Over-the-Counter Acidulated Fluoride Rinses: Effect on Enamel Caries in Vitro

Objectives: Effects of over-the-counter (OTC ) Acidulated Fluoride Rinses (AFR) on in vitro enamel caries formation were compared with OTC Fluoride Rinses (FR) without Acidulation.
Methods: Sound enamel surfaces from caries-free permanent teeth (n=10) underwent debridement and a fluoride-free prophylaxis. Teeth were sectioned into tooth quarters, and acid-resistant varnish was placed with 2 sound enamel surface windows exposed on each tooth quarter. Each quarter from a single tooth was assigned to a treatment group: 1) No Treatment Control (Control; Synthetic Saliva Treatment Only); 2) 0.05% NaF fluoride rinse (FR-A: Kids Anticavity Fluoride Rinse, Amazon); 3) 0.02% NaF Acidulated Fluoride Rinse (AFR-W; Anticavity Rinse, Walgreens); and 4) 0.04% NaF Acidulated Fluoride Rinse (AFR-CP; Phos-Flur OrthoDefense, Colgate-Palmolive). Tooth quarters were treated with dentifrice twice daily (60s) followed by synthetic saliva rinsing over a 10-day period. In vitro enamel caries were created using acidified gel (pH 4.25, 42 days). Longitudinal sections (3/tooth quarter, 60/group) were evaluated for mean lesion depths (water imbibition, polarized light, ANOVA, DMR).
Results: Mean lesion depths were 315 ± 26 μm No Treatment Control; 262 ± 22 μm FR-A; 220 ± 19 μm AFR-W; and 206 ± 21 μm AFR-CP. All fluoride rinse groups had mean lesion depths significantly less than No Treatment Control group (P<.05). There were significant differences in mean lesion depths between FR-A group and both AFR-W and AFR-CP groups (P<.05). There was no significant difference between AFR-W and AFR-CP groups (P>.05). All fluoride rinse groups had well-defined surface zones; whereas the no treatment control group had discontinuous surface zones on polarized light examination.
Conclusions: All fluoride rinnses provided significant reductions in in vitro enamel caries lesion depths compared with enamel surfaces exposed only to synthetic saliva rinsing (P<0.05). AFR-W and AFR-CP groups had the greatest reduction on in vitro caries lesion depths compared with control and FR-A groups (P<.05). The addition of phosphoric acid to over-the-counter sodium fluoride rinses may be quite effective in preventing and reducing caries experience, and perhaps remineralizing existing white spot lesions.