Pérez Jardón, AlbaChamorro Petronacci, Cintia MicaelaReboiras López, María DoloresE Silva, Fábio França VieiraPadín Iruegas, María ElenaPérez-Sayáns García, MarioAlmeida, Janete Días2026-04-222026-04-222026-03érez-Jardón, A., Carvalho, B. F. D. C., Chamorro-Petronacci, C. M., Reboiras-López, M. D., Faria, N. C., Prado, R. F. D., Alves, M. G. O., Silva, F. F. V. E., Padín-Iruegas, M. E., Pérez-Sayáns, M., & Almeida, J. D. (2026). Impact of Electronic Nicotine Delivery Systems on Oral Mucosa: A Cytopathological and Molecular Study. Journal of oral pathology & medicine : official publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology, 55(3), 331–339. https://doi.org/10.1111/jop.70095https://hdl.handle.net/10347/46892Background: The packaging and marketing of electronic cigarettes (e-cigs) often target younger demographics. This study aimed to evaluate gene expression in e-cig users through exfoliative cytology. Methods: Samples were collected from 17 e-cig users and 10 nonsmokers as controls. Clinical data included age, gender, heart rate, oximetry, capillary blood glucose, carbon monoxide levels, sialometry, alcohol-related risk scores, alcohol consumption, and e-cig use parameters. Smears from the left tongue edge were obtained using a Rovers Orcellex Brush. The Papanicolaou method assessed epithelial maturation and cytological features, categorized from normal to conclusive for malignancy. Cellular composition, inflammation, microbial presence, and atypia were evaluated using a semiquantitative scoring system. Gene expression (p16, IL1-beta, CXCL8, TNF, and KRT13) was analyzed by RT-PCR. Statistical comparisons used the Mann-Whitney test, and correlations were assessed via Spearman's test (p ≤ 0.05). Results: Fruit flavors were the most preferred. Some users were former smokers (average abstention: 3.15 months). Bacterial colonies were more prevalent in the e-cig group (64.7% vs. 20%, p = 0.085), mucus and inflammatory changes were found exclusively in e-cig users (p = 0.062). No significant differences were found in the Papanicolaou classification by gender (p = 0.904). Gene expression analysis showed a differential expression of p16 and TNF between the groups. Significant correlations were found between carbon monoxide and p16 expression (r = -0.41, p = 0.02), vaping sessions per day and p16 expression (r = -0.37, p = 0.02), and daily alcohol dose and TNF expression (r = -0.42, p = 0.04). Conclusion: E-cigarette use may induce early molecular and cytological changes in the oral mucosa, affecting inflammation, immunity, and epithelial differentiation.engThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2025 The Author(s). Journal of Oral Pathology & Medicine published by John Wiley & Sons Ltd.Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Papanicolaou testBiomarkersElectronic nicotine delivery systemsGene expressionInflammationOral mucosajournal article10.1111/jop.700951600-0714open access