Factors associated with the development of postoperative pneumonia in lung cancer surgery patients with perioperative oral management

Factors associated with the development of postoperative pneumonia in lung cancer surgery patients with perioperative oral management | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Factors associated with the development of postoperative pneumonia in lung cancer surgery patients with perioperative oral management Moe Yamaguchi, Mitsuyoshi Yoshida, Mieko Okamoto, Miyuki Yokoi, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7057022/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Nov, 2025 Read the published version in Supportive Care in Cancer → Version 1 posted 9 You are reading this latest preprint version Abstract Background Postoperative pneumonia is a serious lung cancer surgery complication. Perioperative oral management can help prevent its development. Objectives This study aimed to determine the characteristics of patients who developed postoperative pneumonia despite perioperative oral management. Methods This study included 396 consecutive patients who underwent lung cancer surgery under general anesthesia at Fujita Health University Okazaki Medical Center from April 2020, the opening of the hospital, to the end of December 2023. Patient data, including age, gender, body mass index, underlying disease, smoking index, spirogram, operative time, amount of blood loss during operation, and operative procedure, were obtained from medical records. Oral examinations were conducted to determine the number of remaining teeth and whether dental caries is present and to examine tooth mobility and probing pocket depths > 4 mm. Furthermore, the patients were asked whether they had regular dental check-ups. The patients were divided into the pneumonia and no-pneumonia groups following lung surgery, and the factors involved in postoperative pneumonia were investigated. Results A total of 390 patients were analyzed (six were excluded), of whom 33 developed postoperative pneumonia. Among them, 17 were excluded from the analysis due to preoperative interstitial pneumonia. Consequently, the incidence of postoperative pneumonia was 16 of 373 patients (4.3%). Significant differences were observed between the groups in terms of age, sex, chronic obstructive pulmonary disease, smoking index, operative time, number of remaining teeth, and regular dental check-ups ( P < 0.05). Logistic regression analysis using these significant items revealed that fewer than 20 remaining teeth was significantly associated with the development of postoperative pneumonia ( P < 0.05). Conclusions The results of this study indicated that the incidence of postoperative pneumonia following perioperative oral function management was maintained as low as that reported previously. The importance of dental intervention in the perioperative period was also elucidated. A high number of patients who developed postoperative pneumonia despite these interventions had fewer than 20 remaining teeth, suggesting that more attention should be paid to perioperative oral management, including prevention of aspiration pneumonia. Consecutive patients Lung cancer Postoperative pneumonia Perioperative oral management Remaining teeth number Figures Figure 1 1. Introduction In Japan, lung cancer is the second most common cancer in men, fourth in women, and third in men and women combined.( 1 ) Lung cancer treatments are broadly classified into “surgery,” “drug therapy,” and “radiotherapy.” Although the choice of surgical treatment is based on cancer type, location, and stage, surgical resection remains one of the most effective treatments for early- to middle-stage lung cancer. In recent years, surgical techniques have undergone major changes in the field of surgery. Instead of traditional surgery, which is performed through an open wound under direct visualization, endoscopic surgery, which involves the use of an endoscope camera and a monitor screen for visual guidance, is being proactively performed. In the thoracic region, surgery using a thoracoscope is referred to as video-assisted thoracic surgery (VATS). In addition to simple partial lung resection for a pneumothorax and other conditions, it can be applied to almost all types of thoracic surgery, including surgery for lung cancer and mediastinal tumors as well as extended thymectomy to treat myasthenia gravis. VATS has been shown to decrease postoperative pulmonary complications, such as atelectasis, pneumonia, and acute respiratory failure.( 2 ) Postoperative pneumonia is a serious complication of pneumonectomy for lung cancer and is difficult to treat.( 3 ) The estimated incidence of respiratory infections following lung cancer surgery is 12–14%;( 4 , 5 ) these infections increase the length of hospital stay, resulting in prolonged ventilator management and reintubation.( 6 ) Poor expectoration and silent aspiration have been recognized as factors associated with postoperative pneumonia.( 7 ) Perioperative oral management is reportedly important to reduce the sources of infection and bacteria in the oral cavity. In 2012, Japan became the first country to introduce perioperative oral management into its medical insurance system. At present, many medical institutions provide perioperative oral management to patients undergoing surgery, chemotherapy, and radiotherapy. In perioperative oral management, dentists and dental hygienists provide comprehensive oral care during the perioperative period to prevent or reduce perioperative complications, maintain or improve nutritional status, improve treatment outcomes and quality of life, shorten the length of hospital stay, and optimize medical costs.( 8 , 9 ) They have demonstrated that perioperative oral management effectively reduces the incidence of postoperative pneumonia, but only in comparison of cases in which dentistry intervened versus those in which it did not. Because there is no oral information on nonintervention cases, we believe that oral information on all cases during the study period is necessary to elucidate the association between dental intervention and pneumonia development. Our hospital provides perioperative oral management to all patients undergoing lung resection for lung cancer. This retrospective cohort study aimed to examine more effective perioperative oral management by identifying the characteristics of patients who developed postoperative pneumonia despite the implementation of perioperative oral management. 2. Methods This study included consecutive patients who underwent lung resection for lung cancer under general anesthesia at the Fujita Medical University Okazaki Medical Center from April 2020, the opening of the hospital, to the end of December 2023. In our hospital, lobectomy is the standard surgical procedure for solid lung cancer. Limited resection is performed for patients with pulmonary ground-glass opacities, and for patients with low pulmonary function and predicted postoperative forced expiratory volume in 1 second of less than 800 ml. Uniportal video-assisted thoracoscopic surgery was employed as the standard approach, in which all procedures were performed through a single incision of less than 4 cm.( 10 ) In cases where lymph node metastasis was suspected, multiport robot-assisted surgery using five ports was performed. Meanwhile, bronchoplasty, angioplasty, and pneumonectomy were performed through a lateral thoracotomy that preserved the latissimus dorsi muscle. In all cases, postoperative pain management consisted of continuous administration of paravertebral nerve blocks using 0.2% bupivacaine for 2 days. If the pain was severe, 15 mg of pentazine was intravenously administered. All patients were started on oral loxoprofen 60 mg three times daily from the first postoperative day. The patients’ medical charts were reviewed to investigate the factors associated with the development of postoperative pneumonia, such as age, gender, body mass index, underlying disease (heart failure, cerebrovascular disease, chronic obstructive pulmonary disease [COPD], diabetes mellitus, dementia), smoking index, spirogram (FEV1.0: forced expiratory volume in 1 second, FEV1.0%: forced expiratory volume in 1 second as percent of forced vital capacity), operative time, amount of blood loss during operation, and operative procedure.