Also, wish I had a link to the article, but I was reading about how whether you "have" a cavity depends on your dentist's interpretation of the x-rays and their philosophy about treatment. Some dentists will see a light area and say "let's fill that before it gets worse" and others will note it and see how things develop. It was actually pretty alarming because sounds like professional standards for dentistry are looser than some other areas of medicine, and the description rang true for some of the dentists I've seen.