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What Is Functional Electrosonography (ESG) — And What Can It Reveal About Your TMJ That MRI Cannot?
When patients present with clicking, popping, grating or crepitus in their temporomandibular joints, static imaging like MRI can only tell part of the story. Functional Electrosonography (ESG) — integrated into the K7 Evaluation System — records and quantifies joint sounds in real time during functional opening and closing cycles. It distinguishes early, mid and late opening and closing clicks, identifies reciprocal sounds, and detects severe degenerative joint disease (DJD) patterns through high-frequency low-amplitude signatures. It is the only technology that objectively documents what is happening inside the joint while the jaw is actually moving — and it is exclusively available to GNM trained dentists using the Myotronics K7.
Regulatory Recognition of Electrosonography in Dentistry
Electrosonography has received formal regulatory recognition as a diagnostic aid in the management of temporomandibular disorders. The American Dental Association’s Council on Scientific Affairs awarded electrosonography (ESG) its “Seal of Acceptance” as a diagnostic aid in the management of temporomandibular disorders (JADA 1996;127:1615-1616). The Myotronics K7 system, which integrates ESG with computerized mandibular scanning and surface electromyography, received its own ADA Council Acceptance Seal for K7/ESG in November 2003, with the Acceptance Seal extended across all K7 modalities in April 2004.¹ The ADA Seal Program for professional products was subsequently phased out effective April 29, 2007, as an administrative discontinuation of the program rather than a clinical determination about TMD instrumentation. Electrosonography measurement devices are FDA-cleared under 510(k) for use in the diagnosis and management of TMD.
The American Academy of Head and Neck and Facial Pain established standards in 1990 stating that “Digital Sonography may be used to record and analyze temporomandibular joint sounds providing the doctor with valuable information for diagnosis and treatment planning.” Recording of joint sounds has been part of the recommended screening examination for TMD patients and is the standard of care during examination of TMD patients.
For the broader regulatory framework and chronological documentation, see our companion pages: Science of K7 Electronic Diagnostic Instrumentation → and Computerized Electro-Diagnostic Instrumentation →.
The Etiologic Value of Electrosonography
The clinical value of electrosonography extends beyond the documentation of joint sounds. ESG records the acoustic signature of the temporomandibular joints during real function — and joint sounds are the audible evidence of mechanical conditions inside the capsule. Clicks indicate disc-condyle relationships. Crepitus indicates surface-to-surface contact between structures that should not be in contact. High-frequency signatures above 300 Hz indicate degenerative change. These are not subjective interpretations. They are physical acoustic events produced by the mechanical state of the joint.
In most TMD patients presenting to general dental practice, joint sounds are documented in the chart as a clinical observation but rarely as a measurement. The patient reports clicking; the clinician confirms it on auscultation; treatment proceeds based on symptom severity rather than acoustic signature. What this approach misses is that joint sounds are not just symptoms — they are mechanical evidence. A click without analysis tells the clinician little. A click recorded, characterized by frequency, amplitude, and timing, tells the clinician what is happening structurally inside the joint and how it is changing.
When a GNM orthotic alters the mechanical loading of the temporomandibular joint, the acoustic signature changes. Clicks resolve. High-frequency degenerative patterns diminish. Joint sounds shift from pathologic toward physiologic. These changes are not the consequence of the orthotic suppressing symptoms — they are the consequence of altering the mechanical conditions that were producing the pathologic sounds in the first place. This is the etiologic chain that ESG measurement makes visible. Conventional examination treats the symptoms of joint pathology because conventional examination cannot quantify the pathology itself. Electrosonography quantifies it and allows mechanical correction to be objectively verified.
ESG is also categorically diagnostic in a way the other K7 channels are not. Trajectory normalization, resting EMG reduction, and recruitment gap closure are quantitative changes — values that move from one number toward another. ESG signature change is often qualitative. A joint that produced clicks and high-frequency sounds before treatment, and produces only soft-tissue sounds below 300 Hz after treatment, has undergone a categorical change in its acoustic state. This qualitative shift is direct structural evidence that the mechanical conditions producing pathology have been resolved.
For documented case examples of ESG-confirmed treatment response, see The Evidence Behind GNM →.
What ESG Measures
Electrosonography (ESG) is another measuring tool which allows the GNM trained dentist to better understand the dynamic functional movements of the temporomandibular joints. Temporomandibular joint derangement problems can be quantified beyond static MRI data. These tests and recordings can assist in identifying early, mid and late opening clicks and pops. ESG is able to also quantify early, mid and late closing (reciprocal) clicks and pops. Grating, crepitus (bone on bone) sounds within the TM Joint can be recorded.
Documented ESG Treatment Response
The left window of 4 ESG recordings shows late closing joint sounds occurring in the right joint (blue) before orthotic treatment.
The right window of 4 ESG recordings shows improved late closing reciprocal joint sounds after GNM orthotic treatment.
Four consecutive open closing cycles are recorded using K7 ESG (electrosonography, Myotronics, Inc., Kent, WA). These joint sound recordings distinguish specific left and right temporomandibular joints sounds and characteristic signature patterns. Velocity, timing, amplitude, duration and frequency are accurately documented and used to detect and distinguish high and low frequency as well as high and low amplitude signature sound patterns. Severe degenerative joint (DJD) patterns are distinguished by low amplitude high frequency patterns (bone grating on bone).
