Abstract
Objectives In this study, the cytotoxic responses of six different over-the-counter mouthwashes on L929 cells were analyzed by two different techniques: the traditional colorimetric tetrazolium-based reduction assay (MTT) and the modern impedance-based real-time cell analysis (RTCA) system to investigate their biocompatibility in vitro. Thus, the investigation of the antiproliferative effects of the specified materials via different techniques is vital to reach this goal. Materials and Methods First, L929 mouse fibroblasts were exposed to the dilutions of mouthwashes for 2 minutes. After incubation, the tetrazolium reduction method was used to assess the metabolic viability of cells measured by colorimetric MTT assay and morphological inspection of cells was performed via phase-contrast microscopy. Furthermore, the effect of each mouthwash on the proliferation, morphology, and adhesion of L929 cells was monitored continuously by a noninvasive and label-free RTCA system for 140 h. Results Our data showed that all of the mouthwashes had varying cytotoxic effects on fibroblasts compared to the control group in MTT assay. In addition to that, RTCA technology has provided the growth kinetic profiles that can be used to analyze if the treatment is causing antimitotic or DNA-damaging effect on cells. Thus, analysis via this system can tell us the mechanism of toxicity behind the cell growth inhibition in vitro. Here, we found that only mouthwash 1 moderately maintained the viability of the L929 cells, yet displaying antimitotic effects and the other mouthwashes (mouthwash 2-mouthwash 6) showed toxicity via DNA-damaging effects. Conclusions Of the six types of mouthwash tested, the most biocompatible result was obtained from a mouthwash containing alcohol (i.e., mouthwash 1). On the other hand, sodium fluoride- (NaF-) and cetylpyridinium chloride- (CPC-) containing mouthwash (i.e., mouthwash 2) showed the most cytotoxic effect.
Highlights
The dental plaque is a layer of bacterial complex and found naturally on the tooth surfaces which is the main cause of gingivitis, chronic periodontitis, and dental caries [1]
L929 cells (ATCC CCL1, LGC Standards GmbH, Wesel, Germany), one of the standard cell lines frequently used in the cytotoxicity tests, were cultivated in DMEM supplemented with 10% Fetal Bovine Serum (FBS, Gibco Invitrogen, Karlsruhe, Germany) and 1% penicillin/streptomycin (Gibco Invitrogen, Karlsruhe, Germany) at 37 °C in a humidified atmosphere of 5% CO2
Despite the evidence shown here that the mouthwashes can be cytotoxic in vitro, it should be noted that this may not be transferable to the buccal cavity due to the complexity of the oral environment with different variables such as host immunity, saliva, pH, and enzymes
Summary
The dental plaque is a layer of bacterial complex and found naturally on the tooth surfaces which is the main cause of gingivitis, chronic periodontitis, and dental caries [1]. The use of antimicrobial mouthwashes with mechanical oral hygiene regimens is often considered a crucial combination to decrease dental plaque [3]. The quantity and diversity of chemical agents in mouthwashes are considerable, but many have antiseptic or BioMed Research International antimicrobial effects, and their efficacy is highly variable [4]. These types of substances should be biocompatible to tooth and oral tissues, reduce plaque formation and block the activity of microorganisms without altering the ratio between gram-positive and gram-negative anaerobic bacteria [5, 6]. Since oral health contributes to total health, the maintenance of healthy oral soft and hard tissues is the most important aim of modern dentistry [7]
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