title: Jaw osteoradionecrosis and dental extraction after head and neck radiotherapy: A nationwide population-based retrospective study in Taiwan.
abstract: OBJECTIVE
  Osteoradionecrosis of the jaws (ORNJ) is painful for patients and relatively difficult to treat clinically. The high risk of ORNJ for post radiotherapy R/T dental extraction is known; however, many patients still have to have teeth extracted after head and neck R/T. The objective of the present study is to review post R/T dental extraction and determine the ORNJ risk.
  
  
  METHODS
  We preformed a retrospective cohort study of 1759 patients with head and neck cancer s/p R/T from a random sample of 1,000,000 insurants in the National Health Insurance Research Database during 2000-2013 in Taiwan. Statistical methods included two-proportion Z-test.
  
  
  RESULTS
  We evaluated two cohorts: 522 patients with post R/T dental extraction and 1237 patients without post R/T extraction. Overall moderate-to-severe ORNJ after R/T was 2.22% (39/1759), and a total of 39 ORNJ cases were noted during an average of 3.02years (range: 0.62-8.89years, ±2.07). ORNJ prevalence in the overall post R/T extraction-exposed cohort (5.17%, 27/522) was significantly greater than that in the unexposed cohort (0.97%, 12/1237). In a group of patients with ⩽5 post R/T dental extractions (n=373), the ORNJ risk was 2.4% (ORNJ case n=9); in a group of patients with >5 dental extractions (n=149), the ORNJ risk was 12.1% (ORNJ case n=18) (Z-score=4.5062; p-value<0.0001). In the extraction-exposed cohort, the ORNJ risk is higher if the index day to first extraction day was ⩽0.5year (n=103) compared with the group with the index day to first extraction day >0.5year (n=419) (Z-score=-2.1506; p-value=0.0315).
  
  
  CONCLUSIONS
  A tooth extraction time less than half a year after R/T or during the head and neck R/T period, and extraction tooth number ⩽5 would significant lower the ORNJ prevalence.
authors.affiliation: Department of Stomatology, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Tsu-Jen
authors.initials: TJ
authors.lastname: Kuo
authors.affiliation: Department of Radiation Oncology, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Chung-Man
authors.initials: CM
authors.lastname: Leung
authors.affiliation: Department of Stomatology, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Hao-Sheng
authors.initials: HS
authors.lastname: Chang
authors.affiliation: Department of Dentistry, Kaohsiung Veterans General Hospital, Taiwan, ROC. Electronic address: tjkuo@vghks.gov.tw.
authors.forename: Chao-Nan
authors.initials: CN
authors.lastname: Wu
authors.affiliation: Department of Stomatology, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Chen
authors.affiliation: Department of Stomatology, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Guang-Jhong
authors.initials: GJ
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Lai
authors.affiliation: Section of Critical Care Medicine, Kaohsiung Veterans General Hospital, Taiwan, ROC.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Huang
mesh_terms: D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007571:Jaw Diseases / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010025:Osteoradionecrosis / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects*; D012189:Retrospective Studies; D013624:Taiwan; D014081:Tooth Extraction
keywords: Dental extraction; ORN; ORNJ; Osteoradionecrosis of jaw