Xerostomia has been reported in association with radiotherapy (RT), chemotherapy, and some immunotherapies involving the major salivary glands. In radiotherapy, clinically, xerostomia has been reported with as little as two or three doses of 2 Gy, although many changes occurring with less than 60 Gy are reversible. However, doses greater than 30 Gy can cause permanent xerostomia [12]. The mean radiation doses that have been associated with permanent impairment of parotid gland saliva secretion are approximately 24 Gy for unstimulated saliva and 26 Gy for stimulated saliva [13]. Scoring systems that grade the severity of acute and late radiation-induced salivary hypofunction have been published by several organizations, including the NCI (Table 14.3) [14].

Xerostomia (dry mouth) changes the ability of the mouth to neutralize acid, clean the teeth and gums, and protect the mouth from infection. It is associated with an increased risk of radiation caries, which results from an increased number of caries-forming bacteria in the oral cavity, low salivary PH with loss of buffering capacity, decreased mechanical flushing, and decreased production of salivary proteins, immunoglobulins (i.e., IgA and IgG), lysozymes, and peroxidases [15]. Accumulation of plaque and other debris on teeth and periodontal tissues resulting from xerostomia may develop to a greatest risk of osteoradionecrosis [16]. Symptoms include dryness, a sore or burning feeling (especially on the tongue), cracked lips, cuts or cracks at the corners of the mouth, and changes in the surface of the tongue. As saliva is needed for taste, swallowing, and speech, xerostomia is associated with the development of dysgeusia or ageusia [11, 17]. An extremely dry mouth will also impair proper speaking, wearing dentures, mastication, and the swallowing of foods.

To minimize the severity of xerostomia and oral complications, it is important to begin aggressive oral care before RT. Appropriate nutritional intake, effective oral hygiene, and early detection of oral lesions are important pretreatment practices. Evaluation in several weeks advance of therapy is essential to determine oral health status, perform necessary dental and oral interventions, and allow time for healing from any invasive procedures that are required. In particular, attention should be given to mucosal lesions, dental caries and endodontic disease, periodontal disease, ill-fitting dentures, orthodontic appliances, temporomandibular dysfunction, and salivary abnormalities. A stringent oral hygiene program is critical and should be continued before, during, and after therapy [11].

Frequent sips of water and water rinses are most commonly used and are essential for partial control of radiation-induced xerostomia. Patients are instructed to carry with them plastic bottles of water for constant use. Sugarless chewing gum and tart candy may be helpful. In some patients, pilocarpine hydrochloride solution (1 mg/mL) or Salagen tablets (5 mg) have been effective in stimulating saliva production [18]. Five milligrams, three or four times daily, has been an optimal dosage for most patients. The most common side effects include sweating, a “flushed” feeling, and stomach discomfort, but these usually occur only at higher dosages [19].

Osteoradionecrosis (ORN), which is defined as necrosis of the bone in areas that have received radiotherapy, is one of the most serious complications of the postradiotherapy patient. Bone cells and vascularity may be irreversibly injured, and when ORN is progressive, it can lead to intolerable pain and interference with function or fracture. The preventive and therapeutic use of antibiotics and hyperbaric oxygen (HBO) can be effective, but reproducible beneficial results remain uncertain [20]. The incidence of ORN varies from 4 % to 22 % depending on the reporting institution, aggressiveness of radiotherapy, and follow-up time [21–23].

The risk of developing spontaneous ORN is somewhat unpredictable but is related to the dose of radiation. Patients who have received doses of radiation in excess of 60 Gy have the highest risk of this pathological entity. Irradiated areas of bone supplied by damaged vessels with lack of oxygen and nutrients become ischemic and ultimately necrotic. The mandible is affected more frequently because it has less of a blood supply than the maxilla. Obviously, acute or chronic irritation or trauma to avascular mucosa and bone increases the risk of tissue breakdown and ORN. The risk seems to be increased in dentulous patients, even more so if the teeth within the treatment field are removed after therapy [21]. Spontaneous bone exposure usually occurs more than 1 year after radiation is completed. Any oral surgery procedure increases the risk of the development of spontaneous ORN, even if it is performed years after the last radiotherapy treatment (Fig. 14.2). The risk of ORN will be present for the remainder of the patient’s life. Unfortunately, the passage of time does little to reverse the damage and the subsequent risk of ORN [24].

Certain facts emerge from UCSF (University of California, San Francisco) study [21, 24]:

Treatment for ORN is variable. The risk of osteomyelitis, an infection of the bone, is increased in the postradiotherapy patient. Analgesic drugs can be taken depending on the severity of pain and patient response. The bony segments that perforate the mucosal tissues create a portal of entry for microbial organisms of the oral flora. If flares of swelling and suppuration occur only occasionally, antibiotics are usually effective. If pain and/or flares occur too frequently or present other difficulties for the patient, surgery must be considered. Aggressive surgical and antibiotic treatment is needed to debride the area and resolve the infection. Sequestrectomy must be done when sequestration develops. Small pieces of necrotic bone can be removed under local anesthesia; on the other hand, larger segments of bone may require hospitalization for their removal. Hyperbaric oxygen (HBO) treatments may help in the regeneration of new blood vessels with a resultant increase in the oxygen supply to the affected bone [25]. The only possible effectiveness is combining HBO with surgery and antibiotics. HBO involves sequential daily exposure to oxygen under pressure (2 h daily in hyperbaric chamber at 2 atmospheres of oxygen, 20–30 times) [19].