UNASSIGNED: Paleoanthropologists and vertebrate paleontologists have for decades debated the etiology of @entity3356 and its implications for understanding the diets of @entity1 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 @entity3356 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., @entity3440 phytoliths) do not wear teeth. We scored @entity1 enamel using a microfabrication instrument fitted with soft particles ( @entity3775 and brass spheres) and an atomic force microscope (AFM) fitted with @entity3440 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. @entity692 crystallites are "glued" together by proteins, and tissue removal requires only that contact pressure be sufficient to break the bonds holding enamel together.

New model to explain XXXX with implications for microwear formation and diet reconstruction.

@entity1 :: ('9606', 'Species') :: ['human'] @entity3775 :: ('MESH:D000535', 'Chemical') :: ['aluminum'] @entity3356 :: ('MESH:D057085', 'Disease') :: ['tooth wear'] @entity692 :: ('MESH:D017886', 'Chemical') :: ['Hydroxyapatite'] @entity3440 :: ('MESH:D012822', 'Chemical') :: ['silica']
@entity3356 :: (MESH:D057085,Disease) :: ['tooth wear']
