Toothbrushing Mistake No. 10: Not Changing the Toothbrush Often Enough

The American Dental Association recommends getting a new brush every three or four months, or even sooner if the bristles look frayed.

But rather than go by a strict timeline, Price says a visual inspection of the bristles is better. "Once the bristles lose their normal flexibility and start to break apart, change your toothbrush," he says.

"Look more at the state of the bristles than the time period," he says.

Some brushes have colored indicators that alert you when they need replacing, says Price.



cited from http://www.webmd.com/oral-health/healthy-teeth-10/brushing-teeth-mistakes?page=2