The dental floss results are hidden in the Supplementary Information document linked in the original Nature article: https://www.nature.com/articles/s41370-018-0109-y#MOESM1
https://static-content.springer.com/esm/art%3A10.1038%2Fs413...
These products contained fluorine, a marker for PFASs, as determined by particle-induced γ-ray emission (PIGE) spectroscopy:
Colgate Total Dental Floss Mint
CVS Health SuperSlip Ease Between Waxed2
Oral-B Glide Pro-Health Mint
Oral-B Glide Pro-Health Original
Crest Glide Deep Clean Cool Mint Floss3
Signature Care Mint Waxed Comfort Floss2
These products were found not to contain any fluorine:
CVS Unwaxed
Desert Essence Tea Tree Oil Dental Tape
EcoDent Gentle Floss Premium Dental Floss with Essential Oils Mint Vegan Waxed
Johnson & Johnson Listerine Cool Mint Mint Floss
Johnson & Johnson Reach Clean Paste Icy Mint Woven Floss
Johnson & Johnson Reach Mint Waxed
Reach Mint Waxed
Reach Waxed Unflavored
Oral-B Complete Deep Clean Ultra Mint
Oral-B Satin Floss Mint
Rite-Aid Premium Waxed Mint Floss2
Tom's of Maine Naturally Waxed Antiplaque Flat Floss