Objective: Fluoride release from fluoride-containing materials depends on environmental pH and salivary flow. The aim of this study was to evaluate the caries inhibition of fluoride-containing systems using a pH cycling model. Methods: Four restorative systems, one glass-ionomer, Fuji IX (FN), two fluoride-containing resin-pastes, Reactmer (RE) and Xeno CF (XE) and one fluoride-containing adhesive, One-up-bond F Plus, (OU) were employed. OU was used with a non-fluoride resin-paste (Estelite∑). Class I cavities in 20 human incisor teeth were filled with each material. A 300µm section through the restorative was obtained from each tooth. Each section was polished to a thickness of 100µm and covered with wax for transverse microradiography (TMR). Five specimens of each material were placed in a plastic beaker with an outlet. One pH-cycle consisted of flowing a demineralizing solution (pH 4.5) into the beaker for 2 minutes followed by a remineralizing solution (pH 7.0) for 60 minutes. In each cycle the total time the solution remained below pH 5.5 was 37 minutes. The cycles were repeated 9 times per day, with 1 hour in remineralizing solution between cycles, and immersion in this solution for the remaining hours. This continued for 7 days. TMR images before and after pH cycling were compared. The intact surface of enamel unaffected by acid was considered a caries inhibition zone. The length of intact enamel away from the cavosurface margin (length: µm) was measured. The results were analyzed using paired t-test, one-way ANOVA and Tukey HSD (p<.05) Result: The results of the lengths were FN=265.7(SD:89.7), RE =130.4(79.0), XE =88.7(77.8), OU =35.7(60.8). FN, RE and XE showed a statistically significant caries inhibition zone (p<.05). FN differed significantly from the other materials in the lengths (p<.05). Conclusion: Fuji IX, Reactmer and Xeno showed caries inhibition under pH-cycling but not One-up-bond F Plus.