In taurodontism, the pulp chamber is enlarged in which direction?

Correct answer: B. Apico-occlusally, so the chamber extends well below the cementoenamel junction

• A. Mesiodistal widening alone does not describe taurodontism; the defining change is in the vertical dimension.
• B. CORRECT. Taurodontism (the bull tooth) results from failure of Hertwig epithelial root sheath to invaginate at the proper level. The pulp chamber is therefore enlarged VERTICALLY — apico-occlusally — with the floor displaced apically well beyond the cementoenamel junction. The result is a rectangular tooth with a very tall chamber, short roots and furcation positioned near the apices.
• C. The roots ARE short, but that is a consequence of the apically displaced furcation — the chamber is definitely enlarged.
• D. Buccolingual enlargement is not the characteristic feature.

Note: Associations: Klinefelter syndrome, Down syndrome, amelogenesis imperfecta and ectodermal dysplasia. Endodontically these teeth are difficult — orifices sit far apically and are hard to locate.