title: A model for predicting wear rates in tooth enamel.
abstract: It is hypothesized that wear of enamel is sensitive to the presence of sharp particulates in oral fluids and masticated foods. To this end, a generic model for predicting wear rates in brittle materials is developed, with specific application to tooth enamel. Wear is assumed to result from an accumulation of elastic-plastic micro-asperity events. Integration over all such events leads to a wear rate relation analogous to Archard׳s law, but with allowance for variation in asperity angle and compliance. The coefficient K in this relation quantifies the wear severity, with an arbitrary distinction between 'mild' wear (low K) and 'severe' wear (high K). Data from the literature and in-house wear-test experiments on enamel specimens in lubricant media (water, oil) with and without sharp third-body particulates (silica, diamond) are used to validate the model. Measured wear rates can vary over several orders of magnitude, depending on contact asperity conditions, accounting for the occurrence of severe enamel removal in some human patients (bruxing). Expressions for the depth removal rate and number of cycles to wear down occlusal enamel in the low-crowned tooth forms of some mammals are derived, with tooth size and enamel thickness as key variables. The role of 'hard' versus 'soft' food diets in determining evolutionary paths in different hominin species is briefly considered. A feature of the model is that it does not require recourse to specific material removal mechanisms, although processes involving microplastic extrusion and microcrack coalescence are indicated.
authors: Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain.
authors: Oscar
authors: O
authors: Borrero-Lopez
authors: Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain.
authors: Antonia
authors: A
authors: Pajares
authors: Department of Biology, Marshall University, Huntington, WV 25755, USA.
authors: Paul J
authors: PJ
authors: Constantino
authors: Department of Biology, Marshall University, Huntington, WV 25755, USA; Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. Electronic address: brianlawn@gmail.com.
authors: Brian R
authors: BR
authors: Lawn
mesh_terms: D001696:Biomechanical Phenomena; D003743:Dental Enamel; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D008954:Models, Biological; D013314:Stress, Mechanical
keywords: Diet; Enamel wear; Tooth wear model; Wear rate