title: Osteoradionecrosis of the jaws: a retrospective study of the background factors and treatment in 104 cases.
abstract: OBJECTIVE
  This study analyzed potential risk factors in patients who received radiation therapy and then developed osteoradionecrosis (ORN).
  
  
  METHODS
  A group of 104 patients who developed osteoradionecrosis of the jaws were reviewed treated between 1972 and 1992.
  
  
  RESULTS
  The most common affected site was the mandible (99 cases, 95.2%), followed by the maxilla (5 cases, 4.8%). Among all cases, 93 (89.4%) were induced-trauma ORN, and 11 (10.6%) were spontaneous ORN. The following risk factors were considered as predisposing factors for the appearance of ORN: Anatomic location of the tumor, tumor surgery, total radiation dose, dose rate/day, mode of radiation delivery, time from radiation therapy until the onset of ORN, and dental status. ORN developed more frequently with oral cancer than other head and neck cancers. The size of the tumor seemed not to influence the incidence of ORN except when the tumor invade the adjacent bone. Type of radiation delivery total bone dose, and modes of radiation appeared to influence the risk of ORN occurrence. After conservative treatment, 44 (42.3%) cases had complete healing and resolution 34 (32.6%) cases had a stable, chronic ORN process, and 26 (25.1%) cases had acute and progressive ORN.
  
  
  CONCLUSIONS
  An understanding of the risk factors is important in preventing ORN after radiation therapy.
authors.affiliation: Department of Oral Surgery, A. C. Camargo Hospital, São Paulo, Brazil.
authors.forename: M M
authors.initials: MM
authors.lastname: Curi
authors.forename: L L
authors.initials: LL
authors.lastname: Dib
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D016371:Cranial Irradiation / Q000009:adverse effects* / Q000379:methods; D017742:Dental Care for Chronically Ill; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D007571:Jaw Diseases / Q000209:etiology / Q000517:prevention & control* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010025:Osteoradionecrosis / Q000209:etiology / Q000517:prevention & control* / Q000628:therapy; D012189:Retrospective Studies; D012307:Risk Factors