That the only thing "building" on top of the toothbrush is tooth paste. Everything else being done to avoid cavities does not depend on toothbrushes. So it wou

That the only thing "building" on top of the toothbrush is tooth paste. Everything else being done to avoid cavities does not depend on toothbrushes. So it would be a platform if you had a dominant company whose brushes would require certain kinds of pastes. Since most toothbrushes are completely interchangable as are pastes created by those same companies, there's nobody really building their business on top of any of those particular "platforms".