Background
Temporomandibular disorders (TMDs) are a set of musculoskeletal conditions affecting the temporomandibular joints, masticatory muscles, and associated structures. TMDs are a common cause of orofacial pain and limited jaw function. Physical therapy, including manual therapy (hands-on techniques like massage, mobilization, manipulation) is commonly used to treat TMDs. However, manual therapy encompasses many different techniques applied to different body regions.
This systematic review specifically examined the effectiveness of manual therapy targeted to the jaw and facial area (craniomandibular manual therapy or CMMT) for improving pain and jaw mobility in TMD patients.
Methods
The authors performed a comprehensive literature search across major medical databases for randomized controlled trials comparing CMMT to other treatments for Temporomandibular disorders. They included 6 studies with a total of 293 participants. The studies examined different craniomandibular manual therapy techniques like jaw muscle massage, jaw joint mobilization, and trigger point release.
Outcomes assessed were pain (self-reported scales) and maximum mouth opening measured in millimeters. Two reviewers independently evaluated study eligibility, risk of bias, and extracted the data. They assessed overall quality of evidence using the GRADE criteria.
Key Findings
- All studies showed improvement in pain and jaw mobility with CMMT from baseline.
- Two studies found CMMT provided superior pain reduction compared to self-care/exercise or a control group.
- One study found greater increase in mouth opening with CMMT versus sham treatment.
- However, CMMT did not show superior effects compared to other therapies like splinting, photobiomodulation, or kinesiotaping.
- Due to heterogeneity and small sample sizes, a meta-analysis was not performed.
- Overall quality of evidence was very low, meaning future research could significantly impact findings.
What specific manual therapy techniques applied to the jaw/facial structures are most effective for reducing pain in TMD patients?
The systematic review found that studies utilized different craniomandibular manual therapy (CMMT) techniques including intraoral myofascial release, temporomandibular joint mobilization, massage of masticatory muscles, and trigger point release. However, the authors were unable to perform subgroup analyses comparing the effectiveness of these different techniques due to the small number of studies overall and their clinical heterogeneity.
To determine the most effective craniomandibular manual therapy techniques for pain reduction in TMDs, future high-quality randomized trials are needed that directly compare outcomes from specific manual therapy protocols applied to the jaw and facial musculoskeletal structures. Based on proposed pain-relieving mechanisms of manual therapy, techniques that address muscular trigger points, joint restrictions, and neural mobilization may provide greater benefit than massage alone for certain TMD patient subgroups.
However, this requires further study through head-to-head comparisons measuring acute and lasting pain changes using validated scales.
Is craniomandibular manual therapy more effective for acute or chronic TMD?
The included studies had variability in the duration of Temporomandibular disorders symptoms among participants, ranging from acute to chronic. The systematic review did not perform subgroup analyses based on symptom duration. There are several factors that could influence whether CMMT has greater effects in acute or chronic Temporomandibular disorders.
In acute TMD, release of muscular spasm through massage and mobilization may help arrest pain and dysfunction before central sensitization occurs. However, in chronic TMD that involves central sensitization, the pain modulatory effects of CMMT mediated through dorsal horn pathways, descending inhibition, and parasympathetic activation may be more important.
High-quality controlled trials are needed that directly compare outcomes from craniomandibular manual therapy between acute and chronic Temporomandibular disorders patients matched for symptom severity. Longer term follow-up would also determine if CMMT can provide sustained benefits or prevent progression in acute Temporomandibular disorders. Overall, effectiveness may depend on the underlying pain mechanisms for each patient.
What are the proposed mechanisms by which CMMT improves pain and function in TMD?
The systematic review did not extensively discuss proposed mechanisms, but several possibilities exist based on prior literature. First, CMMT may decrease local muscular hypertonicity and release trigger points through mechanical pressure and stretch effects. Normalizing muscle tension could alleviate pain and motor dysfunction.
Secondly, craniomandibular manual therapy may improve joint mobility through release of intra-articular adhesions, realignment of disc displacements, and relaxation of protective muscle guarding. Improved joint mechanics and mobility could reduce loading strains on structures.
Third, CMMT may modulate pain signaling through gate control mechanisms, increased large fiber afferent input, reduced dorsal horn excitability, and activation of descending inhibitory pathways.
Finally, CMMT techniques that stimulate the parasympathetic nervous system may promote relaxation and pain reduction through neuroendocrine effects. However, further research is required to confirm the specific neurophysiological effects of CMMT in Temporomandibular disorders patients and correlate these to clinical improvements. This could help optimize techniques.
Discussion and Conclusions
This systematic review provides very low quality evidence that craniomandibular manual therapy improves pain and jaw mobility in Temporomandibular disorders patients, at least in the short and mid-term. However, it remains unclear if CMMT is superior to other conservative treatments for TMDs. The research is limited by few studies, small sample sizes, variability in techniques and comparators, and moderate risk of bias.
More rigorous research is needed to compare different craniomandibular manual therapy techniques and identify optimal protocols for acute versus chronic TMD. Still, clinicians can consider CMMT as one option alongside other evidence-based therapies to improve symptoms for TMD patients. Gaps remain in determining the most effective physical therapy approaches for specific TMD causes and populations.
Importance
This is the first review focusing specifically on CMMT for TMDs. The results support CMMT as an effective option for TMD pain and dysfunction, adding to prior evidence on broader physical therapy approaches.
However, significant research gaps remain in identifying optimal protocols. High quality comparative effectiveness trials are critical for determining best practices and individualizing care for TMD patients.
MD, PhD. Physical Medicine & Rehabilitation Physician from São Paulo - Brazil. Pain Fellowship in University of São Paulo.