Shovel-shaped incisor, a morphological variation on the palatine face of the superior incisor with variable expression, is a trait of Asian origin.
The estimation of genetic mixture was determined based on frequency of shovel-shaped incisor and Carabelli's cusp, using the Berstein method and assuming a population of mixed Amerindian and Caucasian origin (Cavalli-Sforza & Bodmer).
The researchers noted just around the same time when the mutation was spreading, Native Americans and northeast Asians started developing shovel-shaped incisors (with ridges along the sides and biting edge), something that has only been found in people belonging to the two groups.
In fact, they noted almost 100 percent of the early Native Americans and 40 percent of modern-day East Asians had shovel-shaped incisors back in the day.
William King Gregory (1922:476) opined: "Apart from a few striking cases, presently to be noted, racial characters in the teeth are at most not very conspicuous." The traits he considered variable enough to be noted included shovel-shaped incisors, upper molar cusp number, lower molar cusp number, Dryopithecus pattern, and Carabelli's cusp.
In some ways harkening back to Gregory, the two traits are shovel-shaped incisors, characterizing Asian and Native American groups, and Carabelli's cusp, characterizing European and European-derived populations.
Macrodon- tia shovel-shaped incisors
and multituberculism: probable Ekman-Westborg-Julin trait Sep 2012; 79(3): 197-201.
However, the dental morphology is simplified given the low frequency of shovel-shaped incisors
and double-shovel pattern, the layered fold, and cusps 6 and 7 (17,18) .
Talon cusp can be found in isolation or in association with other dental anomalies such as peg-shaped lateral incisors, shovel-shaped incisors
, bifid cingulum, unerupted canines and the large cusp of Carabelli, dens invagi-natus, supernumeraries and complex odon-tomas (2, 23, 26).
The Stata software version 10.0 was later used to determine the correlations of these CMDTs: shovel-shaped incisors
(11 versus 12, 21 versus 22, FDI notation), Carabelli's cusp (16 versus 17, 26 versus 27, FDI notation), cusp pattern (36 versus 37, 46 versus 47, FDI notation), cusp number (36 versus 37, 46 versus 47, FDI notation), cusp 6 and cusp 7 (36 versus 37, 46 vs 47, FDI notation), and protostylid (36 versus 37, 46 versus 47, FDI notation) by means of the Spearman non-parametric correlation test.
Talon cusps may be associated with other dental anomalies, especially in the permanent dentition, such as peg-shaped lateral incisors, impacted mesiodens and canines, odontoma, macrodontia, dens invaginatus, supernumerary teeth, shovel-shaped incisors
, bifid cingulum, additional tubercle on incisors, exaggerated Carabelli cusps, and microdontia of antimere teeth [Al-Omari et al., 1999; Gungor et al., 2000; Segura-Egea et al., 2003].
And he lacked other features, such as shovel-shaped incisors
, that are generally associated with Mongoloid people.