( 11 – 13 ) In addition, items related to oral management, such as the number of remaining teeth, dental caries, tooth mobility, probing pocket depths > 4 mm, and regular dental examination were retrospectively evaluated. The system for dental intervention at our hospital is as follows: Patients who are scheduled for surgery are given an explanation by their attending physician regarding the dental examination. After giving their consent, they are asked to visit the dentist on the day before surgery. At the initial visit, the dentist conducts an oral examination and extracts any mobile teeth identified as potential sources of dislocation or infection at the time of surgery. In the case of teeth with mild-to-moderate mobility, a mouthpiece is made or a fixation procedure is performed. On the preoperative day, dental hygienists perform dental scaling and provide self-care instruction. On the postoperative day, they check for missing teeth and oral injuries as well as provide postoperative self-care instruction, oral care assistance, and weekly interventions until discharge, if necessary. Statistical analysis The patients were divided into two groups: those who developed postoperative pneumonia (pneumonia group) and those who did not (no-pneumonia group). The factors involved in the development of postoperative pneumonia were compared between the groups using the Mann–Whitney U test for continuous variables and the chi-squared or Fisher’s exact test for categorical variables. In the logistic regression analysis, items that were significant in the univariate analysis were used to select items associated with the development of postoperative pneumonia. The same analysis was conducted to divide the patients into two subgroups based on the number of teeth: those who had 20 teeth or more and those who had less than 20 teeth. Statistical analyses were conducted using SPSS software version 25 (IBM, Tokyo), and p-values < 0.05 were considered statistically significant. The study adhered to the Declaration of Helsinki and was approved by the Fujita Medical College Research Ethics Review Committee (No. HM24–208). Written informed consent for treatment was obtained, and for this study, patients were given the opportunity to opt out by posting a notice in our department. 3. Results Among the 397 patients (232 men and 165 women, mean age of 69.0 ± 10.1 years), 297 underwent uniportal VATS; 12, conventional VATS; 28, robotic surgery; and 36, open-heart surgery. However, six cases were excluded from the analysis as surgery was discontinued after only an exploratory thoracotomy. A total of 33 patients developed pneumonia postoperatively. Of them, 17 had preoperative interstitial pneumonia. As the interstitial pneumonia was not postoperative pneumonia, the patients were excluded from the analysis. The pneumonia group consisted of 16 patients, whereas the no-pneumonia group had 357 patients. Sputum culture results indicated that only commensal bacteria were detected in all pneumonia cases and that the bacterial flora was normal. The pneumonia group had a significantly longer hospital stay (45.7 ± 30.2 days) than the non-pneumonia group (12.0 ± 6.6 days) ( P < 0.05). This hospital stay was not used in the following multivariate analysis as it is a natural part of pneumonia treatment. Table 1 presents the results of the univariate analysis, indicating significant differences in age, gender, chronic obstructive pulmonary disease, smoking index, operative time, number of remaining teeth, and regular dental check-ups between the groups ( P < 0.05). Table 1 Characteristics of all participants in the study No pneumonia (N = 357) Pneumonia (N = 16) P -value Age 70.5 ± 9.3 75.7 ± 6.6 0.012* Sex: male 202 (56.6%) 14 (87.5%) 0.028* BMI 22.7 ± 3.5 21.6 ± 4.7 0.172 Underlying disease Heart failure 48 (13.4%) 3(18.7%) 0.467 CVD 33 (9.2%) 4(25%) 0.062 COPD 23 (6.4%) 5(31.2%) 0.004* DM 73 (20.4%) 2(12.5%) 0.749 Dementia 2 (0.5%) 1(6.2%) 0.123 Smoking index 538.1 ± 652.9 1065 ± 829.4 0.007* FEV1.0 (ml) 2195.3 ± 666.5 1884.1 ± 475.3 0.064 FEV1.0% 74.1 ± 11.6 67.5 ± 14.1 0.422 Operation time (min) 138.3 ± 62.7 182.8 ± 81.4 0.030* Amount of blood loss (g) 81.4 ± 175.8 154.2 ± 208.7 0.081 Surgical approach Uniportal VATS 287 (80.4%) 10 (62.5%) VATS 10 (2.8%) 2 (12.5%) Robotic surgery 26 (7.3%) 2 (12.5%) Open-heart surgery 34 (9.5%) 2 (12.5%) Extent of excision Lobectomy 266 (74.5%) 14 (87.5%) Partial resection 54 (15.1%) 2 (12.5%) Segmentectomy 33 (9.2%) 0 (0.0%) Pneumonectomy 4 (1.1%) 0 (0.05) Preoperative pneumonia 4 (1.1%) 1 (6.3%) 0.197 Average number of teeth (teeth) 19.4 ± 9.1 11.1 ± 8.6 <0.001* More than 20 teeth 223 (62.4%) 1 (6.3%) 10 − 19 tooth 76 (21.1%) 9 (56.2%) 1 − 9 tooth 41 (11.4%) 1 (6.3%) Edentulous 22 (6.1%) 5 (31.2%) Mobile tooth 133 (37.2%) 6 (37.5%) 1.000 Mouthpiece required 37 (10.3%) 2 (12.5%) 0.678 Probing pocket depths more than 4 mm 282 (78.9%) 9 (56.2%) 0.056 Tooth extraction 3 (0.8%) 0 (0%) 1.000 Dental caries 110 (30.8%) 4 (25%) 0.784 Regular dental check-ups 107 (29.9%) 1 (6.3%) 0.047* * P < 0.05, Mann–Whitney U test for continuous variables and the chi-squared or Fisher’s exact test for categorical variables. BMI, body mass index; CVD, cerebrovascular disease; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus, FEV1.0, forced expiratory volume in 1 second; FEV1.0%, forced expiratory volume in 1 s as percent of FVC; VATS, video-assisted thoracoscopic surgery Table 2 presents the results of the logistic regression analysis using significant items from univariate analysis. The number of remaining teeth were significantly associated with the development of postoperative pneumonia ( P < 0.05). Also, the group with less than 20 teeth demonstrated 12.9 times (95% confidence interval [CI]: 1.078–154.543) increased risk of developing postoperative pneumonia (Table 3 ). Table 2 Results of the logistic regression analysis for factors related to postoperative pneumonia B p-value Exp(B) 95% CI Age 0.053 0.220 1.055 0.968 1.149 Sex 0.656 0.455 1.928 0.343 10.822 COPD 1.066 0.107 2.905 0.792 10.648 Smoking index 0.0004 0.305 0.999 0.999 1.001 Operative time 0.004 0.194 1.004 0.997 1.012 Number of remaining teeth −0.061 0.049* 0.940 0.883 0.999 Regular dental check-ups -1.477 0.176 0.226 0.026 1.942 * P < 0.05 COPD, chronic obstructive pulmonary disease Table 3 Results of logistic regression analysis when divided into two groups of remaining teeth number B p-value Exp(B) 95% CI Age 0.027 0.554 1.028 0.938 1.127 Sex 0.678 0.444 1.971 0.346 11.007 COPD 1.101 0.111 3.008 0.776 11.631 Smoking index 0.0003 0.415 1.000 0.999 1.001 Operative time 0.004 0.245 1.004 0.997 1.012 Remaining teeth number ( > = 20 vs. <20 teeth) 2.557 0.043* 12.907 1.078 154.543 Regular dental check-ups -1.279 0.249 0.278 0.031 2.457 * P < 0.05 COPD, chronic obstructive pulmonary disease 4. Discussion The results of this study indicated that even with perioperative oral management, having fewer than 20 teeth remains a risk factor for developing pneumonia following lung cancer surgery. Iwata et al.( 14 ) reported that of the 721 patients in their study, 54 (7.5%) developed postoperative pneumonia, with 13 (4.6%) of 280 patients in the oral care group and 41 (9.3%) of 441 in the control group. Furthermore, Jia et al.( 15 ) reported that 4 of 114 (3.5%) in the oral management group and 17 of 107 (15.6%) in the control group. In the present study, the incidence of postoperative pneumonia was 4.3%, which was almost the same as that reported in the aforementioned studies. This result indicates that perioperative oral function management is useful in the prevention of postoperative pneumonia during lung cancer surgery. However, postoperative pneumonia has not been eliminated. To prevent postoperative pneumonia in the future, we identified factors associated with it. We found that COPD and operation time, which were significant in the univariate analysis, were not significant factors in the multivariate analysis. The number of remaining teeth remained associated with the development of postoperative pneumonia, which is a surprising result as all the patients were provided with perioperative oral management. It may also be that the provision of oral care instruction only once immediately before surgery was not effective in preventing pneumonia as those with few teeth had poor self-care habits.( 16 ) In contrast, no difference was observed in the proportion of patients with probing pocket depths ≥ 4 mm or those with caries between the pneumonia and no-pneumonia groups, indicating that the former group no may not have poorer oral hygiene condition. We believe that basing these results solely on oral hygiene status is questionable. Previous studies have reported that interstitial pneumonia is not included in postoperative pneumonia as it is a preoperative condition that affects the patient before surgery and continues thereafter.( 17 , 18 ) Therefore, the postoperative pneumonia that developed in this study was most likely due to aspiration. In fact, sputum examination revealed the presence of only indigenous bacteria. Several studies have demonstrated the association between the remaining teeth and swallowing function. For example, Yoshikawa et al.( 19 ) conducted a videofluoroscopic study on individuals aged over 80 years with 20 or more teeth and those with edentulous teeth. They reported a high proportion of edentulous individuals who experienced penetration during swallowing 10-mL water. In addition, Inui et al.( 20 ) conducted a dysphagia questionnaire and a repetitive saliva swallowing test on 532 community residents aged 50 to 79 years. They reported that those at risk of dysphagia had fewer remaining teeth. Okamoto et al.