The effects of e-cigarette use on the oral microbiome.

AIM: To investigate the effects of electronic cigarette (EC) use on the oral microbiome and gingival inflammation. SAMPLE SELECTION: Saliva and gingival crevicular fluid samples were collected from 150 adult humans between 18 and 34 years in age (50% EC users). Exclusion criteria included professional dental cleaning, antibiotic, or corticosteroid therapy in the last 3 months. Convenience sampling occurred between June 2017 and October 2018. MATERIALS AND METHODS: Clinical gingival inflammation was recorded by a single operator using a novel 4-point scale. RNA sequencing was used to determine microbial composition of samples (16S rRNA amplicon sequencing). Statistical analysis included synthesizing alpha and beta diversity using various indices, taxonomic differential abundance analysis, functional differential abundance analysis and mediation analysis. Taxonomic annotation was performed using QIIME2 with functional annotations generated using PICRUSt2. Age, sex, and frequency of tooth brushed were adjusted for. RESULTS: EC users exhibited significantly greater alpha diversity in microbial species and greater differences between EC users and users in beta diversity. Saliva samples were typically more diverse than subgingival samples. EC users demonstrated greater gingival inflammation when adjusted for age, sex and toothbrushing frequency. CONCLUSION: EC use may increase oral dysbiosis. Further clinical studies on the effects of EC use on the oral microbiome and oral diseases are recommended.