Recording Joint Sounds: Standard of Care
Recording of joint sounds is part of a recommended screening examination for TMD patients and is the “standard of care” during examination of TMD patients. Standards for the history, examination, diagnosis and treatment of temporomandibular disorders (TMD) published by the American Academy of Head and Neck and Facial Pain indicates (1990), “Digital Sonography may be used to record and analyze temporomandibular joint sounds providing the doctor with valuable information for diagnosis and treatment planning”.
Frequently Asked Questions
🔹 What does ESG actually measure that palpation, articulating paper, and MRI cannot? ESG records the acoustic and vibratory signature of the temporomandibular joint during opening, closing, and function — capturing continuous objective data about joint behavior in dimensions no conventional method can replicate. Where palpation captures the subjective impression of one moment, ESG captures the reproducible acoustic truth across the full range of mandibular movement. Where articulating paper records tooth contact, ESG records joint behavior. Where MRI shows static anatomy, ESG shows dynamic function. The K7 ESG records four consecutive open-closing cycles, distinguishing left and right joint sounds with characteristic signature patterns. Velocity, timing, amplitude, duration, and frequency are accurately documented and used to identify high and low frequency as well as high and low amplitude signature patterns. Severe degenerative joint disease (DJD) is distinguished by low amplitude high frequency patterns — the acoustic signature of bone grating on bone. This is not interpretation. This is measurement.
🔹 Why is ESG considered the standard of care for TMD examination? Because the dental profession’s own authoritative bodies have already established it as such. The American Academy of Head and Neck and Facial Pain published standards in 1990 stating: “Digital Sonography may be used to record and analyze temporomandibular joint sounds providing the doctor with valuable information for diagnosis and treatment planning.” Recording of joint sounds is part of a recommended screening examination for TMD patients and is the standard of care during examination of TMD patients. The standard exists. The instrumentation exists. The published authority exists. What is missing in most dental practices is not the recognition that joint sound recording matters — it is the training to incorporate ESG into routine clinical workflow. The OC GNM curriculum closes that gap.
🔹 What does ESG reveal that MRI cannot? Where MRI shows static anatomy, ESG shows dynamic function. A TMJ MRI can confirm the presence of disc displacement, condylar morphology, and structural pathology at the moment the image is captured — but the patient is not actively functioning during the scan. ESG records what the joint is doing during real movement: clicking, popping, grating, crepitus, reciprocal sounds during closing cycles, early/mid/late opening events. These functional events do not appear on MRI because MRI is a snapshot, not a recording. Both modalities are essential. Neither replaces the other. ESG and MRI together — alongside K7 jaw tracking and surface EMG — provide the complete diagnostic picture the GNM clinician needs to make accurate clinical decisions about joint health and treatment direction.
🔹 How does ESG verify whether GNM orthotic treatment is actually working? By recording joint sounds before orthotic delivery and after GNM orthotic adjustment — and comparing the recordings objectively. The page above shows this in clinical practice: the left window of four ESG recordings displays late closing joint sounds occurring in the right joint before orthotic treatment. The right window of four ESG recordings shows improved later closing reciprocal joint sounds after GNM orthotic treatment. This is not subjective improvement reported by the patient. It is the physical acoustic signature of the joint itself confirming that condylar behavior has changed. Pop reduction, click resolution, crepitus reduction, and reciprocal sound improvement are all visible in the ESG data — providing the GNM clinician with objective verification that the orthotic is doing what it was designed to do. Without ESG, treatment outcomes are reported. With ESG, they are measured.
Going Deeper
For dentists asking why electrosonography has remained largely unknown despite decades of validation, see Why Dentistry’s Quiet Tragedy Is the Joint It Cannot Hear →
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References
¹ Chronological Overview of Myotronics ADA Seal Programs (Myotronics archival document). Documents K6 and K7 Acceptance Seal dates and the April 29, 2007 program phase-out. Sourced May 18, 2026.
Continue Learning
🔹 ESG & K7 Diagnostics
- Science of Electrosonography (ESG) →
- Clinical Application of Electrosonography (ESG) for the GNM Dentist →
- Why Dentistry’s Quiet Tragedy Is the Joint It Cannot Hear →
- What Does the K7 Technology Measure? →
- Science of K7 Electro-Diagnostic Instrumentation →
- Science of Computerized Mandibular Scanning (CMS) →
- Science of Electromyography (sEMG) →
- Science of J5 Dental TENS →
- Computerized Electro-Diagnostic Instrumentation →
- Physiologic Standards that Validate Treatment Stability →
🔹 Core Concepts
- What Is Physiologic Occlusion? Why the Answer Determines Everything →
- Treatment: Lower Anatomical GNM Orthosis →
- TMD Treatment Approach: NM or GNM? →
- Cranial Cervical Alignment: Treating Distortions with GNM Orthotic →
🔹 The Original Science Behind GNM
- SCIENTIFIC TRUTHS: Bio-Physiology & Objective Measurements →
- Why OC is Different — The Original Science Behind GNM Dentistry →
- Why Anterior Deprogrammers Fail the Complex TMD Patient — And What GNM Does Instead →
- Why Posterior Occlusal Support Matters — The Neurophysiologic Explanation →
🔹 Ready to Train
Originally published May 9, 2015. Last updated May 19, 2026.
Written by Clayton A. Chan, D.D.S. — Founder and Director, Occlusion Connections | Las Vegas, Nevada
6170 W. Desert Inn Road, Las Vegas, Nevada 89146 | Telephone: (702) 271-2950
Leader in Gneuromuscular Dentistry