Acid erodes tooth structure. It is that simple.
Unfortunately, it is very easy to forget we get a lot more sugar from things that we don't necessarily think of as "sweets." Foods can be very broadly be broken down into carbohydrates (sugars), fats and protein. I'm not pushing an Atkins Diet on anyone, but protein and fat do not cause cavities. Pretty much everything else can. Sticky carbohydrates are some of the worst offenders because they tend to stay in our mouth the longest. Mix a glass of water and sugar and drink it. It goes down the hatch pretty quickly. A nice PB&J sandwich, Tootsie Roll or chocolate bar may taste great, but it tends to stick to the teeth. Once it stays in the mouth, the millions upon millions of bacteria that co-habitate with us begin their feast. And like us, they poop...but they poop acid and they poop it right in our mouth.
Avoiding sugar is getting easier and easier. I can't even keep up with the sugar substitutes that are out there. Guess what? The vehicle we usually get them in is very acidic. We just cut out the middle man of the bacteria and bathe the teeth directly in an acid bath.
Here is a chart of different foods and drinks and the relative acidity of them.
Diet sodas, diet energy drinks, many fruits are very acidic.
I'm not telling you to avoid eating whatever you want. I usually drink a ton of water, but right next to the bottle on my desk is a bag of M&M's. We have means of remineralizing our teeth after an acid attack if we can minimize the attach and raise the pH of our mouths to a more neutral level. After eating or drinking something acidic, wash it down with water, as much as you can. Try and not brush immediately after eating any of the problem foods we listed. Rinse first and wait a bit. We can actually even do damage to our teeth by brushing them in a acid softened state.
Most of the cavities we see are still the traditional "pit of the tooth" cavities were sugary foods get stuck. As more and more acidic drinks come out we are seeing more and more "smooth surface" cavities in teenagers and young adults than we ever have before.
We are hear to prevent damage first and we would rather do that than help fix problems as they arise.
