Fluoride in Plaque Fluid, Plaque, and Saliva Measured for 2 hours after a Sodium Fluoride Monofluorophosphate Rinse

Sodium monofluorophosphate (NaMFP) and sodium fluoride (NaF) are the two most common sources of fluoride used in currently marketed fluoride dentifrices. The purpose of this study was to investigate the effect of mouth rinses containing NaF or NaMFP on the concentrations of fluoride, or the MFP ion, in saliva, whole plaque, and plaque fluid. Twelve subjects abstained from tooth brushing for 48 h, fasted overnight, and then rinsed 1 min with 12 mmol/l (228 ppm [microg/g] F) NaF or NaMFP in the morning. Before the rinse and at 30, 60 and 120 min afterwards, upper and lower molar and premolar plaque samples and whole saliva samples were collected. Aliquots of plaque fluid and centrifuged saliva were obtained from these samples, and the whole plaque residue acid extracted. The F and MFP concentrations were then measured in these samples using ultramicro methods. For both rinses, a higher concentration of plaque fluid fluoride was found at lower molar sites while the reverse was true for the whole plaque fluoride. Furthermore, for both rinses, plaque fluid, whole plaque, but not salivary, fluoride concentrations were above baseline at 120 min. Following the NaMFP rinse, a substantial amount of unhydrolyzed MFP was found in plaque fluid and saliva. Although there was a very large range in these measurements, fluoride in plaque fluid (excluding fluoride in unhydrolyzed MFP) and whole plaque were significantly (p<0.05) greater after the NaF rinse at all time periods. In saliva, the NaF rinse produced a statistically significant greater salivary fluoride (excluding fluoride in unhydrolyzed MFP) only at 60 min. The lack of a clear correlation between these measurements and clinical studies suggest a novel mechanism may enhance the effectiveness of NaMFP dentifrices.