https://orcid.org/0000-0001-6694-0730
Figures
Abstract
Background
The association between oral health and cancer outcomes remains unclear. The purpose of this study was to evaluate the complications and mortality after admission of head and neck cancer (HNC) in patients with and without dental scaling (DS).
Methods
We used data from public health insurance and identified 121,973 patients with admission of HNC aged ≥ 18 years who received inpatient care in 2006–2020. The outcomes during the admission of HNC were compared between patients who had received DS or not within the previous 24 months before admission. The adjusted odds ratios (HRs) and 95% confidence intervals (CIs) of complications and mortality associated with DS were analyzed in the multivariate Cox proportional regression models.
Results
We found that DS was significantly associated with reduced risks of septicemia (OR 0.84, 95% CI 0.81–0.88), stroke (OR 0.87, 95% CI 0.80–0.95), pneumonia (OR 0.88, 95% CI 0.84–0.91), urinary tract infection (OR 0.88, 95% CI 0.80–0.97), and 30-day in-hospital mortality (OR 0.88, 95% CI 0.85–0.92). Compared with HNC patients without DS, HNC patients with DS had a shortened length of hospital stay (p < 0.0001), decreased medical expenditures (p < 0.0001), and reduced risks of intensive care (OR 0.92, 95% CI 0.89–0.95) after admission of HNC.
Conclusion
In conclusion, we suggested that HNC patients who received DS had reduced complications and mortality compared with those without DS. It is essential to interpret this association with caution due to the confounding factors involved. Our study implied the possibility that clinical physicians may encourage HNC patients to receive regular DS.
Citation: Lin C-H, Chang C-C, Lee H-H, Chou Y-S, Lee C-Y, Yeh C-C, et al. (2025) Reduced complications and mortality after admission for head and neck cancer in patients with previous dental scaling: a retrospective cohort study based on real-world data. PLoS One 20(10): e0332992. https://doi.org/10.1371/journal.pone.0332992
Editor: Andrew Birkeland, University of California, Davis, UNITED STATES OF AMERICA
Received: January 23, 2025; Accepted: September 5, 2025; Published: October 3, 2025
Copyright: © 2025 Lin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: The data underlying this study is from the Health and Welfare Data Science Center. Interested researchers can obtain the data through formal application to the Health and Welfare Data Science Center, Department of Statistics, Ministry of Health and Welfare, Taiwan (http://dep.mohw.gov.tw/DOS/np-2497-113.html) and contact the agency with eamil (stpeicih@mohw.gov.tw). Under the regulations from the Health and Welfare Data Science Center, we have made the formal application (included application documents, study proposals, and ethics approval of the institutional review board) of the current insurance data from. The authors of the present study had no special access privileges in accessing the data which other interested researchers would not have.
Funding: This study was supported in part by the National Science and Technology Council, Taiwan (NSTC113-2629-B-532-001; NSTC112-2314-B-038-141; NSTC111-2320-B-532-001-MY3).
Competing interests: The authors have declared that no competing interests exist.
Abbreviations: CI, Confidence interval; DS, Dental scaling; HNC, Head and neck cancer; OR, Odds ratio
Introduction
Head and neck cancer (HNC) is one of the most common cancers in the world, with 1.1 million new diagnoses reported annually [1–5]. The incidence of HNC in the United States increased between 1990 and 2017 [3]. The mortality burden of head and neck cancer is increasing and disproportionately affects those in low- and middle-income countries and regions with limited surgical workforces [5]. It is considered a major public health problem due to its high prevalence and mortality. Several common risk factors for HNC were identified, including poor oral hygiene, smoking, betel nut chewing, alcohol consumption, and infections of Epstein‒Barr virus and human papillomavirus [4,6]. A multidisciplinary approach was required for HNC treatment planning, including surgeons, radiation oncologists, medical oncologists, nutritionists, speech/swallowing pathologists and dentists. According to the National Comprehensive Cancer Network guidelines [7], the treatment options will vary based on different sites and stages, including surgery, radiotherapy and systemic therapy.
Poor oral hygiene is considered an important risk factor for HNC [1]. Dental calculus can lead to overgrowth of pathogenic bacteria in the oral cavity and irritation of the oral mucosa and further induce inflammation [8]. In addition, poor oral hygiene may also promote the progression of HNC [9]. It promotes the entry of oral microbes into the bloodstream, which in turn triggers a systemic inflammatory response [8,9]. Dental scaling (DS) can reduce systemic inflammation, further prevent loss of kidney function [10], and decrease the risk of cardiovascular disease [11] and infective endocarditis [12].
