Labial talon cusp
A case study of pre-European–contact American Indians
Arion T. Mayes, PhD
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ABSTRACT
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Background. First documented by Mitchell in 1892, the talon cusp is a rare and much-debated morphological variant. The author presents a case study from a pre-European–contact American Indian population. In addition, the author addresses debates in the literature regarding the definition, etiology and description of the talon cusp and provides new evidence within an archaeological context.
Methods. The author examined the dentition of 301 skeletons for the presence or absence of talon cusp; five skeletons (2 percent) in the population had the trait.
Results. This skeletal sample exhibited variations of the labial talon cusp that can be graded.
Conclusions. The results of this study provide further evidence of the antiquity of labial talon cusp in the assemblage of modern humans and, in particular, in American Indians.
Key Words: Dental morphology; ectopic enamel; talon cusp; archaeology
First documented by Mitchell in 1892,1 the talon cusp is a rare and much-debated morphological variant. I present a case study from a pre-European–contact North American Indian population from the Late Woodland period (A.D. 300-A.D. 800). The Illinois Bluff–Titterington collection is housed at the National Museum of Natural History, Washington. P.F. Titterington, a dentist from St. Louis, excavated this collection from 33 burial mounds in Jersey County, Illinois, in the late 1920s and early 1930s. I examined 301 skeletons and recorded their dental morphology. I recorded the presence of labial talon cusps for five skeletons (2 percent) in this population.
There has been debate in the literature regarding the morphological description of the talon cusp.2–12 Llena-Puy and Forner-Navarro2 noted a lack of agreement in the definitions of some of the dental form anomalies. Generally located on the anterior dentition, the talon cusp trait has been described on the labial and lingual surfaces. On the lingual surface, it takes the form of a cingulum that has grown into a free-form cusp. Observations of a talon cusp on the labial surface enable us to better understand the origin of its name. Projecting from the tooth on the labial surface, the talon cusp has the appearance of an eagle’s talon from an occlusal view. Both labial and lingual talon cusps are rare forms of ectopic enamel not commonly discussed in the literature.2–5
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LINGUAL AND LABIAL TALON CUSPS
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A review of the literature suggests a difference in etiology for lingual and labial talon cusps, yet they are discussed as a singular entity with regard to form. Given my observations, it seems that lingual and labial talon cusps are two different traits necessitating the use of different terminology, but both fall within the category of ectopic enamel. Both forms of talon cusp have been observed and described in clinical studies.2–8,11,12
Researchers have used a grading system to describe lingual talon cusps.6 However, as far as I am aware, the labial talon cusp has not been described in the literature according to a grading system, nor have authors reported its occurrence with conditions such as double-shoveling (that is, raised mesial and distal margins on the labial surface). The population described below indicates that labial-form cusps, like lingual-form cusps, are subject to graded differences. Several characteristics of the labial talon cusp and its presence with other forms of ectopic enamel suggest a separate group of related characteristics.2–5,10 In American Indian populations, this trait often is observed in conjunction with marked double-shoveling, which gives the appearance of fluidity in the enamel, with the labial surface appearing wrinkled.
Although different studies have made opposing claims as to the occurrence rate of labial talon cusp in one sex over the other, one point is indisputable: this trait has been observed in both males and females, as well as in many of the world’s populations.2–8,12 Mays8 reported that the highest occurrence rate was in Asians but made no mention of American Indians. However, hypotheses regarding relationships between populations suggest a strong link between modern American Indian and Asian populations.13 Therefore, observations in both populations follow a predictable, yet potentially varied, pattern. It is not surprising, then, that researchers have documented the talon cusp trait in archaeological American Indian populations.9,10
In addition to the first debate regarding the identification and description of talon cusp—whether lingual or labial—is a second debate regarding its cause. Some authors3,5,8,9 have suggested that environmental factors are the cause of the talon cusp, with damage to the tooth bud occurring during development. However, greater evidence points toward a genetic influence.4,5,8–12 Variations in the description of this trait in the modern dental literature are mirrored somewhat in archaeological publications.8–10 Continued examination of larger sample sizes from various geographical regions, as well as a range of expression, negates the hypothesis that this variation in morphology is caused by damage to the tooth bud during development, but, rather, supports a genetic influence during germination.
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TALON CUSP STAGES
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Hattab and colleagues6 graded the lingual talon cusp from 1 (the most extreme form) to 3 (slightest form). However, this system is counterintuitive to that typically used by dental anthropologists, in which the lowest score reflects the lowest stage of morphological trait and the highest score reflects the highest stage. The labial talon cusp, when observed carefully, also falls into one of three stages.
- – Stage 1, the slightest form, consists of a slightly raised triangle on the labial surface of an incisor extending the length of the crown, but not reaching the cementoenamel junction or the incisal edge. Adjusting the tooth, or the light source, to cause shadows to form may be necessary to observe the cusp, which can be palpated (Figure 1
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- – Stage 2, the moderate form, is a raised triangle on the labial surface of an incisor that extends the length of the crown, does not reach the cementoenamel junction, but does reach the incisal edge. Labial talon cusps in this stage can be observed clearly and palpated easily.
- – Stage 3, the most extreme form, is a free-form cusp extending from the cementoenamel junction to the incisal edge on the labial surface of an incisor (Figure 2).
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ARCHAEOLOGICAL STUDY OF AMERICAN INDIANS
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An archaeological study of skeletal remains from the Illinois Bluff–Titterington collection revealed that they exhibited an interesting degree of variation in the labial form of talon cusp that can only be described as appearing in grades not definable as simply "present" or "absent" (stages 1–3). Figure 2
is an example of the extreme form of labial talon cusp. Note the marked lingual shoveling and double-shoveling, as well as an interruption groove.
