Ok parents, for younger growing patients the key word in nutrition is calcium. Adequate calcium intake is essential for strong teeth and bones. You too need calcium in your diet as well. But since you are fully-grown, it is less critical. Sufficient calcium in your diet ensures that your body does not utilize calcium from other sources within your body.
Your body will actually take calcium from your bones if your diet sources are not sufficient. Since teeth have a minor blood supply, your body does not remove calcium from the enamel of teeth. Instead, acid from plaque and acidic foods depletes calcium levels in your teeth. Reduced calcium in your tooth's enamel leaves the tooth weakened and subject to decay.
To avoid calcium loss in your teeth stay away from candies and sweets. Avoid acidic foods that raise acid levels in your mouth. A healthy balanced diet and regular oral hygiene goes far in maintaining a strong and healthy set of teeth and gums.