It is known that adequate oral hygiene plays an important protective role in the risk of HNC [13]. Dental management before radiation therapy can effectively reduce the occurrence of various complications after radiation therapy [14]. However, the benefits of DS in patients with HNC during the treatment period are misunderstood. The role of DS in improving treatment complications such as infections, cardiovascular diseases and survival rates in patients with HNC has not been discussed in depth. In this study, we used population-based insurance data to evaluate the beneficial effects of regular DS on the outcomes of hospitalized patients with HNC.
Methods
Ethics statement
With reference to the Declaration of Helsinki, patient identification was decoded and scrambled in the insurance research database for the protection of the patient’s right to privacy. According to the regulation of the Ministry of Health and Welfare in Taiwan, informed consent from the study participants in this study was waived by the ethics committee because of the use of decoded and scrambled patient identification and. The results of analysis was reviewed and assessed by the Ministry of Health and Welfare. Our study was also reviewed and evaluated by the Institutional Review Board of Taipei Medical University (TMU-JIRB-202203134; TMU-JIRB-202006057).
Study design
This insurance data were accessed for research purposes in 04/04/2023. To approach a large representative sample, we used research data from the National Health Insurance (details of this database were described in previous studies) to identify the cohort with HNC [10–12,15,16]. Patients aged more than 18 years who first underwent inpatient care due to HNC were screened and selected as eligible subjects in this study. Patients with HNC who had a previous history of other cancers were excluded from this study. Overall, we identified 121,973 patients with HNC admission in 2006–2020, and 45,849 of them had received the medical service of DS provided by dentists in the clinical settings during the 24 months before hospitalization. The outcomes of this study were complications and mortality during the hospitalization of HNC that were compared between patients with and without DS.
Criteria and definition
In the insurance research database, we collected information and data on gender (male and female), age (18−29, 30−39, 40−49, 50−59, 60−69, 70−79, and ≥80 years), state of income (low income or not low income), medical conditions (including hypertension, mental disorders, diabetes, ischemic heart disease, hyperlipidemia, chronic obstructive pulmonary disease, liver cirrhosis, heart failure, and renal dialysis), volume of hospital (low, medium, and high), and medical use (emergency care and hospitalization). To strictly identify the medical conditions of patients with HNC, we used previous definitions to evaluate medical care with the physician’s primary diagnosis before HNC hospitalization within 24 months. ICD-9-CM and ICD-10-CM were used to identify medical conditions and types of HNC. The use of emergency care and inpatient care were also considered important baseline characteristics that may affect the outcomes after HNC hospitalization. The types of HNC included oral cancer, oropharyngeal cancer, nasopharyngeal cancer, hypopharyngeal cancer, other cancers in the lip, oral cavity and pharynx, nasal and sinus cancer, and laryngeal cancer.
Statistical analysis
By using chi-square tests and t tests, we analyzed and compared the baseline characteristics (including continuous variables and categorical variables) of HNC patients with and without DS. To assess the potential effects of DS on complications and mortality after HNC hospitalization, we calculated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) using multiple logistic regressions and adjusted for potential confounding factors listed in the baseline characteristics. We further applied stratified analysis to evaluate the association between DS and adverse events after HNC hospitalization in age groups, sexes, income status, volume of hospital, previous hospitalizations, previous emergency visits, and history of diseases. We additionally assessed the effects of visiting frequency and time period of receiving DS on adverse events after HNC hospitalization by calculating ORs and 95% CIs in the multiple logistic regressions.
Results
The usage of DS within the previous 24 months among 121,973 HNC patients was 37.6% (Table 1), and patients with DS had higher proportions of female (p < 0.0001), younger age (p < 0.0001), stay in high volume of hospital (p < 0.0001), nasopharyngeal cancer (p < 0.0001), hypertension (p < 0.0001), mental disorders (p < 0.0001), ischemic heart disease (p = 0.0002), and hyperlipidemia (p < 0.0001) than those without use of DS. Compared with patients who did not use DSs, patients who used DSs had lower proportions of baseline characteristics, such as low income (<0.0001), hospitalizations ≥3 visits (<0.0001), emergency care ≥3 visits (<0.0001), chronic obstructive pulmonary disease (<0.0001), liver cirrhosis (p = 0.0221), and heart failure (p = 0.0015).
