Effects Exercises in Temporomandibular Joint Disorders on Pain, Joint and Tongue Functions

The study will be conducted with two groups. While the control group will receive myofunctional therapy, the intervention group will receive orofacial and tongue exercises in addition to myofunctional therapy. The inclusion of orofacial and tongue exercises in the intervention group constitutes the main hypothesis of the study. The myofunctional therapy consists of home exercises, normal cervical joint movements, and massage techniques targeting the masticatory muscles.

At baseline, participants' eligibility for inclusion will be assessed. Individuals who meet the inclusion criteria will be randomly assigned to one of the two groups using a sealed envelope randomization method. Evaluation of participants will begin with the collection of demographic data. After recording the demographic information, further assessments will be conducted through questionnaires and instrumental measurements.

The first assessment will focus on pain evaluation, using three different methods.

• Numerical Pain Scale (NPS): This scale assesses pain intensity in three different conditions - during chewing, at rest, and during sleep. Participants will rate their pain on a scale from "0" (no pain) to "10" (worst imaginable pain).
• Pain Catastrophizing Scale (PCS): This self-administered questionnaire evaluates the participant's thoughts and emotional responses related to pain.
• Algometry: The pain thresholds of the superficial masticatory muscles (masseter and temporalis) will be determined. Three measurements will be taken from the most prominent point of each muscle with the algometer applied perpendicularly to the skin. The highest value among the three will be recorded as the pain threshold for that muscle.

Jaw function will be another measured parameter, assessed using two different methods-one questionnaire and one physical evaluation.

• Jaw Functional Limitation Scale-20 (JFLS-20): This 20-item self-reported scale evaluates the functional limitations of the jaw and masticatory system. Higher scores indicate greater functional limitation.
• Orofacial Myofunctional Evaluation with Scores (OMES): This protocol includes multiple subcomponents that assess facial and temporomandibular function, appearance, and range of motion.

Tongue strength and endurance will be measured using the same device. Participants will be seated upright in a chair during the assessment. Tongue strength will be evaluated in two parts - anterior and posterior.

• For anterior tongue strength, the device bulb will be positioned on the palate just behind the upper front teeth, and the participant will be asked to press it with the tongue.
• For posterior tongue strength, the bulb will be placed on the posterior palate, and the participant will press it with the middle part of the tongue.

Three measurements will be taken, and the highest value will be recorded as the maximal tongue strength.

Quality of life will be evaluated using a self-administered questionnaire - the Oral Health Impact Profile (OHIP) - which assesses the perceived impact of oral health on daily life.

After completing all baseline assessments, participants will receive the assigned intervention according to their group allocation. Regardless of group assignment, all participants will be given home exercises, which include patient education about the joint, eating and drinking habits, and behavioral training. Diaphragmatic breathing exercises will be taught to promote relaxation of cervical muscles and proper breathing patterns. Posture exercises will be included to improve neck and back mechanics. Relaxation training will be provided to help reduce joint overactivity during stress. Participants will also be instructed on the appropriate use of thermal agents (hot and cold packs) when needed.

Myofunctional therapy will begin with cervical stretching, relaxation of paraspinal cervical muscles, and release techniques for the sternocleidomastoid and scalene muscles. Exercise intensity will be adjusted according to the patient's tolerance and tissue response. Massage techniques targeting the masticatory muscles and the temporal region will be applied to promote relaxation. Passive range of motion exercises will be performed to increase temporomandibular joint mobility.

Orofacial and tongue exercises aim to improve tongue mobility and include four-direction tongue mobilizations, resisted forward and upward tongue movements, safe mouth opening exercises, as well as cheek and lip exercises.

The intervention program will consist of 12 sessions conducted twice a week for 6 weeks, with each session lasting approximately 45 minutes. Every two weeks, tongue strength and endurance, pain thresholds (via algometry), and pain levels (via NPS) will be reassessed.

Adherence to home exercises will be monitored at each session. Participants' compliance with both supervised and home exercise programs will be recorded using exercise logs.

Inclusion criteria

• 18 - 65 aged people
• Not having received physical therapy for the neck or jaw within the past three months.
• No history of surgical or oncological treatment related to the neck or jaw.
• Having a diagnosis of temporomandibular disorder according to the RDC/TMD criteria, specifically Group Ia, Group Ib, or Group IIa under Axis I.

Exclusion criteria

• Individuals who are pregnant or suspected to be pregnant.
• Individuals with rheumatologic diseases affecting the temporomandibular joint.
• Individuals with a diagnosed psychiatric disorder.