Loss of molar occlusion and mandibular morphology in adults in an ancient human population consuming a coarse diet

Abstract

The purpose of the study is to investigate the link between number of molar teeth retained in occlusion and mandibular morphology in adults in an ancient, high dental wear human population. The study material comprises skeletons from Mediaeval Wharram Percy, England (N = 50 female, 69 male adults). It was hypothesized that adults retaining fewer occluding molars would show reduction in mandibular dimensions, particularly in the ascending ramus and gonial regions where the main muscles of mastication have their insertions. Molar occlusal status is assessed using the concept of functional units. Mandibular morphology is assessed using a suite of ten linear measurements plus the mandibular angle. Results show no evidence for any association between number of molars retained in occlusion and mandibular angle. There was an association between mandibular size and number of molars retained in occlusion, with smaller mandibular dimensions in those retaining fewer occluding molars. Some measurements were affected more than others so that there was also some shape alteration. Alteration of mandibular dimensions was more clearly demonstrable in females than in males. Only in females could significant reduction in the ascending ramus and gonial regions be demonstrated. Reasons for the apparent difference in response to loss of molar occlusion between male and female mandibles are unclear, but sex differences in bony metabolism mediated by hormonal factors may be implicated. Results suggest that care should be exercised when including mandibles from individuals showing loss of molar occlusion in morphological studies.

Mandibular morphology in two archaeological human skeletal samples from northwest Europe with different masticatory regimes

“…As well as leading to localised alveolar resorption at the tooth socket, ante-mortem molar loss appears to result in alteration of some other aspects of the conformation of the adult mandible, most likely due to alteration of biomechanical forces with progressive loss of molar dentition (Mays, 2013), the teeth at which maximum bite forces are normally generated (Helkimo et al, 1977;Linderholm and Wennström, 1970). Ideally, one would therefore wish to restrict study to mandibles retaining the full compliment of molar teeth.…”

Asynchronous dentofacial development and dental crowding: a cross-sectional study in a contemporary sample of children in France

“…Several arguments published in the literature can be put forward to support this interpretation of our results. For example, a recent study showed that there was an association between mandibular size and number of molars retained in occlusion, with smaller mandibular dimensions found in individuals retaining fewer occluding molars [38]. A study of nonhuman primates found that hyraxes raised on cooked food had significantly less growth (approximately 10%) in the ventral (inferior) and posterior portions of the face [39].…”

The relationship between ante‐mortem molar loss and mandibular ramus shape in an archaeological population from Korea

“…Although interpopulation variation in mandibular shape is expected to reflect differing masticatory regimes (Katz, Grote, & Weaver, ; von Cramon‐Taubadel, ), it is also possible for intrapopulation variation in mandibular morphology to be related to altered masticatory function (Mays, ). Specifically, ante‐mortem tooth loss (AMTL) is likely to affect (e.g., reduce) masticatory load, leading to alterations in mandibular morphology (Mays, ). AMTL is most likely to occur in relation to oral pathology (e.g., abscess), osteopenia, or osteoporosis related to the aging process (Darcey et al, ; Larsen, ; Mays, ; Taguchi, Tanimoto, Suei, & Wada, ).…”

“…Specifically, ante‐mortem tooth loss (AMTL) is likely to affect (e.g., reduce) masticatory load, leading to alterations in mandibular morphology (Mays, ). AMTL is most likely to occur in relation to oral pathology (e.g., abscess), osteopenia, or osteoporosis related to the aging process (Darcey et al, ; Larsen, ; Mays, ; Taguchi, Tanimoto, Suei, & Wada, ). Although AMTL is generally more likely to occur as individuals age, many archaeological populations show a higher prevalence of AMTL than modern populations due to their more strenuous diets and/or poor oral health (Larsen, ; Mays, ).…”

“…AMTL is most likely to occur in relation to oral pathology (e.g., abscess), osteopenia, or osteoporosis related to the aging process (Darcey et al, ; Larsen, ; Mays, ; Taguchi, Tanimoto, Suei, & Wada, ). Although AMTL is generally more likely to occur as individuals age, many archaeological populations show a higher prevalence of AMTL than modern populations due to their more strenuous diets and/or poor oral health (Larsen, ; Mays, ). AMTL impacts masticatory function, by decreasing muscle size (e.g., masseter muscle) and altering mandibular ramus morphology (Mays, ; Newton, McManus, & Menhenick, ; Newton, Yemm, Abel, & Menhinick, ).…”