Inherited condition that affects the enamel of the
teeth, making them soft and thin. The teeth are easily damaged and appear
yellow because the dentin is visible through the thin enamel.
1:20,000 live births for the
most common form (enamel hypocalcification, see Clinical Aspects). Most often autosomal
dominant inheritance, with the defect mapped to 4q21 and 4q11-q21. However,
some forms are X-linked dominant with the defect located on Xp22 and
Xq22-28, and other forms are autosomal recessive.
Both the primary and the secondary dentitions are
affected. Two types of amelogenesis imperfecta have been described:
1. Hereditary enamel hypocalcification, where the amount of enamel is
normal but the degree of calcification is insufficient. This is the most
frequent type of enamel dysplasia.
2. Hereditary enamel hypoplasia, where the quality of the enamel is normal
but the quantity is deficient.
The enamel defect becomes obvious soon after the teeth erupt and is lost
soon thereafter. In the case of enamel hypocalcification, the enamel can
easily be scraped off the teeth. Anterior open bite is present in
approximately two thirds of patients. The clinical course in the autosomal
recessive form is more severe than in the other forms. This can be confirmed
by radiologic and histologic findings.
Obtain history and document loose
teeth. Teeth are soft and may be easily damaged, especially during
Tricho-Dento-Osseous (TDO) Syndrome: Features of this autosomal
dominant inherited disorder are enamel hypoplasia and hypocalcification,
combined with curly, dry hair.
Amelogenesis Imperfecta, Hypomaturation-Hypoplasia-Type with
Taurodontism Syndrome: Clinically very similar but genetically slightly
different. The dental changes seen in this syndrome are
identical to those occurring in trichodentoosseous syndrome, but hair
changes and osteosclerosis are absent.
Laryngo-Onycho-Cutaneous (LOC) Syndrome: Severe progressive
multisystem disorder involving the skin (dermal granula and ulcerations) and
larynx (vocal cord granuloma), often lethal during childhood.
Backman B, Holmgren G: Amelogenesis imperfecta: A genetic study. Hum Hered
Rajpar MH, Harley K, Laing C, et al: Mutation of the gene encoding the
enamel-specific protein, enamelin, causes autosomal-dominant amelogenesis
imperfecta. Hum Mol Genet