An Investigation of Cranio-Cervico-Mandibular Factors Predicting the Severity of Temporomandibular Disorders

TMD severity will be assessed using the Fonseca Anamnestic Index, which evaluates the severity of temporomandibular dysfunction symptoms. It is a 10-item self-report questionnaire. Each item is scored as "Yes" (10 points), "Sometimes" (5 points), or "No" (0 points), with a total score calculated by summing all items.

Cervical extension joint position sense will be assessed in a sitting position using an Acumar dual digital inclinometer. Participants will be asked to actively move their neck to 30° of cervical extension, memorize the target position, and then reproduce the same angle. The procedure will be repeated three times, and the average absolute error will be recorded.

Cervical flexion joint position sense will be assessed in a sitting position using an Acumar dual digital inclinometer. Participants will be asked to actively move their neck to 30° of cervical flexion, memorize the target position, and then reproduce the same angle. The procedure will be repeated three times, and the average absolute error will be recorded.

Cervical lateral flexion joint position sense will be assessed in a sitting position using an Acumar dual digital inclinometer. Participants will be asked to actively move their neck to 30° of lateral flexion, memorize the target position, and then reproduce the same angle. The procedure will be repeated three times, and the average absolute error will be recorded.

Cervical rotation joint position sense will be assessed in a supine position using an Acumar dual digital inclinometer. Participants will be asked to actively rotate their head to 50° of cervical rotation, memorize the target position, and then reproduce the same angle. The procedure will be repeated three times, and the mean absolute error will be recorded.

Craniovertebral angle will be measured using a two-dimensional image analysis method with Kinovea software from standardized lateral photographs. The tragus and C7 vertebra will be used as anatomical reference points to calculate the angle, and the mean of three measurements will be recorded for each participant.

Musculoskeletal symptoms will be assessed using the Standardized Nordic Musculoskeletal Questionnaire. The questionnaire evaluates the presence of symptoms in different body regions over the past 12 months and past 7 days. Only neck pain-related variables will be used for analysis in line with the study objectives, while other data will be reported descriptively.

Mandibular function will be assessed using the Mandibular Function Impairment Questionnaire (MFIQ). The MFIQ is a 17-item self-report scale evaluating functional limitations during activities such as chewing, speaking, and yawning. Each item is scored on a 0-4 Likert scale, with higher scores indicating greater impairment.