Often, taurodontism has a genetic component; for example, in tricho-dento-osseous syndrome, which is associated with DLX3 mutations.21 Mutations in DLX3 are also associated with amelogenesis imperfecta hypoplastic-hypomaturation with taurodontism in humans.22 Of note, the ablation of Smad4, Nfic, or Wnt10a in mice leads to similar phenotypes.23,24 Taurodontism has been well recognized in the relatively common form of OI. Here, SMAD4 is linked to taurodontism.