Anti-erosive effect of rinsing before or after toothbrushing with a Fluoride/Stannous Ions solution: an in situ investigation: Application order of Fluoride/Tin products for erosive tooth wear

Objective: To evaluate the impact of the application of a F^-/Sn²⁺-containing mouthrinse before or after toothbrushing with a F^-/Sn²⁺/chitosan toothpaste on the progression of erosion/abrasion on enamel and dentin. Methods: This crossover in situ study had five arms: Control (toothbrushing without toothpaste), Brushing (toothbrushing with toothpaste), Brushing + Rinsing, Rinsing + Brushing, and Rinsing (without toothbrushing). Fifteen subjects used removable mandibular appliances containing 3 enamel and 3 dentin specimens, which were subjected to erosion-abrasion cycling of 60 min salivary pellicle formation followed by 5 min extra-oral erosion with 1% citric acid (4x/day for 5 days). Treatments were performed in situ after first and last erosive challenges with rinse (10 ml; 30 s) and/or toothbrushing with/without toothpaste (with electric toothbrush; 5 s per specimen; total 2 min contact with slurry). Surface loss (SL) was evaluated with an optical profilometer. Data were analyzed by two-way repeated measures ANOVA and Tukey tests (α = 0.05). Results: The Control showed the highest SL (mean ± SD for enamel: 24.58 ± 11.32; dentin: 32.32 ± 10.10; all μm). Rinsing alone resulted in significantly lower SL value (enamel: 8.30 ± 4.96; dentin: 16.15 ± 8.29) compared with arms that applied toothpaste, except Brushing + Rinsing. None of the arms that underwent toothbrushing with the toothpaste differed from each other (p > 0.05). Dentin specimens showed significantly higher SL values than enamel (p < 0.001). Conclusion: The order of treatment applications had no influence on their anti-erosive effect; however, toothbrushing with F^-/Sn²⁺/chitosan toothpaste reduced enamel surface loss. Additional rinsing with F^-/Sn²⁺ mouthrinse did not offer improved protection. Clinical significance: The use of fluoride- and stannous- containing toothpastes and mouthrinses is an important approach in the prevention of erosive tooth wear. Further evidence is needed to support the benefit of combining these products against this condition.