Oral hygiene procedures including scaling, polishing, sub-gingival root planing and curettage should be performed and home-care instructions and fluoride prescriptions given between the initial screening appointment and commencement of external beam radiation therapy (EBRT).7 In addition, overhanging and faulty
restorations should be removed and replaced appropriately. Ill-fitting partial and/or complete dentures should be corrected during this period. Temporary soft liners should be removed and changed (relined) to a permanent acrylic resin (less porous material) to decrease the risk to surrounding soft tissues by a potential nidus for chronic candidiasis.
Patients are instructed about effective daily plaque removal and are instructed to use soft toothbrushes and high-potency fluoride applications. Instructions are given to floss daily and brush the teeth at least 3 to 4 times daily. A neutral 1 percent sodium fluoride gel, either as a 5,000 ppm brush-on with a toothbrush or self-applied every night for 5 minutes in a mouthguard carrier, or a 5,000 ppm fluoride mouth rinse used routinely is prescribed. Usually, acidulated gels are not prescribed because they might lead to significant decalcification without sufficient remineralization potential in the presence of xerostomia. Sodium fluoride preparations are preferred to stannous fluoride because the latter has unpleasant side effects such as a bad taste, sensitivity of teeth and gingiva, and the staining of arrested lesions. Daily compliance in the use of high-potency fluoride for the rest of the patient's life is more important than the type of fluoride or the modality of fluoride application.8
Many recent studies of long-term survivors report lack of compliance with a fluoride regimen (Figure 20-3). It has been reported that 75 to 95 percent of patients who receive head and neck radiation probably use a standard dentifrice as their only means of oral hygiene. Trays have been reported as being inconvenient, time consuming, and cumbersome.
They are particularly not used during acute episodes of mucositis. It is difficult to persuade patients who are sore and depressed to continue complicated prophylactic dental care.9,10 In addition, patients who have undergone surgical resections 4 to 6 weeks before radiation therapy, find fluoride application via mouthguard carriers difficult, if not impossible, during the immediate postoperative period.
Patients should be monitored weekly during their radiation therapy for compliance with fluoride application and oral hygiene. Monitoring should continue on a monthly basis for the first 6 months post-treatment. The frequency of these visits is necessary because of the quick-acting nature of radiation caries, and the sequence establishes a pattern for continuity of care, possibly reducing the frequency and severity of oral complications from cancer therapy.
Several long-term oral complications can result from head and neck radiation therapy. Many of these adversely affect the patient's quality of life, of which xerostomia is probably the most prevalent and disabling major sequela of the irradiated oral cavity.11 Radiotherapy causes loss of parenchyma and atrophy of glandular elements with development of fibrosis, and lack of saliva production. Severity depends on total radiation dosage, source and fractionation as well as location of tumor, portion of exposed salivary glands. Concurrent chemotherapy further aggravates the situation. Xerostomia affects speech, oral comfort, eating, fit of prostheses, and increases the risk of caries which can ultimately lead to osteoradionecrosis. Some recent clinical investigations concerning xerostomia have not correlated actual caries development via measuring decayed, missing, or filled (DMF) rates of tooth sur-faces.12 Many potentially carious bacterial measurements are increased (Streptococcus mutant and Lactobacillus sp.) but can be transient. Salivary dysfunction might not affect caries development in the fluoride-compliant patient particularly if three-dimensional conformal radiation or electron beam radiation is used, minimizing the radiation dosage to contralateral salivary glands. Xerostomia is best relieved by frequent use of water. Pilocarpine as a sialagogue has been reported to provide subjective relief in some patients, however, its efficacy is unpredictable.
Treatment-related sequelae of head and neck irradiation also include soft-tissue fibrosis and oblit-
erative endarteritis. These changes become more pronounced over time and may include trismus and non- or slow-healing mucosal ulcerations. The muscles of mastication located within the field of radiation can lose their elasticity over time and become fibrotic with clinical symptoms (trismus). During the post-radiation period, exercising with trismus appliances (eg, tongue depressors taped together or an acrylic resin cork screw) 10 to 15 times a day for 10 minutes can decrease or even prevent the severity of this sequela.
