45 Posttreatment Dental Considerations
Summary
Exposure to cancer therapeutics can cause multiple complications including rapidly progressive dental caries, periodontal diseases, and osteoradionecrosis. These complications are relatively common and can significantly compromise functionality and quality of life. Frequent, consistent follow-up with an oral health provider during the posttreatment period is advised. Recommendations for the prevention and treatment of these common dental complications are reviewed in this chapter.
45.1 Introduction
Frequent, consistent follow-up with an oral health provider is an integral part of both the short- and long-term management of a patient with oral cancer. Salivary dysfunction, dietary changes, immune compromise, direct toxicity to oral structures, and decreased ability to maintain oral hygiene after cancer therapy can lead to the rapid development of dental caries and other odontogenic pathology. 1 These complications can affect overall health as well as seriously compromise quality of life. This chapter will introduce common dental complications of oral cavity cancer, with recommendations for both prevention and treatment. Mucosal complications are explored in Chapter 46, “Oral and Dental Complications of Oral Cancer Treatment.”
45.2 Dental Caries
Patients treated for oral cancer are at elevated risk of dental caries, predominantly secondary to salivary dysfunction. 2 Saliva naturally debrides the oral cavity, contains antimicrobial enzymes, and buffers cariogenic acid from foods, beverages, and microorganisms. 3 Although newer treatment techniques, such as parotid transfer and parotid-sparing radiation, are aimed at preserving salivary function, the subjective experience of dry mouth or xerostomia is still commonly reported. 4 Symptoms can be relatively nonspecific: difficulty or painful swallowing, difficulty chewing, pain while eating, taste changes, or a subjective “dry feeling” can all be reported. Patients often describe waking up at night to drink and often present to office visits with a large bottle of water. Clinically, patients can exhibit oral mucosa that is desiccated, cracked, and bleeding. Without a significant serous component, saliva can appear thick and mucus-based. Patients may exhibit rapidly progressive dental caries that are discussed below, and a greater frequency and severity of oral infections such as candidiasis and periodontitis. It is important to note that these sequelae of hyposalivation can be present without the subjective report of xerostomia. Salivary gland dysfunction is mentioned here as it relates to other diseases on topic for this chapter. Treatment recommendations are further discussed in Chapter 46.
Radiation-related hyposalivation and changes in salivary composition favor a shift toward pathogenic bacteria, rapid demineralization of hard tissues, and decreased antimicrobial activity. 5 Salivary flow and composition can be affected by surgical treatment and chemotherapy, but is most compromised after radiation and is worst with concurrent chemoradiation. Decreased salivary function has been reported after exposure to as low as 20 Gy of therapeutic radiation. 5 , 6 Direct toxicity to odontogenic structures secondary to radiation exposure has also been reported, leading to a decreased repair capacity of hard tissues. 7 Postradiation fibrosis can also make it more difficult to maintain oral hygiene, thereby increasing the risk of dental caries.
45.2.1 Epidemiology
Robust long-term data on the development of caries in postradiation patients are not available. That being said, dental caries after radiation and chemoradiation are common, estimated at 24 and 21%, respectively based on a literature review conducted by Multi-national Association of Supportive Care in Cancer/ International Society of Oral Oncology. 8 , 9 Patients treated with radiation to the head and neck had decayed, missing, and filled teeth scores roughly four times that of healthy controls, indicating an elevated burden of dental caries in this population, with a prevalence that increases with time from treatment. 10 , 11
45.2.2 Considerations for Prevention
Prevention is arguably the most important aspect of posttreatment oral care. Oral cancer itself is associated with preexisting poor oral health 12 . Pretreatment dental extractions, infrequent or emergency-only visits to dentist, residence in a community without fluoridated municipal water, a heavily restored dentition, exposed root surfaces, poor oral hygiene, preexisting xerostomia, and a history of gastroesophageal reflux disease/eating disorder are just some factors that may place a patient at additional risk of dental caries. What follows is an outline of daily preventative recommendations that can be reviewed during visits with any member of the treatment team.
