The Role of Dust, Grit and Phytoliths in Tooth Wear

Lucas, Peter W.; Casteren, Adam van; Al‐Fadhalah, Khaled J.; Almusallam, Abdulwahab S.; Henry, Amanda G.; Michael, Shaji; Watzke, Jörg; Reed, David A.; Diekwisch, Thomas G.H.; Strait, David S.; Atkins, A.G.

doi:10.5735/086.051.0215

Cited by 111 publications

(106 citation statements)

References 62 publications

(66 reference statements)

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“…They argue instead that phytoliths deter predation by reducing nutrient uptake during feeding (13) or by mimicking grit without actually wearing teeth (14). Indeed, Sanson et al (15) challenged Baker et al's (1) original assertion that phytoliths are harder than tooth enamel and therefore capable of wearing it.…”

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confidence: 82%

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New model to explain tooth wear with implications for microwear formation and diet reconstruction

Xia

Zheng

Huang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

105

114

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Paleoanthropologists and vertebrate paleontologists have for decades debated the etiology of tooth wear and its implications for understanding the diets of human ancestors and other extinct mammals. The debate has recently taken a twist, calling into question the efficacy of dental microwear to reveal diet. Some argue that endogenous abrasives in plants (opal phytoliths) are too soft to abrade enamel, and that tooth wear is caused principally by exogenous quartz grit on food. If so, variation in microwear among fossil species may relate more to habitat than diet. This has important implications for paleobiologists because microwear is a common proxy for diets of fossil species. Here we reexamine the notion that particles softer than enamel (e.g., silica phytoliths) do not wear teeth. We scored human enamel using a microfabrication instrument fitted with soft particles (aluminum and brass spheres) and an atomic force microscope (AFM) fitted with silica particles under fixed normal loads, sliding speeds, and spans. Resulting damage was measured by AFM, and morphology and composition of debris were determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Enamel chips removed from the surface demonstrate that softer particles produce wear under conditions mimicking chewing. Previous models posited that such particles rub enamel and create ridges alongside indentations without tissue removal. We propose that although these models hold for deformable metal surfaces, enamel works differently. Hydroxyapatite crystallites are "glued" together by proteins, and tissue removal requires only that contact pressure be sufficient to break the bonds holding enamel together. dental microwear | diet reconstruction | tooth wear

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confidence: 82%

“…(14) also found phytoliths to be softer than enamel. Lucas et al (14) argued that phytoliths are more likely to rearrange enamel on the nanoscale, creating ridges alongside an indentation, than to separate tissue from the surface.…”

mentioning

confidence: 99%

New model to explain tooth wear with implications for microwear formation and diet reconstruction

Xia

Zheng

Huang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

105

114

View full text Add to dashboard Cite

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“…Also, because the peak fracture stress of quartz particles increases as particle size decreases (Lucas et al, 2014), medium sand grains are more likely than fine sand grains to break into smaller, angular and more abundant grains capable of abrading enamel. Therefore, we suggest the medium sand 'grit effect' (an increased abundance of pits smaller than 25 µm) resulted from fracturing medium sand grains through mastication, with masticatory movement (i.e.…”

Section: Discussionmentioning

confidence: 99%

Controlled feeding trials with ungulates: a new application of in vivo dental molding to assess the abrasive factors of microwear

Hoffman

Fraser

Clementz

2015

Journal of Experimental Biology

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Microwear, the quantification of microscopic scratches and pits on the occlusal surfaces of tooth enamel, is commonly used as a paleodietary proxy. For ungulates (hoofed mammals), scratchdominant microwear distinguishes modern grazers from browsers, presumably as a result of abrasion from grass phytoliths (biogenic silica). However, it is also likely that exogenous grit (i.e. soil, dust) is a contributing factor to these scratch-dominant patterns, which may reflect soil ingestion that varies with feeding height and/or environmental conditions (e.g. dust production in open and/or arid habitats). This study assessed the contribution of exogenous grit to tooth wear by measuring the effects of fine-and medium-grained silica sand on tooth enamel using a novel live-animal tooth-molding technique. It therefore constitutes the first controlled feeding experiment using ungulates and the first in vivo experiment using abrasives of different sizes. Four sheep were fed three diet treatments: (1) a mixture of Garrison and Brome hay (control), (2) hay treated with fine-grained silica sand (180-250 µm) and (3) hay treated with medium-grained silica sand (250-425 µm). We found a significant increase in pit features that was correlated with an increase in grain size of grit, corroborating earlier chewing simulation experiments that produced pits through grit-induced abrasion (i.e. the 'grit effect'). Our results support an interpretation of large silica grains fracturing to create smaller, more abundant angular particles capable of abrasion, with jaw movement defining feature shape (i.e. scratch or pit).

