Permeability of eroded enamel following application of different fluoride gels and CO₂ laser

This study evaluated the combined effect of fluoride compounds and CO₂ laser in controlling the permeability of eroded enamel. Bovine enamel slabs (3 × 2 mm) were cycled twice through an alternating erosion and remineralization regimen. Slabs were immersed in 20 ml of orange juice (pH 3.84) for 5 min under agitation, rinsed with deionized water, and stored in artificial saliva for 4 h to form erosive lesions. Specimens were then divided into four groups (n = 10), which were treated for 1 min with either a control or with one of the following gels: amine fluoride (AmF), titanium tetrafluoride (TiF₄), or sodium fluoride (NaF). Half of the specimens were irradiated with a CO₂ laser (λ = 10.6 μm; 2.0 W). Specimens were cycled two more times through the aforementioned erosion–remineralization regimen and were subjected to permeability assessment. ANOVA demonstrated a significant interaction between fluoride and laser treatment (p = 0.0152). Tukey’s test showed that when fluoride was applied alone, TiF₄ resulted in lower enamel permeability than that observed after application of the placebo gel. Intermediate permeability values were noted after NaF and AmF had been used. A significant reduction in enamel permeability was obtained when fluoride was combined with CO₂ laser treatment, with no difference between fluoride gels. Permeability of eroded enamel may be reduced by combining the application of fluoride gels with CO₂ laser irradiation.