- Silver diamine fluoride, more precisely silver diammine fluoride (SDF, chemical formula [Ag(NH₃)₂]F), is a colorless to slightly blue, water-soluble complex widely used in modern dentistry as a non-invasive treatment for dental caries. It is composed of a silver(I) ion coordinated by two ammonia molecules—forming a stable diammine complex—and one fluoride ion. This coordination stabilizes the silver ion, dramatically increasing its solubility and making it far less reactive than simple silver salts, while still allowing the compound to release biologically active silver and fluoride species at the tooth surface.
- Chemically, SDF functions through a combination of antimicrobial activity and tooth-hardening effects. The silver ion possesses broad-spectrum antibacterial properties: it interferes with bacterial enzymes, disrupts cell walls, and denatures proteins, effectively killing cariogenic bacteria such as Streptococcus mutans. The fluoride ion contributes to remineralization by forming fluorapatite-like mineral phases that enhance the acid resistance of tooth enamel and dentin. The ammonia ligands help stabilize the compound in solution, preventing premature precipitation of silver and ensuring controlled release of active ions when applied to teeth.
- Clinically, silver diammine fluoride is used to arrest existing carious lesions, especially in situations where restorative treatment is difficult—such as in young children, patients with limited access to dental care, or individuals with special needs. Application is simple: a small amount of SDF is painted onto the affected tooth surface. Within minutes, the compound reacts with demineralized dentin, forming a protective, mineral-rich layer and inhibiting further bacterial growth. The most recognizable outcome of SDF treatment is the black staining of the treated caries, caused by the formation of silver oxide or metallic silver deposits. Although the discoloration is harmless, it is cosmetically significant, which is why SDF is often used on posterior teeth or as an interim therapy.
- Beyond caries arrest, SDF has shown benefits in reducing dentin hypersensitivity, as the silver and fluoride ions precipitate within dentinal tubules, decreasing fluid movement and nerve stimulation. Its ease of use, low cost, and high effectiveness have made it an important tool in public health dentistry and in minimally invasive dental care. It is also valuable in preventing caries progression while patients await definitive restorative treatment.
- Safety-wise, SDF is generally well tolerated. Transient mild irritation of oral tissues may occur, but systemic toxicity is exceedingly unlikely at clinical doses. The most notable adverse effect is the aforementioned permanent black staining of carious lesions and potential temporary staining of soft tissues or skin. Care must also be taken to avoid inadvertent contact with clothing or clinical surfaces, as SDF can cause dark stains upon exposure to light.
