Can Unusually Shaped Teeth Reveal a Meaningful Ancestral Story?

By Genni Burkhart

Thanks to global diversity spanning thousands of years, variations in human tooth formation are to be expected. However, when specific patterns appear repeatedly, such as shovel-shaped incisors or additional roots, they suggest more than surface-level differences. These unusually shaped teeth are formed by genes that direct tooth development and function. Two of the most studied in this context are EDAR and PITX2.

Understanding the influence of these genes enhances diagnosis, supports personalized treatment planning, and opens meaningful conversations with patients. Dental anomalies aren't simply entries in a patient's chart. They provide insight into biology and, in many cases, ancestral origin.

EDAR and the Architecture of Teeth

EDAR stands for Ectodysplasin A Receptor, a gene essential to the development of tissues like teeth, hair, and glands. One well-known variant, EDAR V370A, involves a single nucleotide change that substitutes valine with alanine at position 370.

This variant is most common in East Asian, Indigenous American, and Inuit populations. It's believed to have originated in Northern China approximately 35,000 years ago and spread through positive selection. Researchers suggest it may have provided evolutionary benefits in cold environments by altering sweat glands, mammary ducts, and dental structures (Fujita et al., 2012).

Clinically, EDAR V370A is linked to:

• Shovel-shaped maxillary incisors.
• Single-rooted maxillary premolars.
• Three-rooted mandibular first molars.
• Larger anterior teeth.

These traits define the sinodont pattern, common in Northern Asian populations. In contrast, the sundadont pattern found more frequently in Southeast Asian populations features a simpler crown and root anatomy.

In a study of Japanese patients, EDAR V370A accounted for nearly 19% of incisor shape variation (Kimura et al., 2009). Reaction-diffusion modeling suggests this variant influences root development by modifying early odontogenic signaling (Tao et al., 2021).

These patterns aren't simply academic. A third root in a mandibular molar or a single-rooted premolar can significantly impact treatment decisions. For example, identifying an extra root on a radiograph can change the complexity of a root canal procedure. Broader incisors may influence veneer placement or bracket spacing in orthodontics. Awareness of these traits during preoperative planning can help prevent procedural complications and reduce the need for mid-treatment adjustments.

PITX2 and Early Tooth Development

PITX2, short for Paired Like Homeodomain 2, is a transcription factor critical during early odontogenesis. It regulates the enamel knot, a signaling center that controls the number, placement, and shape of tooth cusps and roots.

Mutations in PITX2 are associated with Axenfeld-Rieger syndrome, a rare disorder marked by ocular, craniofacial, and dental anomalies. Affected individuals may present with hypodontia, microdontia, or malformed and displaced teeth. One case study described a family with a splice-site mutation in PITX2 that led to microdontia and hypodontia across multiple generations (Dressler et al., 2010).

Mouse models have also reinforced the gene's importance. In PITX2-deficient mice, researchers have observed defective enamel, delayed tooth eruption, and malformed roots (Sun et al., 2024). These findings suggest that even subtle dental anomalies may reflect underlying genetic variants, particularly when several traits co-occur.

While PITX2 mutations are uncommon, their influence demonstrates how genes shape even routine anatomical variations. When dentists encounter missing or malformed teeth, considering a genetic basis may provide valuable context and inform referral decisions.

Using Genetic Clues

Understanding the genetic basis of dental morphology supports more precise treatment and better patient communication. Radiographs, clinical exams, and patient histories already form the foundation of diagnostic work. When root anomalies, congenital absences, or unusual crown forms are observed, considering their genetic origins can sharpen clinical interpretation.

Family and cultural context also matter. If a patient presents with multiple anomalies that resemble those seen in close relatives, a genetic referral may be warranted. Clinicians who recognize when to explore these connections can provide more informed and proactive care.

In the operatory, sharing the biological background behind an unusual tooth form can help patients feel more supported. For example, a teenager with missing lateral incisors may feel self-conscious. Explaining that the trait reflects inherited biology rather than a developmental error can improve case acceptance and build trust. These conversations help reframe abnormalities as differences rooted in ancestry, not flaws that simply need fixing.

Forensic and Historical Context

Teeth can preserve their structure long after other biological tissues degrade, making them uniquely valuable in forensic science. Variants like EDAR V370A help estimate ancestry when DNA is unavailable or degraded. For example, the presence of three-rooted molars or shovel-shaped incisors can support assessments that an individual may have East Asian or Indigenous American ancestry (Fujita et al., 2012).

