Definition and Characteristics of Shovel-shaped Incisors
- Shovel-shaped incisors refer to a dental trait characterized by the concavity or scooping of the incisal edge of the tooth.
- This trait is commonly observed in populations of Asian, Native American, and Polynesian descent.
- Shovel-shaped incisors are more prevalent in primary (baby) teeth compared to permanent teeth.
- The shovel shape is most commonly found in the maxillary central incisors.
- The presence of shovel-shaped incisors can be determined through dental examinations.
Genetic and Evolutionary Factors
- Genetic studies have identified a correlation between the presence of shovel-shaped incisors and the EDARV370A variant.
- The EDARV370A variant is associated with hair, sweat gland, and tooth development in East Asian populations.
- Mouse models expressing the EDARV370A variant have shown dental traits similar to shovel-shaped incisors.
- The inheritance of shovel-shaped incisors follows a complex genetic pattern involving multiple genes.
- Environmental selection during the last ice age may have influenced the prevalence of shovel-shaped incisors.
Forensic Importance
- Shovel-shaped incisors can be useful in forensic investigations for human identification.
- Dental records and the presence of shovel-shaped incisors can aid in establishing the identity of an individual.
- Forensic dentistry plays a crucial role in cases involving missing persons, mass disasters, and criminal investigations.
- The uniqueness of dental traits, including shovel-shaped incisors, can help in narrowing down potential matches.
- Dental examinations, including the analysis of shovel-shaped incisors, can provide valuable evidence in forensic cases.
Cultural and Anthropological Significance
- Shovel-shaped incisors have been observed in various ethnic groups, including Asian, Native American, and Polynesian populations.
- The prevalence of shovel-shaped incisors in these populations suggests a shared ancestry or migration patterns.
- Anthropological studies have explored the relationship between shovel-shaped incisors and cultural practices.
- The presence of shovel-shaped incisors among certain populations may have cultural or traditional significance.
- Shovel-shaped incisors can provide insights into human evolution, migration, and population history.
Dental Evolution and Variation
- Shovel-shaped incisors are considered a dental variation that can be observed in different populations.
- Dental evolution studies have explored the development and changes in dental traits over time.
- The presence of shovel-shaped incisors in different populations highlights the diversity and adaptability of human teeth.
- Dental variations, including shovel-shaped incisors, can be influenced by genetic, environmental, and cultural factors.
- Understanding dental evolution and variation contributes to our knowledge of human biology and history.
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 significantly common in Amerindians from North, Central, and South America. They are also common in East Asians and Central Asians, Hungarians, Inuit, and Aleut peoples of Northeast Asia and North America (including but not limited to Inuit in eastern Alaska, Arctic Canada, and Greenland). In European and African groups, shovel-shaped upper incisors are uncommon or not present. There is a spectrum of the degree of shoveled-ness, ranging on a scale from 0 to 7 of spatulate incisors to shoveled incisors. It was theorized that positive selection for shovel-shaped incisors over the spatulate incisors is more commonly found within cultures that used their teeth as tools due to a greater structural strength in increased shovel-shaped incisors.
In some instances, incisors can present a more pronounced version of this called double shovel-shaped. When present, shovel-shaped incisors can indicate correlation among populations and are considered to be one of the non-metrical traits in osteology. Structurally resembling the shovel-shaped incisors, double shovel-shaped incisors are distinguished by a more pronounced mesial ridge compared to the distal ridge. Similarly, the grades for both shovel-shaped incisors and the double shovel-shaped incisors in females are significantly greater than that in males.
Shovel-shaped dental characteristics are also observed in Homo erectus like the Peking Man and in Neanderthals, although the morphology of these shoveled incisors is distinct from the modern human form of shoveling. 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.
