2019 Volume 64 Issue 1 Pages 34-42
Purpose: To reveal the impact of titanium dioxide-based scanning powder for intraoral digital impression on the biological activity of oral fibroblasts.
Methods: Murine L929 cells and human periodontal ligament (PDLF) and gingival fibroblasts (GF) were treated with ten-fold serial dilutions of scanning powder and the corresponding conditioned medium (filtrate of overnight incubation of powder in medium) starting with 30 mg/ml. Bicinchoninic acid protein assay, formazan- and resazurin-based toxicity assays, live/dead and annexin V/propidium iodide (PI) staining and immunoassays for interleukin (IL) -6 and IL-8 were performed. Powder composition was analyzed using energy dispersive X-ray spectroscopy (EDS).
Results: Formazan and resazurin conversion was lesser in L929 cells than PDLF and GF in the presence of scanning powder. Induction of cell death was caused by 30 mg/ml of powder in L929 cells but not in PDLF and GF. No pronounced impact of the conditioned medium was seen in cytotoxicity assays or live/dead-, and annexin V/PI staining. In PDLF and GF IL-6 expression was increased by the powder, while there was a decrease in IL-8. Powder particles did not deplete protein from medium. EDS showed a heterogeneous mixture consisting predominantly of titanium dioxide.
Conclusions: Scanning powder decreased cell activity and induced cell death in L929 cells at high concentrations. Human oral fibroblasts showed an increase in IL-6 levels but more resistance to the cytotoxicity of the powder. Within the limitations of an in vitro study our results suggest that proper cleaning after scanning is of clinical relevance to avoid potential unwanted effects of the powder.
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