Recently I posted this question on Hygiene Town and this was the explanation that I got:
"In general think of calculus as having an alkaline etiology and decay related to acid.This is why the lower anteriors usually have the greatest amount of calculus. The lingual gland puts out an alkaline fluid. This is natures way of protecting the tiniest, most fragile teeth in the mouth.
The people who get decay on the lower anteriors usually are those with a very acidic mouth who have depleted their alkaline mineral reserves via excess sugars and the strong acids of soda pop or candy.
To see how fast a person drinking soda amps up their depletion of minerals get some litmus paper and do the following experiment:
Take a neutral pH with nothing to eat or drink (including gum) 30 min prior. Take an oral pH optimal is 7.0 - 7.4 (similar to blood)-people with a pH of 6.0 or lower always have the most symptoms, diseases, take the most medications and have the most pain. Give the person a sip of soda pop and watch the pH change.
You would think that an acid drink would result in a more acidic mouth. NOT AT ALL, because the body has to protect the blood stream and its organs and tissue from strong acids it instantly pumps out huge amounts of alkaline minerals to neutralize this strong poison. The litmus paper turns deep purple.
This is how people eventually get weak and sick from consuming strong acid.
Soda has a pH 50,000 times more acidic then blood."
Dr. Elizabeth Walker