Dose and delivery of radiation; generally speaking, higher doses of radiation are more likely to result in ORN, especially when doses exceed 65 Gy. While minimizing radiation doses and avoiding excess radiation to bone can reduce ORN, there does not appear to much evidence that different radiation strategies (i.e. conventional radiotherapy, IMRT, brachytherapy) reduce risk. Smoking; tobacco use is associated with significant increases in risk of developing ORN. This increased risk is attributed to the vasoconstrictive properties of nicotine, which coupled with damage to endothelium by radiation, exacerbate the decreased perfusion of affected tissues. Diabetes mellitus; diabetes is a known cause of microvascular disease, which similar to smoking, can worsen the blood supply and perfusion to tissues affected by radiation. Dental disease and extractions; patients with poor oral hygiene and dental disease prior to radiation, including edentulous patients and those with dentures, are more susceptible to developing ORN. Diseased teeth near the radiation field may need to be extracted, and should be evaluated prior to radiation treatment. Staging
The staging system can be useful as a baseline reference for management after a definitive diagnosis of ORN has been established. Prevention and management
There is currently no universally accepted prevention and management of ORN and in many cases depends on how severe the condition presents. Currently, there are many preventive approaches for ORN proposed, but yet to be justified by high quality evidence. Studies have been conducted to measure effectiveness of current interventions. However, there lacks evidence to conclude that one approach is more effective than others.
Osteoradionecrosis (ORN) is a serious complication of radiation therapy in cancer treatment where radiated bone becomes necrotic and exposed. ORN occurs most commonly in the mouth during the treatment of head and neck cancer, and can arise over 5 years after radiation. Common signs and symptoms include pain, difficulty chewing, trismus, mouth-to-skin fistulas and non-healing ulcers. The pathophysiology of ORN is fairly complex and involves drastic changes to bone tissue as a result of DNA damage and cell death caused by radiation treatment. Radiation therapy targeting tumor cells can affect normal cells as well, which can result in the death of bone tissue. Advances in radiation therapy have decreased the incidence of ORN, estimated at around 2%. Certain risk factors including the size and location of tumor, history of smoking or diabetes, and presence of dental disease can affect the chances of developing ORN. Osteoradionecrosis is difficult to prevent and treat. Current prevention strategies are aimed at avoiding excess doses of radiation as well as maintaining excellent dental hygiene. Treatments are variable depending on the provider and disease severity, and can range from medical treatment with antibiotics to hyperbaric oxygen therapy (HBO) to surgical debridement or reconstruction. Clinical findings
There are not many specific clinical signs of ORN. It may be first seen as an area of exposed bone which is not healing, or the non-specific signs may become evident prior to this. Symptoms vary depending on the degree of ORN that has occurred. Early indicators may be numbness or paresthesias within the mouth or jaw.