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

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

PHASE4

Total Enrollment

56 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-09-01

Study Completion Date

2026-12-01

Brief Summary

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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.

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Detailed Description

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This study is a prospective, randomized, controlled, parallel-group clinical trial designed to investigate the effects of occlusal splints and BTX-A injections in adult patients with myofascial pain syndrome (MPS), as diagnosed by the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). A total of 56 adult participants (both male and female) will be recruited and randomly divided into four equal groups (n=14): (1) BTX-A injection only, (2) occlusal splint only, (3) BTX-A combined with occlusal splint, and (4) control group receiving no treatment. All participants must be within the normal BMI range and have complete dentition.

Exclusion criteria include pregnancy or lactation, systemic neuromuscular or bleeding disorders, prior BTX-A treatment in the masseter region, recent facial aesthetic procedures, and any condition that may hinder study compliance.

BTX-A will be injected into the masseter muscles at three standardized sites per side (total 20 IU per muscle) using a 1 ml syringe with a 26-gauge, 13 mm needle. The injections will be performed by a neurologist in a hospital setting. For participants in the occlusal splint group, upper jaw impressions will be taken using alginate, and splints will be fabricated from 2 mm thick hard vinyl acetate sheets. Splints will be positioned intraorally with autopolymerizing acrylic resin to ensure consistent fit and occlusal contact.

EMG measurements will be conducted at Bezmialem Vakıf University using surface electrodes placed over the masseter, temporalis, sternocleidomastoid, splenius capitis, and trapezius muscles. The skin will be cleaned with 70% alcohol, and electrode placement will follow anatomical landmarks. Recordings will be obtained during maximal voluntary clenching with participants seated and relaxed. Measurements will be taken before treatment, at 4 weeks, and at 12 weeks post-intervention to monitor short- and long-term effects.

All patients will complete the DC/TMD symptom questionnaire and rate their pain using a Visual Analog Scale (VAS) at each time point. Statistical analysis will be performed using SPSS v22. Parametric and non-parametric methods will be applied based on data distribution. Intergroup comparisons will be performed using one-way ANOVA or Kruskal-Wallis tests, and intragroup comparisons will utilize repeated measures ANOVA or Friedman tests. Chi-square tests will be used for categorical data. A significance level of p\<0.05 will be considered statistically meaningful.

The study was approved by the Clinical Research Ethics Committee of Istanbul University Faculty of Dentistry and will be funded by the university (BAP). All procedures will be carried out under professional supervision to ensure safety and reliability of data collection.

Conditions

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Myofascial Pain Syndrome (MPS) Masticatory Muscle Pain

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Patients with myofascial pain syndrome will be included, and their muscle activity will be measured using electromyography (EMG).

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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Botulinum toxin injection group

Patients will receive a total of 20 units of botulinum toxin injected into the masseter muscle on each side. EMG measurements will be taken before and after treatment to evaluate changes in muscle activity.

Group Type EXPERIMENTAL

Botulinum toxin injection

Intervention Type 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 group

Patients will use occlusal splints during sleep. EMG recordings will assess the effect of splint therapy on muscle activity.

Group Type EXPERIMENTAL

Occlusal splint

Intervention Type 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 group

Patients will receive 20 units of botulinum toxin injections into the masseter muscle on each side and use occlusal splints during sleep. EMG will monitor the combined effect on muscle activity.

Group Type EXPERIMENTAL

Botulinum toxin + Occlusal splint combined

Intervention Type 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.

Control group

Patients will not receive any active treatment. EMG measurements will observe natural changes over time.

Group Type NO_INTERVENTION

No interventions assigned to this group

Interventions

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Botulinum toxin injection

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.

Intervention Type DRUG

Occlusal splint

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.

Intervention Type DEVICE

Botulinum toxin + Occlusal splint combined

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.

Intervention Type COMBINATION_PRODUCT

Eligibility Criteria

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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.

Minimum Eligible Age

18 Years

Maximum Eligible Age

55 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No