FJ, I think you'll find that it isn't COMMON on single root teeth. Doesn't mean it can't happen. Not that I'm an expert! (clearly LOL!).

Relle, the only thing that occurred to me the other day when i first saw your post was that it could be a 'supernumerary' tooth. Which is basically just an extra tooth. Supernumerarys are typically smaller than an average tooth. I wasn't, and still am not, too sure about how common it is in deciduous teeth though. Not impossible though, so it could be the explanation. The fact that the site has been bleeding makes me think it's more likely to be an enamel pearl, but who knows?

I would imagine whatever it is, it is something that will exfoliate at some stage, so he won't have it forever. As long as it's not troubling him too much, I would just wait until your MCHN is back, and take him to see her. The other option is a paediatric dentsist.

Try not to worry about it too much, although it's not common, it shouldn't be a big drama. It's just knowing what it is LOL!

Good luck, and keep us updated