SoftIntelligent Toothbrush - Can dramatically improve your dental health by ensuring that you brush for two minutes and by telling you to change the bristles every 90 days, Dentists say that these actions are the most important ingredients in a good oral care regimen.When to replace worn bristles: The Intelligent Toothbrush will beep and flash with a green light for the first 180 uses. After 180 uses - the green light will turn red indicating time to change the head. Dentists recommend changing bristles every 90 days with twice a day brushing.Radial bristling- Bristles radiate out from the head giving a substantial bristle tip area for a small head size, makes brushing teeth and gums easier and more effective.Thin Bristles- Thin DuPont Tynex nylon bristles let you comfortably remove plaque and massage gums.