Effect of Silver Diamine Fluoride (SDF) Solution on the Stem Cells from Human Exfoliated Deciduous Teeth (SHEDs)

Abstract

Background: SDF is a solution containing silver, fluoride, and ammonia. Clinically, it is used to arrest the progression of carious lesions in primary teeth. Recent studies have shown that SDF has indirect effect on pulp tissues by triggering reparative/reactionary dentine formation, similar to pulp capping agents. Such effect could be attributed to mobilization of growth factors from dentine that was subjected to SDF. However, this assumed mechanism of action has not been investigated. Moreover, the effect of SDF on a cellular level has not been studied extensively yet.

Aim: This in-vitro study aimed to investigate the effect of SDF on SHEDs at the cellular level, in addition to the ability of SDF to mobilize growth factors from dentine.

Materials and Methods: SDF was diluted into concentrations of 3.8%, 0.38%, 0.038% and 0.0038% by (mesenchymal stem cell) MSC media. SHEDs were seeded and grown over 7 days with MSC media and MSC media supplemented with 38% SDF, along with the diluted concentrations. Cell cytotoxicity and proliferation of SDF were performed in triplicates using CyQuant assay. The CyQuant assay was validated using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyl-2H-tetrazolium bromide (MTT) assay on SDF concentrations that showed the least ii cytotoxicity. Cell differentiation assay was used to investigate the differentiation ability of SHEDs exposed to non-cytotoxic SDF concentration. The ability of SHEDs to release transforming growth factor beta 1 (TGF β-1) from dentine was also investigated using enzyme-linked immunoassay (ELISA). Groups tested were 38% SDF, 10% Citric acid and phosphate-buffered saline (PBS) that were incubated on dentine discs for 3 days at 37°C.

Results: CyQuant assay revealed that 38%, 3.8% and 0.38% SDF were cytotoxic. Highest cell proliferation rate was detected with 0.0038% SDF. MTT assay confirmed that 0.38% SDF was cytotoxic, while 0.0038% SDF showed no cytotoxicity. Osteogenic differentiation assay revealed no inhibition of differentiation in SHEDs treated with 0.0038% SDF. Highest TGF β1 release was detected in 10% citric acid, followed by 38% SDF and PBS.

Conclusion: Cell viability and proliferation assay revealed that clinical concentration of SDF (38%) was cytotoxic on SHEDs. 0.0038% SDF promoted cell proliferation and osteogenic differentiation. ELISA experiment showed that dentine exposed to 38% SDF released TGF β1, indicating that SDF could promote reactionary dentinogenesis.