Repeated Botulinum Toxin Type A Injections on Intramuscular Fat Accumulation in Individuals With Sleep Bruxism.

Melek Volkan Yazici

Status: Completed

Conditions: Bruxism; Bruxism, Sleep-Related; Bruxism, Sleep

Treatments: Other: Botilinum Toxin injection

Study type: Interventional

Funder types: Other

Identifiers

NCT07266064

Botox series

Details and patient eligibility

About

This study investigates whether repeated botulinum toxin type A (BoNT-A) injections used to manage sleep bruxism lead to structural changes-specifically intramuscular fat accumulation-in the masseter muscle. Adults with probable sleep bruxism receive BoNT-A injections every six months and undergo ultrasound evaluations before each injection. By tracking fat percentage in the masseter muscle over multiple treatment cycles, the study aims to determine whether long-term BoNT-A use causes progressive structural alterations or remains safe for repeated clinical use.

Full description

Botulinum toxin type A (BoNT-A) is commonly used for the management of sleep bruxism, yet concerns persist regarding its long-term effects on muscle structure, including the possibility of intramuscular fat accumulation in the masseter muscle. This prospective longitudinal study follows adults with probable sleep bruxism who receive bilateral BoNT-A injections at six-month intervals. Ultrasound imaging is performed immediately before each injection, resulting in four injection cycles and five standardized ultrasound assessments.

Intramuscular fat percentage is quantified from B-mode images at rest and during maximum voluntary contraction using binary segmentation techniques. By examining changes over repeated treatment cycles, the study evaluates whether BoNT-A leads to progressive fat infiltration or instead demonstrates a stable or adaptive pattern. Findings will help clarify the structural safety of long-term BoNT-A use in non-spastic masticatory muscles and guide clinical decision-making for ongoing bruxism management.

Enrollment: 27 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Adults aged 18 years or older.
• Clinical diagnosis of probable sleep bruxism according to the international consensus criteria proposed by Lobbezoo et al.
• Indication for BoNT-A injection in the masseter muscle due to bruxism-related pain or muscle hypertrophy.
• Willingness to undergo repeated BoNT-A injections at six-month intervals.
• Willingness to participate in ultrasonographic evaluations at each follow-up visit.

Exclusion criteria

• Presence of neurological or neuromuscular disorders affecting the masticatory muscles (e.g., dystonia, myasthenia gravis).
• History of orofacial trauma, temporomandibular joint dysfunction, or maxillofacial surgery.
• Systemic diseases that may affect neuromuscular transmission or muscle metabolism.
• Use of medications known to interfere with neuromuscular function, including aminoglycoside antibiotics or corticosteroids.

Trial design

Primary purpose: Screening

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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27 participants in 1 patient group

BoNT-A

Experimental group

Description:

At baseline, all participants underwent ultrasonographic evaluation of both masseter muscles (U0). Two weeks later, the first BoNT-A injection was administered bilaterally (U1). Thereafter, ultrasonography was repeated at six-month intervals (U1-U4). Each of the intermediate assessments was followed by a BoNT-A injection two weeks later (U2-U4), whereas the final assessment (U4) was not followed by injection. Thus, the protocol comprised five ultrasound sessions (U0-U4) and four BoNT-A sessions (U1-U4), unless the participant discontinued the study. All ultrasound examinations were performed by the same experienced examiner using the same device and standardized probe settings.

Treatment:

Other: Botilinum Toxin injection