Temporomandibular joint dysfunction (TMD) is a multifactorial musculoskeletal disorder affecting the masticatory muscles, temporomandibular joint, and related structures, characterized by pain and functional limitations. In TMD, myofascial pain is particularly prominent, leading to decreased mandibular range of motion, impaired masticatory function, and reduced quality of life. Current literature shows that conservative treatment approaches, especially multimodal physiotherapy programs, are effective in reducing TMD symptoms. However, evidence regarding the clinical effectiveness of adding EMG-Biofeedback-based relaxation training, aimed at increasing awareness of muscle activity, to multimodal treatment programs is limited. The aim of this randomized controlled trial is to investigate the effect of EMG-Biofeedback-based relaxation training, added to a multimodal exercise program, on pain levels and functional parameters in individuals diagnosed with temporomandibular joint dysfunction. Participants will be divided into two groups using a simple randomization method. The control group will receive multimodal physiotherapy consisting of manual therapy and a home exercise program, while the experimental group will receive EMG-Biofeedback-based relaxation training in addition to the same program. Assessments will be conducted before the intervention and at the end of the 4-week intervention.

Pain intensity will be measured with a Visual Analog Scale (VAS), pressure pain threshold with a digital algometer, mandibular joint range of motion with a linear scale, and cervical joint range of motion with a digital goniometer. Functional status will be assessed using the Fonseca Anamnestic Index, Neck Disability Index, and Oral Health Impact Profile-14. The obtained data will be compared using appropriate statistical analysis methods. This study is expected to provide scientific evidence regarding the clinical effectiveness of adding EMG-Biofeedback-based relaxation training to multimodal exercise programs in the conservative treatment of TMD and to contribute to filling the methodological gap mentioned in the literature.

The primary aim of this study is to investigate the effect of EMG-Biofeedback-based relaxation training, added to a multimodal exercise program, on pain levels and temporomandibular joint function in individuals diagnosed with temporomandibular joint dysfunction (TMD). It is known that in TMD, myofascial muscle pain is particularly prominent, and increased masticatory muscle activity leads to involuntary contractions and increased pain sensitivity, negatively impacting chewing, speaking, and daily living activities. This reduces the individual's functional capacity and quality of life. Therefore, this study aims to determine the contribution of adding EMG-Biofeedback-based relaxation training, which aims to increase awareness of muscle activity and promote neuromuscular relaxation, to a multimodal physiotherapy program to clinical outcomes. The primary objective of this study is to evaluate the change in pain level after the intervention. Pain will be assessed using the Visual Analog Scale (VAS), a subjective assessment method, and pressure pain threshold measurements using a digital algometer, an objective measurement method. The values obtained before and after the intervention will be compared both within and between groups. The secondary objectives of the study are to determine the changes in maximum mouth opening and mandibular range of motion, cervical joint range of motion, functional status (Fonseca Anamnestic Index), neck disability level, and quality of life related to oral health. In this context, the measurable objectives of the study are as follows:

