The analysis of dental remains is a valuable tool to archaeologists. Teeth are hard, highly mineralised and chemically stable, therefore preserve well and are one of the most commonly found animals remains.Forshaw 2015, p. 51. Analysis of these remains yields a wealth of information. It can not only be used to determine the sex Nagare et al. 2018, p. 61. and age of the individual Dirkmaat 2012, p. 214. whose mandibular or dental remains have been found, but can also shed light on their diet, pathology,Forshaw 2015, p. 52. and even their geographic origins through isotope analysis.Forshaw 2015, p. 59.
As a result, dental analysis is applied to both the recent and long-dead. It is a crucial part of forensic anthropology in terms of identifying the deceased,Krishnan et al. 2015, p. 250. and can be applied to archaeological remains to learn about an individual from a burial, or track larger changes in diet of a population if more data is available.
The study of teeth in archaeological contexts is supported by the Dental Anthropology Association, founded in 1986, which publishes the peer-reviewed journal Dental Anthropology."Dental Anthropology Association". https://dentalanthropology.org/
Age determination The methods to estimate age based on dentition are divided into two groups; the methods based on the development and growth of teeth that are applied to infants, children and juveniles, and the methods that are based on changes to dentition after formation used to estimate the age of adults.Adserias-Garriga 2019, p. 78.
It is easier to estimate the age of an individual using their dental remains during infancy and childhood than it is during adulthood since the emergence of teeth and their development in young people provide good and relatively reliable indicators of age.Brothwell and Pollard 2005, p. 240. Since teeth eruption follows a pattern, with the eruption of deciduous teeth occurring after birth to the end of infancy at the age of two, and permanent teeth erupting between the ages of five and fourteen, observing which teeth are erupted and developing in a mandible, or whether a tooth is deciduous or permanent in isolated remains, can reveal the age of the individual. This evaluation of tooth eruption can be done by viewing images of the dental remains via radiographs, MRIs, and CT scans.Adserias-Garriga 2019, p. 84.
Among adults with fully developed dentition, numerous techniques have been developed for age estimation by looking at various characteristics including periodontosis, cementum apposition, tooth-root translucency, root resorption, secondary dentine deposition and the attrition of the occlusal surface.Brothwell and Pollard 2005, p. 241. The tooth-root translucency method was pioneered in the 1990s and involves taking two measurements of a tooth when viewing it under a light, and then placing the values into a formula to gain an age estimation. Another common method involves counting the number of alternating light and dark bands in the cementum. Methods based on post-formation changes rely more on microscopic observations. A more holistic approach can be taken to assess the overall wear of the teeth, for example using the Brothwell chart of 1963.Mays et al., 2022, p. 1. Assessing teeth wear is common due its reliable indicator of age than signs of wear in bones.Mays et al., 2022, p. 2.
Sex determination The simplest methods of estimating the sex of an individual are based on common differences in size between the teeth of male and female individuals. The dimensions measured are the mesiodistal and buccolingual dimensions, and are commonly applied to the mandibular canines which show the greatest sexual dimorphism, but premolars and some molars and maxillary incisors also show size differences between males and females.Nagare et al. 2018, p. 62. Other morphological differences can be used to support sex estimation, for example by comparing the frequencies of discrete traits such as the deflecting wrinkle of the lower first molars and the distal accessory ridge of the canines.Vodanović et al. 2007, p. 906. These nonmetric dental traits are typically recorder using the Turner-Scott Dental Anthropology System (formerly the Arizona State University Dental Anthropology System, or ASUDAS), which provides standardized reference plaques and scoring procedures for over 40 crown and root traits, enabling systematic comparison of dental morphological variation across populations.Scott, G.R.; Irish, J.D.; Turner, C.G. (2016). "The Turner-Scott Dental Anthropology System". A Companion to Dental Anthropology. Wiley-Blackwell. pp. 190–237. One potential problem with these forms of morphological identification, aside from the fact that the variation in teeth is continuous, is that the possibility of mistakes increases in cases where the morphology of the teeth has been altered by taphonomic processes.Vodanović et al. 2007, p. 912.
More advanced methods for sex determination involve DNA analysis, in which DNA extracted from dental pulp can be amplified using the polymerase chain reaction and then analysed. However this is a destructive process that tends to destroy the sample, either via the cryogenic grinding, or the opening of the root canals to extract the pulp.Ramarkrishnan et al. 2015, p. 6. Protein enamel analysis is another molecular technique in which different signatures of amelogenin in males and female individuals provides the basis of sex estimation.Nagare et al. 2018 p. 63.