( 21 ) also conducted a 5-year study involving 1988 elderly community-dwelling residents and reported that those who developed dysphagia had a small number of teeth. It is possible that the high risk of aspiration in patients with few remaining teeth was associated with the development of postoperative pneumonia. However, in this study, we did not conduct screening of swallowing function. For patients with few remaining teeth, rehabilitation evaluation and intervention before surgery to prevent aspiration may be useful in preventing postoperative pneumonia. We hope to conduct further research in the future. The limitation of this study is the lack of an objective measure of how much perioperative oral management improved oral hygiene. For example, if oral bacteria are involved in the development of postoperative pneumonia, it is possible that people with fewer remaining teeth have more oral bacteria. Moreover, oral bacteria may be more common in people who have developed pneumonia. However, this study did not investigate oral bacteria, which should be a subject for future research. Furthermore, perioperative oral management before surgery ranges in intervention timing from the day to several days before surgery. Nobuhara et al.( 22 ) reported that perioperative oral management on the day before surgery helps prevent the development of remote surgical site infection following colorectal cancer surgery, highlighting the need for dental intervention on the day before surgery. Therefore, future studies are warranted to collect detailed information on the timing, frequency, and content of interventions related to perioperative oral management. 5. Conclusion The results of this study indicated that the incidence of postoperative pneumonia following perioperative oral function management was kept as low as that previously reported. Furthermore, the importance of dental intervention in the perioperative period was elucidated. A high number of patients who developed postoperative pneumonia despite these interventions had fewer than 20 remaining teeth, suggesting that more attention should be paid to perioperative oral management, including prevention of aspiration pneumonia. Declarations Acknowledgments This study was supported by Foundation Nakao for Worldwide Oral Health. We would like to express our deepest gratitude to all our colleague dental hygienists. We thank Enago (www.enago.jp) for the English language editing. Ethics statement: This study received approval from the Fujita Health University Ethics Review Committee (Approval No. HM24–208). Conflict of interest statement: None. Data availability statement: Data supporting the findings of this study can be obtained from the corresponding author upon reasonable request. Authors’ contributions: The conception or design of the work: M. Yoshida The acquisition of data: M. Yamaguchi, M. Okamoto, T. Aizawa Data analysis: M.Yoshida, M Yokoi Interpretation of data: M. Yoshida, T Suda Drafting the work: M. Yamaguchi, M. Yoshida Reviewing it critically for important intellectual content: T Suda, K. Ono Informed consent: All participants signed an informed consent form. Funding This study was supported by Foundation Nakao for Worldwide Oral Health. References National Cancer Center. Cancer mortality from Vital Statistics in Japan; 1958-2020. https://ganjoho.jp/reg_stat/statistics/data/dl/en.html Madelaine L, Baste JM, Trousse D, et al. Impact of robotic access on outcomes after lung cancer surgery in France: Analysis from the Epithor database. JTCVS Open . 2023;14:523-537. doi: 10.1016/j.xjon.2023.02.018. Planchard D, Popat S, Kerr K, et al. Metastatic non-small cell lung cancer: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol . 2018;29(suppl 4):iv192-iv237. doi:10.1093/annonc/mdy275 Li S, Lin J, Ye L, et al. Surgical site infection following open lobectomy in patients with lung cancer: a prospective study. J Evid Based Med . 2023;16(2):194-199. doi:10.1111/jebm.12544 Zhang C, Fu Y, Chen Q, Liu R. Risk factors for postoperative pulmonary infections in non-small cell lung cancer: a regression-based nomogram prediction model. Am J Cancer Res . 2024;14(11):5365-5377. doi:10.62347/BIBD8425 Imperatori A, Nardecchia E, Dominioni L, et al. Surgical site infections after lung resection: a prospective study of risk factors in 1,091 consecutive patients. J Thorac Dis . 2017;9(9):3222-3231. doi:10.21037/jtd.2017.08.122 Stuart CM, Bronsert MR, Dyas AR, et al. Risk-adjusted discrete increases in length of stay by complication following anatomic lung resection: an analysis of 32133 cases across the USA. Eur J Cardiothorac Surg . 2024;66(2):ezae293. doi:10.1093/ejcts/ezae293 Liang S, Zhang X, Hu Y, Yang J, Li K. Association between perioperative chlorhexidine oral care and postoperative pneumonia in non-cardiac surgical patients: a systematic review and meta-analysis. Surgery . 2021;170(5):1418-1431. doi:10.1016/j.surg.2021.05.008 Sakai H, Kurita H, Kondo E, et al. Dental and oral management in the perioperative period of surgery: A scoping review. Jpn Dent Sci Rev . Dent. 2024 December;60:148-153. doi:10.1016/j.jdsr.2024.03.002 Suda T, Kitamura Y, Hasegawa S, et al. Video-assisted thoracoscopic extrapleural pneumonectomy for malignant pleural mesothelioma. J Thorac Cardiovasc Surg . 2007;134:1088-1089. doi: 10.1016/j.jtcvs.2007.03.062. Lee JY, Jin S-M, Lee C-H, et al. Risk factors of postoperative pneumonia after lung cancer surgery. J Korean Med Sci . 2011;26(8):979-984. doi:10.3346/jkms.2011.26.8.979 Shiono S, Abiko M, Sato T. Postoperative complications in elderly patients after lung cancer surgery. Interact Cardiovasc Thorac Surg . 2013;16(6):819-823. doi:10.1093/icvts/ivt034 Bian H, Liu M, Liu J, et al. Seven preoperative factors have strong predictive value for postoperative pneumonia in patients undergoing thoracoscopic lung cancer surgery. Transl Lung Cancer Res . 2023;12(11):2193-2208. doi:10.21037/tlcr-23-512 Iwata E, Hasegawa T, Yamada S-I, et al. Effects of perioperative oral care on prevention of postoperative pneumonia after lung resection: multicenter retrospective study with propensity score matching analysis. Surgery . 2019;165(5):1003-1007. doi:10.1016/j.surg.2018.11.020 Jia C, Sun M, Wang W, Li C, Li X, Zhang X. Effect of oral plaque control on postoperative pneumonia following lung cancer surgery. Thorac Cancer . 2020;11(6):1655-1660. doi:10.1111/1759-7714.13448 Hamasha AA, Sasa I, Al-Qudah M. Risk indicators associated with tooth loss in Jordanian adults. Community Dent Oral Epidemiol . 2000;28(1):67-72. doi:10.1034/j.1600-0528.2000.280109.x Ozawa Y, Suda T, Naito T, et al. Cumulative incidence of and predictive factors for lung cancer in IPF. Respirology . 2009;14(5):723-728. doi:10.1111/j.1440-1843.2009.01547.x Sato T, Teramukai S, Kondo H, et al. Impact and predictors of acute exacerbation of interstitial lung diseases after pulmonary resection for lung cancer. J Thorac Cardiovasc Surg . 2014;147(5):1604-1611.e3. doi:10.1016/j.jtcvs.2013.09.050 Yoshikawa M, Yoshida M, Nagasaki T, Tanimoto K, Tsuga K, Akagawa Y. Influence of aging and denture use on liquid swallowing in healthy dentulous and edentulous older people. J Am Geriatr Soc . 2006;54(3):444-449. doi:10.1111/j.1532-5415.2005.00619.x Inui A, Takahashi I, Kurauchi S, et al. Oral conditions and dysphagia in Japanese, community-dwelling middle- and older- aged adults, independent in daily living. Clin Interv Aging . 2017;12:515-521. doi:10.2147/CIA.S132637 Okamoto N, Morikawa M, Yanagi M, et al. Association of tooth loss with development of swallowing problems in community-dwelling independent elderly population: the Fujiwara-kyo study. J Gerontol A Biol Sci Med Sci . 2015;70(12):1548-1554. doi:10.1093/gerona/glv116 Nobuhara H, Yanamoto S, Funahara M, et al. Effect of perioperative oral management on the prevention of surgical site infection after colorectal cancer surgery: a multicenter retrospective analysis of 698 patients via analysis of covariance using propensity score. Medicine . 