These features carry not only clinical value but also anthropological significance. Their distribution patterns reflect ancient human migration routes, such as the movement across Beringia into the Americas. In this way, tooth morphology acts like a biological passport, serving as a record of human evolution.

Emerging research has also connected dental variation to interbreeding between early Homo sapiens and archaic species. The HS3ST3A1 gene, associated with enamel development, may have entered the modern gene pool through Denisovan or Neanderthal admixture. This gene may contribute to variations in enamel thickness and crown morphology (Bailey et al., 2019). While further studies are needed, these findings expand our understanding of how evolution shapes modern anatomy.

Clinical Application, Patient Insight

Genetic factors that influence tooth structure matter in everyday practice. Dentists regularly observe anatomical differences during exams and procedures, but recognizing when those differences reflect inherited patterns can shape how treatment is approached and discussed. A variant that explains why a patient presents with an atypical root formation or missing teeth may also explain why those same features are seen in a parent or sibling. When the connection is understood, the clinical picture becomes clearer.

What begins as an unusual finding on a radiograph or during a routine exam may carry more profound significance. Knowing when to pause, ask about family history, and document what is observed can strengthen treatment planning. It also helps determine whether a referral or further evaluation is appropriate. When similar traits appear across family members, it can point to an inherited pattern. Noting that early makes it easier to watch for related concerns down the line, especially in children or teens.

One cannot overlook how these subtle conversations help patients feel respected, informed, and supported. Even a brief explanation of the biology behind a patient's tooth shape can provide reassurance. For a patient concerned about atypical anatomy, understanding that their features reflect long-established genetic patterns can turn a moment of concern into one of curiosity and confidence.

Teeth Hold A Meaningful History

Tooth morphology is far from arbitrary. It reflects a genetic blueprint influenced by biology, family heritage, and extensive human history. Genes like EDAR and PITX2 do more than explain the form and structure of teeth; they offer insights into development, identity, risk assessment, and therapeutic decisions. Understanding these patterns does not change the basics of good dentistry. It adds depth. It helps dentists explain findings more clearly, make informed decisions, and connect the dots when a patient’s anatomy is outside the norm. Sometimes, just knowing the reason behind a trait can help a patient feel more at ease with their own features. 

Each oddly-shaped incisor or molar presents more than a technical challenge. It holds a record of human evolution and a blueprint for personalized care. Dentistry that engages with this complexity stands to be more personalized, more precise, and more profoundly human.

References

1. Kimura, R., Yamaguchi, T., Takeda, M., et al. (2009). A common variation in EDAR is a genetic determinant of shovel-shaped incisors. American Journal of Human Genetics 85(4):528–535. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756549. Accessed June 9, 2025.
2. Tao, J., Yamashita, T., et al. (2021). The human EDAR 370V/A polymorphism affects tooth root morphology potentially through modification of a reaction-diffusion system. Scientific Reports. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7933414. Accessed June 9, 2025.
3. Dressler S, Meyer-Marcotty P, Weisschuh N, Jablonski-Momeni A, Pieper K, Gramer G, Gramer E. Dental and Craniofacial Anomalies Associated with Axenfeld-Rieger Syndrome with PITX2 Mutation. Case Rep Med. 2010;2010:621984. doi: 10.1155/2010/621984. Epub 2010 Mar 21. PMID: 20339518; PMCID: PMC2842968.
4. Sun, Y., et al. 2024. PITX2 expression defines early tooth development and enamel knot formation in mice. Development. https://journals.biologists.com/dev/article/147/11/dev186023. Accessed June 9, 2025.
5. Fujita, H., et al. 2012. A morphofunctional hypothesis for selection on EDAR V370A. Journal of Dental Anthropology 34(1):59–72. Accessed via journal.dentalanthropology.org. Accessed June 9, 2025.
6. Bailey, S. E., et al. (2019). Three-rooted lower molars in Denisovans and modern Asians suggest gene flow. Proceedings of the National Academy of Sciences 116(28):13971–13976. https://www.pnas.org/content/116/28/13971. Accessed June 9, 2025.

Author: With over 15 years as an award-winning journalist, editor, and writer, Genni Burkhart has covered everything from news, politics, and healthcare to finance, corporate leadership, and technology. As editor-in-chief of The Incisor newsletter and blog and features writer at DOCS Education, she brings a refreshing insight and a passion for storytelling to the world of sedation dentistry.