I haven't heard one way or the other. The fuzz on the real tennis balls holds up better but she doesn't sit and chew on them either. She just carries them around But I'd venture a guess, a GUESS, that the enamal would be harmed by other things more then the rubber or fuzz on these balls. Bones anyone?
for what it's worth, my General Manager doesn't see how the rubber or the fuzz would be abrasive to the tooth enamal. I'll try to remember to poke around and see if I can find an answer one way or the other
My boy is almost 12 and has been chasing tennis balls for that entire time. I try to keep them away when not playing fetch because they ARE a chocking hazard. But he gets them sometimes. His teeth seem fine to me. I never would have thought about tennis ball fuzz hurting his teeth, but I'd never brush a dogs teeth either (like so many people tried to tell me to)