Brushing your teeth twice a day (last thing at night before you go to bed and on one other occasion) with fluoride toothpaste and having regular check-ups with a dentist can help keep your teeth healthy. Diet, smoking and drinking alcohol also have an effect on dental health.moking can stain your teeth yellow, cause bad breath, and increases your risk of gum disease, breathing problems, lung cancer and mouth cancer. If you smoke 20 or more cigarettes a day, you're six times more likely to develop mouth cancer than someone who doesn't smoke.