CLINICAL AND LABORATORY EVALUATION OF POWERED ELECTRIC TOOTHBRUSHES -RELATIVE DEGREE OF BRISTLE END-ROUNDING

Toothbrush bristles with sharp edges have been postulated to represent a greater threat to dental tissues than end-rounded bristles. This st udy evaluated the effect of both in vivo and laboratory use on bristle wear rate, tip geometry and in vitro abrasivity. Three soft manual br ushes (Oral-B(R) P40, Crest(R) Complete and Butler GUM(R)) and one pow ered brush (Rota-dent(R)) were tested. The results of this study show that the wear rate varied directly with brushing load and amount of de ntifrice, and inversely with bristle diameter. Despite the initial geo metry, a flat tip with rounded rims was typically observed after only 30 minutes of manual or Rota-dent brush use. There was no statistical difference in in vitro abrasion for new brushes versus used brushes.