Method: Dentin beams (1×2×6mm) were completely demineralized in 10% phosphoric acid. After baseline measurements of the dry mass, the beams were divided into test groups (n=10) and incubated at 37 °C in an 1mL of artificial saliva (AS, control), or AS containing 250, 500, 1000, 2000, 5000, 7500 or 10000 ppm NaF. The changes in the dry mass of the beams were measured after 1, 7 and 21 days of incubation. The aliquots of the incubation medium were used for C-terminal telopeptide (CTX) analysis to determine CC-mediated degradation. The data were analysed using ANOVA, α=0.05.
Result: The cumulative dry mass loss in the control group was 10.84(±1.70)% and in the NaF groups ranged between 6,73(±1.01)%-8.43(±1.15)% after 21 days of incubation. NaF concentrations equal or higher than 500 ppm resulted in significantly less mass loss after 7 days of incubation (p<0.05). The total CTX release over incubation time was significantly different among groups (p<0.05). The control specimens released a total amount of 795 pg CTX/mg dentin whereas 7500 ppm NaF containing group released only 198 pg CTX/mg dentin after 21 days of incubation.
Conclusion: High concentrations of sodium fluoride can inhibit cathepsin-mediated degradation of demineralized dentin matrix.