Population affinity Dental morphological traits can also be used to estimate the population affinity of skeletal remains. Certain nonmetric traits occur at significantly different frequencies across major geographic populations. For example, incisor shoveling is found at higher frequencies in East Asian and Indigenous American populations, while Carabelli's cusp is more common in European-derived populations.Scott, G.R.; Turner, C.G. (1997). The Anthropology of Modern Human Teeth: Dental Morphology and its Variation in Recent Human Populations. Cambridge University Press. These patterns of dental morphological variation reflect underlying genetic differences between populations and have been used to trace migration routes and population relationships, including the three-wave model of migration into the Americas proposed by Turner.Turner, C.G. (1987). "Late Pleistocene and Holocene population history of East Asia based on dental variation". American Journal of Physical Anthropology. 73 (3): 305–321.
Diet and disease Since dental apparatus comes into direct contact with the foods consumed, teeth provide direct and some of the best evidence for the diet that an individual ate in life.Forshaw 2015 p. 51. The analysis of features on the teeth and jaws such as cavities, hypoplasias and striations can all reveal the foods that were consumed.Forshaw 2015 p. 52.
Starting with cavities, usually the result of high-sugar and high-carbohydrate diets, the prevalence of cavities in dental remains suggests the existence of such foods in the diet. Dental analysis of skeletal remains of hunter-gatherers in Morocco from 15,000 -13,700 years BP revealed a diet that was high in starchy foods may have caused high rates of tooth decay seen in the population.Pearson 2014 When inferring a high-carbohydrate and sugar diet from the prevalence of cavities, it is necessary to consider other factors that may increase the severity of dental diseases such as the immune system of the individual. If it is already impaired by other infections then cavities and signs of dental diseases will be more prevalent, thus such features should not automatically be attributed to just more sugar consumption.Forshaw 2015 p. 53.
Enamel hypoplasia is the result of disturbances in the enamel, and can take the form of thinner or missing areas of enamel, lines, furrows and pits.Nikita 2017, p. 333. Most enamel hypoplasias are the result of external, negative, environmental conditions, like poor nutrition and diseases, and as a result they can tell us about the lifestyle of the individual.Forshaw 2015, p. 55. Metabolic disorders resulting from poor diet or disease have a particularly significant effect on enamel, and a range of other non-specific diseases can cause the feature, such as measles, diphtheria and deficiency in vitamin A, D and C.Peko 2013, p. 14. The identification of enamel hypoplasias is best done with microscopic analysis of tooth thin sections.Upex et al. 2012, p. 3. The position of the hypoplasia on the tooth can also tell you when childhood stress caused disruption in the tooth enamel occurred by measuring the distance from the hypoplasia to the cemento-enamel junction since the enamel does not remodel once formed.
When there is a large sample size, tracking changes in dentition over many generations can show how diets and lifestyles changed, this line of inquiry has been successful in many cases. An example that looked at enamel hypoplasia was conducted by Starling and Stock who examined the hypoplasias of five populations in the Nile Valley from different time periods. The population from 13,0000 to 15,000BCE had fewer hypoplasias that the proto-agriculturalist population of 5000-4000 BCE, which demonstrates that the period in which early agriculture emerged was one with high levels of stress.Forshaw 2015, p. 56. In a similar vein, dental remains of a population from Roman Cibalae were analysed and revealed a significantly higher frequency of enamel hypoplasias in females than males. This has been interpreted as showing that women in the area were worse off in terms of diet and disease.Peko 2013, p. 12.
Some hypoplasias are related to inherited conditions. Stress is not the sole cause. Additionally, when hypoplasias do occur, the severity of the hypopplasia does not directly correlate to the severity of stress - characteristics such as tooth morphology, enamel structure, developmental timing and speed are all factors as well.Towle and Irish 2020, p. 1. As a result, it is necessary to use multiple teeth types to infer the stress that an individual may have experienced.
Tooth wear is another feature of dental remains that can be analysed to infer past diets. Wear that is the result of natural contact between upper and lower teeth is called attrition, and wear that is the result of external objects like food coming into contact with the teeth is called abrasion.Mahajan 2019, p. 1 Wear is further subdivided into that which is studied and seen with the naked eye (macrowear), and that which is studied and seen with a microscope (microwear).Mahajan 2019, p. 1-2. This microwear constitutes the pits and scratches seen on the enamel surface, and different patterns of microwear can occur as a result of different diets.Forshaw 2015, p. 8.
Some of the most conspicuous microwear constitutes chips in the teeth seen in irregular surfaces, in contrast to crown wear which is more gradual and incremental.Scott and Winn 2011, p. 723. Chipping usually occurs when the enamel cannot withstand the force exerted by the jaws, and as a result can cause tooth fracture, particularly when a foreign element is between the teeth. Causes, therefore, include inclusions within food, such as a bit of grit or bone, or more commonly today, actions like biting your nails or chewing a pen. Injuries and force also cause dental trauma like this.Scott and Winn 2011, p. 724 In relation to inferred diet, chipping can suggest inclusions within a meal, potentially bits of loose grindstone making its way into the finished cereal, studies have also shown that hunter-gatherers have more chipping on their molars, whilst agricultural communities have the highest frequencies of chippings on the incisors.Scott and Winn 2011, p. 729.