the American Dental Association (ADA) as well as most Dentist, recommend you change your toothbrush every 3 months. As time goes on, toothbrushes go through normal wear and tear which makes them become less effective at removing plaque from teeth and gums. Studies have shown that around 3 months is when the bristles break down and are less effective.
Something else we need to think about and that we probably dislike thinking about is the fact that germs can hide and build up in toothbrush bristles. This is just another reason why you should replace your toothbrush after you were sick to minimize the risk of infection.
In addition to germs, there can be a build up of fungus and bacteria accumulating in the bristles if taken care of properly. After using your toothbrush make sure you rinse and dry it thoroughly. Store uncovered and in an upright position to keep it away from other used toothbrushes.
If you can’t remember exactly how long it’s been, pay attention to the head of the toothbrush for signs of wear and tear. Replace your toothbrush whether the bristles are worn out, fan out, or frayed, or especially if you see dark color changes, as it is a sign of mold.