Abstract
ObjectivesPeriodontal ligament stem cells (PDLSCs) have an underlined significance as their high proliferative capacity and multipotent differentiation provide an important therapeutic potential. The integrity of these cells is frequently disturbed by the routinely used irrigative compounds applied as periodontal or endodontic disinfectants (e.g., hydrogen peroxide (H2O2) and chlorhexidine (CHX)). Our objectives were (i) to monitor the cytotoxic effect of a novel dental irrigative compound, chlorine dioxide (ClO2), compared to two traditional agents (H2O2, CHX) on PDLSCs and (ii) to test whether the aging factor of PDLSC cultures determines cellular responsiveness to the chemicals tested.MethodsImpedimetry (concentration-response study), WST-1 assays (WST = water soluble tetrazolium salt), and morphology analysis were performed to measure changes in cell viability induced by the 3 disinfectants; immunocytochemistry of stem cell markers (STRO-1, CD90, and CD105) measured the induced mesenchymal characteristics.ResultsCell viability experiments demonstrated that the application of ClO2 does not lead to a significant decrease in viability of PLDSCs in concentrations used to kill microbes. On the contrary, traditional irrigants, H2O2, and CHX are highly toxic on PDLSCs. Aging of PLDSC cultures (passages 3 vs. 7) has characteristic effects on their responsiveness to these agents as the increased expression of mesenchymal stem cell markers turns to decreased.Conclusions and clinical relevanceWhile the active ingredients of mouthwash (H2O2, CHX) applied in endodontic or periodontitis management have a serious toxic effect on PDLSCs, the novel hyperpure ClO2 is less toxic providing an environment favoring dental structure regenerations during disinfectant interventions.
Highlights
For the last two decades, the discovery of the dental stem cells (DSCs) has opened new perspectives in regenerative dentistry and medicine
In short-term (0–2 h) detection (Fig. 1a), a rapid decrease of normalized cell index” (CI) profile was recorded in 0.3% H2O2 and 0.02% CHX treatments which effects were identical to strong surface membrane level cytotoxic effects resulting loss in electrical insulating capacity
In long-term relations (2–120 h) (Fig. 1b), treatments with 0.3% H2O2 and 0.02% CHX retained their short-term cytotoxic effects, while the characteristics of curves in samples treated with 0.00025% and 0.0025% ClO2 differed as a consistent increase of the curves (0.00025%—30 h; 0.0025%—50 h) was detected, which points out the presence of a surviving and proliferating subpopulation of cells
Summary
For the last two decades, the discovery of the dental stem cells (DSCs) has opened new perspectives in regenerative dentistry and medicine. Due to the lack of consensus criteria defining dental stem cells based on the surface antigen expression pattern, in most of the studies, PDLSCs are characterized by positivity for MSC markers. These cells are able to differentiate into osteogenic, adipogenic [3], chondrogenic [11], neurogenic [12], and myogenic [13] lineages In vivo, they have fundamental importance in the physiology of PDL, which does anchor the cementum covering the root to the alveolar bone and contributes to its nutrition, homeostasis, and repair. The differentiation potential of these stem cells is similar to pericytes, while their immunomodulatory character is well described [16, 17] The integrity of these cells in the PDL is vital for the whole life of the tooth. It is of paramount importance to know the effect of the disinfectant substances used routinely in the oral cavity on the physiological processes of these stem cells
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