Objective: The purpose of this study was to analyze the effects of head and neck radiation therapy on jaw opening and mobility.
Study design: Maximum jaw opening and mandibular mobility were measured before and after radiation treatment in 58 patients presenting for angle down wedge, homolateral wedge pair, and parallel pair head and neck radiation treatment.
Results: As dose to the temporomandibular joint and pterygoid muscles increased, maximal jaw opening decreased linearly. Mandibular dysfunction appeared to increase as radiation dose to the pterygoid muscles increased. Similar effects were not observed with temporomandibular joint irradiation. Irradiation of the pterygoid muscles appeared critical in the development of trismus. Angle down wedge treatment irradiated the temporomandibular joint and pterygoid muscles with clinical effects similar to those seen in homolateral wedge pair and parallel pair patients. Doses as low as 1493 cGy resulted in functional impairment.
Conclusions: Future investigations into radiotherapy delivery and appropriate postradiation trismus treatment may reduce head and neck radiation morbidity.