Sexual dimorphism in permanent teeth of modern Greeks

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Abstract

Sex determination is considered an important step in reconstructing the biological profile of unknown individuals from a forensic context. Forensic anthropologists have long used teeth as an additional tool for sex determination as they resist postmortem destruction. In this case the use of population-specific data is necessary since sexual dimorphism varies between different populations. Currently there are no odontometric standards for determining sex in Greek populations. The purpose of this study is to examine the degree of sexual dimorphism in permanent teeth of modern Greeks. A total of 839 permanent teeth in 133 individuals (70 males and 63 females) from the Athens Collection were examined. Mesiodistal and buccolingual crown and cervical diameters of both maxillary and mandibular teeth were measured. It was found that males have bigger teeth than females and in 65 out of 88 dimensions measured, male teeth exceeded female teeth significantly (P < 0.05). Canines were the most dimorphic teeth followed by first premolars, maxillary second premolar and mandibular second molar. Although other teeth were also sexually dimorphic they did not have a statistically significant difference in all dimensions. The most dimorphic dimension was buccolingual cervical diameter followed by buccolingual crown diameter. A comparison of sexual dimorphism in teeth between different populations showed that it differs among different groups. European population groups presented the highest degree of sexual dimorphism in teeth whereas Native South Americans the lowest.

Introduction

Sex determination is considered an important step in reconstructing the biological profile of unknown individuals from the forensic context. The most commonly used techniques are based on the assessment of the morphological characteristics of the pelvis and skull [1]. However, it is not uncommon to recover the pelvis and the skull in a fragmentary state in forensic settings. In this case, teeth can be used as an additional tool for sex determination as they are very resilient to destruction and fragmentation in comparison with skeletal tissues. Metric and non-metric analyses of the human dentition have played an important role in human biological research and have formed a central focus in the field of dental anthropology for over a century [2], [3].

Most studies of sexual dimorphism in tooth size are based on the measurement of the mesiodistal and buccolingual crown diameters [4], [5], [6]. However, a number of other studies have used alternative measurements such as the mesiodistal and buccolingual cervical and diagonal diameters of teeth [7]. In addition, some investigations have examined the distances of molar cusps [8], while some more recent research has focused on studying crown tissue measurements since it has been proved that tooth formation and tissue proportions are highly regulated by sex-linked genes [9], [10], [11], [12], [13], [14], [15], [16], [17], [18]. Sexual dimorphism in crown morphology and size of the permanent dentition is the result of the different amount of enamel, dentin, and pulp tissue between males and females.

A number of investigations have established that sexual dimorphism exists in the permanent dentition of humans particularly in the canines, which exhibit the greatest degree of difference [2], [11], [12], [14], [15], [19], [20], [21]. According to Butler [22] and Garn et al. [15], a “canine field” exists in the permanent dentition around which adjacent teeth (lateral incisors and first premolars) share a tendency for greater sexual dimorphism than do more distant teeth. In the past, research on sex differences in tooth morphology has assessed the dimorphism of the mesiodistal and buccolingual diameters of tooth crowns [15], [19], [23]. The extent of this sexual dimorphism varies among populations [14] although current intra-specific data may not be representative of the total range of variation across archaeological and contemporary populations [24]. Furthermore, no positive correlation exists between the deciduous tooth size and the degree of sexual dimorphism [25]. Metric approaches confirmed that sexual dimorphism exists in overall crown size with values for males exceeding on average those for females [26]. As sexual dimorphism varies between different populations the collection of population-specific data is of major importance. Thus far there are no odontometric standards of Greek populations for sex determination.

The purpose of this study is to analyze crown and cervical tooth dimensions and assess the degree of sexual dimorphism in permanent teeth of modern Greeks.

Section snippets

Materials and methods

A total of 839 permanent teeth from 133 individuals (70 males and 63 females) from the Athens Collection were examined. The Athens Collection of the Department of Animal and Human Physiology at the University of Athens currently consists of 225 skeletons of known sex, age, occupation, cause of death, and place of birth [27]. The skeletons belong to individuals who lived mainly in the second half of the twentieth century and come from cemeteries in the region of Athens. This sample is considered

Intra-observer error

Table 2 shows the intra-observer error between two measurements for each diameter and each tooth taken in different times using a paired t-test. For this analysis all maxillary and mandibular teeth were tested. In most cases there was no statistically significant difference between the base and the test measurement. However, a statistically significant difference was observed for cervical MD diameter in upper P1, lower C and lower M2, and for BL diameter in upper C and lower I1.

Sexual dimorphism

Table 3, Table 4

Intra-observer error

For the vast majority of dimensions that were measured in each tooth, there is no statistically significant difference between the base and the test measure. Nevertheless, the upper P1, lower C and lower M2 show intra-observer variation in cervical MD dimension and the upper C and lower I1 in BL dimension. Pérez-Pérez et al. [28] mention that the measurement error may be either systematic or random, depending not only on the researcher but also on the tool used, the variable measured and the

Conclusions

Our conclusions are summarized as follows:

  • Greek males have larger teeth than females.

  • Maxillary teeth are more sexually dimorphic than mandibular teeth.

  • Canines and first premolars in both jaws as well as maxillary second premolar and mandibular second molar are the most dimorphic teeth for all dimensions.

  • Although other teeth show an overall significant degree of sexual dimorphism, they do not show a statistically significant difference between males and females in every dimension examined.

  • The

Acknowledgements

The authors wish to thank Dr. Constantine Eliopoulos for his editorial suggestions on this paper. We also thank Dr. Velissaria Vanna for her assistance.

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