this study Randomized controlled study will be conducted to study (the effect of high power laser therapy on radiotherapy induced trismus in head and neck cancer patients).

the study group will receive high power laser therapy in combination with conventional tempromandibular joint exercises.

the control group will receive conventional tempromandibular joint exercises.

Inclusion Criteria:

• head and neck cancer patients who complain of decreased mouth opening and received or receiving radiotherapy.
• patients who complain from pain and inflammation in the tempromandibular joint due to radiotherapy.
• radiotherapy should be above 40 GY.
• patient ages between 20 to 65 years old.

Exclusion Criteria:

• patients with poor general health.
• patients with difficulties in filling questionnaire.
• patients who are complaining of other tempomandibular problems other than trismus such as (disc discplacement and trumatic mandibular fractures.

study limitations and recommendations