Investigation of the Association Between Upper Crossed Syndrome and Temporomandibular Joint Dysfunction in University Students: An Observational Cross-Sectional Study

Temporomandibular Disorder is a musculoskeletal condition affecting the temporomandibular joint and masticatory muscles, and it may lead to pain, mandibular movement limitations, joint sounds, and functional impairment. Upper Cross Syndrome is a postural imbalance involving the head, cervical spine, and shoulder girdle, commonly characterized by forward head posture, rounded shoulders, and increased thoracic kyphosis. The cervical spine, shoulder girdle, and temporomandibular region are anatomically and biomechanically interconnected. Alterations in head and shoulder posture may influence mandibular function through changes in muscle activity, joint loading, and cervical alignment. Therefore, postural changes associated with Upper Cross Syndrome may be related to temporomandibular symptoms and functional limitations. This observational cross-sectional study is designed to examine the correlation between Upper Cross Syndrome-related postural parameters and temporomandibular disorder-related clinical findings in university students aged 18-35 years. No intervention will be applied, and all assessments will be completed during a single assessment session. Participants will complete demographic and clinical information forms and the Oral Health Impact Profile-14 questionnaire to assess oral health-related quality of life. Temporomandibular joint assessment will include clinical examination and mandibular range of motion measurements, including maximum mouth opening, lateral deviation, and protrusion. Postural assessment will include craniovertebral angle, head-shoulder angle, and thoracic kyphosis angle measurements. Craniovertebral angle and head-shoulder angle will be assessed using standardized lateral-view photographs through the PhysioMaster® digital photogrammetry application. Thoracic kyphosis angle will be measured using the inclinometer function of the same application.The data obtained from this study will be used to examine the correlation between upper body postural alignment and temporomandibular dysfunction-related findings. The results may contribute to a better understanding of the relationship between posture and jaw function in young adults and may provide guidance for interdisciplinary assessment approaches