Osteoradionecrosis (ORN) is a devastating complication of RT in the head and neck cancer. According to the most recent literature, ORN of the jaws is defined as exposed irradiated bone that fails to heal over a period of 3 months without any evidence of persisting or recurrent tumor. Although the pathogenesis mechanism is still under investigation, the most frequently reported reason is radiation arteritis, which leads to the development of a hypocellular, hypovascular, and hypoxic environment.
The average age of patients with ORN is over 55 years. Mandibular ORN predominates when compared to the maxillary (ratio between mandible and maxilla is 24:1). In previous studies, the incidence of ORN in head and neck–irradiated population was estimated to be 4.74- 37.5%. Recent studies have shown an incidence decrease to lower than 5% and have attributed the phenomenon to improved dental preventive care and improved radiation techniques, such as 3-dimensional conformal RT (3D-CRT) and intensity-modulated RT (IMRT).
Numerous factors have been associated with the risk of ORN development. They can be divided into three main groups:
- Treatment-related factors (total dose, photon energy, brachytherapy, field size, fraction size, volume of the mandible irradiated)
- Patient-related factors (periodontitis, preirradiation bone surgery, bad oral hygiene, alcohol and tobacco abuse, bone inflammation, dental extraction after RT)
- Tumor-related factors (size and stage of tumor, anatomic tumor site, proximity of tumor to bone).
Some of these factors are related to a high risk of developing ORN; others account for a lower risk depending on the population under investigation and other parameters.
Diagnosis of ORN is based on clinical signs and symptoms. They include ulceration or necrosis of the mucosa with exposure of necrotic bone for longer than 3 months. Other symptoms include pain, trismus and suppuration in the area. Associated symptoms are neurologic symptoms such as pain, dysesthesia or anesthesia. Other symptoms such as fetor oris, dysgeusia and food impaction in the area are usually seen.
Exposure of rough and irregular bone can result in physical irritation of adjacent tissues. Progression of ORN may lead to pathological fractures, intraoral or extraoral fistulae and local or systemic infection. Difficulties in mouth opening, mastication and speech arise frequently. In patients treated with external beam radiation therapy osseous alterations usually appear in the body of mandible (premolar and molar regions) whereas in those managed with brachytherapy, on the lingual or buccal surface.
Diagnosis of septic ORN appears to be easier. Primary symptom in this case is marked pain. A thorough clinical examination will reveal intra- or extraoral draining fistulae, ulcerations of the mucous membrane, exposed devitalized bone, hemorrhages, cellulitis or pathologic fractures. However, final diagnosis will be given through a biopsy in order to exclude metastatic cancer.
Although many reports have been published on the management of ORN, it remains a difficult and challenging problem. Various different treatment methods of ORN have been reported depending on several factors such as presentation of necrotic lesion, response to conservative nonsurgical therapy, general health of the patient, prognosis for successful management of the cancer, wishes of the patient, dose of irradiation and time interval after RT.
Management of ORN includes medical and surgical intervention. Medical management is the conservative treatment and includes oral care, local debridement, ultrasonography, or hyperbaric oxygen therapy (HBO). Surgical management includes resection of the necrotic bone with reconstruction and is indicated if conservative therapy does not resolve the pathologic condition or in late stages of ORN which include fistula, fracture and a large area of exposed bone. Some investigators agree that initial treatment of ORN should be conservative, since failure of this course can always be followed with a more radical approach. Others believe that a radical approach should be instituted at initial diagnosis. Most of the authors advocate a treatment approach according to stage of necrosis.
Conservative treatment is usually used for almost all patients; however, the ultimate need for radical resection after conservative treatment is reported to be as high as 70% to 83%. Protocols combining surgery and HBO have shown success rates 15-90% but are also denoted as being impractical by other authors because of costs and time. Recent studies have shown good results with use of stem cells in order to promote healing.