• Wood, Robert J. K.
• Cook, Richard
• Pratten, Jonathan
• Baig, Mahdiyyah

Abstract

OBJECTIVES<br/>An undesirable outcome of cleaning your teeth is wear of enamel. Tooth brushing is a complex tribological problem with many variables working in combination. The most commonly used abrasive particles in toothpastes are alumina and silica particles with a typical size between 4µm – 12µm. The objective of this study was to investigate the effect of size, type and morphology of abrasive particles on the wear of enamel using a micro-abrasion rig and develop an understanding of the magnitude of wear caused by two, three and mixed- mode abrasion. <br/> METHODS<br/>Micro-abrasion testing using a nylon ball was undertaken on bovine enamel disks using a range of slurry concentrations (5 – 20% volume fraction) and loads of 0.5N, 0.2N and 0.1N, to determine wear rates and mechanisms. The slurries consisted of either mono-sized or bimodal, 5µm and 10µm silica and alumina abrasive particles in artificial saliva. Results were interpreted by scar analysis using the Scanning Electron Microscope (SEM).<br/>RESULTS<br/>Mixed mode (2-body grooving with 3-body rolling) abrasion provided higher wear rates than solely 2-body grooving in all the tests. The bimodal tests produced higher wear rates than the single component sized particle tests. This can be explained by a change in wear mechanism from 2-body grooving to mixed-mode. Bimodal silica particle tests caused more wear than bimodal alumina particle tests. <br/><br/>CONCLUSIONS<br/>The highest wear rates were produced by the bimodal particle size distributions due to a shift to mixed-mode abrasion. Mixed mode gave higher wear rates compared to 2-body grooving in all the tests. A change in wear mechanism from 2-body grooving to mixed-mode, resulted in silica producing more wear than alumina. <br/>

Topics

• impedance spectroscopy
• morphology
• scanning electron microscopy