Apparently dentists and doctors are warning against doing oral body piercing. Apparently the mouth doesn't heal from piercing like elsewhere in the body, and infection is always a threat. This is due to the fact that the exposed skin in the mouth is specialized to deal with the environment it's in, and the skin that heals from the piercings (and other things like tongue splitting is thinner and offers less protection. Then there's the worries about the jewelry coming loose and being swallowed or inhaled.