ICSE Class 10 Answered

Tooth enamel is made up of calcium phosphate which does not dissolve in water, but is corroded when the pH is below 5.5. Bacteria present in the mouth produce acids by the degradation of sugar and food particles remaining in the mouth after eating food. This lowers the pH of mouth making it more acidic and resulting in tooth decay.

We can prevent it by cleaning our mouth after eating using toothpaste. They are basic in nature and can neutralize the excess acid produced in the mouth thus preventing tooth decay.