All my teeth came in behind my baby teeth. It's funny now, but my mom used to threaten me with pulling it out while I was asleep, or using the old string tied to the door handle. She never did either one. And, weirdly enough, all the permanent teeth moved into place. Yes, they somehow make their way forward and I had perfectly straight teeth. Anyway, if you call for an appointment today, chances are he won't be seen until a few weeks anyway. My dentist is quite popular and I can't get in for a few months. (If it's an emergency, of course they leave room for that.) Also, you might want to call the dentist office and see what they think you should do. Bottom line is: I don't think you should worry.