplastic type is defined by thin enamel, the hypomaturation type is defined by weak or brittle enamel, and the hypocalcified type is defined by soft enamel. The hypomaturation and hypocalcified with taurodontism type involves weak and soft enamel and teeth that are too large for the size of their roots, which are small (this combination is known as taurodontism). These four types of amelogenesis imperfecta are further divided into subtypes according to their pattern of inheritance and their genetic cause.

Some doctors simplify the classification of amelogenesis imperfecta by grouping structural problems with enamel into one group (quantitative enamel defect) and strength or hardness issues with enamel into a second group (qualitative enamel defect).

Amelogenesis imperfecta can occur without any other signs and symptoms (isolated) or it can occur as part of a syndrome that affects multiple parts of the body (syndromic). A subtype of type I, known as amelogenesis imperfecta type IG, can affect the kidneys and is called enamel-renal syndrome. People with this condition may develop calcium deposits in the kidneys (nephrocalcinosis) later in life.