A review of current toothbrush bristle endo-rounding studies

Rounded toothbrush bristle tips are desirable because they are less likely to abrade hard and soft tissue and restorative materials than sharp-pointed bristles. Studies evaluating different types of toothbrushes have compared the degree of the end-roundness of different brands of toothbrushes, but have yielded conflicting results. Nine studies and three methods of evaluating end-rounding are reviewed in this article. Within the limits of the review, it appears that visual inspection of a bristle tip by scanning electron microscopy or a stereomicroscope at a 45-degree angle is the technique of choice for evaluating end-roundness. Of the 9 studies reviewed, 3 studies that used the 45-degree microscopic techniques provide the most useful information of toothbrush bristle end-roundness to date. Of the brushes compared in these three studies, Crest Complete and Improved Crest Complete toothbrushes were shown to have the highest degree of end-roundness. Future research should include longitudinal studies to clarify the relationship of the degree of end-rounding of toothbrush bristles and soft-and hard-tissue abrasion.