Treatment of head and neck cancers has oral sequelae and treatment-related toxicities requiring intervention by dentists. Dental team intervention should begin prior to radiation therapy, surgical resection, and/or chemotherapy. For optimal post-treatment oral functional outcomes, regardless of cancer therapies, a comprehensive dental assessment is para-mount.1 The multidisciplinary team should encompass trained dentists with interests and training in comprehensive oral/dental care of the patient. A comprehensive dental team includes the maxillofa-cial prosthodontist, oral and maxillofacial surgeon and dental oncologist, all of whom can contribute to quality of life issues such as restoring oral defects and facial deformities, eliminating or decreasing the intensity of dental disease and/or complications of cancer treatment.
Oral sequelae of treatment can vary from patient to patient even with the same modality of treatment and stage of disease. Generally, surgical resections can, but may not always, compromise oral function. Many, if not most of these resections, (eg, soft palate, hard palate, mandible, tongue, floor of mouth, or a combination of these) can be restored adequately by means of intervention with maxillofacial prostheses2 alone or combined with surgical reconstruction.
Complications related to radiation therapy for head and neck cancers can vary with a range of sequelae including caries, mucositis, trismus, xerostomia, fungal infections and, rarely, osteoradionecrosis, all of which can be minimized, and many of which can be prevented with pretreatment intervention.3
A comprehensive oral/dental evaluation should include clinical and radiographic surveys to identify potential sources of dental infection and elimination of ongoing dental caries, symptomatic periapical lesions, calculus and plaque, and clinical and symptomatic periodontal disease. Dental screening at least 2 weeks before commencement of radiation therapy and/or chemotherapy is recommended. This period generally allows for appropriate healing of extraction sites (10 to 14 days), recovery of soft-tissue manipulations and restoration of key teeth, all of which are elements critical in maintaining an overall mucosal integrity during and after treatment. The initial dental evaluation should include a thorough prophylaxis, scaling and root planing, unless there is a visible or palpable tumor at the site of anticipated dental manipulation. The dentist should establish pretreatment baseline data against which subsequent examinations and treatments can be compared. During the initial appointment, the patient's dentition should be checked for carious lesions and defective restorations which are sources of potential irritation to the oral mucosa and should be replaced. In addition, the periodontium and the vitality of the pulp must be evaluated. Periodontal status is a major consideration with pocket-depth measurements and assessment of furcation and mobility included as a pretreatment routine. Eliminating symptomatic peri-odontal disease including plaque, gingival hemorrhage or dental pocket probing are very helpful in describing the treatment plans regarding dental intervention such as pre-radiation extractions.
To eliminate extractions, the patient must possess motivation to maintain dentition properly and to comply completely with prescribed oral hygiene and preventive measures. Principal maintenance of teeth (if possible), prevention of extractions after radiation therapy and prevention of mucosal or gingival ulcerations are the dentist's primary goals.
Discussion with the referring head and neck surgeon, radiation oncologist or medical oncologist is paramount in decision making. The subsequent rendered dental treatment should correlate with the overall prognosis of the patient. Each TMN classification, anatomic subset and cancer treatment modality has a unique effect on both the short (acute) and long-term (chronic) oral sequelae. The patient's dental awareness and previous dental compliancy is as much a major factor as tumor prognosis for subsequent dental treatment.4 Patient and family education, counseling and motivation are essential for successful dental preventive strategies.
Radiation therapy delivered for tumors of the oral cavity, oropharynx, nasopharynx, paranasal sinuses, base of skull, to salivary gland tumors, or to the neck for unknown primaries will have a sequelae to the oral cavity. On the other hand, radiation therapy for tumors of the thyroid, larynx and hypopharynx lead to minimal or possibly no direct effect on the teeth, periodontium, or mucous membranes of the oral cavity. However, if levels I and II of the neck are included in the radiation portal, the posterior body of the mandible, submandibular glands and mandibular canal are exposed to radiation and thus have a potential clinical significance and oral sequelae. Such exposure can lead to mucositis, xerostomia, radiation caries, advancement of pre-existing periodontal disease, temporary loss of taste, trismus from fibrosis of muscles of the temporomandibular joint and possibly, but not usually, osteoradionecrosis. Acute incidents of focal infection, such as periodontal or peri-apical infection, may necessitate an adjustment or an interruption of the radiation therapy schedule.
Most preventive procedures described in the literature are based on clinical experience and observation and are empirically prescribed, resulting in diverse treatment policies and preventive approaches in daily dental practices. Usually each institution has its own protocol and treatment guidelines, which are considered extremely precise.
Screening patients at least 2 weeks before radiation therapy allows adequate time for fabrication of radiation-protective mouthguards for those patients who have extensive metal fillings (gold, gold-based, or amalgam) which the direct beam of radiation will pass through. Such mouthguards potentially decrease scatter radiation to adjacent non-keratiniz-ing mucous membranes. In addition, a minimum of 2 weeks usually allows wound healing from possible dental extractions, periodontal surgery and/or restorations, and root canal therapy for symptomatic teeth (Figure 20-1).
A lack of patient motivation should lead to a decision to extract those questionable teeth before radiation therapy. Radiation exposure, type, field, and dosage also are parts of the decision formula regarding extraction of teeth. Usually not all of the mandibular teeth are included in the radiation portal. For example, teeth and anterior mandible between the mental foramen in radiation for base of tongue tumors receive less than 3,000 cGy, (absorbed bone dosage), and are thus at a very low risk for osteora-dionecrosis. On the other hand, posterior mandibular teeth receive a much higher dose of radiation.
Extraction of teeth is usually indicated in the following circumstances: (1) Advanced carious lesions with questionable pulp status or pulpal involvement that are non-restorable; (2) advanced or symptomatic periodontal disease, especially with advanced bone loss, mobility, and/or root furcation involve-
ment; (3) residual root tips not fully covered by alveolar bone or showing radiolucency; and (4) symptomatic impacted or incompletely erupted teeth that are not covered fully by the alveolar bone. Deeply impacted teeth usually are left without risk of later problems. Alveolectomy and primary soft-tissue wound closure are suggested to eliminate sharp ridges and bony spicules that could project to the overlying soft tissues5 (Figure 20-2). This issue is particularly important for later prosthetic considerations, especially in the beam portals involving the mandible because negligible bone remodeling can be expected after bone absorption dosages that are greater than 6,500 cGy.
Asymptomatic nonvital teeth located in the portal fields without periapical radiolucencies can be treated endodontically.6 In restorable mandibular molars that are not periodontally involved, endodon-tics with retrograde fillings are preferred over extractions. Teeth which are important for retentive abutments for maxillofacial prostheses (obturators), but with small, moderate periapical granulomas or radiolucencies without periodontal involvement can be treated with apicoectomy.
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