Simple experiments will prove this. Rub your teeth together and feel how smooth they are. Eat a citrus fruit or pineapple, rub again and one will feel a roughness caused by the citrus acids etching the tooth surface. Another test is to cover a seashell half way with citrus juices and leave overnight. The next day the acid etching will be quite obvious.
Seashells have a chemical composition very similar to teeth.
Although my general level of health, energy and consciousness increased dramatically over the next several years, several bizarre phenomena were being manifest by my teeth. The first noticeable symptom was a gradual transparency occurring on the cutting edge of the incisors. Other mysterious events, such as gum line erosion and subsequent pain at the base of the teeth when eating dried fruit, began. As tooth enamel is thinnest at the gum line, this area is the first to manifest observable damage. This erosion can be felt with a fingernail.