2018;97(40):e12545. doi:10.1097/MD.0000000000012545 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 18 Nov, 2025 Read the published version in Supportive Care in Cancer → Version 1 posted Editorial decision: Revision requested 30 Sep, 2025 Reviews received at journal 29 Sep, 2025 Reviewers agreed at journal 29 Sep, 2025 Reviews received at journal 20 Aug, 2025 Reviewers agreed at journal 12 Aug, 2025 Reviewers invited by journal 11 Aug, 2025 Editor assigned by journal 11 Aug, 2025 Submission checks completed at journal 08 Jul, 2025 First submitted to journal 06 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7057022","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":499636771,"identity":"27833217-4eeb-432d-a8eb-c97d20a62c35","order_by":0,"name":"Moe Yamaguchi","email":"","orcid":"","institution":"Fujita Health University Okazaki Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Moe","middleName":"","lastName":"Yamaguchi","suffix":""},{"id":499636772,"identity":"4168840c-2faa-4b48-9314-71939adb3a4c","order_by":1,"name":"Mitsuyoshi Yoshida","email":"data:image/png;base64,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","orcid":"","institution":"Fujita Health University School of Medicine","correspondingAuthor":true,"prefix":"","firstName":"Mitsuyoshi","middleName":"","lastName":"Yoshida","suffix":""},{"id":499636773,"identity":"89808817-b41f-4746-927d-4df02730cdda","order_by":2,"name":"Mieko Okamoto","email":"","orcid":"","institution":"Fujita Health University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Mieko","middleName":"","lastName":"Okamoto","suffix":""},{"id":499636774,"identity":"87663571-8e31-4ee1-9535-0f9605498486","order_by":3,"name":"Miyuki Yokoi","email":"","orcid":"","institution":"Fujita Health University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Miyuki","middleName":"","lastName":"Yokoi","suffix":""},{"id":499636775,"identity":"fb1c6eee-331b-4034-bf5a-171aec333c9e","order_by":4,"name":"Takako Aizawa","email":"","orcid":"","institution":"Fujita Health University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Takako","middleName":"","lastName":"Aizawa","suffix":""},{"id":499636776,"identity":"a011a662-4e74-4068-ab7b-56a830cfb0bb","order_by":5,"name":"Takashi Suda","email":"","orcid":"","institution":"Fujita Health University Okazaki Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Takashi","middleName":"","lastName":"Suda","suffix":""},{"id":499636777,"identity":"27ff2033-546f-438a-abba-e77572f254cd","order_by":6,"name":"Kazuhiro Ono","email":"","orcid":"","institution":"Niigata University Graduate School of Medical and Dental Sciences","correspondingAuthor":false,"prefix":"","firstName":"Kazuhiro","middleName":"","lastName":"Ono","suffix":""}],"badges":[],"createdAt":"2025-07-06 09:38:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7057022/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7057022/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00520-025-10177-6","type":"published","date":"2025-11-18T15:58:43+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":89453837,"identity":"4f5bbc2d-cc1b-43e0-b22c-303c812b0894","added_by":"auto","created_at":"2025-08-20 06:43:19","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":27791,"visible":true,"origin":"","legend":"\u003cp\u003eThe flowchart of subject selection\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7057022/v1/99ac85f6280b2eefbceded5a.png"},{"id":96650209,"identity":"d5ae6334-d66d-485a-8596-72aac2a1104b","added_by":"auto","created_at":"2025-11-24 16:09:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":889234,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7057022/v1/71a79c1c-3f7a-4cb3-a637-42e693b9551a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Factors associated with the development of postoperative pneumonia in lung cancer surgery patients with perioperative oral management","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn Japan, lung cancer is the second most common cancer in men, fourth in women, and third in men and women combined.(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) Lung cancer treatments are broadly classified into \u0026ldquo;surgery,\u0026rdquo; \u0026ldquo;drug therapy,\u0026rdquo; and \u0026ldquo;radiotherapy.\u0026rdquo; Although the choice of surgical treatment is based on cancer type, location, and stage, surgical resection remains one of the most effective treatments for early- to middle-stage lung cancer.\u003c/p\u003e\u003cp\u003eIn recent years, surgical techniques have undergone major changes in the field of surgery. Instead of traditional surgery, which is performed through an open wound under direct visualization, endoscopic surgery, which involves the use of an endoscope camera and a monitor screen for visual guidance, is being proactively performed. In the thoracic region, surgery using a thoracoscope is referred to as video-assisted thoracic surgery (VATS). In addition to simple partial lung resection for a pneumothorax and other conditions, it can be applied to almost all types of thoracic surgery, including surgery for lung cancer and mediastinal tumors as well as extended thymectomy to treat myasthenia gravis. VATS has been shown to decrease postoperative pulmonary complications, such as atelectasis, pneumonia, and acute respiratory failure.(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003cp\u003ePostoperative pneumonia is a serious complication of pneumonectomy for lung cancer and is difficult to treat.(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) The estimated incidence of respiratory infections following lung cancer surgery is 12\u0026ndash;14%;(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) these infections increase the length of hospital stay, resulting in prolonged ventilator management and reintubation.(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e) Poor expectoration and silent aspiration have been recognized as factors associated with postoperative pneumonia.(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) Perioperative oral management is reportedly important to reduce the sources of infection and bacteria in the oral cavity.\u003c/p\u003e\u003cp\u003eIn 2012, Japan became the first country to introduce perioperative oral management into its medical insurance system. At present, many medical institutions provide perioperative oral management to patients undergoing surgery, chemotherapy, and radiotherapy. In perioperative oral management, dentists and dental hygienists provide comprehensive oral care during the perioperative period to prevent or reduce perioperative complications, maintain or improve nutritional status, improve treatment outcomes and quality of life, shorten the length of hospital stay, and optimize medical costs.(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e) They have demonstrated that perioperative oral management effectively reduces the incidence of postoperative pneumonia, but only in comparison of cases in which dentistry intervened versus those in which it did not. Because there is no oral information on nonintervention cases, we believe that oral information on all cases during the study period is necessary to elucidate the association between dental intervention and pneumonia development. Our hospital provides perioperative oral management to all patients undergoing lung resection for lung cancer. This retrospective cohort study aimed to examine more effective perioperative oral management by identifying the characteristics of patients who developed postoperative pneumonia despite the implementation of perioperative oral management.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cp\u003eThis study included consecutive patients who underwent lung resection for lung cancer under general anesthesia at the Fujita Medical University Okazaki Medical Center from April 2020, the opening of the hospital, to the end of December 2023.\u003c/p\u003e\u003cp\u003eIn our hospital, lobectomy is the standard surgical procedure for solid lung cancer. Limited resection is performed for patients with pulmonary ground-glass opacities, and for patients with low pulmonary function and predicted postoperative forced expiratory volume in 1 second of less than 800 ml. Uniportal video-assisted thoracoscopic surgery was employed as the standard approach, in which all procedures were performed through a single incision of less than 4 cm.(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e) In cases where lymph node metastasis was suspected, multiport robot-assisted surgery using five ports was performed. Meanwhile, bronchoplasty, angioplasty, and pneumonectomy were performed through a lateral thoracotomy that preserved the latissimus dorsi muscle. In all cases, postoperative pain management consisted of continuous administration of paravertebral nerve blocks using 0.2% bupivacaine for 2 days. If the pain was severe, 15 mg of pentazine was intravenously administered. All patients were started on oral loxoprofen 60 mg three times daily from the first postoperative day.\u003c/p\u003e\u003cp\u003eThe patients\u0026rsquo; medical charts were reviewed to investigate the factors associated with the development of postoperative pneumonia, such as age, gender, body mass index, underlying disease (heart failure, cerebrovascular disease, chronic obstructive pulmonary disease [COPD], diabetes mellitus, dementia), smoking index, spirogram (FEV1.0: forced expiratory volume in 1 second, FEV1.0%: forced expiratory volume in 1 second as percent of forced vital capacity), operative time, amount of blood loss during operation, and operative procedure.(\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e) In addition, items related to oral management, such as the number of remaining teeth, dental caries, tooth mobility, probing pocket depths\u0026thinsp;\u0026gt;\u0026thinsp;4 mm, and regular dental examination were retrospectively evaluated.