Purpose: The purpose of this study was to investigate the acquired acid resistance of human dental enamel and dentin treated with 38% diamine silver fluoride [Ag(NH3)2F] solution and CO2 laser irradiation in vitro.
Materials and Methods: Eighty incisors were used for the enamel study and 80 molars for the dentin study. Buccal enamel surfaces were used after cutting at the cementoenamel junction, and dentin surfaces were prepared by horizontal bisection through the middle third of the crowns. Samples were then divided into four categories as follows: control (no treatment), 38% Ag(NH3)2F solution treatment only, CO2 laser irradiation only, and CO2 laser irradiation after Ag(NH3)2F solution treatment. Each sample was immersed in 2 mL of lactic acid solution (0.1 mol/L, pH 4.8) for 24 h at 37°C and 100% humidity. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometry. The samples were also observed with stereoscopy and scanning electron microscopy (SEM).
Results: The lowest mean Ca2+ ppm was recorded for the samples treated by laser irradiation with Ag(NH3)2F solution. Statistical analysis of the data was considered significant (p < 0.01). SEM observation showed that when CO2 laser irradiation was applied with Ag(NH3)2F solution, the surface acquired a melted, smooth, mirror-like appearance, which was thought to be caries resistant.
Conclusion: It can be concluded that Ag(NH3)2F solution improves the efficiency of the caries-preventive effect of CO2 laser irradiation.