Dust and grit matter: abrasives of different size lead to opposing dental microwear textures in experimentally fed sheep (<i>Ovis aries</i>)

Abstract

External abrasives ingested along with the herbivore diet are considered main contributors to dental wear, though how different abrasive sizes and concentrations influence wear remains unclear. Dental microwear texture analysis (DMTA) is an established method for dietary reconstruction which describes a tooth's surface topography on a micrometre scale. The method has yielded conflicting results as to the effect of external abrasives. In the present study, a feeding experiment was performed on sheep (Ovis aries), fed seven diets of different abrasiveness. Our aim was to discern the individual effects of abrasive size (4 , 50 and 130 µm) and concentration (0, 4 and 8 % of dry matter) on dental wear, applying DMTA to four tooth positions. Microwear textures differed between individual teeth, but surprisingly, showed no gradient along the molar tooth row, and the strongest differentiation of experimental groups was achieved when combining data of all maxillary molars. Overall, a pattern of increasing height, volume, and complexity of the tooth's microscopic surface appeared with increasing dietary abrasive size, and when compared to the control, the small abrasive diets showed a polishing effect. Results indicate that a diet's abrasive size is more important for DMT traces than its abrasive concentration, and that different sizes can have opposing effects on the dietary signal. The latter finding possibly explains conflicting evidence from previous experimental DMTA application. Further exploration is required to understand if indeed, and how microscopic traces created by abrasives translate quantitatively to tissue loss.