IADR Abstract Archives
Understanding the effects of tooth brushing using an abrasive dentifrice on enamel
Objectives: Cleaning your teeth comes with a drawback. Toothpastes contain abrasive particles that have the potential to damage tooth enamel, resulting in wear and enamel loss. The aim of this study is to compare the abrasivity of alumina and silica particles in a brushing simulation experiment and to identify the wear mechanisms resulting in removal of enamel.
Methods: A modified Phoenix TE77 tribometer was used to reciprocate a firm brush head against bovine disks to simulate the tooth brushing action. The tests ran for 6 hours to replicate 3 months of brushing with per stroke friction data collected during testing. Two toothpaste slurries (40% abrasive, 60% artificial saliva) consisting of angular alumina and silica particles (size range: 1-34µm) were drip fed into the contact for the duration of the test. A Talysurf profilometry was used pre-test and at 2 hour intervals to record the sample topography to enable wear depth comparisons. Post-test scanning electron microscopy (SEM) was used to characterise the wear processes on the enamel surface.
Results: Results revealed that both the friction during brushing and the wear rate was higher with alumina particles. The SEM imaging identified a bi-modal wear process of grooving and polishing, with more grooving evident on the alumina brushed surfaces. The grooving is as a result of a 2-body mechanism where by a single abrasive particle has been lodged beneath a bristle and dragged across the surface, while the polishing results from 3-body rolling of abrasives.
Conclusions: The wear mechanism is a 2-stage process of grooving which causes pile-up and the subsequent removal of this piled up material by successive brushing cycles. The increased grooving by the alumina particles has resulted in increased friction measured during brushing and the increased wear of the enamel.
Methods: A modified Phoenix TE77 tribometer was used to reciprocate a firm brush head against bovine disks to simulate the tooth brushing action. The tests ran for 6 hours to replicate 3 months of brushing with per stroke friction data collected during testing. Two toothpaste slurries (40% abrasive, 60% artificial saliva) consisting of angular alumina and silica particles (size range: 1-34µm) were drip fed into the contact for the duration of the test. A Talysurf profilometry was used pre-test and at 2 hour intervals to record the sample topography to enable wear depth comparisons. Post-test scanning electron microscopy (SEM) was used to characterise the wear processes on the enamel surface.
Results: Results revealed that both the friction during brushing and the wear rate was higher with alumina particles. The SEM imaging identified a bi-modal wear process of grooving and polishing, with more grooving evident on the alumina brushed surfaces. The grooving is as a result of a 2-body mechanism where by a single abrasive particle has been lodged beneath a bristle and dragged across the surface, while the polishing results from 3-body rolling of abrasives.
Conclusions: The wear mechanism is a 2-stage process of grooving which causes pile-up and the subsequent removal of this piled up material by successive brushing cycles. The increased grooving by the alumina particles has resulted in increased friction measured during brushing and the increased wear of the enamel.