According to the American Dental Association, tooth brushes should be changed every 3-4 months, kids should get a new one more often. With time, the bristles get damaged, making brushing less effective. It’s also important to know, that your tooth brush could provide a perfect environment for germ growth. There are few things to put in mind. Replace the tooth brush if you get sick with the flue, cold, cold sore, or sore throat. Don’t store your brush in a closed container, let it hang in upright position, allowing it to dry up, hence reduce the chances of microbial growth. Don’t share your tooth brush with others. Rinse your tooth brush with worm water (or antibacterial) before brushing.