This study is a randomized, double-blind, placebo-controlled clinical trial designed to evaluate the effectiveness of botulinum toxin type A (BoNT-A) in patients with temporomandibular myofascial pain who have not improved after at least 3 months of conservative treatment.
Eligible patients aged 18-60 years will be randomly assigned to one of two groups:
* Intervention group: Intramuscular injection of 100 U BoNT-A into the bilateral masseter and temporalis muscles. * Control group: Intramuscular injection of 0.9% normal saline (placebo) using the same technique.
The primary outcomes will be:
* Pain intensity, measured using a 0-10 pain scale (VAS/NRS). * Maximum mouth opening (maximal interincisal distance), measured in millimetres.
Assessments will be performed before treatment (baseline) and at 1 week, 1 month, and 3 months after injection. The study will also monitor adverse events associated with the injections.
The aim is to determine whether BoNT-A provides greater pain relief and improved mouth opening compared with placebo in patients with temporomandibular myofascial pain. The findings may help support the use of BoNT-A as a treatment option for patients who do not respond to conventional therapy and provide valuable evidence for clinical practice in Pakista
History of TMD, no relief with conservative therapy after at least three months.
Clinical diagnosis of bilateral arthrogenous disorder and myalgia.
Moreover, TMD can be confirmed by diagnosis through MRI and CT examinations
Pregnancy or lactation.
None
Parallel
Botulinum Toxin Type A (BoNT-A)
DrugParticipants will receive a total dose of 100 units of Botulinum Toxin Type A (BoNT-A) administered by intramuscular injection into the bilateral masseter and temporalis muscles (25 U per side in each muscle). The injections will be performed using a 31G × 12 mm needle. Participants will be followed at 1 week, 1 month, and 3 months to assess pain intensity and maximal interincisal mouth opening.
0.9% Normal Saline (Placebo)
DrugParticipants will receive 0.9% normal saline by intramuscular injection into the bilateral masseter and temporalis muscles using the same injection technique, volume, and follow-up schedule as the experimental group. The placebo is used to maintain blinding and serve as the comparator.
Pain Intensity Numerical Rating Scale
Changes in pain intensity can be measured using various scales, such as the 11-point Pain Intensity Numerical Rating Scale (PI-NRS), where 0=no pain and 10=worst possible pain. The PI-NRS is commonly used to assess pain intensity in chronic pain management. However, interpreting the clinical importance of changes from baseline on this scale can be challenging. Studies have estimated a clinically important difference on the PI-NRS by relating it to global assessments of change in multiple studies of chronic pain.
Change in maximal interincisal mouth opening (MIO)
The maximum interincisal distance (MID) is a crucial measurement for assessing the function of the temporomandibular joint (TMJ) and the masticatory muscles. It is measured by the distance between the upper and lower incisors when the mouth is fully opened. This measurement is particularly important in evaluating TMJ disorders and can indicate the health of the jaw and its associated muscles.
Incidence of adverse events
Incidence of adverse events
Pain during mandibular movements
Pain during mandibular movements
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