Background: Occurrence of open dentinal tubules as a cause of dental hypersensitivity is a very common phenomenon in patients. The aim of this in vitro study was to assess the effect of a silver diamine fluoride solution (Ag(NH3)2 F) on human dentin samples.
Methods: A total of five fully retained wisdom teeth were selected for this study. The crowns of the teeth were separated from the roots and the occlusal enamel surface was removed. All dentin samples were treated for 60 seconds with phosphoric acid (36%) and rinsed thoroughly to remove the smear layer. Then the desensitizing agent (Riva Star, SDI; 38% Ag(NH3)2 F) was placed according to the manufacturer’s instruction. Three dentin samples were prepared for element analysis using an electron beam microprobe analyzer (JEOL JXA 8900RL). The Ag concentrations in the dentin samples were measured in depths ranging from 5 to 40 µm. The other two dentin samples were vertically fractured and accordingly prepared for visualization with SEM (Zeiss DSM).
Results: The application of the desensitizing agent on the dentin areas demonstrated an increased Ag concentration (JEOL JXA 8900RL). On the dentin surface an Ag concentration of 1.7 weight % (± 0.7) was measured, but at a depth of 20 µm only 0.3 weight % (± 0.1) were detected. In depths greater than 40 µm the Ag concentration was below the detection limit. The SEM results showed that deposits could be found in a covering on the dentin layer and in the dentinal tubules to a depth of 20 µm.
Conclusions: In this ex vivo study, the effect of silver diamine fluoride on dentin surfaces could be demonstrated. The desensitizing agent formed a film on the dentin surface and in some dentinal tubules deposits were detected. These findings can explain a certain desensitizing effect, but a direct translation to in vivo conditions can only be done with caution.