Every Three Months
Many dental professionals recommend changing your toothbrush approximately every three to four months, or sooner if the bristles are frayed.
Changing Your Toothbrush Or Brush Head
That's because, no matter what type of toothbrush you use, its bristles can become frayed and worn and may lose their effectiveness. And clinical research shows that a new toothbrush can remove more plaque than one that's worn out, ensuring that your brush is working its hardest to help keep your teeth clean and healthy.
Toothbrush bristles do not kill bacteria in the mouth, protect you against disease or prevent you from getting sick. So be sure to change your brush regularly for maximum effectiveness and to practice diligent hygiene, despite the type of toothbrush you're using.