1. Clinical studies of temporomandibular disorders We continued our studies of screening questionnaires and evaluation of quality of life in patients with temporomandibular disorders (TMDs). 2. Morphological and histological studies of the temporomandibular joint We continued our anatomical and histological examinations of the temporomandibular joint (TMJ) and articular disk in Mammalia. 3. Clinical studies of obstructive sleep apnea-hypopnea syndrome We examine the relationship between body-mass index (BMI) and the fatty change of the suprahyoid muscles in patients with obstructive sleep apnea (OSA).