Abrasion and stain removal by different manual toothbrushes and brush actions: studies in vitro

Background and aims: A limited amount of data using flat trim multitufted t oothbrushes shows that abrasion of substrate surfaces by a standard toothpa ste varies dependent on filament stiffness and configuration; soft brushes producing the most abrasion. The aims of these studies in vitro were to ass ess toothpaste abrasion of acrylic and stain removal by 5 proprietary mediu m toothbrushes with different head filament arrangements, and a prototype b rush with rectangular filaments. The prototype brush had a medium texture i n the long axis and soft texture at right angles to the long axis. Material and method: Optically clear acrylic was used as the substrate for abrasion by a standard toothpaste. Loss of substrate was determined by prof ilometry after 5000, 10 000, 15 000 and 20 000 linear or rotary brushing ac tions. Stain removal was determined spectrophotometrically from optically c lear acrylic specimens stained by chlorhexidine tea soaking sequences. Stai ned specimens were brushed with water using linear or rotary actions and me asurements taken every 10 s to 60 s. Results: Abrasion was progressive with increasing strokes and the pattern f or each brush and brush action was to a first approximation linear. Overall , abrasion was significantly greater with linear compared to rotary action. Also overall brushes differed in the abrasion produced with both actions a nd particularly at greater exposure times. Within brush differences for the two motions were all significant by 20 000 strokes except for the prototyp e brush. Stain removal was progressive over time with each brush but the pa ttern was non-linear. For the proprietary brushes the rotary motion removed less stain. For the prototype brush more stain was removed with the rotary action. Overall brushes differed significantly in stain removal within eac h motion and for each motion most differences between the proprietary and p rototype brushes reached significance. Conclusions: The differences between brushes for both abrasion and stain re moval must in large part relate to the filament contact area with the subst rate surface. Whilst the model may not be predictive of clinical difference s, it could find use to establish minimum criteria for toothbrush action.