I was also under the impression that Teflon's properties are mostly due it's high chemical stability up to around 260*C, so I wouldn't e.g. expect it react with anything inside your body. Not sure if PTFE chips accumulate inside tissue or are excreted, but maybe that's a problem. I searched for studies how degrading/chipping PTFE coatings in cookware may affect health but couldn't find any good ones, mostly articles from biased sources.
Afaik, the main concern in cookware was PFOAs used in manufacturing that may outgas during use, not the PTFE itself. The PFOA have now been mostly replaced by something called GenX, which isn't proven to be safer yet.
I'm not sure the cited studies really apply unless there's some proof that the PFOAs (generally no longer used, but same may apply to GenX replacement chemical) leach out during flossing; afaik heating is the main concern in cookware, not contact. And the latter ones are mostly about alum nano-particles accumulating in the body, I don't know into what size particles Teflon coating on floss would break down if at all.
