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Chemotherapy, Radiotherapy and Dental Health

Cancer patients undergoing chemotherapy and/or radiotherapy may experience numerous oral complications. One of the most common changes following these treatments is oral mucositis, which develops due to disruption of the integrity of the oral mucosa. Radiotherapy applied to the head and neck region and antimetabolite or alkylating chemotherapeutic agents significantly increase the incidence and severity of mucositis. As epithelial cell turnover slows or ceases after treatment initiation, mucositis develops and the mucosa appears erythematous and inflamed.

In patients receiving chemotherapy, mucositis most frequently affects the non-keratinized, movable mucosa of the soft palate, cheeks, lips, ventral surface of the tongue, and the floor of the mouth; less commonly, it involves the gingiva, dorsal tongue, and hard palate. In patients receiving radiotherapy, the location of mucositis depends on the irradiated field.

Clinical manifestations range from mild erythema and discomfort to severe, painful ulcerations. Severe oral mucositis may significantly impair nutrition, swallowing, and speech, thereby reducing quality of life. Secondary infections may develop due to inflammatory changes, with Candida albicans being the most common opportunistic pathogen.

Radiotherapy to the head and neck region may also cause taste disturbances, often beginning within the first weeks of treatment. Another potential complication is soft tissue necrosis in the irradiated area, characterized by ulcerations without residual malignancy. The risk of necrosis is related to radiation dose, duration, and tissue volume exposed.

Radiation-induced damage to the parotid, submandibular, sublingual, and minor salivary glands results in reduced salivary flow and altered saliva composition, leading to xerostomia. Symptoms associated with xerostomia include burning sensation, difficulty chewing, food adherence to teeth and mucosa, thermal sensitivity, and increased fungal infections. The severity of xerostomia is related to the number of major salivary glands irradiated.

Xerostomia is a major etiological factor in radiation caries. Loss of saliva’s protective and cleansing functions alters the oral flora, and these changes may persist for up to four years after radiotherapy. Radiation also causes demineralization of dental hard tissues and may adversely affect developing teeth.

Significant changes also occur in irradiated bone tissue. Bone becomes more fragile, healing after trauma is delayed, vascular alterations develop, and susceptibility to infection increases. Reduced or absent regenerative capacity increases the risk of osteoradionecrosis, defined as exposed bone in the irradiated field persisting with or without pain following high-dose radiotherapy. Due to its higher density, bone absorbs approximately 1.8 times more radiation than soft tissue, and the mandible is at greater risk than the maxilla.

Dental extractions, aggressive periodontal therapy, infection, or mechanical irritation in irradiated patients may lead to severe complications. Therefore, all necessary dental treatments should ideally be completed at least 14 days prior to radiotherapy.

Some patients may develop trismus due to radiation-induced muscular fibrosis, particularly following treatment of nasopharyngeal, palatal, or paranasal sinus tumors involving the temporomandibular joint and masticatory muscles.

Chemotherapy patients may experience similar oral complications. In addition to mucositis, stomatitis may develop due to prosthetic trauma, orthodontic appliances, or infections. Unlike mucositis, stomatitis is related to a specific cause and resolves when the causative factor is eliminated.

Candida albicans remains the most common opportunistic infection, although HSV, gram-negative bacilli, and gram-positive cocci may also be involved. Candida infections typically affect the tongue, buccal mucosa, and pharynx, presenting with burning, pain, and ulceration following vesicle rupture.

Chemotherapy-induced thrombocytopenia and coagulation disorders may result in oral bleeding. Some chemotherapeutic agents alter salivary flow and quality from the second day of treatment, with xerostomia worsening as therapy continues. Neurotoxicity may occur with certain agents, depending on dose and duration, potentially causing partial paresthesia in trigeminal nerve–innervated regions, particularly in head and neck cancer patients. Severe toothache-like pain, especially in the mandibular molar region, may also be reported. Neurotoxicity is difficult to diagnose, but symptom resolution following drug discontinuation supports the diagnosis.

Preventive Measures

Patients should consult a dentist at least one month before the initiation of radiotherapy or chemotherapy. In particular, it is recommended that there be a minimum interval of two weeks between tooth extraction and the start of radiotherapy/chemotherapy

Prior to treatment, patients should be instructed on oral hygiene practices and encouraged to apply them effectively. Existing restorations and prostheses should be adjusted if necessary, and teeth with poor prognosis – especially those located within the radiation field and not amenable to treatment – should be extracted before radiotherapy. One of the possible complications, oral mucositis, may cause discomfort during prosthesis use.

Prostheses that are not used during treatment may develop stability problems over time. After completion of therapy, patients should be monitored for treatment-related side effects, and supportive oral health recommendations – such as the use of high-fluoride toothpaste – should be provided.

Before radiotherapy, scaling and root planning should be performed, and advanced periodontal treatments should be completed if indicated. Optimal oral hygiene must be achieved, and patients should be motivated and reduced to maintain regular and effective oral care. Due to chemotherapy, chronic periodontal disease may transition into an acute phase; therefore, meticulous oral hygiene is essential. To prevent dental caries, topical fluoride applications should be performed, and fluoride-containing toothpastes should be used.

Oral Care During Radiotherapy and Chemotherapy

Excellent oral hygiene should be maintained. A soft, small-headed toothbrush should be used, and excessive pressure during brushing avoided. The use of oral irrigators and electric toothbrushes is not recommended. If tooth brushing is not possible due to nausea, gingival burning, or other reasons, rinsing with a bicarbonate solution is appropriate.

In cases of acute mucositis, meticulous oral hygiene is essential. Gargling every 3–4 hours with a solution prepared by adding half a teaspoon of salt or baking soda to a glass of lukewarm water is highly beneficial. If chewing is painful, a 0.5% Dyclone solution may be used 20–30 minutes before meals.

When mucosal changes are accompanied by Candida albicans lesions, gargling with warm saline-bicarbonate solutions or topical anesthetics can help alleviate symptoms. Oral nystatin is effective in the treatment of acute or chronic oral candidiasis. Applying the same treatment to removable prostheses is important for controlling fungal infection.

Antimicrobial mouthwashes (chlorhexidine gluconate, benzydamine hydrochloride) may be used to manage inflammation and ulcerations caused by treatment. For ulceration and inflammation, analgesic and protective adhesive gels (such as Anestol or Protofix) are recommended.

In cases of xerostomia (dry mouth), bicarbonate rinses, chewing gum, sugar-free candies, ice chips, and frequent fluid intake are advised. Acidic or spicy foods, as well as very hot or very cold foods and beverages, should be avoided. Alcohol and tobacco products must not be used. Additionally, potassium iodide-containing medications, lemon tablets, sialogogue agents (e.g., Biotene), and artificial saliva substitutes may be utilized.

If trismus develops, regular home exercises should be performed, and special appliances may be fabricated by the dentist if necessary.