EvaluationoftheEffectivenessofDryNeedlingintheTreatmentofMyogenousTemporomandibularJointDisorders

Temporomandibular joint (TMJ) disorders are a common source of pain and dysfunction, affecting approximately 12% of adults and elderly patients in Spain. These disorders are multifactorial, involving anatomical, occlusal, parafunctional, traumatic, and psycho-emotional factors. They frequently co-occur with tension-type headaches, depression, and anxiety, and show greater prevalence in women. Multiple therapeutic strategies exist—from splints and medications to physiotherapy and surgery—but there remains uncertainty about optimal treatment approaches.

The current consensus favors non-invasive treatments unless symptoms severely worsen. Deep dry needling (DDN) has emerged as a promising minimally invasive technique for chronic muscle involvement, involving the insertion of a fine needle into myofascial trigger points to generate controlled microspasms and muscle relaxation. While several studies have examined DDN in masticatory muscles, results have been mixed, with some authors attributing effects to placebo. This study aimed to evaluate DDN's effectiveness specifically for myogenous temporomandibular disorders by monitoring masseter muscle activity, bite force, mouth opening, and jaw position changes.

The researchers conducted a double-blind randomized clinical trial with 36 patients aged 18-40 years who had myofascial pain due to temporomandibular dysfunction, diagnosed using Research Diagnostic Criteria (RDC). Participants had not received prior TMJ treatment. Exclusion criteria included inflammatory disorders, infections, neurological conditions, head trauma, anticoagulant use, metal allergies, and cognitive impairments. Patients were randomly assigned to Group E (experimental, receiving bilateral deep dry needling on masseter muscles) or Group C (control, receiving a simulated/sham procedure where the safety piece prevented actual needling).

Evaluations occurred at three time points: pre-needling, 10 minutes post-needling, and 15-day follow-up. Assessments included pain via Visual Analog Scale (VAS), bilateral muscle palpation with pressure algometer, mouth opening pattern and range with digital caliper, joint sounds, dental occlusion using T-scan digital analysis, and electromyography (EMG) of masseter muscle activity. The DDN technique used 0.30×0.30 mm acupuncture needles with guides, targeting identified trigger points with the patient supine and head rotated appropriately.

The study revealed several significant findings. For muscle activity measured by EMG in relaxed jaw position, notable reductions occurred in both right masseter (from 19 µV to 23.71 µV pre/post—note: this appears to be an increase in the text; likely the post-needling values represent the sham group or there may be a table reading issue) and left masseter (20.36 µV to 17.65 µV). More striking reductions appeared in centric relation positions using Dawson's bimanual technique: right masseter decreased from 94 µV to 37.71 µV, and left from 85 µV to 34.14 µV. The authors report significant reductions in muscle activity between pre- and post-needling with p>0.05 (though conventionally p<0.05 indicates significance; this may reflect a reporting convention in the original).

Mouth opening increased significantly from a mean of 44.92 mm pre-needling to 51 mm post-needling. Symmetry of opening and closing improved dramatically: pre-needling, 75% showed asymmetry versus 25% symmetry; post-needling, this reversed to 37.5% asymmetry and 62.5% symmetry. Digital occlusion analysis (T-scan) showed significant reduction in posterior disclusion time and time to reach maximum force in maximum intercuspation position. Articular sounds improved, with 25% presence pre-needling dropping to 0% at 10 minutes post-needling (though 12.5% at follow-up).

Facial pain showed substantial reduction (mean 7.75 to 0.95), while articular pain showed smaller reduction (mean 2.50 to 1.0). The EMG activity in maximum intercuspation position also decreased from 130.73 µV/125.55 µV (right/left) pre-needling to 112.86 µV/90.71 µV post-needling, though without statistical significance—attributed to probable sample size limitations.

This study provides evidence that deep dry needling of masseter trigger points can produce meaningful improvements in multiple domains for patients with myogenous temporomandibular disorders. The immediate pain reduction, improved mouth opening range, restored symmetry of mandibular movement, and changes in occlusal parameters suggest that DDN acts as an effective "neuromuscular de-programmer." The technique appears to reduce hypertonicity in the masseter muscles, which in turn allows the jaw to settle into a more physiologic position, improving occlusion patterns and reducing dysfunctional loading. For clinicians, this supports using DDN as a first-step intervention before proceeding with other dental procedures, since needling may facilitate return to baseline physiological jaw position in centric relation. The short-term nature of evaluation (10 minutes and 15 days) means longer-term durability of effects remains uncertain, consistent with other literature noting that DDN effects may be brief.

Patients may benefit from understanding that while needling can provide swift relief, optimal management of chronic myofascial pain likely requires combining DDN with exercise, psychological support, and sleep management as part of a multidisciplinary approach. The study's small sample size and lack of long-term follow-up are important limitations, but the comprehensive assessment battery (EMG, digital occlusion, physical measures) strengthens confidence in the observed changes.