The philosophy of the contemporary dentistry encompasses the minimal intervention to manage enamel and dentin caries. Among the minimal intervention procedures, the use of silver diamine fluoride (SDF) has been indicated to halt the progression of caries lesions, including those extending into the inner half of the dentin, providing there are no clinical and radiographic signs of irreversible pulpitis. The concentration of marketed SDF varies from 12 to 38% and one of the main shortcomings of this cariostatic agent is the black staining of carious enamel and dentin. To counteract this undesirable effect, a new 38% SDF system is available, in which a potassium iodide (KI) solution is applied after the use of the SDF. Although there are clinical studies available about the performance of SDF as a cariostatic agent, there is no scientific evidence to support the lack of toxicity of this new product on the metabolism of pulp cells. Therefore, the aim of this study is to investigate the response of odontoblast-like cells to the application of a 38% SDF and KI on carious dentin. Forty non-carious human molars will be selected to produce flat dentin surfaces. Then, the dentin surface will be submitted to a microbiological protocol to induce caries. Dentin disks (0.4 mm-thick) will be cut and adapted into artificial pulp chambers (APCs). Odontoblast-like cells MDPC-23 will be seeded on the sound dentin surface of the discs whereas the carious surface will be treated with water (negative control), 29% hydrogen peroxide (positive control), 38% SDF, KI or SDF+KI (n=8/group). After 24 hours from the treatments, the viability (alamarBlue; n=6) and morphology (SEM; n=2) of the MDPC-23 seeded on the dentin will be evaluated. The conditioned medium (extract) will be collected and applied on new MDPC-23 seeded on culture plates. These cells will be also evaluated with regards the viability and the formation of mineralized nodules (Alizarin red) after 24 hours of contact with the extracts. The distribution of the dataset of each response variable will be analyzed and the homoscedasticity of the groups will be checked. After the application of the recommended statistical tests, inferences will be made at the 5% level of significance. Cellular morphology in SEM will be descriptively analyzed.
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