Relative influence of brushing force transmission factors on substance loss of eroded dentine

Abstract

This study was carried out to evaluate the influence of factors (such as tip form, brush tension and slurry viscosity) transmitting brushing force onto eroded dentine surface by measuring thickness of substance loss using an electron probe micro-analyzer.Dentine slabs each with an exposed window (4 mm 2 ) made using nail varnish were eroded through immersion into 0.83 M acetic acid for 30 minutes. Half of the window area was then covered with nail varnish and served as the control area. The slabs were fixed and the tips (flat trim or tapered) of the bristles were placed on the eroded window, applying adequate pressures (2 g or 4 g per mm 2 ) respectively. The slabs were then brushed for one minute using a sonic toothbrush (480 Hz) with slurry containing silica abrasive and aqueous solutions of carboxymethylcellulose (0.5% or 1%) in a ratio of 10 g to 50 mL. The slabs from which the nail vanish was removed were then sputter-coated with platinum and embedded in methacrylate to be cross-sectioned in the middle of the windows. The cross-sectional surface was polished, coated with carbon and examined using backscattered electron imaging to measure the thickness of dentine loss in the brushed and the control areas within the window.The loss values (µm, mean ± SD) in the treated and the control areas were 24.6 ± 3.61 and 21.5 ± 3.36 respectively. ANOVA analysis indicated that abrasion thicknesses defined as the differences of loss values between brushed and control surfaces were affected only by tip form with no significant interactions among the other factors. Eroded dentine wear by a sonic toothbrush was deeper with tapered tip (3.82 ± 2.73) than with flat trim (2.40 ± 1.54).The results suggested that the influence of factors transmitting brushing force on eroded dentine wear was limited.