After adjustment for the potential confounding factors listed in Table 1, patients who received DS had decreased risks of pneumonia (OR 0.88, 95% CI 0.84–0.91), septicemia (OR 0.84, 95% CI 0.81–0.88), urinary tract infection (OR 0.88, 95% CI 0.80–0.97), stroke (OR 0.87, 95% CI 0.80–0.95), and 30-day mortality (OR 0.88, 95% CI 0.85–0.92) compared with those without DS (Table 2). Decreased use of intensive care (OR 0.92, 95% CI 0.89–0.95), length of hospital stay (p < 0.0001), and medical expenditure (p < 0.0001) were also found in patients who used DS compared with patients without DS.
In Table 3, the decreased risk of post-HNC adverse events (included) was associated with DS in females (OR 0.85, 95% CI 0.78–0.93), males (OR 0.85, 95% CI 0.82–0.87), and patients aged 18−39 years (OR 0.84, 95% CI 0.74–0.96), 40−49 years (OR 0.86, 95% CI 0.80–0.92), 50−59 years (OR 0.84, 95% CI 0.80–0.89), 60−69 years (OR 0.83, 95% CI 0.77–0.88), and ≥70 years (OR 0.86, 95% CI 0.80–0.92). DS was negatively associated with post-HNC adverse events in patients with various characteristics, such as low income (OR 0.85, 95% CI 0.75–0.95), no low income (OR 0.84, 95% CI 0.82–0.87), stay in low (OR 0.83, 95% CI 0.75–0.92), medium (OR 0.82, 95% CI 0.78–0.86), and high volume of hospital (OR 0.87, 95% CI 0.83–0.90).
In Table 4, the adjusted ORs of post-HNC adverse events for patients with recent DS within 1, 3, and 6 months were 0.58 (95% CI 0.51–0.66), 0.64 (95% CI 0.59–0.69), and 0.71 (95% CI 0.67–0.75), respectively, compared with those who had no DS. We also found that there was a biological gradient relationship between the visit frequency of DS and reduced post-HNC adverse events (p for trend <0.0001). Regular use of DS (≥4 visits within 24 months) was significantly associated with reduced post-HNC adverse events (OR 0.61, 95% CI 0.53–0.72). Table 5 showed the reduced adverse events after admission of head and neck cancer associated with different time period of dental scaling. The results showed that dental scaling within 6 months prior to admission for head and neck cancer was associated with reduced adverse outcomes, compared with those who did not receive routine dental care within the previous 12 months (OR 0.69, 95% CI 0.65–0.73), 24 months (OR 0.71, 95% CI 0.67–0.75), 36 months (OR 0.71, 95% CI 0.67–0.75), 48 months (OR 0.71, 95% CI 0.67–0.76), and 60 months (OR 0.72, 95% CI 0.68–0.76).
Discussion
In this retrospective cohort study consisting of 121,973 patients admitted for HNC, we investigated whether DS was significantly associated with decreased risks of complications and 30-day mortality even among those with coexisting medical conditions. Compared with patients without DS, patients with DS had a shortened length of hospital stay, decreased medical expenditures, and reduced risks of intensive care after admission related to HNC.
Previous studies have demonstrated that DS is associated with reduced stroke, urinary tract infection, pneumonia, sepsis, and all-cause mortality [10,16, 17–19]. DS treatment for periodontal disease was associated with a lower risk of further ischemic stroke events [16]. A recent study suggested that regular DS was associated with reduced complications and mortality in patients with stroke admission [20]. The findings of our study were consistent with the above reports showing that DS was associated with a 25% reduced risk of 30-day in-hospital mortality, a 32% reduced risk of septicemia, and a 31% reduced risk of stroke in patients with HNC.
A previous study suggested that poor oral hygiene is not only a risk factor but may also be a prognostic factor of HNC [9]. However, the effects of dental treatment on the survival and adverse events of patients with HNC have not been reported. In this study, the benefits of DS in patients with HNC during the treatment period were evaluated comprehensively. Our study may be the first to show the role of DS in improving complications such as pneumonia, septicemia, urinary tract infection, stroke, and survival rates in patients with HNC.
