In situ evaluation of fluoride-, stannous- and polyphosphate-containing solutions against enamel erosion

Abstract

Objective: To evaluate the anti-erosive effect of solutions containing sodium fluoride (F: 225 ppm of fluoride), sodium fluoride + stannous chloride (F + Sn: 225 ppm of fluoride + 800 ppm of stannous), sodium fluoride + stannous chloride + sodium linear polyphosphate (F + Sn + LPP: 225 ppm of fluoride + 800 ppm of stannous + 2% of sodium linear polyphosphate), and deionized water (C: control), using a four-phase, single-blind, crossover in situ clinical trial.

Methods: In each phase, 12 volunteers wore appliances containing 4 enamel specimens, which were submitted to a 5-day erosion-remineralization phase that consisted of 2 h of salivary pellicle formation with the appliance in situ, followed by 2 min extra-oral immersion in 1% citric acid (pH 2.4), 6x/day, with 90 min of exposure to saliva in situ between the challenges. Treatment with the test solutions was performed extra-orally for 2 min, 2x/day. At the end of the experiment, surface loss (SL, in mu m) was evaluated by optical profilometry. Data were analyzed using ANOVA and Tukey tests (alpha = 0.05). The surface of additional specimens was evaluated by x-ray diffraction after treatments (n = 3).

Results: C (mean SL +/- standard-deviation: 5.97 +/- 1.70) and F (5.36 +/- 1.59) showed the highest SL, with no significant difference between them (p > 0.05). F + Sn (2.68 +/- 1.62) and F + Sn + LPP (2.10 +/- 0.95) did not differ from each other (p > 0.05), but presented lower SL than the other groups (P < 0.05). Apatite and stannous deposits on specimen surfaces were identified in the x-ray analysis for F+ Sn and F + Sn + LPP.

Conclusions: Sodium fluoride solution exhibited no significant anti-erosive effect. The combination between sodium fluoride and stannous chloride reduced enamel erosion, irrespective of the presence of linear sodium polyphosphate.

Clinical significance: Under highly erosive conditions, sodium fluoride rinse may not be a suitable alternative to prevent enamel erosion. A rinse containing sodium fluoride and stannous chloride was shown to be a better treatment option, which was not further improved by addition of the sodium linear polyphosphate.