In Vitro Demineralization Prevention by Fluoride and Silver Nanoparticles when Applied to Sound Enamel and Enamel Caries-like Lesions of Varying Severities

Objectives: To investigate the effect of fluoride and silver nanoparticles on the prevention of in vitro demineralization of sound enamel and enamel caries-like lesions of varying severities.

Methods: Caries-like lesions of different severities (1/6/15 days) were created in bovine enamel specimens. One group remained sound. All specimens were demineralized again using a partially saturated acetic acid solution. Mimicking the intra-oral retention of fluoride and silver in vitro, this solution was supplemented with fluoride (0/1/10 ppm) and/or silver nanoparticles (0/10 ppm) in a factorial design. Changes in lesion depth (ΔL) and integrated mineral loss (ΔΔZ) were evaluated by digital transverse microradiography. Data was analyzed using three-way ANOVA.

Results: Lesion severity significantly affected ΔΔZ and ΔL, after no treatment and after the treatment of fluoride and silver independently (p = 0.012 and p = 0.037, respectively). Fluoride and the fluoride × lesion severity interaction were shown to be significant (p < 0.001) on ΔΔZ and ΔL. Silver nanoparticles significantly affected ΔΔZ (p = 0.041), but not ΔL (p = 0.15). The silver nanoparticles × lesion severity interaction was significant for ΔΔZ and ΔL (p = 0.032 and p = 0.024, respectively). No interaction was observed for ΔΔZ and ΔL between fluoride and silver (p = 0.962 and p = 0.971, respectively) as well as lesion severity and the use of fluoride and silver combined (p = 0.722 and p = 0.158, respectively).

Conclusion: Fluoride and silver nanoparticles had a significant effect on the prevention of in vitro demineralization of sound enamel and enamel caries-like lesions of varying severities.

Clinical Significance: Fluoride and silver nanoparticles may potentially allow for more tailored caries prevention.