Tricho–dento–osseous syndrome (TDO) is a rare, systemic, autosomal dominant genetic disorder that causes defects in hair, teeth, and bones respectively.

TDO has been shown to occur in areas of close geographic proximity and within families; most recent documented cases are in Virginia, Tennessee, and North Carolina.

The cause of this disease is a mutation in the DLX3 (distal-less 3) gene, which controls hair follicle differentiation and induction of bone formation.

All patients with TDO have two co-existing conditions called enamel hypoplasia and taurodontism in which the abnormal growth patterns of the teeth result in severe external and internal defects.

Additionally, severe underbites where the top and bottom teeth fail to correctly align may be present; it is common for the affected individual to have a larger, more pronounced lower jaw and longer bones.

The physical deformities that TDO causes become more noticeable with age, and emotional support for the family as well as the affected individual is frequently recommended.

Adequate treatment for TDO is a team based approach, mostly involving physical therapists, dentists, and oromaxillofacial surgeons.

The presence of this hair texture type is a defining characteristic between a diagnosis of TDO verses amelogenesis imperfecta with hypomaturation.

The under maturation of the enamel causes the tooth structure to be softer, and more susceptible to the effects of bruxism due to abnormalities in skeletal development.

A team based approach between dental specialists, oral and maxillofacial surgeons, and physicians is necessary for treating the systemic effects and improves the prognosis.

It is also recommended for affected individuals to seek counseling to be better able to cope with any psychosocial problems due to oral and facial abnormalities that occur with TDO.

A series of appointments with the healthcare team are usually necessary to correct TDO abnormalities with treatment duration lasting from several months to through full oral-facial maturation stages.

[citation needed] Endodontic procedures are routinely recommended due to treatdental pulp exposure or periodontal abscess.

Maxillofacial surgery may be required to establish a more appropriate mastication, skeletal, and esthetic relationship vertically between the teeth to improve functioning.

Polymerase chain reaction also known as PCR is used to amply pieces of DNA and observed for the 141 base pair allele as a result of a deletion of four nucleotides in exon 3 of the DLX-3 gene.

[4] Additionally, the current research shows that there is heavy reliance on the physical characteristics in the differentiation of TDO verses AIHHT and the severity and prevalence of their expression.