If you have been using the same toothbrush (or toothbrush head) for three months or more, it is time to replace it. If you use a power toothbrush, many of the heads now have indicators that let you know when it’s time to replace it (may be sooner than 3 months).
We recommend this because toothbrushes can become worn, the bristles become less effective at removing plaque, and the brushes can harbor germs.
Also, it is important to replace your toothbrush after suffering an illness or if you have (accidentally?) shared your brush with someone else.