\u003c/p\u003e\u003cp\u003eThe system for dental intervention at our hospital is as follows: Patients who are scheduled for surgery are given an explanation by their attending physician regarding the dental examination. After giving their consent, they are asked to visit the dentist on the day before surgery. At the initial visit, the dentist conducts an oral examination and extracts any mobile teeth identified as potential sources of dislocation or infection at the time of surgery. In the case of teeth with mild-to-moderate mobility, a mouthpiece is made or a fixation procedure is performed. On the preoperative day, dental hygienists perform dental scaling and provide self-care instruction. On the postoperative day, they check for missing teeth and oral injuries as well as provide postoperative self-care instruction, oral care assistance, and weekly interventions until discharge, if necessary.\u003c/p\u003e\u003cp\u003e\u003cb\u003eStatistical analysis\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe patients were divided into two groups: those who developed postoperative pneumonia (pneumonia group) and those who did not (no-pneumonia group). The factors involved in the development of postoperative pneumonia were compared between the groups using the Mann\u0026ndash;Whitney U test for continuous variables and the chi-squared or Fisher\u0026rsquo;s exact test for categorical variables. In the logistic regression analysis, items that were significant in the univariate analysis were used to select items associated with the development of postoperative pneumonia. The same analysis was conducted to divide the patients into two subgroups based on the number of teeth: those who had 20 teeth or more and those who had less than 20 teeth. Statistical analyses were conducted using SPSS software version 25 (IBM, Tokyo), and p-values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered statistically significant.\u003c/p\u003e\u003cp\u003e The study adhered to the Declaration of Helsinki and was approved by the Fujita Medical College Research Ethics Review Committee (No. HM24\u0026ndash;208). Written informed consent for treatment was obtained, and for this study, patients were given the opportunity to opt out by posting a notice in our department.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eAmong the 397 patients (232 men and 165 women, mean age of 69.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.1 years), 297 underwent uniportal VATS; 12, conventional VATS; 28, robotic surgery; and 36, open-heart surgery. However, six cases were excluded from the analysis as surgery was discontinued after only an exploratory thoracotomy.\u003c/p\u003e\u003cp\u003eA total of 33 patients developed pneumonia postoperatively. Of them, 17 had preoperative interstitial pneumonia. As the interstitial pneumonia was not postoperative pneumonia, the patients were excluded from the analysis. The pneumonia group consisted of 16 patients, whereas the no-pneumonia group had 357 patients. Sputum culture results indicated that only commensal bacteria were detected in all pneumonia cases and that the bacterial flora was normal. The pneumonia group had a significantly longer hospital stay (45.7\u0026thinsp;\u0026plusmn;\u0026thinsp;30.2 days) than the non-pneumonia group (12.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6 days) (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). This hospital stay was not used in the following multivariate analysis as it is a natural part of pneumonia treatment. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the results of the univariate analysis, indicating significant differences in age, gender, chronic obstructive pulmonary disease, smoking index, operative time, number of remaining teeth, and regular dental check-ups between the groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of all participants in the study\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNo pneumonia\u003c/p\u003e\u003cp\u003e(N\u0026thinsp;=\u0026thinsp;357)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePneumonia\u003c/p\u003e\u003cp\u003e(N\u0026thinsp;=\u0026thinsp;16)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAge\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e70.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e75.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.012*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSex: male\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e202 (56.6%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (87.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.028*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBMI\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.172\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eUnderlying disease\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHeart failure\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e48 (13.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3(18.7%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.467\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCVD\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e33 (9.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4(25%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.062\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCOPD\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23 (6.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5(31.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.004*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDM\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e73 (20.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2(12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.749\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDementia\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2 (0.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1(6.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.123\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSmoking index\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e538.1\u0026thinsp;\u0026plusmn;\u0026thinsp;652.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1065\u0026thinsp;\u0026plusmn;\u0026thinsp;829.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.007*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFEV1.0\u003c/b\u003e \u003cb\u003e(ml)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2195.3\u0026thinsp;\u0026plusmn;\u0026thinsp;666.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1884.1\u0026thinsp;\u0026plusmn;\u0026thinsp;475.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.064\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFEV1.0%\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e74.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e67.5\u0026thinsp;\u0026plusmn;\u0026thinsp;14.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.422\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eOperation time (min)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e138.3\u0026thinsp;\u0026plusmn;\u0026thinsp;62.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e182.8\u0026thinsp;\u0026plusmn;\u0026thinsp;81.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.030*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAmount of blood loss (g)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e81.4\u0026thinsp;\u0026plusmn;\u0026thinsp;175.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e154.2\u0026thinsp;\u0026plusmn;\u0026thinsp;208.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.081\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSurgical approach\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eUniportal VATS\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e287 (80.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 (62.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eVATS\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10 (2.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2 (12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRobotic surgery\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26 (7.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2 (12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eOpen-heart surgery\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e34 (9.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2 (12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eExtent of excision\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLobectomy\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e266 (74.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (87.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePartial resection\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e54 (15.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2 (12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSegmentectomy\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e33 (9.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0.0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePneumonectomy\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4 (1.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0.05)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePreoperative pneumonia\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4 (1.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (6.