Osteoradionecrosis (ORN) is a relatively uncommon clinical condition. However, its risk increases if the radiation dosage is greater than 6,500 cGy to any portion of the mandible13 (Figure 20-4). The maxilla is rarely affected due to its inherent rich blood supply. Radiotherapy causes endothelial damage to blood vessels within the mandible, causing fibrosis and ischemia, increasing the risk of necrosis of hypovascular or avascular bone when exposed to the insult of bacterial infection. It can be devastating and may even develop many years after completion of radiation therapy. As many as 30 percent of cases of ORN are reported to be of a spontaneous origin. However, most reports in the literature focus on caries and extraction sites as precipitating factors. Acute and chronic periodontal disease and mandibu-lotomy sites can also be a focus of origin for ORN. Traditional and conservative treatment of ORN consists of antibiotics (when symptoms are present), surgical debridement and curettage; all of which can be effective in early disease. In advanced and extensive ORN, the use of hyperbaric oxygen (HBO) as an adjunct to aggressive surgical approach, to boost
tissue oxygenation and promote angiogenesis in damaged irradiated bone is advocated. However, controversy exists in the literature regarding use of HBO, and conservative surgery versus resection and reconstruction of the mandible.1415 No controlled, prospective clinical trials have assessed the efficacy of HBO, and all reports attesting to its effectiveness are anecdotal. Further well-designed studies are needed to verify the positive clinical outcomes claimed by Marx in 1983 and 1985. Individual cases of osteoradionecrosis usually are complicated by so many etiologic and treatment-related variables that separating the efficacy of hyperbaric oxygen alone becomes difficult. Routine advocacy of HBO should not be a standard of care until it undergoes unbiased investigations, the methodology and results of which must survive vigorous scientific analysis and scrutiny.16 Decisions to use HBO should be made on a case by case basis. It must, however, be emphasized that necrotic bone with a sequestrum will not heal with HBO. Angiogenesis stimulated by HBO is most beneficial in soft-tissue necrosis and in ischemic but viable bone at risk of necrosis.
Radiation therapy protective devices, or shields, can be fabricated and used to optimize delivery of radiation while reducing morbidity. Lead-lined mouthguards can prevent scatter radiation (radiation reflecting off gold and amalgam tooth restorations) to the tongue, cheek, and floor of mouth regions (Figure 20-5).
Most patients receiving chemotherapy for head and neck cancer have previously undergone radiation therapy or receive concomitant radiation therapy. Chemotherapy-related toxicities can exhibit several different clinical presentations including mucous membrane inflammation and ulceration, oral candidiasis, and/or viral or bacterial oral infections (Figure 20-6). When or if ulcerations occur, dental intervention can be instituted to reduce the debilitating symptoms associated with mucous membrane lesions such as secondary systemic bacterial or fungal infections (septicemia and fungemia). Chemotherapy-induced toxicities are reflected in the mouth by changes in color, contour, character, and continuity of the
mucosa. These oral complications from chemotherapy (usually a stomatitis) can vary in pattern, direction, intensity, and progression.18 Oral complications and manifestations from chemotherapy are well documented and more common for hematologic diseases (leukemia, lymphoma), but have not frequently been reported for head and neck cancers.
Lockhart and Clark examined 82 patients receiving chemotherapy with stage III or IV head and neck disease to determine the incidence and severity of oral sequelae.19 Taste alteration (37%), mucositis (30%), ulceration (22%), xerostomia, weight loss, dysphagia, hemorrhage and infection were encountered. However, these reported sequelae could have originated with previous radiation therapy.
Some of the agents used most commonly for head and neck tumors (eg, methotrexate, bleomycin, cisplatin, and 5-fluorouracil) are considered stom-ato-toxic when used alone, and in combination they likely can result in dose-limiting stomatitis. Lockhart and Clark's study suggested no significant increase in incidence or severity of complications with each successive cycle of chemotherapy. The number of patients for whom second and third cycle data were available was too small for statistical assessment. Nearly one-third of the chemotherapy cycles resulted in at least mild mucositis and ulceration or in problems with nutrition.
In general, current regimens of chemotherapy for head and neck cancer result in less frequent and less severe oral complications than seen in hematologic disease. In the future, intensification of chemotherapy to obtain increased response rates could result in more frequent and severe mucositis as a sequela. This outcome has been especially true when patients received concomitant radiation therapy and chemotherapy or when radiation therapy follows chemotherapy within a short time period.
All patients receiving head and neck chemotherapy are advised to visit a dentist at least 10 days before commencement of chemotherapy. The hema-tologic status should be reviewed with the oncologist in regard to platelets, neutrophils, total white blood cell count, partial thromboplastin time, and pro-thrombin time. Home-care hygiene initiatives and caries control are also commenced. Third-molar pathology is evaluated and addressed appropriately. All potential oral sources of bacteremia, including advanced or acute periodontal disease, should be eliminated. If symptomatic teeth with periapical lesions are present, pulpotomies or extractions should be considered.20
Stage III or IV head and neck patients might not desire or require the so-called ideal dental treatment due to guarded or poor tumor prognosis. Asymptomatic but periodontally involved teeth might be salvaged with alternate dental treatment plans. Retaining asymptomatic anterior teeth (maxillary and mandibular) could be considered even in the presence of peri-odontal disease, caries, or periapical pathology. Considerations for this patient population could be maintenance of mandibular cuspids and first bicus pids for abutment retention of a mandibular anterior stay-plate prosthesis instead of full-mouth extractions. Control of carious teeth with an intermediate restorative material instead of more definitive restorations (crowns, fixed bridges, onlays) might suffice until all chemotherapy cycles are completed.
During chemotherapy for head and neck cancer, the dental team should emphasize oral hygiene with frequent saline and baking soda oral rinses and tooth-brushing. Unlike chemotherapy for hematologic diseases, bleeding usually does not occur from brushing the gingival surfaces with a soft toothbrush.
Many medical decisions about the type and timing of cancer therapy are based on the dental-oral findings and recommendations are made at the time of referral or at periodic oral examinations.
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