After doing experiments for 20 years and watching my dental checkups, I believe I have found the substance, found in almost all colas, which causes cavities, and it's NOT SUGAR.
While in middle and high school we did not buy pop, it was too expensive, so we drank a lot of coolaid. We brushed our teeth after every meal (especially since we had braces), and I never got a cavity. One year we had a lot of family reunions. They brought pop, so we drank a lot of pop. At the end of that year I got my first cavity at age 18.
Now during my life I had begun to drink colas, Pepsi was my favorite. During the time I drank Pepsi I got even more cavities, sometimes 2 at one dental checkup. They were always small pinhole cavities and my dentist wisely decided to fill them before they got bigger.
Then for whatever reason, I stopped drinking Pepsi and any other colas. Cavities dropped to zero. So I started looking at the ingredients on the labels. I always drank the sugared soft drinks, the diet ones always gave me a weird after taste and I distrusted aspartame. I noticed the one common element among all the cavity-producing sodas: phosphoric acid.
I believe phosphoric acid is what causes cavities, it's not the sugar. Though the sugar can cause you to put on the pounds.
As an experiment in high school the chemistry teacher would always ask for someone's baby tooth. He would put it in a jar of cola and it would be a pile of white dust after about 7 days. Thus illustrating that too much pop is bad for your teeth.
So if you have teeth problems, the colas may very well be the cause. Stop drinking the colas if you don't want more cavities and switch to a new pop without cola. I found that root beer and lemon lime sodas usually don't have phosphoric acid, but you must check every label.