Toothbrushes should be replaced after three to four months of use, as recommended by the American Dental Association. However, brushes used for less than three months that have visibly frayed bristles should also be replaced.
The main basis for the ADA's recommendation to replace a toothbrush periodically is the reduced cleaning power of a worn toothbrush. To maintain good oral health, individuals are also encouraged not to share toothbrushes with others, as this could lead to the spread of infections. Users should also care for their toothbrushes by thoroughly rinsing them with water after brushing to remove residual toothpaste and organic matter from the brush surfaces.