Effect of Plax prebrushing rinse on enamel fluoride deposition

This in vitro study evaluated the effect of Plax prebrushing rinse on fluoride uptake by enamel from sodium fluoride (NaF) and sodium monofluorophosphate (MFP) solutions in the presence and in the absence of saliva. Human enamel powder (particle size between 0.074 and 0.149 mm), pretreated or not with Plax, was exposed to aqueous solution of 250 ppm F as either NaF or MFP. The exposure time was 1 minute followed by washing in deionized water and methanol. The amounts of alkali-soluble fluoride (CaF2) and firmly bound fluoride (FBF) on enamel were determined with a specific electrode and statistically analyzed with ANOVA. Plax reduced the formation of both CaF2 and FBF on enamel whether the F was supplied as NaF or MFP. The percentage inhibition of uptake from NaF was increased and that from MFP was decreased by the presence of saliva. The commercial prebrushing rinse formulation tested inhibits in vitro the reactivity of the fluoride with enamel.