To decay your teeth you need 3 things – a tooth surface, a mature plaque and some refined carbohydrates (sugars). Without one of these you cannot get tooth decay.
No plaque = no tooth decay. Learning an effective brushing and flossing technique will save you teeth and $. Brushing and flossing once a day is more than enough.
Over brushing with the wrong technique, too often and with too much toothpaste can also cause problems.