title: Association of Unfinished Root Canal Treatments with the Risk of Pneumonia Hospitalization.
abstract: BACKGROUND
  The objective of root canal treatments (RCTs) is to control pulpal diseases and salvage infected teeth by eradicating microorganisms within the root canal system. However, an unfinished RCT can leave a space for bacterial accumulation, which can leak into the oral cavity and then aspirate into the lower respiratory tract and the lungs, causing infection. This study investigated the association of unfinished RCTs with the possible risk of pneumonia hospitalization using a nationwide population-based database.
  
  
  METHODS
  After a matching process, we recruited 116,490 subjects who received an initiated RCT and had no history of pneumonia before 2005 and observed until the end of 2011. An unfinished RCT was operationally defined as an endodontic session that was started on a tooth but had no subsequent completion records. Cox proportional hazards models and subgroup analyses were used to estimate the association of unfinished RCTs on the risk of pneumonia hospitalization.
  
  
  RESULTS
  In total, 1285 subjects were hospitalized for pneumonia during 2005 to 2011 with an overall pneumonia hospitalization incidence rate of 0.22% per person year. After adjusting for confounding factors, the adjusted pneumonia hospitalization hazard ratio for subjects who had unfinished RCTs was 1.40 (95% confidence interval, 1.24-1.59) compared with subjects without unfinished RCTs (P < .0001). For middle-aged patients, the hazard ratio was 1.81 (95% confidence interval, 1.45-2.24).
  
  
  CONCLUSIONS
  Patients with unfinished RCTs had a higher risk of pneumonia hospitalization. Thus, dentists are advised to complete endodontic treatments once started.
authors.affiliation: Department of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan; Department of Dentistry, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.
authors.forename: Po-Yen
authors.initials: PY
authors.lastname: Lin
authors.affiliation: Department of Restorative and Aesthetic Dentistry, School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Chiang
authors.affiliation: Office of Preventive Medicine, Center of Disease Control, Ministry of Health and Welfare, Taipei, Taiwan.
authors.forename: Yu-Ju
authors.initials: YJ
authors.lastname: Chou
authors.affiliation: Department of Dentistry, Cheng Hsin General Hospital, Taipei, Taiwan.
authors.forename: Hong-Ji
authors.initials: HJ
authors.lastname: Chang
authors.affiliation: Department of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan. Electronic address: chily@ym.edu.tw.
authors.forename: Lin-Yang
authors.initials: LY
authors.lastname: Chi
mesh_terms: D000328:Adult; D003786:Dental Pulp Cavity / Q000382:microbiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000209:etiology*; D016016:Proportional Hazards Models; D012307:Risk Factors; D012390:Root Canal Therapy / Q000009:adverse effects*; D055815:Young Adult
keywords: Pneumonia; Taiwan national health insurance research database; survival analysis; unfinished root canal treatment