Cigarette smoking contributes to a less diverse oral microbiota and may be associated with a decreased incidence of recurrent aphthous stomatitis (RAS), according to results of a retrospective cohort study published in the Journal of Investigative Medicine.

In this study, investigators used the V3/V4 region of salivary microorganism 16S rRNA gene sequencing to compare the differences in the microbial composition of saliva among a total of 78 patients. Of these patients, 19 were active smokers with RAS, 31 were nonsmokers with RAS, and 28 were nonsmokers without RAS (controls).

The investigators performed a metastats analysis and found 71 different genera between patients in the nonsmoking RAS group vs healthy controls, and 55 different genera between those in the nonsmoking RAS group vs healthy controls (P <.05). In addition, there were 110 bacterial species identified among patients in the nonsmoking RAS group vs healthy controls, and 99 bacterial species identified among those in the smoking RAS group vs healthy controls (P <.05).

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At the genera level, patients in the smoking and nonsmoking RAS groups had an increased abundance of Veillonella, Rothia, and Sneathia, and a decreased abundance of Bacteriodales, Bacteroides, Wolinella, Moryella, Pyramidobacter, and Christensenellaceae. Of note, the investigators observed a significant difference in the abundance of Anaerovorax, Candidatus Endomicrobrium, Lactococcus, Sneathia, Veillonella, and Cloacibacterium between patients in the smoking and nonsmoking RAS groups. They also noted a significant difference on analysis of numerous species from the Prevotella and Treponema genus between patients in the nonsmoking and smoking RAS groups.

The investigators found that the relative abundance of Megasphaera was positively correlated with age at initial onset of smoking (P =.009), and the relative abundance of Haemophilus, Leptotrichia, Lautropia, Aggregatibacter, Rothia, Bergeyella, and Atopobium was positively correlated with smoking frequency.

This study was potentially limited by the variation in the number of patients included in each group.

According to the investigators, “the target microbiome will be further explored in patients with RAS [who smoke cigarettes], which may provide new and therapeutic insights for improving RAS by regulating the oral microbiota.”


Wang X, Luo N, Mi Q, et al. Influence of cigarette smoking on oral microbiota in patients with recurrent aphthous stomatitis. J Investig Med. Published online November 25, 2021. doi:10.1136/jim-2021-002119