If not stopped, the erosion enters the lower, center part of the tooth, called the pulp, where the nerve is. Then the pain begins. We call it a toothache. However, certain things help produce tooth decay. These include sugary foods, sticky foods, and acid foods.
Cola drinks do an excellent job of melting teeth.
Coca Cola, and similar cola beverages, contain phosphoric acid and lots of sugar. Frankly, the fluid is so terribly acid that it would be intolerable without lots of sugar to mask the acidity. Acid, sugar, and phosphorous are very dangerous when combined. The powerful acid melts part of the teeth, and the phosphorous chemically locks with the melted calcium, and quickly carries it off. All that sugar does its part to ruin the teeth also.