The Effect of Electronic Cigarette Liquid on Oral Bacterial Biofilm

Abstract

Background The Electronic-cigarettes (E-cigarettes) are an emerging class of Electronic nicotine-delivery systems (ENDS) defined as battery-operated rechargeable apparatus that made up of a metal heating element in a stainless steel shell that vaporises the e-cigarette liquid mixture (e-liquid) that had similar basic components of water, propylene glycol (PG) or glycerol (VG), nicotine and a flavouring agent, which contained in a cartridge and an atomizer to produce a tobacco-free plume of smoke that is inhaled by users. the oral apparatus is the first area of contact with the chemical and thermal products of e-cigarettes, this exposure can induce alterations in the hard and soft oral tissues. Several studies have revealed that e-cigarette vapours can cause a range of mucosal symptoms, dental caries, exaggerate periodontal tissue breakdown, connective tissue destruction and bone loss, Although studies are controversial with much uncertainty remains regarding the influence of e-cigarettes on oral bacterial biofilm composition and very little attention has been paid to the biological impact of ENDS on normal oral microbiota, even though the number of e-cigarette users continues to grow. Therefore, The aim of this study is to evaluate the effects of non-flavoured e-cigarette liquid on oral biofilms cultivated on porcine oral mucosa. Methods Eight-millimetre-punch mucosal discs were cut from from the snout of a porcine head, rinsed with PBS then disinfected by of 0.1% acetic acid and 5% hydrogen peroxide. Oral bacterial biofilms obtained from saliva samples of healthy non-smoking individuals were cultured overnight in Broth , the concentrations were adjusted and the bacteria were counted before being added to the obtained oral discs. Different strengths of neutral e-liquid extract (0.1%, 1%, 5% and 10%) were prepared by diluting the e-liquid mixture with DMEM and applied to the infected discs, which were then incubated then Ten per cent PrestoBlue reagent was added to the grafts’ mucosa in DMEMan and set for PrestoBlue viability testing. Bacterial viability was measured using a fluorescent plate reader. Data management and analyses were performed using SPSS v.20. Results lowest fluorescence intensities were detected in the samples exposed to the 5% (12,019.8) and 10% concentrations (12,699.2). one-way ANOVA test showed a significant difference in the effects of the different concentrations (F=14.172, p=.000). the mean fluorescence intensity of samples exposed to 0% concentration was significantly higher than that of the bacteria exposed to the 0.1%, 5% and 10% concentrations (all p- values = .000). Conclusion Overall, this study suggest that the viability of oral biofilms significantly decreases after treatment with non flavoured e-cigarette liquid. Significant reduction in fluorescence intensity was seen upon exposure to high e-liquid strengths.