Management of the Patient Undergoing Radiotherapy or Chemotherapy Edward Ellis Ill C 1 1 \ P 'I' E Ti - - DENTAL MANAGEMENT OF PATIENTS UNDERGOING Beginning of Radiotherapy RADIOTHERAPY TO HEAD AND NECK Impacted Third Molar Removal Before Radiotherapy Radiation Effects on Oral Mucosa Method of Dealing with Carious Teeth After Radiation Effects on Salivary Glands Radiotherapy Treatment of Xerostomia Tooth Extraction After Radiotherapy Radiation Effects on Bone Denture Wear in Postirradiation Edentulous Patients Other Effects of Radiation Use of Dental Implants in Irradiated Patients Evaluation of Dentition Before Radiotherapy Management of Patients Who Develop Condition of Residual Dentition Osteoradionecrosis Patient's Dental Awareness DENTAL MANAGEMENT OF PATIENTS ON SYSTEMIC Immediacy of Radiotherapy CHEMOTHERAPY FOR MALIGNANT DISEASE Radiation Location Effects on Oral Mucosa Radiation Dose Effects on Hematopoietic System Preparation of Dentition for Radiotherapy and Effects on Oral Microbiology Maintenance After Irradiation General Dental Management Method of Performing Preirradiation Extractions Treatment of Oral Candidosis Interval Between Preirradiation Extractions and DENTAL MANAGEMENT OF PATIENTS experience some undesirable effect. Any neoplasm can UNDERGOING RADIOTHERAPY be destroyed by radiation if the dose delivered to the TO HEAD AND NECK -" - - -- -- neoplastic cells is sufficient. The limiting factor is the Radiotherapy (i.e., radiation therapy, x-ray treatment) is amount of radiation that the surrounding tissues can a common therapeutic modality for malignancies of the tolerate. head and neck. Approximately 30,000 cases of head and Radiotherapy destroys neoplastic (and normal) cells by neck cancer occur each year. Many of these are man- interfering with nuclear material necessary for reproduc- aged by therapeutic irradiation. Its use is ideally tion, cell maintenance, or both. The faster the cellular predicated on the ability of the radiation to destroy neo- turnover, the more susceptible the tissue is to the damag- plastic cells while sparing normal cells. In practice, how- ing effects of radiation. Thus neoplastic cells, which are ever, this is never actually achieved, and normal tissues usually reproducing at higher rates than normal tissue, 406 PART IV m Infections are selectively destroyed (relatively). In practice, normal Treatment of Xerostomia tissues with rapid turnover rates are also affected to some After radiotherapy, patients often complain of chronic degree. Therefore hematopoietic cells, epithelial cells, dry mouth. At present no general agreement exists con- and endothelial cells are affected soon after treatment cerning how to prevent these changes. Unfortunately, in when radiotherapy begins. many cases, xerostomia never improves substantially, Early in the course of radiotherapy, the oral mucosa and exogenous replacement of saliva is necessary. For the shows the effects of treatment. The changes in and simplest form of replacement, water can be sipped around the oral cavity as the result of destruction of the throughout the day. In addition, several saliva substitutes fine vasculature are most notable to dentistry. Salivary can be obtained without a prescription at the pharmacy. glands and bone are relatively radioresistant, but because These substitutes contain several of the ions in saliva and of the intense vascular compromise resulting from radio- other ingredients (e.g., glycerin) to mimic the lubricating therapy, these tissues bear a considerable hardship in the action of saliva. Unfortunately, artificial salivas on the long run. market do not possess the protective proteins that are present in the salivary secretions. The patients are there- Radiation Effects on Oral Mucosa fore still prone to the problems induced by xerostomia. For comfort, however, many patients seem to be just as The initial effect of radiotherapy on the oral mucosa, satisfied with plain water as artificial salivas and keep which is seen in the first 1 or 2 weeks, is an erythema that small quantities available at all times to sip. may progress to a severe mucositis with or without ulcer- Efforts to stimulate the patient's residual saliva have met ation. Pain and dysphagia may be severe and make ade- with some success. The Food and Drug Administration quate nutritional intake difficult. These mucosal reac- (FDA) has now approved the use of two medications to tions begin to subside after completion of the course of stimulate the flow of saliva: (1) pilocarpine hydrochloride radiotherapy. The taste buds, also comprised of epithelial and (2) cevimeline hydrochloride have been shown to cells, show similar reactions. Loss of taste is a prominent relieve symptoms of xerostomia for patients with xerosto- complaint