Influence of E-smoking liquids on human periodontal ligament fibroblasts

Introduction: Over the last years, electronic cigarettes (ECs) have become more popular, particularly in individuals who want to give up smoking tobacco. The aim of the present study was to assess the influence of the different e-smoking liquids on the viability and proliferation of human periodontal ligament fibroblasts. Method and materials: For this study six test solutions with components from ECs were selected: lime-, hazelnut- and menthol-flavored liquids, nicotine, propylene glycol, and PBS as control group. The fibroblasts were incubated up to 96 h with the different liquids, and cell viability was measured by using the PrestoBlue (R) reagent, the ATP detection and the migration assay. Fluorescence staining was carried out to visualize cell growth and morphology. Data were statistically analyzed by two-tailed one-way ANOVA. Results: The cell viability assay showed that the proliferation rates of the cells incubated with nicotine or the various flavored liquids of the e-cigarettes were reduced in comparison to the controls, though not all reductions were statistically significant. After an incubation of 96 h with the menthol-flavored liquid the fibroblasts were statistically significant reduced (p < 0.001). Similar results were found for the detection of ATP in fibroblasts; the incubation with menthol-flavored liquids (p < 0.001) led to a statistically significant reduction. The cell visualization tests confirmed these findings. Conclusion: Within its limits, the present in vitro study demonstrated that menthol additives of e-smoking have a harmful effect on human periodontal ligament fibroblasts. This might indicate that menthol additives should be avoided for e-cigarettes.