Same thing just happened to me. I did, however, switch to a dentist with far better equipment who was able to show me pictures of gaping problems in my molars and I had just spent 6 months dosing myself with diet coke to stay awake while writing up a paper for grad school, so it wasn't terribly shocking.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.