[Vexs]

Hm, It's not really being too heavily "interfaced" with the body. I wouldn't stick it under your skin, but this would probably be fine I think. I'd also think that most things are unsafe in molten form, heh.

[Fomite]

If it's friendly toward bacterial growth, you might not want it near your gumline. Oral infections can get nasty fast.

[Eduard]

Rubbing drugs on gums is a popular way of administration, as the substances get easily absorbed into blood vessels here.

[pyre]

Well, people put BPA in plastics even though it was known to be toxic because the thought was that the material would bind the BPA in place (i.e. it would always stay in the material).