Retention of topical fluoride in the mouths of xerostomic subjects.

The total fluoride concentration in unstimulated whole saliva was measured before and at selected intervals after a self-applied 1.1% neutral NaF topical fluoride gel or use of a 0.05% neutral NaF fluoride mouthrinse in both normal individuals and patients with radiation-induced xerostomia. As expected, the gel resulted in higher peak fluoride values than the rinse and was retained in the mouth for longer periods of time in both groups. The xerostomic group expressed a mean oral fluoride concentration of 575 micrograms fluoride per gram of saliva within 1 min after the gel application and 150 micrograms/g following use of the mouthrinse, whereas the normal group exhibited peak concentrations of 112 and 71 micrograms/g, respectively, within 1 min after the same two treatments. The initial high levels of fluoride observed in normal subjects following the gel application decreased rapidly to less than 1 microgram/g within 2 h, whereas fluoride levels in the xerostomic subjects remained elevated above 12 micrograms/g for longer than 2 h. Similarly, following use of the mouthrinse, normal subjects' saliva fluoride levels decreased to less than 1 microgram/g within 1 h, whereas xerostomic subjects' saliva fluoride levels remained above 4 micrograms/g for longer than 2 h.