(Editor's Note: This is the second installment in a three-part series on dental care for cancer patients.)
Post irradiation tooth decay can occur rapidly and is so pervasive the teeth can become flexible and/or break apart in the mouth. It is so significant that it resembles “baby bottle syndrome” — the rampant tooth decay that can occur in a toddler if he/she is put to bed with a bottle of sugary drink and the baby falls asleep with this sugary liquid pooled in the mouth. It is just fertilizer for tooth decay! Frequently, the post irradiation caries encircles the teeth and can destroy an otherwise intact dentition in months. The good news is that it can be prevented!
Saliva can “wash” the teeth, and by virtue of secretory IgA in the saliva can help prevent tooth decay. Saliva can also buffer the acidity of the oral cavity as well. Absent saliva, or with only the sticky mucinous saliva, the teeth are prone to have foods stick to them and the oral environment tends to be more acidic. There is an inverse relationship between the amount of secretory IgA in the saliva and how much decay people develop. The less IgA there is, the more tooth decay occurs. Obviously, without saliva there is no IgA, so you get the idea.
Ideally, prior to commencing radiation therapy (RT) the patient is seen by a dentist knowledgeable in management of patients receiving radiation therapy to the head and neck. After a thorough examination — both clinical and using x-rays — the dentist prepares the patient to prevent these side effects. Assuming the dentition is “good” the dentist would prepare custom fluoride applicators, which resemble flexible vinyl mouth guards, for the patient. A prescription for a neutral pH fluoride gel is given, so the patient can give himself/herself a fluoride treatment each night. It takes only 5-10 minutes and is highly effective since it holds the fluoride gel directly against all the teeth — even the ones far in the back where rinsing with a fluoride solution just does not reach. Between the daily fluoride treatment and good follow up with the dentist, post radiation caries can essentially be prevented.
If there are teeth which are in poor periodontal health and in the planned field of radiation, the dentist might elect to remove these teeth prior to commencement of the radiation therapy. This proactive approach helps to prevent osteoradionecrosis of jaw bone, a subject for discussion in a future article.
Trismus: Inability to Open the Mouth
When we open our mouth, it just does not fall open due to gravity — there are muscles which are responsible for opening/closing. Much of the time, some or most of these muscles are in the field of radiation and become fibrotic and lose their flexibility and some function as a result. The result can be the inability to open the mouth as widely as before — and that can impact food intake (no more big bites!) and in severe cases, the ability to brush and clean the teeth.
Before the radiation therapy begins, it is a good idea to measure the opening. Once measured, I just hold a wooden tongue depressor in front of the teeth and mark the amount of opening — the actual number is not critical. The patient needs to open the mouth a few times a day, five opens/set and make sure they are opening to those marks. They do this during and after the active radiation therapy and this keeps their muscles limber and able to open the mouth fully or almost fully. Simple. If you don’t keep the opening going, and the opening decreases, it is effectively impossible to get it back, so it only makes good sense to just do these simple exercises and things work out well.
As always, your dentist is a great resource for your care.
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