What value of pH in the mouth leads to tooth decay ? Why ?

Explanation

1) Tooth decay starts when the pH of the mouth is lower than 5.5.
2) Tooth eN/Amel, made of calcium phosphate is the hardest substance in the body.
3) It does not dissolve in water, but is corroded when the pH in the mouth is below 5.5.
4 ) Bacteria present in the mouth produces acids by degradation of sugar and food particles remaining in the mouth
Preventions:
1) Clean the mouth after eating food.
2) Using tooth pastes. Which are generally basic neutralize the excess acid and prevent tooth decay.