early in treatment and gradually returns, de- mia.' Both are parasympathomimetic agents that function pending on the quantity and quality of saliva that remains primarily as muscarinic agonists, causing stimulation of after treatment. exocrine gland secretion. This can increase the production The long-term effects of radiotherapy to the oral of saliva, even in patients whose salivary glands have been mucosa are characterized by a predisposition to breakdown exposed to radiation. An oral dose of 5 mg of pilocarpine and delayed healing, even after minor insult. The epitheli- four times each day or 30 mg of cevimeline three times a um is thin and less keratinized, and the submucosa is less day has been shown to improve many symptoms of xeros- vascular, which gives a pale appearance to the tissue. tomia without significant drug-related side effect^.^ The Radiotherapy induces 5ubmucosal fibrosis, which makes administration of these medications may prove to be ben- the mucosal lining of the oral cavity less pliable and less eficial for some patients with postradiation xerostomia. resilient. Minor trauma may create ulcerations that take weeks or months to heal. These ulcerations are often diffi- cult to differentiate from recurrent malignant disease. Radiation Effects on Bone One of the most severe and complicating sequelae of radiotherapy for patients with head and neck cancer is Radiation Effects on Salivary Glands osteoradionecrosis (Fig. 18-2). Basically, osteoradionecro- Salivary gland epithelium has a very slow turnover rate; sis is devitalization of the bone by cancericidal doses of therefore the salivary glands might be expected to be radiation. The bone within the radiation beam becomes radioresistant. However, because of the destruction of the virtually nonvital from an endarteritis that results in fine vasculature by the radiation, the salivary glands elimination of the fine vasculature within the bone. The show considerable damage, with resultant atrophy, fibro- turnover rate of any remaining viable bone is slowed to sis, and degeneration. This manifests clinically as xeros- the point of being ineffective in self-repair. The continu- tomia (the decreased production of saliva) and gives the al process of remodeling normally found in bone does patient a "dry mouth." The severity of xerostomia not occur, and sharp areas on the alveolar ridge will not depends on which salivary glands were within the field of smooth themselves, even with considerable time. The radiation. A dry mouth may be the patient's most signif- bone of the mandible is denser and has a poorer blood icant complaint. supply than that of the maxilla. Thus the mandible is the The effects of xerostomia on the oral cavity are devas- jaw most commonly affected with nonhealing ulcera- tating. Because saliva is the principal protector of the oral tions and osteoradionecrosis. tissues, absence results in serious complications. Rampant "radiation caries" can swiftly destroy the remaining den- Other Effects of Radiation tition and predispose the patient to severe infections of the jaws. Teeth thus affected exhibit decay around the Patients undergoing radiotherapy may have an alteration entire circumference of the cervical portion (Fig. 18-1). in the normal oral flora, with overgrowth of anaerobic Periodontitis is also accelerated in the absence of saliva. species and fungi. Most researchers feel that oral flora col- Dysgeusia, dysphonia, and dysphagia are also caused by onizing the mucous membranes play an important role xerostomia. in the severity of mucositis and subsequent healing ,Mnt~n'yer?~erltof tllc Prztierlt Undergoir~~yRtzdiotlfer(zpy or Cl~rtnotlferizpy m CHAPTER 18 407 FIG. ": ' A, Typical clinical appearance of radiation caries. B, Typical radiographic appear- ance of radiation caries. Note the erosion around the cervical portion of the teeth. pro~ess.~*"andida albicans commonly thrives in the oral tion have residual teeth throughout the course of radio- cavities of patients who have been irradiated. It is not therapy. Thus the clinician may wonder what to do with known whether the alteration in the flora is caused by the teeth before irradiation. Should teeth be extracted? the radiation itself or the resultant xerostornia. Patients This question has no categorical answer; however, sever- frequently require the application of topical antifungal al factors must be con~idered.~-I~' agents, such as nystatin, to help control the amount of Comiition of ri'~i~!1lc?1 riontjfioii. A11 teeth with a Candida organisms present. Another oral rinse frequently questionable or poor prognosis should be extracted prescribed is 0.1% chlorhexidine (Peridex). This agent has before radiotherapy. The more advanced the periodontal been shown to have potent in