Tricho-Dento-Osseous (TDO) Syndrome

Genetic condition characterized by abnormal development of teeth (enamel hypoplasia), bones (hypocalcification), and curly hair.

Autosomal dominant. It is linked to a mutation on gene locus 17q21.3-q22, which results in altered function of a protein that has an important role in the development of hair (keratin), teeth (enamel), and bone (so-called DLX3 protein).

Abnormalities of keratin, enamel, and dentin are described; however, the pathogenesis of the TDO syndrome is unknown at present.

Presence of “kinky curly hair,” enamel hypoplasia, taurodontism (a variation in tooth form characterized by prism-shaped molars with large pulp spaces), and thick cortical bone.

Three subtypes or phenotypes for TDO have been suggested.

TDO-I demonstrates a normal calvarium with thickening of the chondrocranium, curly hair, delayed dental eruption with enamel hypoplasia and increased cavities, osteosclerosis, and only occasionally brittle nails. Premature sagittal craniosynostosis results in dolichocephaly. Calvarial thickness and density are normal; however, the chondrocranium may show some thickening.

TDO-II demonstrates more pronounced nail dystrophy (either with laminated splitting of the superficial layers or thick cornification), sparse, curly hair, and thickening and sclerosis of the calvaria. Males may show narrowing of the ear canal. In contrast to TDO-I, not only is dental eruption precocious, but also, in addition to the enamel hypoplasia, the dentin is dysplastic.

TDO-III demonstrates increased calvarial density and macrocephaly. Patients have an increased incidence of dental caries and abscess formation. Sagittal synostosis may result in dolichocephaly. Nails may be brittle or demonstrate increased cornification. There is no facial phenotype associated with the syndrome, although an increase in the length of the body of the mandible has been shown.

Assess airway for abnormal anatomy or trismus related to abscess formation. Inspect dentition for teeth at risk during airway manipulation.

There are no specific considerations other than those relating to poor dentition and potential for difficult airway management in the presence of dental abscesses and trismus. As for other ectodermal dysplasias associated with dental anomalies, laryngoscopy must be performed very carefully to avoid any damages to the teeth.

There are no known specific implications with this condition.

Amelogenesis Imperfecta: An inherited condition that affects the enamel of the teeth making them soft and thin. The teeth appear yellow because the dentin is visible through the thin enamel and are easily damaged.

Hypomaturation-Hypoplasia type with Taurodontism Syndrome: The dental findings are apparently identical to those of tricho-dento-osseus syndrome from which it differs only by the lack of changes in the hair and bones. True taurodontism is defined by a change in the mandibular first permanent molar.