For new-adopted babyz, it is possible to re-enable the babyz tooth ballz -- but they don't look very good done the way P.f.Magic had them. I guess that P.F.Magic disabled them because they just didn't have time to make 'em look right. Here's how it's done:
Put the [Omissions] list in your chosen baby .lnz, making sure that the tooth ballz which you want are not listed. The tooth ballz are 124, 125, 126, 127, 128, 129. I'll show here how to have only the top teeth. Trust me, it looks _really_ awful with the bottom one too!
Now, to see the teeth, in [Add Ball] change the addGroup number for all your tooth ballz from 1, 2 or 3 to 0. Those numbers will have something to do with the "growing" idea, but that growth doesn't seem to be enabled. So you can either have them grow in in the same way as I've frigged the "growing" for the body and hair, or you can make it so that the baby is adopted complete with teeth.
Finally, add some linez in (you need 'em! teeth are made up of linez)
Adopt your baby and see it with little grey teeth, which seems to have been a favourite colour of P.F.Magic for teeth and default diapers, LOL!