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

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

Methods: 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.

Results: 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%.