Penetration of Silver Diamine Fluoride in Deep Carious Lesions of Human Permanent Teeth: An In Vitro Study

Abstract

Background. When silver diamine fluoride (SDF) is used in conjunction with conservative caries removal in deep carious lesions, the distribution depth of silver is critical for safety and effectiveness. Objective. The purpose of this study is to determine the effect of selected caries removal on silver penetration when 38% SDF is applied to deep carious lesions in permanent teeth. Methods. Extracted permanent teeth with caries extending to the inner third of the dentin were used (N = 18). The periphery of the carious lesion was completely removed to the dentinoenamel junction (DEJ). In group A (n = 9), no further removal of carious tissue was performed, leaving necrotic dentin inner to the DEJ, whereas in group B (n = 9) superficial necrotic dentin was completely removed until leathery, slightly moist, reasonably soft dentin remained. SDF was applied for 3 minutes in both groups. Microcomputer tomography (micro-CT) and field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FESEM-EDS) were used to measure mineral density and silver distribution. The silver penetration depth/lesion depth (PD/LD) ratio was calculated for each sample. The Mann–Whitney U test was used to compare differences between the two groups. Results. The micro-CT analysis showed that the PD/LD ratios of group B (1.07–2.29) were marginally greater than those of group A (1.00–1.31). However, a statistically significant difference was not observed ( p value = 0.5078). When stratified by remaining dentin thickness (RDT), the PD/LD ratios of group B were still greater than those of group A only when RDT was >500 µm. The FESEM-EDS analysis indicated that silver particles precipitated throughout the entire thickness of the carious lesions. Conclusion. Applying SDF on a deep carious lesion and leaving the necrotic dentin pulpally did not affect silver penetration. However, the extent to which silver penetrates the remaining dentin beneath the lesions is dependent on the amount and characteristics of that dentin.

Radiographic Changes to Silver Diamine Fluoride Treated Carious Lesions after a Rinsing Step

“…This is likely due to the presence of silver ions [ 11 ]. However, other compounds such as Calcium Fluoride (CaF2) could also have formed and contributed to the change in radiopacity of the carious lesion after SDF application [ 7 ]. Furthermore, the radiopacity of carious lesions was increased significantly after PI application ( Figure 2 and Figure 3 b), likely due to the presence of radiopaque iodine and the formation of a white creamy silver iodine precipitation [ 8 , 12 ].…”

“…Our results are consistent with previous reports using SDF on primary teeth. Carious lesions are less radiopaque at the outside layer and increase gradually in radiopacity until sound dentin is reached [ 7 ]. This gradual transition poses a challenge in terms of successful separation between the affected and infected dentin using micro-CT images.…”

“…This difficulty increased after SDF application as an overlap between the radiopacity of the carious lesion and intact dentin was noted after SDF application ( Figure 3 ). Furthermore, previous reports suggested that the penetration depth of silver was larger than the depth of the distinct carious lesion [ 7 ]. This was based on the changes in the mineral density of the carious lesion before and after SDF application using a repositioning index for micro-CT scanning [ 7 ].…”

“…Furthermore, previous reports suggested that the penetration depth of silver was larger than the depth of the distinct carious lesion [ 7 ]. This was based on the changes in the mineral density of the carious lesion before and after SDF application using a repositioning index for micro-CT scanning [ 7 ]. In our study, we attempt to reduce the overall variability by scanning the same samples and applying a coregistration technique to reposition the 3D reconstructed images and ensure that the region of interest is consistent throughout the experiment.…”

“…Multiple protocols for SDF application were reported in the literature. Although the manufacturer recommends only blot drying the tooth after SDF application, others have recommended trying to keep the tooth isolated for at least 3 min [ 5 , 7 ]. Nonetheless, many clinical situations require application of restorative materials (e.g., composite resin and glass ionomer) following SDF to seal the carious lesion or to improve esthetics.…”