Shovel-shaped incisors

Shovel-shaped incisors (or, more simply, shovel incisors) are incisors whose lingual surfaces are scooped as a consequence of lingual marginal ridges, crown curvature or basal tubercles, either alone or in combination.

Shovel-shaped incisors are relatively common in Central, East and Southeast Asians; the Eskimo and Aleut peoples of Northeast Asian and North America (including but not limited to the Inuit peoples of eastern Alaska, arctic Canada and Greenland); and Aboriginal North and South Americans.[1][2][3] In Europeans and Africans, shovel-shaped upper incisors are uncommon or not present.[1] In some instances, incisors can present a more pronounced version of this called double shovel-shaped. The differences observed in tooth morphology is believed to be partly determined by genetics.[4] When present, shovel-shaped incisors can indicate correlation among populations and are considered to be one of the non-metrical traits in osteology. The characteristic could also be attributed to hormones, duration of development, and the capacity of the maxillary dental arch.

The shovel-shaped dental characteristic can also be traced back to Homo erectus and in Neanderthals.[1] The morphology of Neanderthal's anterior teeth has been seen as an adaptation to the heavy use of their canines and incisors in processing and chewing food, and the use of their teeth for activities other than feeding.[5]

History

The first description of shovel-shaped incisors was in 1870.[6]

Historic racial categorization

In the mid 20th century, shovel-shaped incisors were considered to be a trait useful for racial categorization, since the occurrence of shovel-shape incisors varies between many populations.[7] A 1964 text said that many anthropologists at the time used the trait of shovel-shaped incisors as a diagnostic for race.[7]

See also

References

  1. 1 2 3 Kimura, Ryosuke; Yamaguchi, Tetsutaro; Takeda, Mayako; Kondo, Osamu; Toma, Takashi; Haneji, Kuniaki; Hanihara, Tsunehiko; Matsukusa, Hirotaka; Kawamura, Shoji (2009-10-09). "A Common Variation in EDAR Is a Genetic Determinant of Shovel-Shaped Incisors". American Journal of Human Genetics. 85 (4): 528–535. doi:10.1016/j.ajhg.2009.09.006. ISSN 0002-9297. PMC 2756549. PMID 19804850.
  2. ↑ Acs, G., Pokala, P., & Cozzi E. (1992). Shovel incisors, three-rooted molars, talon cusp, and supernumerary tooth in one patient. In Pediatric Dentistry, 14(4). Page 264. Retrieved December 27, 2016, from link.
  3. ↑ DeLong, L. & Burkhart, N.W. (2008). General and Oral Pathology for the Dental Hygienist. USA: Lippincott Williams & Wilkins. Page 494. Retrieved December 27, 2016, from link.
  4. ↑ Hemphill, Brian E. (2002-10-01). "Review". Journal of Anthropological Research. 58 (3): 412–414. JSTOR 3631186.
  5. ↑ Clement, Anna F.; Hillson, Simon W.; Aiello, Leslie C. (2012-01-01). "Tooth wear, Neanderthal facial morphology and the anterior dental loading hypothesis". Journal of Human Evolution. 62 (3): 367–376. doi:10.1016/j.jhevol.2011.11.014. PMID 22341317.
  6. ↑ Saukko, P. & Knight, B. (2004). Knight's Forensic Pathology (3rd ed.). USA: Taylor & Francis Group. Page 533. Retrieved January 14, 2016, from link.
  7. 1 2 Suzuki, M. & Sakai, T. (1964). Shovel-shaped incisors among the living Polynesians. In American Journal of Physical Anthropology, 22(1). Page 65. Retrieved December 28, 2016, from link.


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