白井 克幸

Introduction: Temporomandibular joint luxation has various causes, such as bruising and external force, as well as excessive opening of the mouth during eating, yawning, dental treatment, or oral intubation procedures for general anesthesia. Due to its sudden onset, it can have a significant psychological impact on patients, and early and appropriate treatment is necessary. We report a case in which temporomandibular joint luxation occurred during computed tomographic planning for postoperative chemoradiotherapy for oral cancer. <br>Case presentation: The patient was a 74-year-old female with squamous cell carcinoma of the right mandibular gingiva （cT4aN2bM0, stage Ⅳ, World Health Organization grade 1, INF-b）. We performed right mandibular segmental resection, right radical neck dissection, a free rectus abdominis muscle dermal flap transfer and wrap-around reconstruction, and tracheotomy with a reconstruction plate for right mandible squamous cell carcinoma. Two months after the surgery, temporomandibular joint luxation was detected during computed tomographic planning （with a mouthpiece） for postoperative chemoradiotherapy. The left mandibular condyle had deviated forward from the glenoid cavity. However, when we subsequently performed computed tomographic treatment planning without a mouthpiece the jaw dislocation could not be confirmed, and the left mandibular condyle was present in the glenoid cavity. There was no recurrence of the temporomandibular joint luxation, and the subsequent radiotherapy （60Gy/30fr） was effective.<br>Conclusion: It is considered that thorough anatomical confirmation during postoperative computed tomographic treatment planning is important in oral cancer cases, especially those involving mandibular segmental resection.