The trial will compare exercises using Therabite® versus wooden spatulas to prevent or relieve trismus in patients with stage 3 and 4 oral/oropharyngeal cancer.

Trismus is defined as a tightening of jaw opening. The negative impact of Trismus on the quality of life of head and neck cancer patients is well established. It affects eating, drinking, speaking and social function and is often as debilitating as any disfigurement resulting from treatment.

The use of jaw exercises using a Therabite appliance following treatment has been shown to reduce the level of Trismus in small studies. Many UK centres, however, use stacked wooden spatulas inserted between the incisors as a means of passive exercise. There is anecdotal evidence that suggests the use of exercises prior to treatment may help reduce the severity of the Trismus experienced by the patient.

This study will enrol 112 head and neck cancer patients allocated by chance to use either the Therabite or wooden spatula and patients will be asked to perform mouth exercises on a daily basis for 6 months.

There is a need to evaluate both the clinical effectiveness and cost-effectiveness of Therabite as opposed to wooden spatulas to determine whether they should be adopted as standard care in head and neck cancer patients.

In this pilot trial, the investigators will measure benefits of Therabite to patients, as compared to usual care with wooden spatulas. Mouth opening will be the key outcome for the study.

Inclusion Criteria:

• Provision of signed, written informed consent
• Aged 18 years and older
• Able to read and write English sufficiently to be able to complete questionnaires
• Stage 3/4 oral and oropharyngeal cancer patients undergoing:

Primary chemoradiotherapy or Surgical free flap plus post operative radiotherapy or post operative chemoradiotherapy

• All patients will receive 60-70 Gy in 30-35 fractions over 6 to 7 weeks to the region of the pterygoid muscles.
• All patients will have at least some trismus as indicated by subjective tightening in the jaw.

Exclusion Criteria:

• <12mm mouth opening (cannot use Therabite)
• Anatomically unable to use Therabite for example patients who may only be partially dentate and to use the Therabite would place extreme stress on the existing teeth
• Cognitive impairment as judged by the clinicians
• International patients treated who will not have routine UK follow up.
• Previous surgery or RT to the head and neck prior to this diagnosis
• Any patient who has no subjective tightening of the jaw.