Dentists advise that we should change our tooth brush every three months. Most of us are aware of this, but it is still something that we never do. Some people can be a bit heavy handed with their tooth brush and maybe mistaken in thinking this is why the bristle are sticking out at angles rather than the fact that they have been using it for 6 months plus and it is long overdue for a change. You can buy brushes that have blue bristles that fade when it is time to change your brush, these are very useful. I think learning about the germs that can live on my tooth brush is much more of an incentive to change it regularly. Once the bristles of a tooth brush have lost their shape they become a lot less effective therefore we are not cleaning our teeth properly. Germs can also grow in the bristles of a tooth brush, so it is important to change your tooth brush if you have been ill. Coughs and colds, flu and any mouth infection can lead to re-infection if you do not change your brush. It is also important to let your brush air dry and not enclose it in a case as this can cause bacteria to grow on your bristles.