Assessment of the microhardness of artificial enamel caries after treatment with a combination of silver nanoparticles and sodium fluoride solution

Background: New technologies have developed to allow newly created enamel caries to be remineralized. Silver nanoparticle (NP) products have a strong inhibitory and bactericidal effect. Silver ions may penetrate carious lesions, which may precipitate and cause enamel to harden. Objectives: This study evaluates and compares the effectiveness of the application of silver NPs with sodium fluoride solution on the microhardness of artificially induced demineralization on the enamel surface in comparison with sodium fluoride alone. Materials and methods: Thirteen upper first premolars that were extracted for orthodontic therapy were used. Each tooth was cleaned, inspected, polished and painted with acid-resistant nail polish to create a circular window with a diameter of 2×2mm. Then it was soaked in a demineralizing solution for four days after that the teeth were divided in to three groups (A: untreated, B: treated with silver NPs and 5% sodium fluoride and C: treated with 5% sodium fluoride) groups were immersed for 4 minutes, and all stages were conducted under room temperature. A digital Vickers microhardness tester with a diamond indenter with 500 g of load applied for 30 s directed vertically to the enamel surface was used to measure microhardness. The Vickers microhardness test results show that the solution of sodium fluoride and silver NPs has higher microhardness ratings (mean surface microhardness [SMH] 286.837) than sodium fluoride alone (mean SMH 191.530) with significant P value = 0.00001. Conclusion: Using silver Silver nanoparticles with sodium fluoride is better than using sodium fluoride alone in increasing surface microhardness; thus, it is more promising in remineralizing enamel caries.