The blue color indicator bristles fade with use, indicating the right time to replace the toothbrush. So smart, it tells you when it's time to replace it. Did you know that a new toothbrush can remove up to 30% more plaque than a toothbrush that has been used for 3 months? The blue bristles of the Oral-B Indicator fade to white when it's time to replace the toothbrush, whose ergonomically designed handle offers exceptional comfort and control. It lets you know when it's time to replace the toothbrush, guarantees optimal control and comfort, and is exceptionally gentle on teeth and gums.