Are Temporomandibular Disorders Really Somatic Symptom Disorders? Part III – Masticatory Function as Revealed by EMG and EGN

**Objectives:** The objectives of this research were; 1) to compare the changes in PHQ-15 scores to the changes in the EMG and EGN chewing data 2) to compare the progression of pain intensity, frequency of symptoms and functional restriction scores to the progression of EMG and EGN measurements. **Methods:** 6 TMD treatment centers recruited 82 TMD patients willing to answer PHQ-15 questions prior to treatment, 3 weeks post treatment and 3 – 4 months post treatment. Pain Intensity, Symptom Frequency and Functional Restrictions were surveyed and masticatory function was recorded at each time point. TMD patients diagnosed with “muscular” symptoms were treated with DTR via Immediate Complete Anterior Guidance Development coronoplasty. TMD patients with TMJ internal derangements revealed by JVA and imaging included application of ULF-TENS, orthotic TMD appliances, NSAIDs, exercises and/or orthodontics or prosthetics for final restoration. Student’s t test was applied to measured data, Wilcoxon Signed Rank test to survey data. **Results:** After 4 months of treatment the group’s PHQ-15 score declined from a pre-treatment median of 10 to a post-treatment median of 4 (p < 0.00001). The Symptom Pain Scale reduced from a pre-treatment median score of 20 to a post-treatment median of 6 (p < 0.00001). The Symptom Frequency Score reduced from a median of 17 to 5 (p < 0.00001) and for the Functional Restriction score from a median of 7 to 1 (p < 0.00001). Significant changes in chewing motion and muscle function were correlated with the reductions in pain, symptom frequency, functional restriction and the PHQ-15 scores (p < 0.05). **Conclusions:** The pre-treatment PHQ-15 median group score was significantly reduced after physical treatments. Thus, a high PHQ- 15 score could be accepted as a false positive indication of SSD prior to treatment. Also, the PHQ-15 scores continued to significantly reduce at 3 – 4 months after the end of physical treatment. The concurrent significant improvements in the masticatory timing, motion and muscle function support a physical rather than psychological etiology for this group’s TMDs.