Which of the following statements is not true?

A

Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth.

B

When pH of the mouth is higher than 5.5. then tooth decay starts.

C

Tooth enamel made of calcium phosphate is the hardest substance in the body.

D

Using toothpaste, which are generally basic, helps neutralise the excess acid and prevent tooth decay.