Toothbrush bristle wear with the Bass brushing method

Abstract

We did an in vivo study with weekly observations of the relationship between toothbrush bristle wear and brushing force, as well as an in vitro study of the relationship between bristle wear and the removal of experimental plaque. In the in vivo study, we found that the brushing forces employed by the subjects tended to increase as the bristles became worn. In the in vitro study, we found that hardness of the bristles decreased with the number of brushing strokes and that the actual area cleansed decreased as the toothbrush became older for all values of brushing force. These results indicate that the average person should replace his toothbrush every 4 weeks for maximum plaque removal effect.