The placement is static- it won't change with the sim's face mesh, so it might work better on some sims than others. It looks fine with maxis-made sims as well as heavily edited sims, though.
Works fine on teens, too:
But not too well with textures. This one has the leopard texture on it to match the rest of this default lady's weird rave-y outfit, but it didnt work too well.
There's no plastic...sucky...thingy inside. Sims look like they're holding it in their mouth when talking, but it looks weird from the side when their mouth is wide open.
All credit for the mesh goes to dyokabb at SimsThings, I just resized and repositioned it. Thanks for letting me upload it. :D