Dental Caries (tooth decay)

Patients undergoing radiation therapy to the oral cavity have an increased incidence of caries because of the lack of saliva to cleanse the teeth and changes in the quality of the saliva. This promotes oral cavity colonization with a more cariogenic flora. In addition, the discomfort associated with xerostomia and persistent mucositis may result in poor oral hygiene with infrequent brushing, flossing, and oral rinses. Some patients may also alter their diet to include sugar-containing drinks and soft foods to help alleviate the effects of xerostomia. Rampant caries can occur, involving all tooth surfaces (including the cervical portion) after just a few months of xerostomia.

Prevention and Treatment of Dental Caries

To prevent the development of dental caries (which may result in extraction, soft tissue necrosis, bone exposure, and osteoradionecrosis) following a course of radiation therapy, all patients should undergo a thorough dental evaluation before treatment. Nonsalvageable teeth should be extracted and an alveolotomy and primary wound closure performed, if indicated. A thorough dental prophylaxis should be performed, including scaling, root cleaning, curettage, and polishing. Restorative dental procedures including endodontics should be performed for salvageable teeth. A preventive regimen should be initiated including plaque removal using dental floss and thorough instruction for correct toothbrushing. Custom-made fluoride carriers should be fabricated, and a neutral 1.1 percent sodium fluoride gel should be applied to the teeth following breakfast and before bedtime for a period of 2 weeks, beginning as soon as possible after the initiation of radiation therapy. This may be reduced to one bedtime application for 1 month and then twice-weekly fluoride applications indefinitely. The dosage of the fluoride should be modified based on the patient's dental caries history and oral hygiene performance. Patients also should use a calcium phosphate remineralizing rinse immediately following fluoride applications.

Edentulous patients should have their dentures evaluated and ill-fitting dentures corrected. They should be discouraged from wearing their dentures until the mucosa is completely healed from the acute effects of radiation therapy (usually about 3 months).

After radiation therapy, patients should be seen every 3 months for frequent dental checkups. There is no concern regarding the additional x-ray exposure of dental films, since the dose is insignificant compared with the therapeutic dose given for the cancer therapy. All routine dental procedures can be undertaken without unusual precautions after a course of radiation therapy, except radical periodontal treatment and extractions, which may lead to osteoradionecrosis if not undertaken with special care. When extractions are required after a course of radiation therapy, it is best to remove one tooth at a time with as little trauma to adjacent tissues as possible and to obtain complete healing before proceeding to further extractions. Prophylactic antibiotic coverage should be started 1 day before extraction and continued until the site is completely healed. Some institutions favor the use of hyperbaric oxygen before extraction. Primary closure of the wound should be carried out over a smooth bony surface, so that no sharp spicules or ridges are left beneath the mucosa. Postradiation therapy tooth extractions carried out in this manner have a good chance of complete healing without the development of necrosis. When extreme root sensitivity occurs after radiation therapy, brushing fluoride onto the exposed root surface and using specially formulated commercially available toothpaste appears to decrease the sensitivity to some extent.