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EMG-Based Evaluation of Occlusal Splint and Masseter Botox Effects on Head and Neck Muscles

ConditionsMyofascial Pain Syndrome (MPS)Masticatory Muscle Pain
Trial statusRecruiting
Trial phasePhase 4
Trial typeInterventional
Biological sexAll
Age18-55
SponsorIstanbul University

About this trial

This randomized controlled clinical trial aims to evaluate the individual and combined effects of occlusal splint therapy and botulinum toxin type A (BTX-A) injections into the masseter muscle on the activity of head and neck muscles in patients diagnosed with myofascial pain syndrome (MPS). MPS is a common subtype of temporomandibular disorders (TMD), frequently involving the masticatory and cervical muscles. Despite various treatment modalities, there is still no universally accepted protocol. In this study, 56 adult participants of both sexes, without missing teeth and within a normal body mass index (BMI) range, will be randomly assigned to four groups: BTX-A injection only, occlusal splint only, combined BTX-A and splint therapy, and an untreated control group. Surface electromyography (EMG) will be used to assess muscle activity in the masseter, temporalis, sternocleidomastoid, splenius capitis, and trapezius muscles. EMG recordings will be performed at baseline, 4 weeks, and 12 weeks after the intervention. Pain levels and symptom severity will be assessed using the DC/TMD symptom questionnaire and the Visual Analog Scale (VAS). BTX-A injections will be administered by a neurology specialist (20 IU per masseter muscle), and occlusal splints will be custom-fabricated and fitted for each participant. This study seeks to determine the neuromuscular effects of these treatments-both alone and in combination-on masticatory and cervical muscles and to provide insight into the development of more comprehensive and effective treatment strategies for MPS.

Eligibility criteria

This trial does not accept healthy volunteers

Qualifiers

Having a diagnosis of myofascial pain syndrome

No missing teeth

No history of previous temporomandibular disorder treatment

Absence of an arthrogenic temporomandibular disorder

Disqualifiers

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)

Trial design

Design model

Parallel

Treatments tested in this trial

  • Botulinum toxin injection

    Drug

    Patients will receive a total of 20 units of botulinum toxin type A (Botox) injected into each masseter muscle. The injections will be administered at three standardized sites on each side using a fine needle to ensure accurate delivery. Muscle activity will be recorded using electromyography (EMG) before the injection, and follow-up EMG measurements will be taken at one month and four months post-treatment to evaluate changes in muscle activity and treatment efficacy.

  • Occlusal splint

    Device

    Patients with myofascial pain syndrome will receive custom-made occlusal splints to wear during sleep. These splints help reduce abnormal muscle activity and relieve pain by redistributing bite forces. EMG measurements will be taken before and during treatment to monitor changes in muscle activity.

  • Botulinum toxin + Occlusal splint combined

    Combination product

    Patients will receive both botulinum toxin injections (20 units per masseter muscle, injected at three standardized points per side) and will use occlusal splints during sleep. EMG measurements will be conducted before treatment, and at follow-up visits to assess the combined effect of pharmacological and mechanical therapy on muscle activity.

Treatment groups

56 Participants
are divided into 4 treatment groups
Group A: Botulinum toxin injection groupExperimental treatment 1 intervention
Group B: Occlusal splint groupExperimental treatment 1 intervention
Group C: Botulinum toxin + Occlusal splint combined groupExperimental treatment 1 intervention
Group D: Control groupNo intervention 0 interventions

Trial outcomes

Primary outcomes

1

Electromyography results

Electromyographic (EMG) recordings will be used to assess changes in electrical activity in the masseter, temporalis, sternocleidomastoid (SCM), trapezius, and splenius capitis muscles. These muscles are often overactive in individuals with bruxism, parafunctional habits, and postural issues. Baseline EMG recordings will be taken at week 0, with follow-up measurements at the 1st and 12th weeks to observe short- and mid-term effects. EMG activity in the masseter and temporalis muscles will be evaluated to assess changes following botulinum toxin injections, focusing on potential reductions in muscle hyperactivity. Occlusal splint therapy will be analyzed in terms of its effect on normalizing muscle activity over time. The combined treatment group will be examined for additive or prolonged effects. The control group will serve as a reference to monitor natural variations in EMG activity.

Time frame
12 week

Secondary outcomes

1

Diagnostic Criteria for Temporomandibular Disorders - Clinical Examination Form

Using the DC/TMD Clinical Examination Form, secondary outcomes will be assessed, including the precise location of pain reported by the patients, the characteristics and range of jaw opening movements, as well as the presence and intensity of pain elicited during manual palpation of the masticatory muscles and temporomandibular joint. These evaluations will help to comprehensively understand the functional limitations and pain patterns associated with temporomandibular disorders and will complement the primary outcomes measured in the study.

Time frame
12 week
2

Evaluation of Pain and Jaw Function as Secondary Outcomes

As another secondary outcome, pain intensity and jaw functional limitations will be evaluated using a validated pain and jaw function limitation questionnaire. This self-reported tool will allow for the assessment of patients' perceived levels of orofacial pain and the impact of temporomandibular disorders on daily jaw functions such as chewing, speaking, and yawning. These data will support the clinical findings and contribute to a more comprehensive understanding of the functional burden caused by myofascial pain.

Time frame
12 week

Other outcomes

Sponsors and contacts

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Istanbul University

Lead sponsor

Source ClinicalTrials.gov
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