## 5 Discussion  
This study conducted the association between PP and periodontal disease in Korean adults with or without HTN. Periodontal disease was positively associated with high PP in Korean adults with HTN but not in those without HTN. Higher SBP can induce chronic left ventricular overload, leading to myocardial wall stress and enhanced myocardial wall stress. In addition, lower DBP can reduce coronary perfusion pressure, which can decrease myocardial oxygen supply [17]. PP is well established as a predictor of atherosclerosis, coronary heart disease, and left ventricular hypertrophy [18; 19; 20]. Periodontal disease is a multifactorial disease involving chronic 'infectious/inflammatory' factors [21] and plays an important role in chronic inflammation [22]. [PERSON] et al. reported that levels of pro- and anti-inflammatory cytokines (IFN-\(\gamma\), IL-17A, IL-6, and TNF-\(\alpha\)) decreased in an intensive periodontal treatment group and that these are the cytokines associated with cardiovascular disease and systemic HTN [23]. Several studies have investigated the relationship between cardiovascular disease and periodontal disease [24; 25; 26]. In a study of 897 Japanese patients with cardiovascular disease, increased periodontal disease was found in coronary heart disease patients compared to non-coronary heart disease patients [24]. In a meta-analysis of nine cohort studies, periodontal disease increased the event of stroke (relative risk, 1.63; 95% CI, 1.25-2.00) [25]. In a cohort study of 8999 patients with periodontal disease, participants who were not active during periodontal disease treatment had an increased incidence of cardiovascular disease events (incidence rate (IR), 1.28; 95% CI, 1.07 to 1.53) compared with those who were active during periodontal treatment [26]. In addition, the results suggested that periodontal treatment can reduce the cardiovascular disease events. Currently, periodontal disease and blood pressure are closely related--especially SBP. [PERSON] et al. revealed that periodontal disease was positively associated with SBP (\(p\) < 0.001) but was not associated with DBP (\(p\) = 0.082) [27]. In a case-control study, periodontal disease was positively associated with SBP (\(\beta\) = 3.46 \(\pm\) 1.25, \(p\) = 0.005) and the odds of HTN (OR, 2.3; 95% CI, 1.15-4.60). In addition, they mentioned that the treatment of periodontal disease could help reduce the prevalence of HTN and its complications [28]. In our results, periodontal disease was associated with SBP (area under the curve (AUC), 0.636; 95% CI, 0.600-0.672; \(p\) < 0.001) in the HTN group but was not associated with DBP (AUC, 0.526; 95% CI, 0.489-0.562; \(p\) = 0.167). In addition, periodontal disease was not associated with both SBP (AUC, 0.503; 95% CI, 0.476-0.529; \(p\) = 0.849) and DBP (AUC, 0.508; 95% CI, 0.482-0.534; \(p\) = 0.574) in the non-HTN group (Supplementary Table S1). The relationship between periodontal disease and PP is not yet clear and the results in previous studies have been inconsistent. [PERSON] et al. revealed that CPI was positively associated with aortic SBP (\(p\) = 0.03; 95% CI, 0.27 to 7.76) in patients with essential HTN but not with the left ventricular mass index (\(p\) = 0.06; 95% CI, \(-\)0.30 to 16.6) [29]. [PERSON] et al. reported that the OR of HTN (OR, 3.38; 95% CI, 1.30-9.42) in a periodontal disease group (CPI 3 + 4) was higher than in the normal group (CPI 1 + 2), whereas the OR of high PP (OR, 1.77; 95% CI, 0.65-4.90) was not [30]. By contrast, in a meta-analysis of seven cohort studies, the estimated relative risk of coronary heart disease for different categories of periodontal disease (including tooth loss, bone loss, gingivitis, and periodontitis) ranged from 1.24 to 1.34 [31]. [PERSON] et al. reported that periodontal disease in participants with HTN was positively associated with interventricular septum thickness, left ventricular internal diameter, and left ventricular posterior wall thickness (all, \(p\) < 0.0001) [32].