Quality of bristle end-rounding on replaceable heads of powered toothbrushes.

Objectives: The aim of this study was to evaluate the geometry and the quality of bristle tip-rounding using 14 different heads from powered toothbrushes.

Material And Methods: Six powered toothbrushes for children and eight for juveniles and adults were included. Five replaceable heads of each product were randomly selected. Of each sample, 35 bristles were used for examination. This resulted in 175 bristles from each product being evaluated. The quality of end-rounding was assessed by scanning electron microscopy at an original magnification x 80 in two categories of acceptable and five categories of unacceptable rounding according to Silverstone & Featherstone (1988).

Results: The portion of acceptable end-rounding varied strongly between the products (18.9-94.3%). There were significant differences regarding the products for children (p<0.001) and for adults (p<0.001) with respect to end-rounding quality. Only one product achieved more than 90% and eight products had between 68% and 86% acceptable end-rounding. Two products for children and one for adults had less than 25% acceptable end-rounding.

Conclusion: A high standard of bristle tip-rounding is an important feature with respect to the safety of powered toothbrushes. Those products with a greater portion of unacceptably rounded bristles might cause more harm to oral soft tissues during use. The end-rounding quality of some of the products should be improved.