A dental revolution: The association between occlusion and chewing behaviour.

Christopher Martin Silvester,Simon Hillson,Ottmar Kullmer,Luca Bondioli

doi:10.1371/journal.pone.0261404

Abstract

Dentistry is confronted with the functional and aesthetic consequences that result from an increased prevalence of misaligned and discrepant dental occlusal relations in modern industrialised societies. Previous studies have indicated that a reduction in jaw size in response to softer and more heavily processed foods during and following the Industrial Revolution (1,700 CE to present) was an important factor in increased levels of poor dental occlusion. The functional demands placed on the masticatory system play a crucial role in jaw ontogenetic development; however, the way in which chewing behaviours changed in response to the consumption of softer foods during this period remains poorly understood. Here we show that eating more heavily processed food has radically transformed occlusal power stroke kinematics. Results of virtual 3D analysis of the dental macrowear patterns of molars in 104 individuals dating to the Industrial Revolution (1,700–1,900 CE), and 130 of their medieval and early post-medieval antecedents (1,100–1,700 CE) revealed changes in masticatory behaviour that occurred during the early stages of the transition towards eating more heavily processed foods. The industrial-era groups examined chewed with a reduced transverse component of jaw movement. These results show a diminished sequence of occlusal contacts indicating that a dental revolution has taken place in modern times, involving a dramatic shift in the way in which teeth occlude and wear during mastication. Molar macrowear suggests a close connection between progressive changes in chewing since the industrialization of food production and an increase in the prevalence of poor dental occlusion in modern societies.

Highlights

An increased prevalence of misaligned and crowded dental arches among industrialised groups has been attributed to the consumption of a more heavily extraorally processed diet [1, 2]
Dental practitioners need to be aware of the functional consequences changes in food properties have had on the masticatory system and craniofacial development over the past three centuries
The differences interpreted in masticatory power stroke between the pre-industrial and industrial groups in the current study likely underlay the developments in occlusion and craniofacial morphology that have been previously reported as a result of the dietary changes that accompanied industrialisation [2, 14]

Summary

Introduction

An increased prevalence of misaligned and crowded dental arches among industrialised groups has been attributed to the consumption of a more heavily extraorally processed diet [1, 2]. Many of the individuals examined dating to the medieval period were derived from lay cemeteries. The cemetery of All Saint’s Church, Fishergate, was situated south of the medieval city walls of York on the east side of the River Foss. The occupants of the cemetery were likely civilians drawn from a range of socioeconomic groups. It was likely established in the late 11th century and fell out of use shortly after 1585 CE [53]. The skeletons examined from Hereford Cathedral were derived from the excavation of the area west of the Bishop’s Cloister.

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