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“…While these studies indicate positive effects of culture ("cultural buffering") on oral health, it has to be kept in mind that culturally-mediated behaviors can also result in its deterioration. For example, dental ablation/avulsion (Durband et al 2014), paramasticatory activities, and dietary shifts related to agriculture clearly lead to impairment of the dentognathic system (Molnar 1972;Barker 1975;Larsen 1995;Molnar 2011).The effects of environmental factors on oral health have been documented in several studies (Sealy et al 1992;Guatelli-Steinberg 2001;Petersen et al 2005;Lucas et al 2014). Lucas et al (2013) proposed that the presence of quartz dust in the environment (and thus in the diet) substantially affects rates of tooth wear.…”

mentioning

confidence: 99%

“…The effects of environmental factors on oral health have been documented in several studies (Sealy et al 1992;Guatelli-Steinberg 2001;Petersen et al 2005;Lucas et al 2014). Lucas et al (2013) proposed that the presence of quartz dust in the environment (and thus in the diet) substantially affects rates of tooth wear.…”

mentioning

confidence: 99%

Comparative analysis of dentognathic pathologies in the Dmanisi mandibles

Margvelashvili

Zollikofer

Lordkipanidze

et al. 2016

American J Phys Anthropol

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Objectives: Due to the scarcity of the fossil record, in-vivo changes in the dentognathic system of early Homo are typically documented at the level of individual fossil specimens, and it remains difficult to draw population-level inferences about dietary habits, diet-related activities and lifestyle from individual patterns of dentognathic alterations. The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, offers a unique opportunity to study in-vivo changes in the dentognathic system of individuals belonging to a single paleodeme of early Homo. Materials and Methods: We analyze dentognathic pathologies in the Dmanisi sample, and in comparative samples of modern Australian and Greenlander hunter-gatherer populations, applying clinical protocols of dentognathic diagnostics. Results: The Dmanisi hominins exhibit a similarly wide diversity and similar incidence of dentognathic pathologies as the modern human hunter-gatherer population samples investigated here. Dmanisi differs from the modern population samples in several respects: At young age tooth wear is already advanced, and pathologies are more prevalent. At old age, hypercementosis is substantial. Discussion: Results indicate that dentognathic pathologies and disease trajectories are largely similar in early Homo and modern humans, but that the disease load was higher in early Homo, probably as an effect of higher overall stress on the dentognathic system. Key words: aging, tooth wear, caries, periodontitisThe Plio-Pleistocene site of Dmanisi has yielded a large sample of hominin fossils associated with abundant and diverse faunal remains and Mode I stone artifacts (Gabunia et al. 2001;Ferring et al. 2011;Mgeladze et al. 2011). Occupation of the site began shortly after 1.85 Ma. The fossil hominin finds are dated to 1.77 Ma (Ferring et al. 2011). Dmanisi thus represents the earliest evidence of Homo outside of Africa. The well-preserved cranial, mandibular and postcranial remains of five individuals are unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo, and into patterns of growth and aging Margvelashvili et al. 2013;Zollikofer et al. 2014). The craniomandibular morphology of the Dmanisi paleodeme has been described previously (Gabunia and Vekua 1995;Gabunia et al. 2000;Gabunia et al. 2001;Gabounia et al. 2002;Lordkipanidze et al. 2005;Lordkipanidze et al. 2006;Rightmire et al. 2006;Rightmire and Lordkipanidze 2010;Lordkipanidze et al. 2013;Margvelashvili et al. 2013). Cranial and mandibular morphological variation within the Dmanisi paleodeme is wide, but well within the range of variation seen in modern humans populations, and in populations of chimpanzee subspecies (Skinner et al. 2006;Lordkipanidze et al. 2013;Margvelashvili et al. 2013;Zollikofer et al. 2014). Variation in size, shape and dentognathic features among the Dmanisi mandibles has received special attention and has been studied to address questions of phylogeny, taxonomy, sexual dimorphism, die...

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The Role of Dust, Grit and Phytoliths in Tooth Wear

Cited by 111 publications

References 62 publications

New model to explain tooth wear with implications for microwear formation and diet reconstruction

New model to explain tooth wear with implications for microwear formation and diet reconstruction

Controlled feeding trials with ungulates: a new application of in vivo dental molding to assess the abrasive factors of microwear

Comparative analysis of dentognathic pathologies in the Dmanisi mandibles

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