The incidence of ORN has been reported to be 5% to 15%, how- ever, newer techniques — such as intensity modulated radiation ther- apy, brachytherapy, three-dimensional conformal radiation therapy and stereotactic radiation therapy — have decreased the rate to 6% or less. In terms of radiation exposure, gray (Gy) is the unit of absorbed dose and has replaced the old term rad; 1 Gy is equal to 1 Joule per kilogram or 100 rads. The risk factors for ORN are proximity of the tumor to the mandible (especially the posterior mandible), radiation (i.e., field size, dosage > 60 Gy), chemoradiotherapy, poor dentition, poor oral hygiene, advanced tumor stage, and oral trauma (such as extraction or ill-fitting dentures).1 When comparing dentulous and edentulous patients, it was found that, overall, dentate patients had a higher risk of ORN (24%) than edentulous patients (14%) — and the risk increases in patients who received greater than 75 Gy.2 THESE PATIENTS TYPICALLY PRESENT WITH EXPOSED BONE AND INFLAMED, FRIABLE TISSUE — WITH OR WITHOUT PURULENT DRAINAGE CLINICAL PRESENTATION These patients typically present with exposed bone and inflamed, fri- able tissue — with or without purulent drainage. This can progress to oroantral fistulas, orocutaneous fistulas, pathologic fractures and numb- ness of the lips. The soft tissue will show evidence of fibrosis, with little elasticity, making primary closure of extraction sites difficult. These indi- viduals also have fibrosis of the muscles, leading to trismus, and there- fore making oral hygiene and dental care difficult. On a panoramic radiograph, the affected area will have a diffuse radiolucency, without any sclerotic demarcation. Computed tomogram scans and, in some cases, magnetic resonance imaging help clinicians evaluate the full extent of the jaw affected by ORN (Figure 1, Figure 2 and Figure 3, page 18). The numerous ORN classification systems all rely on clinical and radiographic features. One such classification of ORN of the mandible DONITA DYALRAM, DDS, MD, FACS, is an assistant professor and associate program director of the Department of Oral and Maxillofacial Surgery residency training program at the University of Maryland Medical Center in Baltimore. She is also one of the core faculty in the Head and Neck Oncology/Microvascular Reconstruction fellowship training program, as well as a course director and faculty adviser. Dyalram was recognized with the Faculty Educator Development Award by the Oral Maxillofacial Surgery Foundation, and is board certified by the American Board of Oral and Maxillofacial Surgery. She can be reached at [email protected]. The author has no commercial conflicts of interest to disclose. December 2017 • Decisions IN DENTISTRY 17
