Cavities and periodontal disease occur when bacteria and plaque is not adequately removed from the surface of the tooth. That's why your parents tell you to brush your tooth everyday. If you don't, you can be carefree now but later when you get cavities, you will suffer the consequences. You will get toothaches and if the cavities are not removed, they could go to the brain and possibly kill you. Be careful! Brush every place of your teeth.