Cytotoxicity of QMix™ endodontic irrigating solution on human bone marrow mesenchymal stem cells

Abstract

BackgroundDebridement and disinfection of the root canal system is a crucial step in endodontic procedures. The effectiveness of irrigation relies on both the mechanical flushing action and the ability of irrigants to dissolve tissue and kill bacteria. The objective of the present study is to evaluate and compare the cytotoxicity of QMix™ root canal irrigating solution on immortalized human bone marrow mesenchymal stem cells (hTERT-MSC-C1) and to compare it with that of sodium hypochlorite (NaOCl).MethodsImmortalized human bone marrow mesenchymal stem cells (hTERT-MSCs) were exposed to QMix™ and NaOCl. Cell viability was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and alamarBlue assays. The cell morphology was studied after two hours of exposure to QMix™ and NaOCl. Scanning electron microscopy (SEM) analyses were performed after 2- and 4-hour incubation periods. Finally, ethidium bromide/acridine orange (EB/AO) fluorescent stain was applied to the cells in the 8-chamber slides after they were incubated with the testing agents for 2 hours to detect live and dead cells. The observations were tabulated and analyzed statistically.ResultsQMix™ exposure resulted in a significantly higher percentage of cell viability than NaOCl in the MTT and alamarBlue assays at three time points compared to the control. The SEM analysis demonstrated minimal morphological changes associated with cells that were exposed to the QMix™ solution, with little shrinkage and fragmentation of the cell wall. The live/dead analysis showed that the number of live cells after exposure to QMix™ was similar to that of the untreated control. No cell structure could be observed with the NaOCl group, indicating cell lysis.ConclusionBoth the QMix™ and NaOCl solutions were toxic to human bone marrow MSCs. Each solution might have induced cell death in a different way as evidenced in the cell viability, SEM and fluorescent studies. The slower cell death induced by QMix™ might therefore be less aggressive and more acceptable to living tissues.

Effects of auxiliary device use on smear layer removal

“…In the EC group, in which QMix was used for 1 min, the results were similar to those in the group in which QMix was used for 3 min without activation. Although this suggests that the absence of an associated device can be compensated for by increasing the duration of solution action, care is necessary as the toxicity of an agent usually increases with time (14). These results are in agreement with those of a previous study (22), which reported that root canal walls were cleaner, and the time required for satisfactory SL removal was shorter, for sonic activation of QMix than for conventional needle irrigation.…”

“…It is important to point out, however, that agitation of root canal irrigants may increase apical extrusion in conjunction with factors such as root canal anatomy and the technique used. The safety of QMix is comparable to that of the most commonly used root canal irrigant, NaOCl (14). Thus, if the use of auxiliary devices to agitate QMix is performed with caution, apical extrusion of this solution is likely to be limited or nonexistent.…”

“…It was designed for use as a final rinse irrigant for a duration of 60-90 s (13). Furthermore, studies have shown that QMix is relatively safe for use (14) and does not affect tooth structure (15) or adhesion of subsequently used materials (10). The antimicrobial activity of QMix is better than that of 2% CHX (12,13) and equal to that of 6% NaOCl (16).…”

Effect of biomaterials on angiogenesis during vital pulp therapy

“…Alkahtani et al reported that NaOCl solution has toxic effects on human bone marrow mesenchymal stem cells (MSCs) 70) . Martin et al also reported that high concentrations of NaOCl can drastically effect the survival and differentiation of stem cells of the apical papilla (SCAPs) and significantly reduce the expression of dentin sialophosphorprotein (DSPP) 71) .…”

Consideration of the Therapeutic Potential of Irrigants in Endodontic Therapy

“…Unlike NaOCl, QMix leads to cell death more slowly, without any cell lysis (124). Currently, there are no clinical studies investigating the efficacy of QMix as a final irrigant.…”