After radiotherapy or surgery to the head and neck area, the muscles that open and close your mouth may become stiff. Doctors call this trismus. You may have been given mouth exercises to do to help prevent this.
Jaw stiffness can develop a few weeks or sometimes months after treatment. The amount of stiffness varies from person to person.
An easy way to check how wide your mouth can open is to try to put three fingers vertically between your lower and upper front teeth. If you can only manage one or two fingers, you may have a stiff jaw.
Tell your doctor if you have jaw stiffness or pain, even if it is mild. You will usually be referred to a speech and language therapist (SLT) or physiotherapist for assessment and treatment. Without treatment, jaw stiffness can get more severe so it is best to start treatment as soon as possible.
How widely you can open your jaw will be measured at your first appointment. This measurement will be repeated at every appointment. It will help you to see what progress you are making.
Jaw exercises can help reduce stiffness and pain. They help to stretch the tissues and strengthen the muscles in your jaw. When they are done regularly, they help to increase the amount you can open your mouth.
Your SLT, physiotherapist or restorative dentist will show you what jaw stretches to do, how long to hold each stretch and how many times to repeat them. They may also give you aids to help you gently stretch the jaw muscles. Wooden spatulas are often used. You place the spatulas between your upper and lower front teeth for a certain amount of time each day. You increase the number of spatulas you put into your mouth over time and so gradually stretch the jaw muscles.
There are also hand-operated devices such as TheraBite® or OraStretch® that you put inside your mouth to gently stretch the jaw muscles.
If pain in your jaw gets worse during jaw exercises, stop doing them and contact your SLT or physiotherapist for advice.
Your SLT or physiotherapist may also suggest you chew sugar-free gum to keep your jaw moving.
Other things that may help if you have jaw stiffness
If you are having difficulty chewing or swallowing because of a stiff jaw, softer foods can be easier to eat. You may be referred to a dietitian or given supplement drinks to take until you can chew better. You can find more information about eating problems in our section on eating and drinking.
It is important to continue with a regular mouth care routine while your jaw is stiff. If you find it difficult to reach teeth in the back of your mouth, try using a small toothbrush. Tell your dentist or hygienist if you cannot brush your teeth because of a stiff jaw. They can give you more advice.