Effect of Forward Head Correction on EMG of Masticatory Muscles in Patients With TMD

Effect of Forward Head Correction on EMG Activity of Masticatory and Cervical Muscles in Patients With Temporomandibular Disorder

This study aims to investigate the effects of forward head correction exercises on EMG of masticatory and cervical muscles in patients with temporomandibular disorder. The study's design will be double-blinded, randomized controlled trial. Patients suffering from TMD will be included in the program. The participants will allocate to one of two groups at random: the experimental group will perform a program consisting of two strengthening exercises (deep cervical flexors and shoulder retractors) and two stretchings (cervical extensors and pectoral muscles) and the control group will receive only neck flexion exercise.. This exercise program will be repeated 4 times per week for 10 weeks, and each session lasted for 30 minutes. The muscle activity EMG of masseter, temporalis, splenius, upper trapezius, and SCM will be measured pre and post-assessment using a biopic data acquisition system.

1- EMG activity: Electrodes will be placed on the muscle belly parallel to the direction of muscle fibers. The distance between the two electrodes was 2 cm. The subjects will instructs to complete maximum voluntary contraction (MVC) by clenching the teeth for 3 s and repeating twice. The average of the two trials of MVC was used for further analysis.

1. To test the masseter and temporalis muscles: The subjects will be seated on a stable chair and will be instructed to tightly bite a cotton roll 10 mm thick as much as possible.
2. To test splenius muscle: the subjects will be seated on a stable chair and the examiner resist head extension.
3. To test the upper trapezius muscle: The subjects will be seated on a stable chair with the head side bent to the opposite side of the tested muscle; the examiner resist head side bending and shoulder elevation.
4. To test the sternocleidomastoid muscle: The subjects will be placed in a supine position and the examiner resisted the movement of cervical flexion by lifting the head from the table, with the chin depressed and approximated toward the sternum.

2. Measurement of TMJ range of motion. An 11 cm plastic ruler marked in millimeters measured TMJ opening range of motion "Opening. The subject will be instructed to open his mouth as wide as possible without causing pain or discomfort. The rater will measured the intercisal distance by placing one end of the ruler against the incise edge of one of the central incisors, and the other end against the incise edge of the opposing maxillary incisor." TMJ ROM measurements will be taken once for all patients before subdividing into groups and then after treatment intervention methods.

3-Use of the Fonseca's questionnaire to assess the prevalence and severity of temporomandibular disorders The Fonseca's questionnaire which considered to be valid and reliable for collecting a large quantity of information in a relatively short period and at low cost, it was easy to understand and had almost no influence from the examiner.

-intervention program: The program consisted of two strengthening (deep cervical flexors and shoulder retractors) and two stretchings (cervical extensors and pectoral muscles) exercises based on Harman and Mostafa et al's approach..

Inclusion Criteria:

• Men and women/aged between 18-40/ patients suffer from TMJ disorder/ no other treatment such as medications, physical therapy, and joint injections in the past 2 weeks

Exclusion Criteria:

• Previous history of TMG subluxation or dislocation that may interfere with the opening of the mouth/ Neck pain which may affect the head and neck posture/ Head or neck trauma/.Class II or III malocclusion/ posture disorder caused by abnormal curvature of the spine; rheumatic disease; hemorrhagic disease, etc.;/ Lateral deviation of the mandible