Regarding the association between DS and reduced post-HNC adverse events, we proposed some possible explanations as follows. First, people who receive regular DS may have better oral health knowledge, upper middle socioeconomic status, and good family support, which are also factors associated with outcomes of HNC [21–24]. Second, loss of teeth was significantly associated with oral cancer mortality, while regular DS was effective in preventing tooth loss [25]. Thus, we hypothesize that regular DS is beneficial in reducing post-HNC infections and mortality. Third, a previous study found a high systemic immune-inflammation index to be an independent factor for poor outcomes of HNC, including nutritional status, cancer stage, and overall survival [26]. A meta-analysis also suggested that systemic immune inflammation was considered a predictor of adverse outcomes in head and neck cancer prognosis [27]. Nonsurgical periodontal treatment, including DS, is effective in reducing serum leptin, interleukin 6, and levels of C-reactive protein [28]. It can also reduce oxidative stress in both smokers and nonsmokers [29]. Receiving DS may reduce systemic inflammation, gut dysbiosis, dissemination and subsequent infections in an immunosuppressive state [16,30–32]. Therefore, we considered it reasonable that regular DS can help to improve the inflammation status and further reduce adverse outcomes in patients with HNC.
In addition, poor oral hygiene may worsen survival in patients with HNC, and nutritional status in patients with HNC is related to survival and surgical outcome [9,33].
There was an obvious relationship between oral function and nutritional status [34]. Poor oral hygiene was associated with poorer nutritional status, while maintaining oral hygiene may contribute to better nutritional status and quality of life [35,36]. Therefore, we considered that regular DS is one method of maintaining oral hygiene that contributes to better nutritional status and may help reduce complications and mortality in patients with HNC.
To confirm the association between DS and post-NHC adverse events, we performed a sensitivity analysis to evaluate the effects of DS on post-NHC adverse events. The stratified analysis showed that DS was associated with a reduced risk of post-NHC adverse events in the various groups by age stratum, sex, and medical conditions. The different time periods (previous 1, 3, and 6 months) of DS before admission were associated with reduced post-NHC adverse events. The frequency of DS before admission was significantly associated with reduced post-NHC adverse events in this study. In addition, we performed propensity-score matching to balance the baseline characteristics, and the results also showed that patients with DS had lowered risks of adverse events after HNC admission compared with those who had no DS. From the viewpoint of epidemiology and statistics, we have more confidence to suggest that HNC patients who received DS had reduced adverse events compared with those who did not receive DS.
There were some limitations in the current study. First, we could not ensure that all people in the control group (without DS) had not received DS services because very few people who received DS services were not covered in the insurance program. This condition may lead to misclassification that causes the underestimation of the beneficial effects of DS on post-HNC complications and mortality. Second, we used insurance claims data that lacked details on sociodemographic information, lifestyle factors (such as smoking and alcohol consumption), and clinical examination data. Smoking and alcohol consumption are potential confounding factors in the association between dental scaling and post-HNC outcomes. We acknowledge that the lack of these data is a significant limitation that weakens the robustness of our findings. Third, people who received DS services may have better health knowledge, attitudes, and practices than those who had no DS. Our study was also limited to not adjusting for the above health-related factors in the final model. In addition, we could not exclude the possibility of overestimating the effects of DS on the outcomes of HNC in this study. To avoid overstatement or misrepresentation of findings, we conducted an additional analysis to compare the outcomes after HNC using various definitions of dental scaling and non-dental scaling groups. Finally, although we used multiple regression models to control potential confounders in this large-scale insurance database, residual confounding could not be completely excluded
In conclusion, we suggested that receiving DS regularly was significantly associated with reduced complications and mortality in patients admitted for HNC, even in those with coexisting medical conditions. It is essential to interpret this association with caution due to the confounding factors involved. The findings of our study provide references for health authorities and clinical physicians to encourage patients with HNC to receive regular DS against subsequent adverse events. Further clinical trials are encouraged to provide solid evidence to support our suggestions.
Acknowledgments
This study is based in part on data obtained from Taiwan’s Ministry of Health and Welfare. The authors’ interpretations and conclusions do not represent those of the Ministry of Health and Welfare, Taiwan. This study was partially supported by the funds of the Thomas and Dorothy MJ Toung Professorship in Anesthesiology.
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