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.197\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAverage number of teeth (teeth)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e19.4\u0026thinsp;\u0026plusmn;\u0026thinsp;9.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMore than 20 teeth\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e223 (62.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (6.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003e10\u0026thinsp;\u0026minus;\u0026thinsp;19 tooth\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e76 (21.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9 (56.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003e1\u0026thinsp;\u0026minus;\u0026thinsp;9 tooth\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41 (11.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (6.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEdentulous\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22 (6.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (31.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMobile tooth\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e133 (37.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6 (37.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMouthpiece required\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e37 (10.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2 (12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.678\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eProbing pocket depths more than 4 mm\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e282 (78.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9 (56.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.056\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTooth extraction\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3 (0.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0 (0%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDental caries\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e110 (30.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (25%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.784\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRegular dental check-ups\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e107 (29.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (6.3%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.047*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Mann\u0026ndash;Whitney U test for continuous variables and the chi-squared or Fisher\u0026rsquo;s exact test for categorical variables.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eBMI, body mass index; CVD, cerebrovascular disease; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus, FEV1.0, forced expiratory volume in 1 second; FEV1.0%, forced expiratory volume in 1 s as percent of FVC; VATS, video-assisted thoracoscopic surgery\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents the results of the logistic regression analysis using significant items from univariate analysis. The number of remaining teeth were significantly associated with the development of postoperative pneumonia (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Also, the group with less than 20 teeth demonstrated 12.9 times (95% confidence interval [CI]: 1.078\u0026ndash;154.543) increased risk of developing postoperative pneumonia (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eResults of the logistic regression analysis for factors related to postoperative pneumonia\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eExp(B)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.053\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.055\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.968\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.149\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.656\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.455\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.928\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.343\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e10.822\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCOPD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.066\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.107\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.905\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.792\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e10.648\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmoking index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.0004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.305\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperative time\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.194\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.997\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.012\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNumber of remaining teeth\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e\u0026minus;0.061\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.049*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.940\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.883\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.999\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRegular dental check-ups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-1.477\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.176\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.226\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.026\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.942\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eCOPD, chronic obstructive pulmonary disease\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eResults of logistic regression analysis when divided into two groups of remaining teeth number\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eExp(B)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAge\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.027\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.554\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.028\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.938\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.127\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSex\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.678\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.444\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.971\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.346\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e11.007\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCOPD\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.101\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.111\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.008\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.776\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e11.631\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSmoking index\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.0003\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.415\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eOperative time\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.245\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.004\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.997\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.012\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRemaining teeth number\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003e(\u0026thinsp;\u0026gt;\u0026thinsp;=\u0026thinsp;20 vs. \u0026lt;20 teeth)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.557\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.043*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e12.907\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e1.078\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e154.543\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRegular dental check-ups\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e-1.279\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.249\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.278\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.031\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e2.457\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003e*\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eCOPD, chronic obstructive pulmonary disease\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe results of this study indicated that even with perioperative oral management, having fewer than 20 teeth remains a risk factor for developing pneumonia following lung cancer surgery.\u003c/p\u003e\u003cp\u003eIwata et al.(\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e) reported that of the 721 patients in their study, 54 (7.5%) developed postoperative pneumonia, with 13 (4.6%) of 280 patients in the oral care group and 41 (9.3%) of 441 in the control group. Furthermore, Jia et al.