Number, length and end-rounding quality of bristles in manual child and adult toothbrushes

Background. The design of the bristles of a toothbrush can affect the overall efficacy of toothbrushing. Aim. To evaluate and compare a number of selected features associated with the bristle (length, number and end-rounding quality) of manual child and adult toothbrushes. Design. The bristle lengths of 11 child and 29 adult toothbrushes were measured on digital micrographs using open source image analysis software. Bristles of tufts from five regions were counted and classified as acceptable or non-acceptable on stereomicroscopic images according to the end-rounding morphology. The data was evaluated statistically. Results. The number of bristles were similar in child and adult toothbrushes (P > 0.05). Despite significant differences in bristle end-rounding in some regions (P < 0.05), the overall quality of bristles were similar in child and adult toothbrushes (P > 0.05). Conclusions. The variations observed in the number, length and end-rounding quality of the bristles indicate inherent shortcomings of a majority of the tested toothbrushes in plaque removal efficacy, along with the potential for irritation on the gums.