Question

How change in the pH causes tooth decay?​

Answer 1

Bacteria in the mouth create acids after eating through the oxidation of sugar and food particles in the mouth. Tooth decay starts when the mouth's pH is below 5.5. In addition to food particles, masses of bacterial cells bind to the teeth to form dental plaque.

Answer 2

Tooth decay occurs if pH of the mouth lowers than 5.5. As we know tooth enamel is made up of calcium phosphate [Ca3(PO4)2] and it decays when mouth pH goes below to 5.5.

Because bacteria present in mouth produce acid by degration of sugar and food particles which remains in the mouth after eating. That's why in order to prevent tooth decaying we use toothpaste which are basic in nature.