(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e) reported that 4 of 114 (3.5%) in the oral management group and 17 of 107 (15.6%) in the control group. In the present study, the incidence of postoperative pneumonia was 4.3%, which was almost the same as that reported in the aforementioned studies. This result indicates that perioperative oral function management is useful in the prevention of postoperative pneumonia during lung cancer surgery. However, postoperative pneumonia has not been eliminated. To prevent postoperative pneumonia in the future, we identified factors associated with it. We found that COPD and operation time, which were significant in the univariate analysis, were not significant factors in the multivariate analysis.\u003c/p\u003e\u003cp\u003eThe number of remaining teeth remained associated with the development of postoperative pneumonia, which is a surprising result as all the patients were provided with perioperative oral management. It may also be that the provision of oral care instruction only once immediately before surgery was not effective in preventing pneumonia as those with few teeth had poor self-care habits.(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e) In contrast, no difference was observed in the proportion of patients with probing pocket depths\u0026thinsp;\u0026ge;\u0026thinsp;4 mm or those with caries between the pneumonia and no-pneumonia groups, indicating that the former group no may not have poorer oral hygiene condition. We believe that basing these results solely on oral hygiene status is questionable.\u003c/p\u003e\u003cp\u003ePrevious studies have reported that interstitial pneumonia is not included in postoperative pneumonia as it is a preoperative condition that affects the patient before surgery and continues thereafter.(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e) Therefore, the postoperative pneumonia that developed in this study was most likely due to aspiration. In fact, sputum examination revealed the presence of only indigenous bacteria. Several studies have demonstrated the association between the remaining teeth and swallowing function. For example, Yoshikawa et al.(\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) conducted a videofluoroscopic study on individuals aged over 80 years with 20 or more teeth and those with edentulous teeth. They reported a high proportion of edentulous individuals who experienced penetration during swallowing 10-mL water. In addition, Inui et al.(\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e) conducted a dysphagia questionnaire and a repetitive saliva swallowing test on 532 community residents aged 50 to 79 years. They reported that those at risk of dysphagia had fewer remaining teeth. Okamoto et al.(\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e) also conducted a 5-year study involving 1988 elderly community-dwelling residents and reported that those who developed dysphagia had a small number of teeth. It is possible that the high risk of aspiration in patients with few remaining teeth was associated with the development of postoperative pneumonia. However, in this study, we did not conduct screening of swallowing function. For patients with few remaining teeth, rehabilitation evaluation and intervention before surgery to prevent aspiration may be useful in preventing postoperative pneumonia. We hope to conduct further research in the future.\u003c/p\u003e\u003cp\u003e The limitation of this study is the lack of an objective measure of how much perioperative oral management improved oral hygiene. For example, if oral bacteria are involved in the development of postoperative pneumonia, it is possible that people with fewer remaining teeth have more oral bacteria. Moreover, oral bacteria may be more common in people who have developed pneumonia. However, this study did not investigate oral bacteria, which should be a subject for future research. Furthermore, perioperative oral management before surgery ranges in intervention timing from the day to several days before surgery. Nobuhara et al.(\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e) reported that perioperative oral management on the day before surgery helps prevent the development of remote surgical site infection following colorectal cancer surgery, highlighting the need for dental intervention on the day before surgery. Therefore, future studies are warranted to collect detailed information on the timing, frequency, and content of interventions related to perioperative oral management.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eThe results of this study indicated that the incidence of postoperative pneumonia following perioperative oral function management was kept as low as that previously reported. Furthermore, the importance of dental intervention in the perioperative period was elucidated. A high number of patients who developed postoperative pneumonia despite these interventions had fewer than 20 remaining teeth, suggesting that more attention should be paid to perioperative oral management, including prevention of aspiration pneumonia.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by Foundation Nakao for Worldwide Oral Health. We would like to express our deepest gratitude to all our colleague dental hygienists.\u0026nbsp;We thank Enago (www.enago.jp) for the English language editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study received approval from the Fujita Health University Ethics Review Committee (Approval No. HM24\u0026ndash;208).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest statement:\u003c/strong\u003e None.\u003c/p\u003e\n\u003cp\u003eData availability statement: Data supporting the findings of this study can be obtained from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contributions:\u003c/p\u003e\n\u003cp\u003eThe conception or design of the work: M. Yoshida\u003c/p\u003e\n\u003cp\u003eThe acquisition of data: M. Yamaguchi, M. Okamoto, T. Aizawa\u003c/p\u003e\n\u003cp\u003eData analysis: M.Yoshida, M Yokoi\u003c/p\u003e\n\u003cp\u003eInterpretation of data: M. Yoshida, T Suda\u003c/p\u003e\n\u003cp\u003eDrafting the work: M. Yamaguchi, M. Yoshida\u003c/p\u003e\n\u003cp\u003eReviewing it critically for important intellectual content: T Suda, K. Ono\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eInformed consent:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll participants signed an informed consent form.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by Foundation Nakao for Worldwide Oral Health.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eNational Cancer Center. Cancer mortality from Vital Statistics in Japan; 1958-2020. https://ganjoho.jp/reg_stat/statistics/data/dl/en.html\u003c/li\u003e\n\u003cli\u003eMadelaine L, Baste JM, Trousse D, et al. Impact of robotic access on outcomes after lung cancer surgery in France: Analysis from the Epithor database. \u003cem\u003eJTCVS Open\u003c/em\u003e. 2023;14:523-537. doi: 10.1016/j.xjon.2023.02.018.\u003c/li\u003e\n\u003cli\u003ePlanchard D, Popat S, Kerr K, et al. Metastatic non-small cell lung cancer: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. \u003cem\u003eAnn Oncol\u003c/em\u003e. 2018;29(suppl 4):iv192-iv237. doi:10.1093/annonc/mdy275\u003c/li\u003e\n\u003cli\u003eLi S, Lin J, Ye L, et al. Surgical site infection following open lobectomy in patients with lung cancer: a prospective study. \u003cem\u003eJ Evid Based Med\u003c/em\u003e. 2023;16(2):194-199. doi:10.1111/jebm.12544\u003c/li\u003e\n\u003cli\u003eZhang C, Fu Y, Chen Q, Liu R. Risk factors for postoperative pulmonary infections in non-small cell lung cancer: a regression-based nomogram prediction model. \u003cem\u003eAm J Cancer Res\u003c/em\u003e. 2024;14(11):5365-5377. doi:10.62347/BIBD8425\u003c/li\u003e\n\u003cli\u003eImperatori A, Nardecchia E, Dominioni L, et al. Surgical site infections after lung resection: a prospective study of risk factors in 1,091 consecutive patients. \u003cem\u003eJ Thorac Dis\u003c/em\u003e. 2017;9(9):3222-3231. doi:10.21037/jtd.2017.08.122\u003c/li\u003e\n\u003cli\u003eStuart CM, Bronsert MR, Dyas AR, et al. Risk-adjusted discrete increases in length of stay by complication following anatomic lung resection: an analysis of 32133 cases across the USA. \u003cem\u003eEur J Cardiothorac Surg\u003c/em\u003e. 2024;66(2):ezae293. doi:10.1093/ejcts/ezae293\u003c/li\u003e\n\u003cli\u003eLiang S, Zhang X, Hu Y, Yang J, Li K. Association between perioperative chlorhexidine oral care and postoperative pneumonia in non-cardiac surgical patients: a systematic review and meta-analysis. \u003cem\u003eSurgery\u003c/em\u003e. 2021;170(5):1418-1431. doi:10.1016/j.surg.2021.05.008\u003c/li\u003e\n\u003cli\u003eSakai H, Kurita H, Kondo E, et al. Dental and oral management in the perioperative period of surgery: A scoping review. \u003cem\u003eJpn Dent Sci Rev\u003c/em\u003e. Dent. 2024 December;60:148-153. doi:10.1016/j.jdsr.2024.03.002\u003c/li\u003e\n\u003cli\u003eSuda T, Kitamura Y, Hasegawa S, et al. Video-assisted thoracoscopic extrapleural pneumonectomy for malignant pleural mesothelioma. \u003cem\u003eJ Thorac Cardiovasc Surg\u003c/em\u003e. 2007;134:1088-1089. doi: 10.1016/j.jtcvs.2007.03.062.