Shape, size, and quantity of ingested external abrasives influence dental microwear texture formation in guinea pigs

Daniela E Winkler,Thomas Tütken,Ellen Schulz-Kornas,Thomas M Kaiser,Jacqueline Müller,Jennifer Leichliter,Katrin Weber,Jean-Michel Hatt,Marcus Clauss

doi:10.1073/pnas.2008149117

Abstract

Food processing wears down teeth, thus affecting tooth functionality and evolutionary success. Other than intrinsic silica phytoliths, extrinsic mineral dust/grit adhering to plants causes tooth wear in mammalian herbivores. Dental microwear texture analysis (DMTA) is widely applied to infer diet from microscopic dental wear traces. The relationship between external abrasives and dental microwear texture (DMT) formation remains elusive. Feeding experiments with sheep have shown negligible effects of dust-laden grass and browse, suggesting that intrinsic properties of plants are more important. Here, we explore the effect of clay- to sand-sized mineral abrasives (quartz, volcanic ash, loess, kaolin) on DMT in a controlled feeding experiment with guinea pigs. By adding 1, 4, 5, or 8% mineral abrasives to a pelleted base diet, we test for the effect of particle size, shape, and amount on DMT. Wear by fine-grained quartz (>5/<50 µm), loess, and kaolin is not significantly different from the abrasive-free control diet. Fine silt-sized quartz (∼5 µm) results in higher surface anisotropy and lower roughness (polishing effect). Coarse-grained volcanic ash leads to significantly higher complexity, while fine sands (130 to 166 µm) result in significantly higher roughness. Complexity and roughness values exceed those from feeding experiments with guinea pigs who received plants with different phytolith content. Our results highlight that large (>95-µm) external silicate abrasives lead to distinct microscopic wear with higher roughness and complexity than caused by mineral abrasive-free herbivorous diets. Hence, high loads of mineral dust and grit in natural diets might be identified by DMTA, also in the fossil record.

Highlights

Food processing wears down teeth, affecting tooth functionality and evolutionary success
Controlled feeding experiments with small mammals have shown that phytoliths, even though these endogenous plant silica bodies of 10 up to 100 μm are softer than dental enamel [13], cause distinct dental microwear texture (DMT) patterns [14] and that phytolith-rich diets lead to more dentalwear than phytolith-poor diets [9, 10, 15]
Mean particle sizes and overall grain size distribution for all 11 mineral abrasives added to the pelleted diet ranging from clay- to sand-sized particles are given in Table 1 as well as in SI Appendix, Fig. S3

Summary

Introduction

Food processing wears down teeth, affecting tooth functionality and evolutionary success. Controlled feeding experiments with small mammals have shown that phytoliths, even though these endogenous plant silica bodies of 10 up to 100 μm are softer than dental enamel [13], cause distinct dental microwear texture (DMT) patterns [14] and that phytolith-rich diets lead to more dental (macro-)wear than phytolith-poor diets [9, 10, 15]. Merceron et al [12] fed sheep for 70 d with clover- (browse) or grass-dominated silage that was either dust free or had added approximately 1 wt % of quartz-dominated mineral dust (sieved to the size fraction

Methods

Results

Discussion

Conclusion