A study comparing the use of wooden spatulas to the Therabite device for head and neck cancer patients who have mouth opening problems (Trismus Trial)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Head and neck cancers
Mouth (oral) cancer




Phase 2

This study is comparing wooden spatulas to a device called Therabite. Both of these are used to help people who aren’t able to fully open their mouths after radiotherapy for mouth cancer and cancer where the mouth joins the throat (oropharyngeal cancer).

Doctors can use radiotherapy to treat mouth cancer and oropharyngeal cancer. Some people find it difficult to open their mouth properly after radiotherapy to the mouth. This is because the muscles that you use to open and close your mouth are affected by the radiotherapy. It is called trismus.

Trismus can be treated by gently stretching the jaw muscles using wooden spatulas. The spatulas are placed in your mouth between the front teeth for a period of time each day. The jaw muscles are stretched by increasing the number of spatulas over time.

The Therabite device is another way to gently stretch the jaw muscles. It is a hand operated device you put inside your mouth. 

For this study you will use the Therabite device or wooden spatulas before radiotherapy treatment starts and continue during radiotherapy. Because the researchers think starting the exercises before radiotherapy will be beneficial.

The aim of this trial is to compare Therabite with wooden spatulas to find out

  • Which is best to treat trismus
  • Which improves quality of life the most
  • Which exercise routine people stick to best

Who can enter

You may be able to enter this trial if you

  • Have cancer of the mouth or oropharynx that is bigger than 4cm in size, or has spread to surrounding tissue, lymph nodes,or another part of your body (stage 3 or 4)
  • Will be having radiotherapy as part of your treatment
  • Can open your mouth at least 12mm
  • Have some tightening of the jaw muscles that stops you opening your mouth properly
  • Are at least 18 years old

You cannot enter this trial if you

  • Have had surgery or radiotherapy to your head or neck in the past
  • Are unable to use the Therabite device because you can’t open your mouth wide enough to use it or you have a number of missing teeth

Trial design

This is a pilot study. It will recruit 112 people. It is randomised. The people taking part are put into 1 of 2 treatment groups by a computer. Neither you nor your doctor will be able to decide which group you are in.

People in group 1 use the Therabite device. People in group 2 use wooden spatulas.

Trismus trial diagram

You will use the wooden spatulas or Therabite device and do jaw exercises 5 times a day, in total the exercise will take less than 15 minutes each day.

You will record in a diary how wide you can open your mouth at the end of each day. The researchers will show you how to do the exercises and how to measure and record how far you can open your mouth.

You begin the daily exercises before starting radiotherapy and continue after radiotherapy has finished. You do the exercises for 6 months.

Below are pictures of the Therabite device.

Therabite device

You hold the Therabite device in your hand with the white tips between your teeth. You gently squeeze down on the handle of the device. This will open your jaw and gently stretch the muscles.

The study team will ask you to fill out a few questionnaires before you start your exercises and then after 3 and 6 months. The questionnaires will ask about side effects and how you’ve been feeling. This is called a quality of life study.

You will also be asked if you have had help from health professionals such as a speech therapist or dietician at 3 and 6 months and how often you have been into hospital.

The study team may ask if you would like to meet with other people in the study to talk about any issues you had during the study which you feel could be improved upon. It will take about 1 to 1½ hours each time. You don’t have to agree to this. You can still take part in the study.

Hospital visits

You see the study doctor before you start treatment to measure how far you can open your mouth.

You see the doctor or member of the research team again after 3 months and 6 months for the same test.

Side effects

The researchers don’t expect there to be any side effects from taking part in this study.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor Nick Slevin

Supported by

NIHR Clinical Research Network: Cancer
NIHR Research for Patient Benefit (RfPB) Programme
The Christie NHS Foundation Trust

Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:

Oracle 9963

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Charlie took part in a trial to try new treatments

A picture of Charlie

“I think it’s really important that people keep signing up to these type of trials to push research forward.”

Last reviewed:

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