Question

how pH change cause tooth decay​

Answer 1

Answer:

Just like the rest of your body, your mouth needs a balanced pH. The pH level of your saliva can drop below 5.5 when you're drinking acidic beverages. When this happens, the acids in your mouth start to demineralize (break down) tooth enamel. If the tooth enamel becomes too thin, the dentin is exposed.

Answer 2

Answer:

Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. Tooth decay starts when the pH of the mouth is lower than 5.5. Using toothpastes, which are generally basic, for cleaning the teeth can neutralise the excess acid and prevent tooth decay.

The tooth decay got started when acids are produced by action of bacteria on sugars and food particles which tend to soften the enamel. Bacteria in the mouth produce acids by the process of oxidation and the tooth decay starts when pH of mouth is below 5.5.