My son is now 15yrs old, and has chewed them plain since he was about 4yrs old...so far ("knock wood") he hasn't had a single cavity, or discoloration problem. BUT--everyone's teeth are different. The only restriction I made while he was doing this was that he wasn't allowed to chew gum for about 1-2 hours after each dose (he was a BIG gum chewer!) this was so that I knew all the pill remains were out of his teeth & into his stomach & not stuck in the gum & possibly thrown away.