When was the last time you replaced your toothbrush? If you’re not sure, it’s probably time to swap out the old one for a new one that will do a better job of keeping your teeth and gums clean. One sign that your toothbrush has reached its lifespan is flattened, frayed or matted bristles. When bristles are flattened or misshapen, they can’t clean your teeth and gums as effectively, which could lead to dental problems. Even if bristles aren’t noticeably worn, you should replace your toothbrush every three to four months, and after having any cold or flu.