Elsevier

HOMO

Volume 68, Issue 3, May 2017, Pages 157-166
HOMO

The study of dental occlusion in ancient skeletal remains from Mallorca (Spain): A new approach based on dental clinical practice

https://doi.org/10.1016/j.jchb.2017.05.002Get rights and content

Abstract

Occlusal characteristics, fundamental to assess the presence of malocclusion, have been often unexplored in bioarchaeological analyses. This is largely due to the fragmented condition of the skeletal remains. By applying a method that considers dental and maxillary features useful to evaluate occlusion in ancient fragmentary material, the purpose of this work is to define the occlusal features and explore the causes of malocclusion in a mediaeval population from Mallorca. The findings of this study suggest that normocclusion was present in ca. 60% of the individuals (N = 31), and that some characteristics, such as molar relationship, were slightly different from those of modern populations. The analysis of the occlusal features revealed for example that open-bite was absent in 85% of the sample, posterior open-bite was completely absent and overbite and overjet were normal in around 90% of the individuals. Statistically significant correlations between canine and molar relationships and between molar relationship and dental wear of the superior and inferior canines and incisors were observed. In addition, wear could affect the curve of Spee. All these findings strengthen the hypothesis that in ancient times malocclusion was not as generalized as in modern times. Although the factors that lead to malocclusion throughout centuries could have several causes, we suggest that in this population dental wear, which is strongly associated with the diet, was the fundamental causing factor.

Introduction

Dental occlusion is the relationship between both dental arches when the maximum number of contacts between upper and lower teeth is achieved. A correct dental occlusion “refers to how well the teeth are arranged individually and one-to-another within and between the dental arches” (Harris and Corruccini, 2008:1). Conversely, malocclusion is considered a discrepancy between teeth that can modify the maxillary shape, sometimes affecting mastication, diet and health. If these irregularities of the teeth are severe, they should be corrected by orthodontic treatments.

Orthodontic treatments were not common in the past, although evidence of their use dates back to ancient Egypt (Nunn, 2002). Etruscans, for example, employed gold appliance to support inserted teeth, which was useful for improving mastication. However, this bridge work type had mainly an aesthetic rather than a functional purpose (Frati and Giulierini, 2002).

Despite the scarce archaeological and historical evidence of orthodontic treatments, the issue of malocclusion in past populations is still largely unexplored. Moreover, the study of dental occlusion is not frequently included in bioarchaeological analyses due to often fragmented and incomplete skeletal remains, and in particular, the lack of a suitable method for the study of such ancient remains. The analysis of occlusion is generally conducted only when jaws are occluded with condyles placed in their fossae and taking patterns of attrition as a reference for dental position. However, complete skulls from ancient contexts are unusual; in the most habitual scenario, samples suitable for dental occlusion analysis are just a small percentage of the total number of skeletons available. This relates to the vulnerability of bones and the importance of a proper recovery and management of samples, from excavation to laboratory. In several cases the taphonomic process is causative of fragmentation and lack of archaeological skeletal material (Duday, 2006).

The specific aims of this study are: (1) to analyze the occlusal characteristics of a mediaeval population from Mallorca applying the method for ancient fragmentary material elaborated in the frame of this project (Fiorin et al., 2014); (2) to investigate whether there is an association between the analyzed variables and, when possible, to compare them with ancient or modern material; (3) to estimate the prevalence and the severity of malocclusion and to investigate the factors that may have caused it.

Section snippets

Material and methods

The material analyzed in this study belongs to the mediaeval necropolis of Can Reiners (Mallorca, Spain). The skulls were frequently incomplete and fragmented, and thus the material employed for the analysis of occlusion was not numerous (31 of 156 individuals, 19.9%). The samples were chosen according to the state of preservation of the jaws (Fig. 1A). Mandible and maxilla were well preserved in some cases, although in other cases only one fragment or side of the dental arch was present.

Anthropological information

Concerning sex, 71% of the individuals were male, 22.6% were female and 6.4% were undetermined. The sample is composed by 22.6% of young adults, 64.5% of adults and 12.9% of mature adults (Table 1).

Dental features

Among the jaws of the 31 individuals, 93.4% of alveolar cavities and 76.6% of teeth were preserved. Ante mortem tooth loss concerned 2.4% of the alveolar cavities and adult and mature individuals of both sexes were involved. Loss affected mostly the maxillary molars (32%) and premolars (41%). Dental

Discussion

The analysis of the 31 individuals from the mediaeval necropolis of Can Reiners showed that pathologies such as dental decay and tooth loss were not frequent and affected only adult and mature individuals, premolars and molars being the teeth most commonly affected. Change of molar or canine relationship could be caused by the inclination of a tooth subsequent to loss of the adjacent tooth during life, which was not observed in the sample. In addition, impacted, partially erupted or absent

Acknowledgements

The authors thank Dolores Ceperuelo, Eduardo Chimenos and María José Adserias for helping them with the analysis of occlusion conducted on the skeletal remains. They also would like to thank the anonymous reviewers for their helpful and constructive comments which contributed to improve the final version of this article.

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