\u003c/li\u003e\n\u003cli\u003eLee JY, Jin S-M, Lee C-H, et al. Risk factors of postoperative pneumonia after lung cancer surgery. \u003cem\u003eJ Korean Med Sci\u003c/em\u003e. 2011;26(8):979-984. doi:10.3346/jkms.2011.26.8.979\u003c/li\u003e\n\u003cli\u003eShiono S, Abiko M, Sato T. Postoperative complications in elderly patients after lung cancer surgery. \u003cem\u003eInteract Cardiovasc Thorac Surg\u003c/em\u003e. 2013;16(6):819-823. doi:10.1093/icvts/ivt034\u003c/li\u003e\n\u003cli\u003eBian H, Liu M, Liu J, et al. Seven preoperative factors have strong predictive value for postoperative pneumonia in patients undergoing thoracoscopic lung cancer surgery. \u003cem\u003eTransl\u003c/em\u003e\u003cem\u003e Lung Cancer \u003c/em\u003e\u003cem\u003eRes\u003c/em\u003e. 2023;12(11):2193-2208. doi:10.21037/tlcr-23-512\u003c/li\u003e\n\u003cli\u003eIwata E, Hasegawa T, Yamada S-I, et al. Effects of perioperative oral care on prevention of postoperative pneumonia after lung resection: multicenter retrospective study with propensity score matching analysis. \u003cem\u003eSurgery\u003c/em\u003e. 2019;165(5):1003-1007. doi:10.1016/j.surg.2018.11.020\u003c/li\u003e\n\u003cli\u003eJia C, Sun M, Wang W, Li C, Li X, Zhang X. Effect of oral plaque control on postoperative pneumonia following lung cancer surgery. \u003cem\u003eThorac Cancer\u003c/em\u003e. 2020;11(6):1655-1660. doi:10.1111/1759-7714.13448\u003c/li\u003e\n\u003cli\u003eHamasha AA, Sasa I, Al-Qudah M. Risk indicators associated with tooth loss in Jordanian adults. \u003cem\u003eCommunity Dent Oral Epidemiol\u003c/em\u003e. 2000;28(1):67-72. doi:10.1034/j.1600-0528.2000.280109.x\u003c/li\u003e\n\u003cli\u003eOzawa Y, Suda T, Naito T, et al. Cumulative incidence of and predictive factors for lung cancer in IPF. \u003cem\u003eRespirology\u003c/em\u003e. 2009;14(5):723-728. doi:10.1111/j.1440-1843.2009.01547.x\u003c/li\u003e\n\u003cli\u003eSato T, Teramukai S, Kondo H, et al. Impact and predictors of acute exacerbation of interstitial lung diseases after pulmonary resection for lung cancer. \u003cem\u003eJ Thorac Cardiovasc Surg\u003c/em\u003e. 2014;147(5):1604-1611.e3. doi:10.1016/j.jtcvs.2013.09.050\u003c/li\u003e\n\u003cli\u003eYoshikawa M, Yoshida M, Nagasaki T, Tanimoto K, Tsuga K, Akagawa Y. Influence of aging and denture use on liquid swallowing in healthy dentulous and edentulous older people. \u003cem\u003eJ Am Geriatr \u003c/em\u003e\u003cem\u003eSoc\u003c/em\u003e. 2006;54(3):444-449. doi:10.1111/j.1532-5415.2005.00619.x\u003c/li\u003e\n\u003cli\u003eInui A, Takahashi I, Kurauchi S, et al. Oral conditions and dysphagia in Japanese, community-dwelling middle- and older- aged adults, independent in daily living. \u003cem\u003eClin Interv Aging\u003c/em\u003e. 2017;12:515-521. doi:10.2147/CIA.S132637\u003c/li\u003e\n\u003cli\u003eOkamoto N, Morikawa M, Yanagi M, et al. Association of tooth loss with development of swallowing problems in community-dwelling independent elderly population: the Fujiwara-kyo study. \u003cem\u003eJ Gerontol A Biol Sci Med Sci\u003c/em\u003e. 2015;70(12):1548-1554. doi:10.1093/gerona/glv116\u003c/li\u003e\n\u003cli\u003eNobuhara H, Yanamoto S, Funahara M, et al. Effect of perioperative oral management on the prevention of surgical site infection after colorectal cancer surgery: a multicenter retrospective analysis of 698 patients via analysis of covariance using propensity score. \u003cem\u003eMedicine\u003c/em\u003e. 2018;97(40):e12545. doi:10.1097/MD.0000000000012545\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"supportive-care-in-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jscc","sideBox":"Learn more about [Supportive Care in Cancer](https://www.springer.com/journal/520)","snPcode":"520","submissionUrl":"https://submission.nature.com/new-submission/520/3","title":"Supportive Care in Cancer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Consecutive patients, Lung cancer, Postoperative pneumonia, Perioperative oral management, Remaining teeth number","lastPublishedDoi":"10.21203/rs.3.rs-7057022/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7057022/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003ePostoperative pneumonia is a serious lung cancer surgery complication. Perioperative oral management can help prevent its development.\u003c/p\u003e\u003ch2\u003eObjectives\u003c/h2\u003e\u003cp\u003eThis study aimed to determine the characteristics of patients who developed postoperative pneumonia despite perioperative oral management.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis study included 396 consecutive patients who underwent lung cancer surgery under general anesthesia at Fujita Health University Okazaki Medical Center from April 2020, the opening of the hospital, to the end of December 2023. Patient data, including age, gender, body mass index, underlying disease, smoking index, spirogram, operative time, amount of blood loss during operation, and operative procedure, were obtained from medical records. Oral examinations were conducted to determine the number of remaining teeth and whether dental caries is present and to examine tooth mobility and probing pocket depths\u0026thinsp;\u0026gt;\u0026thinsp;4 mm. Furthermore, the patients were asked whether they had regular dental check-ups. The patients were divided into the pneumonia and no-pneumonia groups following lung surgery, and the factors involved in postoperative pneumonia were investigated.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eA total of 390 patients were analyzed (six were excluded), of whom 33 developed postoperative pneumonia. Among them, 17 were excluded from the analysis due to preoperative interstitial pneumonia. Consequently, the incidence of postoperative pneumonia was 16 of 373 patients (4.3%). Significant differences were observed between the groups in terms of age, sex, chronic obstructive pulmonary disease, smoking index, operative time, number of remaining teeth, and regular dental check-ups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Logistic regression analysis using these significant items revealed that fewer than 20 remaining teeth was significantly associated with the development of postoperative pneumonia (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThe results of this study indicated that the incidence of postoperative pneumonia following perioperative oral function management was maintained as low as that reported previously. The importance of dental intervention in the perioperative period was also elucidated. A high number of patients who developed postoperative pneumonia despite these interventions had fewer than 20 remaining teeth, suggesting that more attention should be paid to perioperative oral management, including prevention of aspiration pneumonia.\u003c/p\u003e","manuscriptTitle":"Factors associated with the development of postoperative pneumonia in lung cancer surgery patients with perioperative oral management","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-20 06:43:14","doi":"10.21203/rs.3.rs-7057022/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-01T00:30:27+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-30T03:30:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277333690573686323561349907749451363242","date":"2025-09-30T02:52:58+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-20T10:51:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"235246316460679017102792846258633182913","date":"2025-08-13T00:19:16+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-11T20:52:31+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-11T20:49:29+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-09T01:44:11+00:00","index":"","fulltext":""},{"type":"submitted","content":"Supportive Care in Cancer","date":"2025-07-06T09:32:42+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"supportive-care-in-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jscc","sideBox":"Learn more about [Supportive Care in Cancer](https://www.springer.com/journal/520)","snPcode":"520","submissionUrl":"https://submission.nature.com/new-submission/520/3","title":"Supportive Care in Cancer","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"c37c5a6d-c96e-4293-9570-2f8cd310114a","owner":[],"postedDate":"August 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-24T16:04:21+00:00","versionOfRecord":{"articleIdentity":"rs-7057022","link":"https://doi.org/10.1007/s00520-025-10177-6","journal":{"identity":"supportive-care-in-cancer","isVorOnly":false,"title":"Supportive Care in Cancer"},"publishedOn":"2025-11-18 15:58:43","publishedOnDateReadable":"November 18th, 2025"},"versionCreatedAt":"2025-08-20 06:43:14","video":"","vorDoi":"10.1007/s00520-025-10177-6","vorDoiUrl":"https://doi.org/10.1007/s00520-025-10177-6","workflowStages":[]},"version":"v1","identity":"rs-7057022","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7057022","identity":"rs-7057022","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}