Yah…be true to your teeth or they will be false to you. 
Get thee to a dentist! Trust me, you do NOT want an abscess. I’ve had two of them, and they are among the worst pains in the world. I was given a prescription for codeine pain killers each time. Codeine, an opiate, is a narcotic. They don’t give narcotics for minor pain. I felt like I wanted to cut my head off.
It makes a tremendous difference. Tooth decay results from acidic excretions by oral bacteria that gets trapped next to your tooth enamel and decays it. These bacteria metabolize sugars into acids, and also into the sticky dextrans that help plaque adhere to your teeth. Basically, if you didn’t eat sugar, you wouldn’t get cavities.
As for the cite, I reference this page about tooth decay on Doctor Spiller’s website. Doctor Spiller has been a dentist for 28 years and is also the kind of dentist we’d like to have here on the Straight Dope – he debunks various tooth-related myths on that page, and even addresses myths like the “aspartame gives you gulf war syndrome!” crap. The guy knows his stuff.
He also has plenty of anecdotes about people who had previously had good teeth who began eating sugar without realing it (via raisins, fruit juices, sodas, etc.) and whose teeth suddenly deteriorated.
The link between sugar and dental caries is quite firmly established.
Although I don’t have a cite for it, the vets I have worked with tell me that they only see cavities in dogs who have been given sugary treats. They may have gum disease and plaque, or abcesses or broken teeth, but rarely cavities.
I’m going to read that now; I guess my skepticism is based on this. Is it really sugar in particular, and not other carbohydrates? Do starches really contribute siginficantly less to tooth decay? I guess I’ve always assumed that the sugar thing was an exaggeration generally pushed by parents who wanted to control their kids’ diets; if sugar really is unique in causing tooth decay, then I’m glad to be informed.
Doctor Spiller mentions “fermenting sugars,” so I assume anything simple and sugar-like that is capable of being metabolized into acids by oral bacteria will do the same thing. He mentions a girl who caused her teeth to decay seriously by sucking on squished up balls of bread; when the starches in the bread were broken down by amylase in the saliva, they became just as bad as table sugar as far as the bacteria in her mouth were concerned. So yeah, it’s other carbohydrates too, but evidently just because they can be broken down into simpler carbohydrates and metabolized by the oral bacteria.
There’s another book I read, with a title similar to “Never Have to Visit the Dentist,” that has a lot of specific detail about what oral bacteria are responsible for tooth decay (there are two main kinds, IIRC, and one of them is the kind found in yogurt), and what levels must be present for them to cause decay. He points out that if you keep the levels of bacteria below a certain level, you could eat all the sugar you want and it wouldn’t hurt your teeth. Unfortunately, eating sugar is what tends to make the bacteria population explode, so it’s kind of linked. I’m not sure if the guy in question is a crackpot or not, or how he’s regarded by other dentists, but he does seem to have a lot of data about oral bacteria and tooth decay. I’ll try to find the e-book on my computer.
I should point out, with regards to the “bread balls” girl I mentioned above, that he makes the following statement after talking about her: