TABLE 3.

Clinical studies in relation to the effects of smoking on subgingival microflora (published between 2010 and 2019).

References	Periodontal condition involved	Laboratory techniques	Microorganisms targeted	Main results (smokers vs. non-smokers)
Heikkinen et al., 2012	/	PCR	Aa, Pg, Tf, Pi, Pn, Td	Higher prevalence of Pi, Tf, and Td in female smokers.
Kubota et al., 2011	CP	PCR	Aa, Pg, Pi, Tf, Fn/Fp, Td, Cr	Higher prevalence of Cr and lower prevalence of Aa in smokers.
Guglielmetti et al., 2014	CP	Quantitative PCR	Aa, Pg, Tf, Td	Greater amounts of Pg, Aa, and Tf in smokers; a significant association between smoking and the presence of Aa.
Karasneh et al., 2017	Healthy, CP	PCR	25 species	No difference between smokers and non-smokers in healthy status; higher Ta in smokers with periodontitis.
Lanza et al., 2016	CP, AP	High pure PCR	Pg, Tf, Td, Pi, Aa	No difference.
Bizzarro et al., 2013	Moderate to severe CP	Culture	Aa, Pg, Pi, Tf, Pm, Fn, Cr	No difference.
		Quantitative PCR	Aa, Pg, Pi, Tf, Pm, Fn, Td	No difference.
		16S sequencing	Community	Higher abundance of Fusobacterium, Prevotella, and Selenomonas in smokers; one cluster was identified by PCoA composed mainly of smokers (80%) with lower taxonomic diversity.
Mason et al., 2015	Healthy	16S sequencing	Community	Microbial profiles of smokers and non-smokers were different at all taxonomic levels; a highly diverse, pathogen-rich, commensal-poor, and anaerobic microbiome in smokers.
Kumar et al., 2011	Healthy	16S sequencing	Community	A highly diverse and relatively unstable initial colonization of subgingival biofilms in smokers, with more periodontal pathogens of Fusobacterium, Cardiobacterium, Synergistes and Selenomonas.
Yu et al., 2017	Healthy	16S sequencing	Community	Microbial diversity and composition were not significantly different by smoking status.
Joshi et al., 2014	Gingivitis, healthy	16S sequencing	Community	An early pathogenic colonization that led to sustained pathogen enrichment with periodontal pathogens in the biofilm, and lower resilience of the ecosystem in smokers.
Shchipkova et al., 2010	Moderate to severe CP	16S sequencing	Community	Greater abundance of Parvimonas, Fusobacterium, Campylobacter, Bacteroides, and Treponema and lower levels of Veillonella, Neisseria, and Streptococcus in smokers.
Moon et al., 2015	Moderate CP	16S sequencing	Community	Higher abundance of Fusobacterium, Fretibacterium, Streptococcus, Veillonella, Corynebacterium, and Filifactor, and greater bacterial diversity in smokers.
Camelo-Castillo et al., 2015	CP	16S sequencing	Community	Higher prevalence of Granulicatella and lower bacterial diversity in smokers.

Studies related to smoking cessation and periodontal treatment are not included in this table (discussed in separate parts). Literature search was performed from the year 2000, but no 16S sequencing related study was found between 2000 and 2009. Besides, no additionally valuable information could be extracted from these reports apart from the main results listed in this table. Therefore, only papers published between 2010 and 2019 were summarized in this table. CP, chronic periodontitis; AP, aggressive periodontitis; PCR, polymerase chain reaction; PCoA, principal coordinate analysis. Aa, Aggregatibacter actinomycetemcomitans; Pg, Porphyromonas gingivalis; Tf, Tannerella forsythia; Pi, Prevotella intermedia; Pn, Prevotella nigrescens; Td, Treponema denticola; Fn/Fp, Fusobacterium nucleatum/periodonticum; Cr, Campylobacter rectus; Ta, Treponema amylovorum.