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

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.

Dental wear proxy correlation in a long-term feeding experiment on sheep ( Ovis aries )

“…without a time component) might well suggest an individual variation in tooth quality in the present study population. In previous DMTA studies [60–63], higher Smc , Sq or Sdq values were associated with more abrasive diets. Yet, in the present study, the teeth more susceptible to lower mesowear scores (i.e.…”

“…For example, Sq computes the standard deviation for the surface height (amplitude); Smc as inverse areal material ratio gives the height (amplitude) of the mean plane at a given areal material ratio p; and Vm gives the material volume at a specific height based on the material ratio p (=Smc). Measures of density like medf (mean density of furrows) or Spd (mean density of peaks) have been found to have high discriminatory power to resolve feeding preferences, both in mammals [61][62][63] and lizards [64], but rarely correlate with other well-separating parameters. This is a strong indication for the capacity of isotropy/anisotropy and density parameters to reflect unique features of the enamel surface topography that are not captured by many other DMTA parameters.…”

Strontium Uptake and Intra-Population 87Sr/86Sr Variability of Bones and Teeth—Controlled Feeding Experiments With Rodents (Rattus norvegicus, Cavia porcellus)

“…These pellets were produced from a ground, pelleted diet (formula 2820 Granovit AG, Kaiseraugst, Switzerland) into which 4 wt% of loess or kaolin, respectively, were mixed. The mixture was then re-pelleted and fed to the animals to assess the influence of external, clay-to-silt-sized mineral dust particles on dental wear (see Winkler et al, 2020 for further details and the influence of the external abrasives on dental microwear texture). For Experiment-3: Dust Addition, only incisor enamel was sampled using LA-MC-ICP-MS.…”

Grit and consequence

“…Particle size is the typical measure of grit. Sedimentologists partition grit into clay‐sized (<2 μm), silt‐sized (2–63 μm), and sand‐sized (63–2000 μm) subcategories, 9,10 whereas arenologists describe sand on a scale from ‘very fine sands and silts’ (3.9–125 μm) to fine‐, course‐, and medium‐sized grains (125–1000 μm) 1 . The airborne mobilization of grit by eolian (wind) activity argues for another subcategory, dust, which some authors define as particles <100 μm 3 .…”