Trismus after head and neck cancer is a symptom associated with pain and negatively affected health-related quality of life. The purpose of this study was to compare two different jaw exercise devices and the compliance to exercise.

Fifty patients with head and neck cancer were randomized to jaw exercise with either the TheraBite or Engström jaw device in a 10-week exercise program. Patients were regularly assessed by an oral surgeon, filled in exercise diaries, and answered the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 Head and Neck 35-questions (EORTC QLQ H&N35) and the Gothenburg Trismus Questionnaire (GTQ).

Both groups improved their mouth opening, 7.2 mm (22.9%) and 5.5 mm (17.6%) for TheraBite and Engström, respectively. The largest increase in mouth opening and highest compliance to exercise was seen during the 4 first weeks.

Jaw exercise therapy effectively improved mouth opening capacity and led to less trismus-related symptoms. Both jaw devices were proved efficient and compliance to exercise was comparable.