## 3 Results
denticola_ were most dominant in cigarette smokers with periodontal disease (Smoker peri). _T. forysthia_ and _E. nodatum_ expressed the highest levels in the IQOS group with periodontitis (IQOS peri); see Figure 2.  
Figure 1: Number of perio-pathogenic species in groups formed according to tobacco exposure, presence of periodontal disease, and combination. Boxes represent interquartile ranges, horizontal lines represent medians, whiskers represent minimum and maximum values, and circles represent outliers. A horizontal line connects groups that differ significantly. All classic cigarette smokers with periodontitis (Smokers peri) were positive for _P. intermedia_, _P. gingivalis_, _T. denticola_, _T. forsythia_, and _F. nucleatum_ in subgingival dental plaque. In IQOS users with periodontitis (IQOS peri), _P. gingivalis_, _T. forsythia_, _E. nodatum_, and _F. nucleatum_ were the most prevalent periodontal pathogens; while in non-smokers with periodontitis (CTRL peri), _T. forsythia_, _E. nodatum_, and _F. nucleatum_ were the most frequent (Figure 3). The composition of the bacterial flora was not influenced by age. _P. intermedia_ was more abundant in males than females (median 305 vs. 6; \(p=0.003\); r = \(-0.385\)), but there were no differences in other bacteria by sex. Oral hygiene (assessed by FMPS) was related only to _P. gingivalis_ (r = 0.280; \(p=0.032\)), _T. forsythia_ (r = 0.365; \(p=0.005\)), and _E. nodatum_ (r = 0.290; \(p=0.002\)). The prevalence of perio-pathogenic bacteria in groups formed by tobacco exposure is presented in Table 2, while the data for groups formed by the presence of periodontitis are shown in Table 3.  
Figure 2: Abundance of perio-pathogenic species according to tobacco exposure and presence of periodontitis. Boxes represent interquartile ranges, horizontal lines represent medians, whiskers represent minimum and maximum values, and circles and asterisks represent outliers and extremes. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Bacteria** & **S (N (\%))** & **IQOS (N (\%))** & **CTRL (N (\%))** & **\(p\)*** & **V** \\ \hline _Prevotella intermediia_ & 15/19 (79\%) & 19/22 (86\%) & 9/18 (50\%) & 0.028 & 0.348 \\ _Porphyromonas gingivalis_ & 17/19 (90\%) & 21/22 (96\%) & 11/18 (61\%) & 0.010 & 0.393 \\ _Troponen denicola_ & 18/19 (95\%) & 7/22 (77\%) & 14/18 (78\%) & 0.257 & 0.215 \\ _Campylobacter rectus_ & 13/19 (68\%) & 16/22 (73\%) & 9/18 (50\%) & 0.297 & 0.203 \\ _Tannerella forythia_ & 18/19 (95\%) & 20/22 (91\%) & 15/18 (83\%) & 0.507 & 0.152 \\ _Eubacterium nodatum_ & 14/19 (74\%) & 17/22 (77\%) & 13/18 (72\%) & 0.930 & 0.050 \\ _Parcimonas micra_ & 0 & 1/22 (5\%) & 2/18 (11\%) & 0.303 & 0.201 \\ _Fusobacterium nucleatum_ & 19/19 (100\%) & 22/22 (100\%) & 18/18 (100\%) & - & - \\ _Aggregatibacter_ & & & & & \\ _actinomycetemontintans_ & 2/19 (11\%) & 1/21 (5\%) & 7/18 (39\%) & 0.010 & 0.393 \\ \hline \end{tabular}  
* Chi square test.  
\end{table} 
Table 2: Prevalence of perio-pathogenic bacteria in control group (non-smokers, CTRL), IQOS users, and classic smokers (S). Figure 3: Prevalence of perio-pathogenic species according to tobacco exposure and presence of periodontitis. Asterisks denote bacteria whose prevalence significantly differed between groups. The results in Tables 2 and 3 demonstrate that the prevalence of _P. intermedia_ was higher in smokers (S and IQOS) and in periodontitis-affected subjects. _P. gingivalis_ showed a higher prevalence in the same groups as _P. intermedia. T. denticola_ was more prevalent in cigarette smokers and in those with periodontitis. The prevalence of _C. rectus_ was higher in the periodontitis group and somewhat higher in IQOS smokers. _T. forystthia_ had the highest prevalence in the periodontitis group and in cigarette smokers. _E. nodatum_ was most prevalent in the IQOS and periodontitis groups. _P. micra_ was prevalent in groups without periodontitis and in the non-smoker group. _F. nuclearatum_ was equally prevalent in all tobacco-exposed groups and in those with or without periodontal disease. _A.