______________________________________________ Oral Cancer and Complications of Cancer Therapies
OTHER ORAL COMPLICATIONS OF RADIOTHERAPY
The decreased oxygen and nutrient supply cause scars to form among the muscle fibers. This results in a state of relative contraction and a loss of range of motion. The onset of this problem is more gradual than that of mucositis because the muscle cells have a slower rate of mitosis. The prevalence of trismus increases with greater doses of radiation, and levels in excess of 60 Gy are more likely to cause the condition. Patients who have been previously irradiated and who are being treated for a recurrence appear to be at higher risk of trismus than those who are receiving their first treatment [72]. A physical therapist can recommend exercises for the facial musculature that minimize this problem. Preventive exercises should be employed before trismus becomes established, as it is difficult to regain muscle function and elasticity after this problem is firmly developed. SURGERY AND RADIOTHERAPY: DENTAL CONSIDERATIONS PRETREATMENT CONSIDERATIONS Oral complications secondary to surgery and radiotherapy for the treatment of malignancies may occur in patients with optimal oral health. These problems are exacerbated for those patients who have carious lesions, periodontal disease, problematic wisdom teeth, fractured teeth with sharp exposed edges, and prosthetic appliances that fit poorly and persistently traumatize the tissues. A complete clinical and radiographic examination of the teeth and soft tissues should be completed as far in advance as possible from the surgical phase of oral cancer therapy. This will allow sufficient healing time for the extractions of teeth with unrestorable decay and advanced periodontal disease. Partially erupted wisdom teeth should be removed if they are in an area to be irradiated. Teeth with dental caries should be restored to optimal clinical condition. Teeth in which the carious process has extended into the pulp and has caused irreversible inflammation or necrosis should undergo root canal therapy or be extracted. Those teeth that cannot have deep periodontal pockets reduced to levels that will facilitate oral hygiene should be extracted. Prosthetic appliances should be adjusted so that their use will not promote tissue trauma. The goal is definitive treatment, avoiding a “watch and wait” approach. Patients should be informed that dental problems may exist without any symptoms and that lack of treatment will contribute to infections and even ORN after the completion of oral cancer therapy. All patients should receive oral hygiene instruction and nutritional counseling. Manufacturers offer special sponge- like toothbrushes with toothpaste impregnated into the foamy material that may provide for an adequate means of cleans- ing the teeth without causing soft tissue trauma. The use of dental floss or dentotape for the interproximal areas should only be done if it can be accomplished atraumatically. Patients
Patients can experience a wide range of undesirable effects from any treatment modality, and radiotherapy is no exception. One such experience common to many patients undergoing radiotherapy is hypogeusia, the partial loss of the sensation of taste, or ageusia, the complete loss of this sensory function. Taste buds are very sensitive to ionizing radiation and begin to experience damage when a cumulative dosage of 1,000 cGy has been given. When the cumulative dose of 6,000 cGy has been reached, damage to the taste buds is usually permanent with the sensation of taste being lost [71]. Thus, if the oral malignancy being irradiated is in the area of the taste buds, the extent of damage and the ability to regain the sensation of taste will depend on the cumulative dose of radiation and the number of taste buds involved. The lower the dose and exposure, the better the chance that the sensation of taste will be restored. Patients should be counseled about the problems associated with the overcompensation of this loss by eating foods that are high in sugar content or excessively spicy. A resident oral fungal organism with pathogenic capabilities, Candida albicans , causes a common opportunistic infection in the oral tissues of patients receiving radiotherapy. The normal competitive mechanisms among the microbial species of the oral environment and the immunocompetence of the host are usually sufficient to prevent infection of the mucosal tissues by this fungal organism. After radiotherapy, both of these protec- tive mechanisms are altered, which can result in candidiasis in the oral tissues. This may be especially painful and even difficult to diagnose if it is superimposed on areas of mucositis. The most significant concern is that a Candida infection superimposed over an area of mucositis could be a source of a regional or systemic fungal infection, which could have fatal consequences in a patient already weakened by illness, surgery, radiotherapy, and/or chemotherapy. Treatments for these infections consist of antifungal oral suspensions, such as nystatin, that follow a swish-and-swallow protocol (used with varying degrees of efficacy), or systemic fluconazole (highly effective for prophylaxis and treatment) [72]. Antifungal loz- enges are difficult to use in patients whose salivary flow has diminished. Patients who wear complete or partial dentures, orthodontic retainers, or night guards should disinfect these appliances in accordance with the manufacturers’ directions (e.g., soaking in antifungal solutions). The acrylic portions of these appliances have microscopic porosities in which C. albi- cans organisms thrive and re-infect oral tissues that have been cleared of the infection. Systemic fungal infections in these patients have a high mortality rate and should be treated with intravenous antifungal agents in a hospital setting. Trismus, a condition in which the muscles that coordinate the functional range of jaw movements become spasmodic and contracted, can affect patients weeks or months after radio- therapy has been initiated [72]. Irradiation causes a thickening and scarring of the blood vessels that supply these muscles.
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