Table 1.

Significant differences between the oral microbiomes of smokers and non-smokers in the literature.

Author	Sampling method and cohort	Periodontal health	Increased in smokers	Decreased in smokers
Thomas et al. (2014)	Mucosal swabs 13 smokers 9 never smokers	Not measured	Fusobacteria Actinobacteria Capnocytophaga Prevotella	Firmicutes Cyanobacteria TM7 BD1-5 Neisseria Peptostreptococcus Gemella Granulicatella Staphylococcus
Moon et al. (2015)	Subgingival plaque 134 smokers 134 non-smokers	Moderate periodontitis	Fusobacteria Fusobacterium Streptococcus Veillonella Corynebacterium TM7 Filifactor Parvimonas Tanerella Rothia	Bacteroidetes Neisseria Prevotella Aggregatibacter Selenomonas Veillonellaceae GQ422718
Mason et al. (2015)	Subgingival plaque 200 subjects	Periodontally healthy	Fusobacterium nucleatum Fusobacterium naviforme Filifactor alocis Dialister microaerophile Megasphaera sueciensis Megasphaera geminatus Megasphaera elsdenii Megasphaera micronuciformis Acinetobacter johnsonii Acinetobacter guillouiae Acinetobacter schindleri Acinetobacter baumannii Acinetobacter haemolyticus Pseudomonas pseudoalcaligenes Pseudoramibacter alactolyticus	Streptococcus sanguinis Streptococcus parasanguinis Streptococcus oralis Gemella elegans Gemella adiacens Actinomyces viscosus Actinomyces israelii Actinomyces dentalis Neisseria subflava Haemophilus parainfluenzae
Wu et al. (2016)	Saliva 112 smokers 571 former smokers 521 never smokers	Not measured, no oral examinations	Actinobacteria Firmicutes Atopobium Streptococcus Bifidobacterium Lactobacillus Veillonella	Proteobacteria Neisseria Haemophilus Aggregatibacter Capnocytophaga Corynebacterium Porphyromonas Prevotella Peptostreptococcus Leptotrichia Abiotrophia Selenomonas
Amer et al. (2017)	Mucosal swabs (OLK study, subset analysis) 19 current smokers 10 former smokers 7 never smokers	Not measured		Fusobacterium nucleatum Neisseria Leptotrichia
Hsiao et al. (2018)	Saliva 104 male smokers 47 male never smokers	Not measured	Fusobacterium nucleatum
Wirth et al. (2020)	Saliva 11 smokers 11 non-smokers (8 never, 3 former—>1 year cessation)	Dental examinations, moderation and severe periodontitis excluded	Prevotella Megasphaera	Neisseria Capnocytophaga Porphyromonas Oribacterium
Gopinath et al. (2021)	Buccal mucosa swabs 17 male smokers 13 male non-smokers	Not measured, no oral examinations	Fusobacterium spp. including Fusobacterium nucleatum Saccharibacterium spp. Shuttleworthia spp.

OLK, oral leukoplakia.