Morphological and Elemental Analysis of Silver Penetration into Sound/Demineralized Dentin after SDF application

Objectives: The aim of this study was to evaluate the penetration depth of silver into sound and demineralized dentin after application of 38%silver diamine fluoride (SDF).
Methods: Two hundred and eighty-eight dentin specimens were used. The specimens were divided into 3 groups: (1) sound dentin (control), (2) 30 min EDTA-treated dentin; and (3) 13 h EDTA-treated dentin. SDF was applied to all specimens. Each group was divided into 3 subgroups according to storage time into: 24 h, 2 weeks and 1-year storage time. Each subgroup was further divided into four subgroups (n=8) according to different examinations as optical microscope (OM) observation, scanning electron microscopic (SEM) observation, elemental analysis with energy dispersive spectroscopy (EDS) and micro-focused particle induced X-ray emission (Micro-PIXE) test.
Results: The OM showed discoloration in the superficial layer after 24 h and keep extending deeper after 2 weeks and 1-year. SEM showed silver crystals within dentinal tubules after 2 weeks and 1-year. EDS analysis can detect silver penetration only in the 1-year group reaching around 1200 µm inside dentin.
Conclusions: silver ions can penetrate the full thickness of demineralized dentin with further penetration into the underlying mineralized dentin.