In order to destroy cancer cells during radiation therapy, high doses of X-rays are used that can affect the mouth, teeth and chewing muscles of the patients. X-rays can cause changes in the salivary glands. These changes can cause dry mouth, infections and tooth decay.
Trismus is a condition of restriction of mouth opening, which is frequently seen in patients undergoing radiotherapy for head and neck cancer and reduces the quality of life of patients. (Picture 1) . Restricted mouth opening and reduction in chewing functions affect patients’ daily activities such as eating, chewing, swallowing and speaking, depending on the degree of trismus. These effects can lead to many problems such as severe pain, lack of proper dental care, weight loss, poor oral hygiene. Although there is no definitive treatment for radiation-induced trismus, various treatment methods are used in its treatment. (Picture 2) . Stretching exercises are also used to increase mouth opening. (Picture 3) . If emergency surgical intervention is required, the presence of trismus can become life-threatening as the patient cannot be intubated comfortably.
The simplest way to determine whether there is a limitation in mouth opening is to check whether your three fingers are located between the lower and upper teeth. (Picture 4) . If the mouth is opened enough to accommodate these three fingers, trismus is no longer a problem. However, if it is not opened enough, a diagnosis of trismus can be made and the condition of these patients should be evaluated by the doctor. Therefore, routine dental check-ups have become more important, especially in patients undergoing radiotherapy. Dental examination before radiotherapy is recommended to prevent future problems.
Figure 1: Restricted mouth opening of a patient who received radiotherapy for nasopharyngeal cancer
Picture 2: Mouth opening appliance
Picture 3: Finger stretching exercise
Picture 4: Three finger test