ComparisonoftheEfficacyofBotulinumToxin,LocalAnesthesia,andPlatelet-RichPlasmaInjectionsinPatientsWithMyofascialTriggerPointsintheMasseterMuscle

Myofascial trigger points (TrPs) in the masticatory muscles are a leading cause of non-dental pain in the orofacial region. The masseter muscle, the primary chewing muscle, is one of the most common locations for TrPs in the human body. These hyperirritable spots within taut muscle bands can cause localized pain, referred pain, muscle stiffness, and limitations in jaw movement. Intramuscular injections directly into trigger points are considered a first-line treatment for deactivating these painful nodules.

Among the various injectable options, local anesthesia (LA), botulinum toxin (BTX), and platelet-rich plasma (PRP) have all shown promising results in prior research, yet no previous study had directly compared all three approaches specifically for masseter muscle TrPs. This gap in knowledge left clinicians uncertain about which treatment might offer the best balance of short-term relief and lasting benefit for patients suffering from masticatory myofascial pain.

The researchers conducted a retrospective study reviewing the clinical records of 82 patients treated for myofascial TrPs in the masseter muscle at a Turkish university dental hospital between 2016 and 2019. Patients were divided into three groups based on the treatment they received: Group I (27 patients) received injections of 0.5 mL mepivacaine 3% local anesthetic into each trigger point; Group II (26 patients) received 10 units of botulinum toxin-A per trigger point; and Group III (29 patients) received 0.5 mL of autologous platelet-rich plasma per trigger point, prepared using a double-spin centrifugation protocol. All patients had active trigger points diagnosed according to established criteria including palpable taut bands, hypersensitive tender spots, local twitch response, and referred pain patterns. They also had symptoms lasting at least 3 months with baseline pain scores of at least 3 out of 10 on a visual analog scale.

Outcomes were measured at diagnosis and at 1, 3, and 6 months after treatment using a visual analog scale (VAS) for pain at rest and while chewing, pressure pain intensity (PPI) scores, the Jaw Functional Limitation Scale (JFLS), and the Oral Health Impact Profile-14 (OHIP-14) for quality-of-life assessment.

All three treatments produced significant improvements at the 1-month follow-up. VAS pain scores dropped from a median of 7 to 2 in the local anesthesia group, from 7 to 1 in the botulinum toxin group, and from 8 to 3 in the platelet-rich plasma group. However, the durability of these benefits diverged considerably over time. At 3 months, botulinum toxin showed significantly better outcomes than both other treatments: VAS pain scores were lower in the BTX group compared to LA (P = .006) and PRP (P = .001), with LA also outperforming PRP (P = .003).

Similarly, JFLS improvements were significantly more pronounced with BTX than LA (P = .002) or PRP (P < .001), and OHIP-14 quality-of-life scores were significantly better with BTX than LA (P = .002). Pressure pain intensity improved significantly in both the LA and BTX groups at 3 months but not in the PRP group. By 6 months, the differences became even more striking: only the botulinum toxin group maintained significant improvements in VAS pain (P = .008), JFLS (P < .001), and OHIP-14 (P < .01) compared to baseline. The LA and PRP groups showed no significant improvement at 6 months for any outcome measure.

The BTX group maintained a median VAS pain score of 4 at 6 months, compared to 6 in both the LA and PRP groups.

For patients with myofascial trigger points in the masseter muscle, botulinum toxin injections appear to offer superior and longer-lasting relief compared to both local anesthetic and platelet-rich plasma injections. While all three treatments provide meaningful short-term improvement within the first month, BTX uniquely maintains its benefits for up to 6 months. This extended efficacy likely reflects botulinum toxin's mechanism of reversibly inhibiting acetylcholine release at the neuromuscular junction, reducing muscle hyperactivity that perpetuates trigger point pain, rather than merely providing temporary symptomatic relief. For clinicians, these findings suggest that BTX should be considered the preferred injectable treatment when long-term management of masticatory myofascial pain is the goal.

However, the study's retrospective design and lack of a true control group (such as no treatment or dry needling alone) limit the certainty of these conclusions. Additionally, factors like bruxism, psychological stress, and parafunctional habits that could influence treatment outcomes were not controlled for. Future prospective randomized trials with larger samples and longer follow-up periods would help confirm whether the observed advantages of BTX translate into consistent clinical superiority across diverse patient populations.