## 4 Discussion  
This is the first report of an association between NASH-HCC and periodontalobacteria. Although the periodontal conditions of both groups were similar, the salivary _P. gingivalis_ and _F. nucleatum_ ratios and the serum antibody titers cross-reacting with them were higher in the NASH-HCC group than in the NASH group. Additionally, _F. nucleatum_ ratio in the saliva and the salivary IgA flow rate showed a negative correlation. Clinical test items used in the medical examinations were evaluated based on the Japanese common reference interval [27; 28]. Moreover, CRP levels in the NASH-HCC group and TG, AST, ALT, and GGT in both groups were higher than the reference interval. Furthermore, endotoxin and CBG levels in the NASH-HCC group were higher than those in the NASH group. [PERSON] et al. [29] reported that _P.gingivalis_ expresses dipeptidyl peptidase 4, which is involved in regulation of blood glucose levels, possibly explaining the higher CBG level in the NASH-HCC group. Since T-Bil increases in liver cirrhosis and liver cancer [30], the NASH-HCC group had higher levels than the NASH group. In addition, ALT varied more in the NASH group, possibly because this group included patients who were undergoing treatment. Overall, the above findings suggest that although some differences existed between groups NASH and NASH-HCC, there was no profound pathological difference in the state of infection and inflammation. As mentioned earlier, the NASH-HCC group participants were older and had higher endotoxin and CBG levels than those in the NASH group. However, the results of the periodontal examination were similar for both groups. Notably, the periodontal condition is reportedly maintained by regular supportive periodontal therapy [31]. The NASH-HCC group had more dentist visits than the NASH group; therefore, they received more periodontal care. Hence, even if microbial shift occurred in the periodontal pockets of the NASH-HCC group, severe periodontal disease could have been prevented. We analyzed the ratio of periodontalogenic bacteria in saliva using a next-generation sequencer. _P. gingivalis_ and _F. nucleatum_ ratios were higher in the saliva of the NASH-HCC group than those in the NASH group. This indicates that these bacteria may be involved in the progression from NASH to HCC. The detection rate of _P. gingivalis_ in saliva reportedly increases as the disease severity increases in healthy participants, NAFLD, and NASH [12]; we observed a similar association in NASH-HCC. [PERSON] et al. [32] reported that _P. gingivalis_ was detected in venous blood and hepatocytes of patients with NASH who died of sepsis. This suggests the role of oral _P. gingivalis_ in NASH progression to cirrhosis or HCC. Notably, of the two periodonopathogenic bacteria associated with NASH-HCC, _F. nucleatum_ has recently been associated with other systemic diseases. It is involved in the development and progression of various cancers, including colorectal cancer, by evading immune mechanisms, affecting oncogenes and tumor suppressor genes, promoting cell proliferation, and by adhesion mechanisms with cancer cells [33; 34; 35]. Moreover, _F. nucleatum_ was detected in liver abscesses with extensive necrosis and fibrosis [36]. In the present study, _T. denticola_ ratio was low in the NASH-HCC group. Compared with the 57% detection in the NASH group, _T. denticola_ was detected in 35% of the participants in the NASH-HCC group; this ratio might have decreased with the increase in other bacterial species ratios. We measured serum antibody titers crossing _P. gingivalis_ and _F. nucleatum_. _P. gingivalis_ is the major pathogenic bacterium associated with the development and progression of periodontitis [37]. According to a report, _P. gingivalis_ infection in mice on a high-fat diet increases blood LPS levels, causes hepatic fibrosis, and progresses NASH [14]. Additionally, [PERSON] et al. [38] reported extensive lobular inflammation in the liver of _P.