Question

is pH change cause a tooth decay ????

Answer 1

Yeah because change of pH level cause change from acidic to basic or vice versa which can wear the tooth and make cracks so it can start decaying.

Answer 2

heya!!

tooth decay starts when the pH of the mouth is lower than 5.5.tooth enamel, made of calicium phosphate is the hardest substance in the body. it doesnot dissolve in water ,but is corroded when pH in the mouth is below 5.5 bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth. 

the best way to prevent this is to clean the mouth after eating food .using tooth pastes ,which are generally basic neutralize the excess acid and prevent tooth decay.

hope it helps 
^^"