K. - My son is 6 and has lost both of his front teeth! The first one he lost about 8 months ago, so he was 5 1/2. It was loose on its own. The second one got knocked out by his brother. It was already loose, but they were jumping on the big trampoline and hit heads! out goes the tooth.
They may tighten up on their own, but they may be darker colored. Like a light gray. But, they will fall out and then his pearly white ones should come in.
I hate the wait and see game, but loosing his teeth at 5 doesn't sound that wierd to me!