Bristle end rounding of manual toothbrushes and reproducibility of end rounding classification

To evaluate the bristle end rounding quality of the toothbrushes selected. Furthermore the reproducibility of the bristle tip classification method was assessed.

Fifteen different manual toothbrushes were examined by taking into account the traumatic potential of toothbrushing caused by sharp and edged bristle end geometry. Three brushes for young children (0-4 years of age), eight brushes for children of 5-14 years of age and four brushes for juveniles and adults were included. The macroscopic criteria to which the selected brushes had to conform were: a compact toothbrush handle, a small brush head with rounded contours and a medium or soft bristle stiffness. Bristle tip geometry was investigated under SEM according to a modified scale by Silverstone & Featherstone. End rounding was examined in five regions equally distributed over the brush head. Two brushes of each brand were included in the SEM investigation. For evaluation of reproducibility , end roundings of 119 bristle tips were assessed twice by one experienced examiner and once by two additional unexperienced examiners.

The proportion of acceptably rounded bristle tips varied widely from 65.2 - 99%. Half of the products examined achieved a level of at least 90% acceptable bristle end rounding. Five of the toothbrushes examined had between 70 and 90% acceptable bristle end geometries, while two products had less than 70%. Intraindividual reproducibility regarding acceptable and unacceptable end rounding was 99.16%, interindividual reproducibility varied between 90.76% and 94.96%.