45.2.3 Mechanical Debridement
Tooth-brushing two to three times daily is advised with the use of an extra-soft toothbrush. Bristles can be softened in hot water if needed. Oral tissues exposed to chemotherapeutics and radiation tend to be more friable and less resilient than untreated tissues; reducing the likelihood of trauma to these sites is imperative. Harsh-bristled toothbrushes or overbrushing can cause damage to tissues that are already at risk for delayed healing and infection. As such, patients undergoing cancer therapy should be routinely counseled on appropriate oral hygiene techniques. Mechanized toothbrushes are typically recommended, if tolerated. In the case of patients with dexterity limitations, modifications or assistance by a caregiver may be needed. In situations where the use of a bristled toothbrush is not possible, a foam brush dipped in chlorhexidine or saline solution can be utilized. Daily flossing is recommended unless limited by concerns for bleeding or infection. Brushing and flossing methods should be reviewed at each follow-up visit to ensure an atraumatic technique.
45.2.4 Fluoride Therapy
All patients receiving treatment for head and neck cancer should be prescribed 1.1% sodium fluoride toothpaste for use morning and evening, if tolerated. Products with heavy flavoring such as cinnamon and mint as well as whitening agents should be avoided. Fruit-flavored products are a well-tolerated choice that can be specified on the prescription. Regardless of the product prescribed, patients should be advised to brush all surfaces of the teeth for two minutes and then spit but do not rinse. Eating and drinking should be avoided for 30 minutes after application to allow for maximum benefit of the active ingredient. Fabrication of custom fluoride trays for use with fluoride gel may be of additional benefit and can temporarily stimulate salivary flow. In patients who are not able to tolerate toothpaste, especially those with mucositis, a saline solution, chlorhexidine, or water can be used on gauze or a cotton pad to gently debride the teeth and oral cavity. Over-the-counter dentifrices with more natural ingredients, assuming the inclusion of fluoride, may also be less irritating to tissues.
45.2.5 Oral Rinses
Alcohol-containing products can by drying and generally irritating to already sensitive tissues and should be avoided. These include certain over-the-counter oral care products. Chlorhexidine mouth rinses, particularly alcohol-free formulations, are recommended for the treatment and prevention of gingivitis and periodontitis. Chlorhexidine has been shown to decrease burden of pathogenic Streptococcus mutans in patients receiving cancer therapy as well as overall plaque deposition. 13 , 14 Patients should be advised of chlorhexidine’s potential to cause taste changes and reversible discoloration of the dentition. Warm saline, baking soda, and other bland rinses can also help with mucosal discomfort and hygiene.
45.2.6 Nutrition Counseling
Many patients will have difficulty maintaining adequate nutrition during and after therapy, increasing the likelihood of consumption of cariogenic foods and beverages. While ensuring adequate nutrition is obviously of primary importance, awareness of the sugar and acid content of what is taken by mouth is necessary as well. Frequent consumption of sugary and/or acidic foods and beverages such as tea, coffee, carbonated beverages, juice, water with lemon or lime, energy drinks, sports drinks, nutritional supplements, and syrup-based medications all increase the risk of dental caries. Patients on a soft diet are more likely to consume high-carbohydrate foods that also have the potential to cause caries. When such foods are consumed, the patient should be advised to, at minimum, rinse the oral cavity with water, or ideally brush the teeth. Professional nutritionists or dieticians included on the care team can provide more specific recommendations. Xylitol products may be recommended as well.
45.2.7 Frequent Follow-up
Oral examinations are advised during radiation therapy if tolerated, 1 month post completion and every 3 to 4 months for at least the first year. Typically professional cleanings are also performed at this frequency. The recall schedule may be adjusted if the patient appears low risk for development of disease after the first year. Diagnostic imaging should be obtained, typically every 6 months for at least the first year. Otherwise, the posttreatment oral evaluation is similar to that outlined in Chapter 10, “Pretreatment Dental Evaluation.”
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