Biological Effects of New Chemical-Mechanical Caries Removal Products on Human Dental Pulp Stem Cells

Introduction: The aim of this study was to compare the biological effects of four chemical caries removal materials and to assess their cytotoxicity using human dental pulp stem cells (hDPSCs). Methods: The products evaluated are: 1 - papain-based product (BRIX 3000 (R)); 2 - papain/chloramine based products (NATURAL-CARE and Papac & aacute;rie Duo (R)); and 3 - chloramine based product (Cariesolut). The following in vitro experiments were carried out: IC50 measurement, cell metabolic activity (MTT) assay, cell migration, immunofluorescence experiment, cell apoptosis analysis, and reactive oxygen species (ROS) production analysis. Statistical analyses were performed using one-way ANOVA followed by Tukey's post hoc test (p < 0.05). Results: The IC50 values were: Brix 3000: 0.596%; Papac & aacute;rie Duo: 0.052%; NATURAL CARE: 1.034%; and Cariesolut: 0.020%. The MTT assays showed non-adequate cell viability of all chemical-mechanical caries removal tested at 2% at 24, 48, and 72 h (p < 0.001). The same behaviour was observed at 0.1% in the Papac & aacute;rie Duo and Cariesolut groups. In contrast, 0.1% of Brix 3000 at all times and NATURAL CARE at 24 h treated cells showed cell viability rates similar to the control group. At 0.01% only Brix 3000 did not show statistically significant differences at any time. Delayed cell migration was observed in all hDPSCs treated with Papac & aacute;rie Duo and Cariesolut (p < 0.01 and p < 0.001). Phalloidin staining images showed a high confluence of cells in the presence of NATURAL CARE, similar to the control group. On the contrary, no cells were observed in Brix 3000 and Cariesolut at 2% and 0.1% concentrations. Papac & aacute;rie Duo showed cells at all concentrations, but hDPSCs treated at 0.01% concentration exhibited better proliferation and spreading than those in the control group. Apoptosis essay showed that Brix 3000 at both 0.1% and 0.01% had a percentage of live cells higher than 99%, with 68.4% live cells at 2%, 3.69% early apoptotic cells, and 27.9% late apoptotic cells. Conversely, the rest of the materials showed an abundance of apoptotic cells, even at low concentrations. 0.1% and 0.01% of BRIX 3000 did not affect the ROS production levels, while 2% of BRIX 3000 counterpart very significantly increased the percentage of CM-H2DCFDA positive cells. Again, all concentrations of Cariesolut showed significantly higher levels of ROS production than those observed in control cells. Conclusion: Our results suggest that Brix 3000 would be the most suitable material for chemical caries removal, with Papac & aacute;rie Duo and NATURAL CARE also being good options, and discourage the use of Cariesolut due to its low cytocompatibility on dental pulp stem cells.