The purpose of this study was to evaluate the abrasive effect on toothbrush bristles caused by three brands of commercially distributed dentifrices: Colgate regular favor, Crest tartar-control formula, and Caffree gel. New brushes and brushes tested in distilled water served as controls. Scanning electron micrographs were taken of all test samples, randomly labeled, then presented to independent evaluators. Each bristle evaluated was assigned to one of seven wear categories adapted from previous studies. Crest and caffree produced the most bristle wear and were not significantly different from each other. Colgate and water resulted in less wear, and new brushes the least wear. These results demonstrate that the effective life of a toothbrush will vary with the type of dentifrice used.