Fluoride inhibits the antimicrobial peroxidase systems in human whole saliva.
Fluoride (F-) ions at concentrations present in vivo at the plaque/enamel interface (0.05-10 mM) inhibited the activities of lactoperoxidase (LP), myeloperoxidase (MP) and total salivary peroxidase (TSP) in a pH- and dose-dependent way. The inhibition was observed only at pH < or = 6.5 and with F- concentrations > or = 0.1 mM. At pH 5.5 LP activity was inhibited by 85% and MP by 34% with 10 mM F-. TSP activity was also inhibited only at low pH (5.5) by approximately 25%. Furthermore, the generation of the actual antimicrobial agent in vivo, hypothiocyanite (HOSCN/OSCN-), of the oral peroxidase systems was inhibited by F-, again at low pH (5.0-5.5) both in buffer (by 45%) and in saliva (by 15%). This inhibition was observed only with the highest F- concentrations studied (5-10 mM). Fluoridated toothpaste (with 0.10 or 0.14% F) mixed with saliva did not inhibit TSP or HOSCN/OSCN- generation. This may have been due to the 'buffering' effect of toothpaste which did not allow salivary pH to drop below 5.9. We conclude that the F- ions in acidic fluoride products, e.g. in gels or varnishes (but not in toothpastes), may have the potential to locally inhibit the generation of a nonimmune host defense factor, HOSCN/OSCN/SCN-, produced by oral peroxidase systems. The possible clinical significance of this finding remains to be shown.
Institute of Dentistry, University of Turku, Finland.
S
S
Hannuksela
J
J
Tenovuo
V
V
Roger
M
M
Lenander-Lumikari
J
J
Ekstrand
D000818:Animals; D000890:Anti-Infective Agents / Q000037:antagonists & inhibitors; D002021:Buffers; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005459:Fluorides / Q000008:administration & dosage / Q000494:pharmacology*; D005782:Gels; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007784:Lactoperoxidase / Q000037:antagonists & inhibitors; D008297:Male; D010150:Paint; D009195:Peroxidase / Q000037:antagonists & inhibitors; D010544:Peroxidases / Q000037:antagonists & inhibitors*; D010710:Phosphates / Q000494:pharmacology; D012463:Saliva / Q000187:drug effects / Q000201:enzymology*; D012471:Salivary Proteins and Peptides / Q000037:antagonists & inhibitors*; D013861:Thiocyanates / Q000037:antagonists & inhibitors; D014100:Toothpastes
D000890:Anti-Infective Agents; D002021:Buffers; D005782:Gels; D010710:Phosphates; D012471:Salivary Proteins and Peptides; D013861:Thiocyanates; D014100:Toothpastes; C012980:fluorophosphate; C014607:hypothiocyanite ion; D007784:Lactoperoxidase; D010544:Peroxidases; D009195:Peroxidase; D005459:Fluorides