Penetration of Silver Diamine Fluoride with and without Potassium Iodide in Carious Lesions: An In Vitro Study

Introduction Potassium iodide (KI) has been proposed as an additive to reduce tooth staining caused by silver diamine fluoride (SDF). However, its effect on the penetration depth of SDF has not been thoroughly investigated. This study aimed to evaluate the penetration depth of SDF and SDF/KI in carious lesions. Methods In this in vitro study, 24 extracted deciduous molars with active caries were divided into three groups: SDF, SDF/KI, and control. SDF (Kids-e-dental, India) and SDF/KI (Kids-e-dental, India) were applied to the infected dentin surfaces according to the manufacturer’s instructions. Mineral density and structural analyses of affected dentin were performed using Energy Dispersive X-ray Spectroscopy (EDS) and Scanning Electron Microscopy (SEM). Data were analyzed using one-way ANOVA, the Games-Howell test, and the Kruskal-Wallis test, with p < 0.05 considered significant. Results Fluoride ion penetration was significantly higher in the SDF group (1.37 ± 0.89 wt%) than in the control group (0.28 ± 0.24 wt%, p = 0.024). No significant difference was observed between SDF and SDF/KI ( p = 0.061), or SDF/KI and control ( p = 0.520). Silver and iodine ion penetration also showed no significant differences ( p = 0.097 and p = 0.066, respectively). SEM analysis revealed greater ion diffusion and accumulation in the superficial lesion area of the SDF group. In contrast, the SDF/KI group displayed a more uniform fluoride distribution, while silver and iodine ions showed a more heterogeneous distribution. The control group exhibited minimal silver and fluoride movement. EDS analysis confirmed that silver and fluoride ion concentrations were higher in the SDF and SDF/KI groups compared to the control group. Discussion KI altered fluoride ion distribution by reducing surface concentrations without compromising deeper penetration or silver ion diffusion, suggesting it preserves SDF's effectiveness while enhancing compatibility with adhesive restorations. Conclusion Application of SDF facilitated fluoride ion penetration into infected carious lesions. The addition of KI to SDF reduced surface fluoride ion concentrations in the caries structure compared to SDF alone, without affecting the concentrations of other ions. Importantly, KI did not impair the deep diffusion of SDF.