Occlusal splint and masseter Botox effects on jaw and neck muscles

Evaluation of the Effects of Occlusal Splint and Masseter Botulinum Toxin Injections on Head and Neck Muscles Using Electromyography

We will test whether a custom jaw splint, Botox injections into the masseter muscles, or both, can change head and neck muscle activity in adults with myofascial pain syndrome.

Quick facts

• Phase: PHASE4
• Study type: Interventional
• Enrollment: 56 (estimated)
• Ages: 18 Years to 55 Years
• Sex: All
• Sponsor: Istanbul University (other)
• Locations: 1 site (Istanbul, Vezneciler)
• Trial ID: NCT07082972 on ClinicalTrials.gov

What this trial studies

This is a randomized, parallel-group trial that will enroll 56 adults with myofascial pain syndrome and normal BMI and full dentition, randomly assigning them to one of four groups: masseter Botox only, occlusal splint only, combined Botox and splint, or no treatment. Botox (20 IU per masseter, delivered at three sites per side) will be given by a neurologist and splints will be custom-made from hard vinyl acetate for the upper jaw. Surface electromyography (EMG) of masseter, temporalis, sternocleidomastoid, splenius capitis, and trapezius muscles will be recorded at baseline, 4 weeks, and 12 weeks to measure changes in muscle activity. All procedures and follow-up EMG recordings will take place at Istanbul University in Istanbul.

Who should consider this trial

Good fit: Adults diagnosed with myofascial pain syndrome who have normal BMI, no missing teeth, no prior TMD treatment, and who can attend visits at Istanbul University are ideal candidates.

Not a fit: People who are pregnant or lactating, have missing teeth, BMI outside the normal range, systemic neuromuscular or bleeding disorders, recent facial aesthetic procedures, or prior masseter Botox are unlikely to be eligible or to benefit from this protocol.

Why it matters

Potential benefit: If successful, the treatments could reduce abnormal head and neck muscle activity and help guide better non‑surgical management of myofascial pain syndrome.

How similar studies have performed: Previous studies of masseter Botox and of occlusal splints for TMD-related muscle pain have shown mixed but sometimes promising results, so combining them in a randomized design addresses an open question.

Eligibility criteria

Inclusion Criteria:

1. Having a diagnosis of myofascial pain syndrome
2. No missing teeth
3. No history of previous temporomandibular disorder treatment
4. Absence of an arthrogenic temporomandibular disorder

Exclusion Criteria:

* Pregnancy or lactation; osteoporosis and bisphosphonate use
* Previous botulinum toxin injection to the masseter region
* Bleeding disorders or use of anticoagulant medications
* Presence of systemic muscular or neurological diseases (e.g., myasthenia gravis, ALS)
* Active infection, open wound, or dermatological condition in the facial area
* Undergoing other facial aesthetic procedures (e.g., fillers, PRP, etc.) within the last six months
* Individuals with severe psychiatric disorders or those on regular psychiatric medications
* Patients who are unlikely to comply with the study protocol or complete the follow-up period
* Individuals with a body mass index (BMI) outside the normal range, including underweight or overweight participants, will be excluded from the study.

Where this trial is running

Istanbul, Vezneciler

• Istanbul University — Istanbul, Vezneciler, Turkey (Türkiye) (RECRUITING)

Study contacts

• Study coordinator: Afra Avar, DDS

Conditions: Myofascial Pain Syndrome, Masticatory Muscle Pain, Botulinum Toxin, Occlusal Splint, Bruxism, Head and neck muscles, Sternocleidomastoid muscle, Masseter muscle