1. Comparison of the change in VAS scores between the experimental and control groups after five weeks of intervention.
2. Objectively determining the change in pressure pain threshold values with a digital algometer.
3. Evaluation of the change in mandibular and cervical range of motion using quantitative measurement methods.
4. Statistical analysis of the changes in functional and disability scores. The determined aims and objectives are measurable, analyzable, and achievable within the thesis period. This study aims to scientifically demonstrate the contribution of EMG-Biofeedback-based relaxation training to pain control in TMD. In this study, a Demographic Information Form containing demographic information such as age, gender, occupation, and education level will be collected from the individuals participating in the study. A digital algometer will be used to objectively measure the pain threshold. Before measuring with the algometer, pressure will be applied to the pulp of the thumb of the control point. Then, force will be applied to the same point to create pain so that the individual can differentiate between pressure sensation and pain sensation, and this will be repeated three times. Afterwards, while the physiotherapist passively supports the individual's head with their other hand, pressure will be applied to 4 trigger points (TN) each in the masseter, temporalis, sternocleidomastoid, and upper trapezius muscles, increasing the pressure by 1 kg/cm² every three seconds until the individual feels pain. The individual will be instructed to report when they feel pain while force is being applied with the device (kg/cm²), and this process will be repeated three times for each TN, and the average will be taken to determine the pain threshold values for each TN. Pain intensity will be assessed using the Visual Analog Scale (VAS). This measurement method involves measuring distance in centimeters, which is recorded as a "score." Individuals will be informed that 0 points represent "no pain" and 10 points represent "unbearable pain," and will be asked to mark the point on a horizontal plane that best expresses the intensity of their pain. The determined score will be recorded as their pain intensity. Individuals' pain will be assessed separately according to this scale while eating, yawning, and at rest. Maximum unassisted mouth opening, protrusion, and right and left lateral extrusion movements will be measured using a linear ruler. Individuals will be asked to perform these movements as much as possible without causing pain while in a seated position. The distance between the maxillary and mandibular central incisors will be measured using a millimeter ruler. Since repeated measurements reduce the standard measurement error, measurements will be recorded three times, and the average of the recorded measurements will be noted. Measurement of TMJ movements in all directions has been reported to be reliable. The Fonseca Anamnestic Index, a recommended method in research populations due to its low cost, rapid administration time, and ease of use, will be used for the detection and classification of TMD. The questionnaire consists of 10 questions offering a multifaceted approach to assess temporomandibular joint, head, and back pain in the presence of chewing habits, parafunctional behaviors, movement restrictions, joint sounds, malocclusion, and emotional stress. Participants will be asked to select one of the following options for each question: 'Yes' (10 points), 'No' (0 points), and 'Sometimes' (5 points). Based on the total score of the answers given to the questionnaire, TMD will be classified as absent, mild, moderate, or severe. Sleep quality will be assessed using the Pittsburg Sleep Quality Index (PSQI). This is a 19-item self-report scale that evaluates sleep quality and disturbance over the past month. Its validity and reliability in Turkish have been established. The scale consists of seven components: subjective sleep quality, time to fall asleep, total sleep duration, sleep efficiency, sleep disturbances, sleep medication use, and impaired daytime functioning. Each item is scored between 0 and 3: 0 (never), 1 (less than once a week), 2 (1-2 times a week), 3 (3 or more times a week). The total score ranges from 0 to 21; a higher score indicates a decrease in sleep quality. Individuals with a total score ≤5 are considered to have "good sleep quality," while those with a score >5 are considered to have "poor sleep quality." The internal consistency coefficient (Cronbach's alpha) of the Turkish form of the scale has been reported as 0.80. A digital goniometer will be used to assess Cervical Range of Motion (ROM). Cervical flexion, extension, right and left lateral flexion, and right and left rotation degrees will be recorded before and after treatment.

The Neck Disability Index (NDI) was developed by Vernon et al. in 1991, and its Turkish validity and reliability were confirmed. This questionnaire shows the extent to which neck pain affects the quality of life of the participants. The questionnaire has options from A to F for each question. Participants will be asked to mark the option closest to them. For each question, A (0 points), B (1 point), C (2 points), D (3 points), E (4 points), F (5 points). A total score will be calculated.

The Oral Health Impact Profile-14 (ASEP-14) will be used to assess the impact of oral health on quality of life. This is a questionnaire that shows the extent to which oral health affects quality of life. This scale, consisting of 14 questions in total, includes functional limitations, physical pain, psychological distress, physical, social and psychological disabilities, and impairments.

Inclusion Criteria:

• Having been diagnosed with TMD, meaning having been diagnosed with Group 1 (1a: myofascial pain - 1b: referral myofascial pain) within Axis 1 according to the RDC/TMD diagnostic system.
• Having experienced TMJ pain for at least 3 months
• Having a sufficient cognitive level to follow simple instructions and take tests.

Exclusion Criteria:

• Having a malignant condition in the TMJ and/or cervical spine and having undergone surgery,
• Having neurological or psychiatric disorders, pregnancy,
• Having a history of BTA (Botulinum toxin injection) within the last year,
• Having received physical therapy related to TMJ less than 6 months ago,
• Being under orthodontic treatment,
• Having uncontrolled diabetes,
• Having inflammatory rheumatic diseases (rheumatoid arthritis, etc.)

Patient data may be requested from researchers after the study is completed. For ethical reasons, patient data will not be shared in an online system.