Jaw osteoradionecrosis and dental extraction after head and neck radiotherapy: A nationwide population-based retrospective study in Taiwan

• Extraction time <0.5 year after R/T lowers the ORNJ prevalence.
• Extraction tooth number ≦5 teeth after R/T lowers the ORNJ prevalence.
• Post R/T, dental extraction number >5, ORNJ prevalence: 12.1%.
• Post R/T, dental extraction number ≦5, ORNJ prevalence: 2.4%.

SummaryObjectivesOsteoradionecrosis 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.Materials and methodsWe 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.ResultsWe 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 3.02 years (range: 0.62–8.89 years, ±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 ⩽0.5 year (n = 103) compared with the group with the index day to first extraction day >0.5 year (n = 419) (Z-score = −2.1506; p-value = 0.0315).ConclusionA 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.

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