Extreme bilateral molar rotation in Monodelphis domestica (Marsupialia: Didelphidae).

Journal Article (Review;Journal Article)

Rotation of a tooth around an axis perpendicular to the occlusal plane through angles approaching 180 degrees is a rare anomaly found in the mammalian dentition. A specimen of Monodelphis domestica was found to show such extreme rotation of both lower last molars, with consequent disruption of normal occlusion and wear. A review of the literature discovered 41 other reported cases of extreme rotation, from four different orders of mammals. The distribution of extreme rotation within the dentition can be summarized as follows. It is found only in isolated teeth or in contralateral pairs of teeth. Bilateral rotation is far more common than would be expected based on the chance of the independent occurrence of two rotations. Extreme rotation has a significantly higher frequency in upper rather than lower teeth, in premolars rather than other teeth, and on the left- rather than the right--hand side. The incidence of extreme rotation across mammals was estimated to be approx. 1 in 5850.

Full Text

Duke Authors

Cited Authors

  • Van Nievelt, AF; Smith, KK

Published Date

  • August 1997

Published In

Volume / Issue

  • 42 / 8

Start / End Page

  • 587 - 591

PubMed ID

  • 9347121

Electronic International Standard Serial Number (EISSN)

  • 1879-1506

International Standard Serial Number (ISSN)

  • 0003-9969

Digital Object Identifier (DOI)

  • 10.1016/s0003-9969(97)00048-4


  • eng