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

Abstract

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. 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. 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). 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.