Of particular interest are the observations made in multiple skeletons in this population that exhibited what appear to be two grades (slight [stage 1] and moderate [stage 2]) other than the extreme form of labial talon cusp. Morphological differences followed a pattern similar to that of the most extreme form.
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DOUBLE-SHOVELING
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The evidence from this population of American Indians suggests another trait, double-shoveling, that might be added to the inventory of dental characteristics associated with labial talon cusp. I observed this trait in all five skeletons with labial talon cusp in this Illinois Bluff archaeological population. Double-shoveling is of particular interest given its possible relationship to the talon cusp and because it, too, can be identified via intermediate grades rather than being labeled as simply "present" or "absent." In addition, a relationship is present—at least through visual observations—between the talon cusp and other forms of ectopic enamel.10
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DISCUSSION
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Talon cusps occur in a wide variety of world populations and most often are identified in the clinical setting. Therefore, researchers and clinicians should not be surprised that they have been observed among American Indian populations. In 1892, Mitchell1 first documented this morphological variant in the modern dental literature. In 2005, Mays8 documented the presence of a talon cusp in the primary dentition of a juvenile skeleton from medieval England (A.D. 950-A.D. 1350) and believed this to be the oldest case documented. However, archaeological investigations in the United States,9,10 including the investigation that revealed the five skeletons from the Late Woodland period, provide evidence of much greater antiquity for this trait, particularly among American Indians.
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CONCLUSION
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The labial talon cusp is rare in the dental literature, and no mention has been made of intermediate forms, having been described only as "present" or "absent." Most observations of labial talon cusp probably are of the extreme form, due, in part, to the fact that most documentation has taken place in clinical studies in which a patient seeks treatment for an irritation caused by an extreme form. Clinicians typically reduce the cusp gradually via the application of topical fluoride4 or a calcium hydroxide pulpotomy.4 This allows for the slow removal of a sensitive area, often involving both enamel and dentin, and is done primarily for cosmetic purposes.3–5
I have described a study of a pre-European–contact American Indian archaeological population excavated from Illinois Bluff that has allowed observations of intrapopulation variation of the labial talon cusp. This study has enabled me to observe the labial talon cusp in various stages, as well as in association with double-shoveling, which has not been discussed in the dental literature.
Finally, this study adds to the growing database of information regarding the occurrence rate of labial talon cusp in world population and specifically that among American Indians. The antiquity (A.D. 300-A.D. 800) and high prevalence of this morphological variant in American Indians provide evidence of a greater history and affinity to human ancestral populations, given that it predates European contact.
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FOOTNOTES
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Dr. Mayes is an assistant professor, Department of Anthropology, San Diego State University, 5500 Campanile Dr., San Diego, Calif. 92182-6040, e-mail "amayes{at}mail.sdsu.edu". Address reprint requests to Dr. Mayes.
The research presented here was funded by the National Museum of Natural History, Smithsonian Institution, Predoctoral Fellowship Program and the Native American Awards Program, Smithsonian Institution, Washington. Additional funding was provided by the Clark Scholarship Fund and Walker Van Riper Fund, University of Colorado Museum of Natural History, and the Beverly Sears Graduate Student Grant, University of Colorado, Boulder.
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REFERENCES
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- Mitchell WH. Letter to the editor. Dental Cosmos 1892;34:1036.
- Llena-Puy MC, Forner-Navarro L. An unusual morphological anomaly in an incisor crown: anterior dens evaginatus. Med Oral Patol Oral Cir Bucal 2005;10(1):15–6, 13–5.[Medline]
- Batra P, Enocson L, Hagberg C. Facial talon cusp in primary maxillary lateral incisor: a report of two unusual cases. Acta Odont Scand 2006;64(2):74–8.[Medline]
- Oredugba FA. Mandibular facial talon cusp: case report. BMC Oral Health 2005; 5:9. Available at: "www.biomedcentral.com/1472-6831/5/9". Accessed Feb. 13, 2007.
- Shashikiran ND, Babaji P, Reddy VV. Double facial and a lingual trace talon cusps: a case report. J Indian Soc Pedod Prev Dent 2005; 23(2):89–91. Available at: "www.jisppd.com/article.asp?issn=0970-4388;year=2005;volume=23;issue=2;spage=89;epage=91;aulast=Shashikiran". Accessed Feb. 13, 2007.[Medline]
- Hattab FN, Yassin OM, al-Nimri KS. Talon cusp in permanent dentition associated with other dental anomalies: review of literature and reports of seven cases. ASDC J Dent Child 1996;63(5):368–76.[Medline]
- Hattab FN, Hazza’a AM. An unusual case of talon cusp on geminated tooth. J Can Dent Assoc 2001;67(5):263–6.[Medline]
- Mays S. Talon cusp in a primary lateral incisor from a medieval child. Int J Paediatr Dent 2005;15(1):67–72.[Medline]
- Harris EF, Owsley DW. Talon cusp: a review with three cases from native North America. J Tenn Dent Assoc 1991;71(1):20–2.[Medline]
- Mayes AT. Patterns through time: interactions between changes in subsistence and human dentition at Illinois Bluff, Jersey County, Illinois, and Spiro Mounds, Oklahoma (dissertation). Boulder: University of Colorado; 2001.
- Rusmah M. Talon cusp in Malaysia. Aust Dent J 1991;36(1):11–4.[Medline]
- Glavina D, Skrinjaric T. Labial talon cusp on maxillary central incisors: a rare developmental dental anomaly. Coll Antropol 2005; 29(1):227–31.[Medline]
- Scott RG, Turner CG II. The anthropology of modern human teeth: Dental morphology and its variation in recent human populations. Cambridge, England: Cambridge University Press; 1997.
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ABSTRACT
LINGUAL AND LABIAL TALON...
