Functional wear in the Aboriginal from Yuendumu: A longitudinal study

Dental wear is a gradual and physiological process that consists of loss of tooth structure, which in turn alters the primary crown surface morphology. The analysis of dental wear, at both the microscopic and macroscopic scale, is one of the most widely used tools in archeology and anthropology to reconstruct the diet, culture, and lifestyle of past human populations [1]. To date, there are no comprehensive longitudinal studies that have examined functional molar wear variation in modern humans. The aim of this study is to provide a set of longitudinal quantitative data within a functional context obtained from the analysis of molar macrowear
patterns of children and young adults based on the Occlusal Fingerprint Analysis method [2]. We examined the mixed dentition of Australian Aboriginal children taken from the Yuendumu dental collection, which is housed at the Adelaide Dental School at the University of Adelaide. This is one of the most widely studied dental collections in the world, created from a unique longitudinal research project, where anthropologists annually examined the dentition and growth of Aboriginal children and young adults from Yuendumu in the Northern Territory between 1951 and 1971 [3]. This indigenous population was at an early stage of transition
from a nomadic and hunter-gatherer way of life to a more settled existence, with limited contacts with Europeans. Their dentition was mostly characterised by a normal occlusion, with little evidence of dental caries, tooth crowding, malocclusion, molar agenesis and periodontal disease. For our study, we selected nine pairs of dental casts (taken annually from ages 8 to 17), including both upper and lower arches, belonging to the same individual. The dental casts have been surface-scanned using a white-light scanning system with a xy resolution of 45 μm (smartSCAN3D C5, Breuckmann, GmbH). Our results suggest that the occlusal macrowear patterns of this individual did not significantly change through time. Occlusal contact parameters such as functional area, inclination and directional data, remain relatively unaltered throughout childhood and
young adulthood, indicating little changes in the masticatory function of this individual. This could be related to a compensatory mechanism of the human dentition to resist any changes that could disturb masticatory efficiency. To date, there are no studies in modern humans that demonstrated that dental functionality is maintained through time even in more advanced wear stages. Only a few dental topographic studies in non-human primates have shown that masticatory efficiency is maintained throughout the wear sequence [4]. Thus, tooth wear seems to generally keep teeth mechanically efficient for fracturing specific foods during
the lifetime of an individual. Biomechanical studies have indicated that tooth wear helps to dissipate the mechanical load over the crown surface, thus reducing tooth failure throughout the lifetime of an individual [5]. Our current study was limited to the analysis of one single individual, and did not include information about advanced wear stages. As such, future studies could investigate if masticatory function in modern humans is maintained throughout the wear sequence by employing larger sample size, ideally from populations with different dietary habits. Furthermore, biomechanical analyses could provide additional information about the effect of age and maturation on masticatory efficiency.