The physiological linkage between molar inclination and dental macrowear pattern

Abstract

ObjectivesExact symmetry and perfect balance between opposite jaw halves, as well as between antagonistic teeth, is not frequently observed in natural masticatory systems. Research results show that asymmetry in our body, skull, and jaws is often related to genetic, epigenetic, environmental and individual ontogenetic factors. Our study aims to provide evidence for a significant link between masticatory asymmetry and occlusal contact between antagonist teeth by testing the hypothesis that tooth inclination is one of the mechanisms driving distribution of wear in masticatory phases in addition to dietary and cultural habits.Materials and MethodsThe present work investigates the relationship between dental macrowear patterns and tooth inclinations on a sample of complete maxillary and mandibular 3D models of dental arches from 19 young and adult Yuendumu Aboriginal individuals. The analysis was carried out on first molars (M1) from all quadrants. Occlusal Fingerprint Analysis was used for the quantification of macrowear patterns, and 2D cross‐sectional geometric analysis was carried out to investigate asymmetry in dental arches.ResultsThe asymmetry is highly variable on both arches, and it is associated with differences in the inclination of upper M1 crowns. Each molar has variable inclination (buccal/lingual) which influence tooth to tooth contact, producing greater or lesser variation in wear pattern. Interindividual variability of morphological variation of the occlusal relationship has to be considered in macrowear analysis.DiscussionOur results suggest that overall asymmetry in the masticatory apparatus in modern humans affects occlusal contact areas between antagonist teeth influencing macrowear and chewing efficiency during ontogeny.

Exploring late Paleolithic and Mesolithic diet in the Eastern Alpine region of Italy through multiple proxies

“…A previous analysis of upper molars of recent hunter‐gatherers revealed a wear pattern dominated by Buccal Phase I facets in meat‐eater human groups, and a pattern with large Lingual Phase I facets in groups of individuals who relied on mixed food resources, including a large percentage of plants (Fiorenza, Benazzi, Tausch, et al, 2011). A more recent study, however, has shown a mirrored occlusal relationship in the macrowear pattern of upper and lower molars in an Australian Aboriginal population from Yuendumu (Oxilia et al, 2018).…”

“…Several physical and chemical factors are involved in tissue reduction, depending on food choice, environmental setting (El Zaatari & Hublin, 2014; Fiorenza, 2015; Kullmer et al, 2009; Lussi, 2006) and endogenous organismic biology (Grippo et al, 2004; Lussi, 2006). There are also other variables responsible for the specific appearance of dental wear patterns such as asymmetry of the masticatory system (Kimoto et al, 2000; Molnar & Molnar, 1990; Oxilia et al, 2018), bruxism (Sameera et al, 2017) para‐masticatory activities (Fiorenza & Kullmer, 2013, 2015) dental treatment (Oxilia et al, 2015; Oxilia et al, 2017) and food processing methods (Metcalf et al, 2014).…”

“…Different proxies and methods have been integrated to obtain a comprehensive overview of prehistoric human dietary strategies and for understanding cultural responses to climate and environmental constraints: isotopic analysis (e.g., Drucker & Bocherens, 2004; Lugli et al, 2019, Wißing et al, 2019); lithic and osseous technology (e.g., Arrighi et al, 2019; Caricola et al, 2018; Collina et al, 2020; Marciani et al, 2019; Semenov, 1964; Stout, 2011); faunal remains (i.e., quantification of faunal remains and analysis of bone surface modifications; Gaudzinski‐Windheuser & Kindler, 2012); and dental remains (i.e., formal assessment of paramasticatory and masticatory activities; Arnaud et al, 2016; Been et al, 2017; Fiorenza et al, 2015; Fiorenza, Benazzi, & Kullmer, 2011; Margherita et al, 2016; Margherita et al, 2017; Oxilia et al, 2015; Oxilia et al, 2017; Riga et al, 2018). In particular, dental wear, dental pathologies and, when preserved, prehistoric dental calculus have shown to be pivotal in obtaining data on diet, cultural habits, and health status (Cristiani et al, 2018; El Zaatari & Hublin, 2014; Fiorenza, 2015; Fiorenza, Benazzi, Oxilia, & Kullmer, 2018; Fiorenza & Kullmer, 2013, 2015; Grippo, Simring, & Schreiner, 2004; Henry, Hudson, & Piperno, 2009; Lussi, 2006; Metcalf, Ursell, & Knight, 2014; Molnar & Molnar, 1990; Oxilia et al, 2018; Radini, Buckley, Nikita, Copeland, & Hardy, 2017; Sameera, Singh, & Nitya, 2017; Sorrentino et al, 2018; Warinner et al, 2014; Weyrich et al, 2017). While successfully applied to the analysis of historical contexts (e.g., Baldoni et al, 2018; Figus et al, 2017; Gismondi et al, 2020; Radini, Nikita, & Shillito, 2016; Vazzana et al, 2018), the proxies mentioned above have sporadically been combined in prehistoric reconstructions (Fiorenza et al, 2015), potentially leading to a lack of information about ancient dietary habits.…”

Automated Digital Odontometry: Measurement Data Analyses in Cases of Complicated Dental Morphology

“…Measurements, despite the studied sample variety, are formalised by same algorithms and 3D image processing methods. There is no expertly based measurement landmark setting on teeth or on soft tissues in aDo like in other described techniques (Ghizlanzioni et al, 2017;Oxillia et al, 2017): orientation and measurement algorithms are performed in fully automated mode. Odontometric data can be obtained on any number of teeth and comparisons potentially can be performed with arbitrary number of other measured teeth in relevance to an arbitrary number (from a single to all) of measured parameters.…”

3D Data Analysis for Teeth Morphology Study

“…And among sections those which are oriented in vestibular-oral direction are the most informative due to dental morphological framework. Thus sectioning (performed, however, in a "manual" mode, in contrast to the presented in this article method) is used, as an example, in enamel thickness studies [22] or studies referred to dental wear [23]. Measure-ment automation and appropriately functioning algorithms starts playing an essential role in study objectivity if compared to expert-based research, when discrepancies accompany different attempts to measurements, as well as results vary between experts [24].…”