Science of Computerized Mandibular Scanning (CMS)

What Does Computerized Mandibular Scanning Measure — And Why Can’t a Dentist Practice GNM Without It?

Most dentists make occlusal decisions based on what they can see and feel. Computerized Mandibular Scanning (CMS) changes that entirely — replacing clinical guesswork with objective, three-dimensional measurement of mandibular movement accurate to within 0.1mm. Without this level of precision, determining a truly physiologic, unstrained jaw position in all six dimensions is not possible. GNM is built on this foundation. Dentistry without it is built on estimation.

Regulatory Recognition of Computerized Mandibular Scanning in Dentistry

Computerized Mandibular Scanning 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 jaw tracking technology 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 CMS with surface electromyography and electrosonography, received its own ADA Council Acceptance Seal for K7/CMS 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. Computerized Mandibular Scanning devices are FDA-cleared under 510(k) for use in the diagnosis and management of TMD.

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 Computerized Mandibular Scanning

The clinical value of computerized mandibular scanning extends beyond confirmation of clinical suspicion. CMS reveals what conventional examination cannot capture: the actual three-dimensional trajectory the mandible takes during opening, closing, swallowing, chewing, and rest — a record of how the patient’s jaw is functioning, accurate to within 0.1 mm, that no manual examination can produce.

In most TMD patients presenting to general dental practice, the mandible is not following a physiologic path. It is compensating — drifting anteriorly or posteriorly, deviating laterally, restricted in vertical opening, or following an aberrant velocity profile during function. The patient does not feel these deviations as wrong because adaptation has normalized them. The clinician does not observe them visually because the mandible appears to move adequately. But the trajectory is there, measurable in millimeters, and it documents the mechanical state the masticatory system has been forced into by the occlusion.

When a GNM orthotic establishes a physiologic jaw position, the CMS trajectory normalizes. The retrusive drift resolves. The lateral deviation straightens. The opening velocity becomes symmetrical. These changes are not the consequence of the orthotic encouraging the mandible into a position — they are the consequence of removing the occlusal interferences that were forcing the mandible out of its natural path. This is the etiologic chain that CMS measurement makes visible. Conventional examination treats the symptoms of malposition because conventional examination cannot see the malposition itself. Computerized mandibular scanning sees the malposition and allows it to be addressed.

For documented case examples of CMS-confirmed treatment response across Scan 2 trajectory, Scan 6 swallow, and Scan 13 range of motion, see The Evidence Behind GNM →.

SCIENTIFIC STUDIES SUPPORTING THE EFFICACY OF MANDIBULAR TRACKING IN THE DIAGNOSIS AND TREATMENT OF TMD/ MSD

The following list below is a partial list of the large body of supportive evidence documenting the use and efficacy of Mandibular Tracking in the Diagnosis and Treatment of TMD/ MSD.

Progress in the field of mandibular tracking was limited by the capability of available instrumentation. As early as 1931 Hildebrand used cinematography of a moving reflective point to track mandibular movement (Hildebrand, G.Y. 1931). Cineflourography was used by Klatsky in 1941 (Klatsky, 1941) and was followed by Kurth’s use of stroboscopic photography in 1942 (Kurth, 1942). Mechanical tracking has also been used by several investigators throughout the history of mandibular tracking in dentistry (Boswell, 1951). The interference of mechanical tracking devices with normal mandibular function was a common problem. The first use of electronic recording techniques to record occurrence and duration of occlusal contacts during mastication was reported in 1953 (5). Brewer and Hudson later used miniaturized make or break switches to study tooth contact (Brewer et. al., 1961). Adams and Cannon developed instrumentation to trace actual movement patterns of the mandible during functional and parafunctional movements (Adams et. al, 1964, Cannon et. al., 1964).

K7 Bite Recording Tools - GNM

Jankelson’s 1975 Criteria for a Valid Mandibular Tracking System

In 1975 Jankelson defined the requirements and criteria for a mandibular tracking system that would provide reliable quantitative and reproducible data. The criteria are:

The relationship of the mandible to the maxilla must be determined in three dimensions.
Data output must be continuous to permit analysis of the dynamic components of mandibular function.
The system cannot encroach on the occlusal plane so as to interfere or alter proprioception.
To avoid unnatural proprioceptive input and minimize mechanical limitations on mandibular movement, no supporting structures or wires should protrude from the mouth.
The practical use of the system requires that setup time be minimal and that the system be self-contained
Measurement in the vicinity of the occlusal plane should be accurate to within .1 mm.
The system should be widely available and operable by dental personnel (Jankelson et. al., 1975).

Modern Capability and Clinical Application

Belser and Hannam demonstrated that an early model Myo-tronics Kinesiograph was capable of recording incisal point movement to within .3 mm anywhere within the envelope of chewing (Belser et. al., 1985). The same authors have used this instrumentation in other scientific studies, demonstrating their confidence in the capability and accuracy of this modality (Belser et. al., 1986).

Today’s Mandibular Kinesiograph is a computerized electronic measuring device that can track mandibular movement with .1 mm plus or minus accuracy in three simultaneous planes as well as precisely measuring opening and closing velocity.

The value of this measurement capability to the clinical dentist responsible for establishing a predictable and accurate occlusal position diagnostically and therapeutically is self-evident. The ability to record, measure and capture and desired occlusal position transcends occlusal philosophy.

Clinical Validation: Mandibular Kinesiography in TMJ Internal Derangement

The value of correlative data utilizing the MKG was emphasized in an AADR 1983 report by Bigelow, Slagle, and Chase, Department of Oral and Maxillofacial Surgery, University of Tennessee, entitled “Evaluation of Internal Derangement of TMJ with Mandibular Kinesiograph/Arthrography” (Bigelow et. al., 1983). The report stated:

“Arthrography has established the increasing frequency of internal derangement of the TMJ. Jankelson et al have developed the Mandibular Kinesiograph (MKG) to characterize abnormalities of the TMJ. This study demonstrates a positive correlation between patients with stages of internal derangements and diagnostic MKG tracings. 20 patients were examined in this study. Historical, physical and radiographic criteria were used to diagnose patients with internal derangement of the TMJ. Arthrography was then performed to evaluate the extent of abnormalities. Patients were grouped according to the presence of clicks on opening, closing or both. Also on arthrography findings: normal, anterior dislocation with reduction, or anterior dislocation without reduction. Velocity tracings of the MKG were compared concerning characteristic and morphologic patterns. The velocity tracings were classified according to the irregularities in the opening and closing velocities. Correlations occur between velocity tracings and the arthrogram presentation of internal derangement which resulted in reduction or nonreduction during jaw excursions. Patients with arthrographic diagnosis of internal derangement without reduction demonstrated MKG tracings of impaired vertical opening deviation toward the affected side and characteristic irregularities in the velocity tracing. Patients with reduction showed only deviation to the affected side. MKG evaluation appears to be a reliable means to diagnose internal derangement of the TMJ.”

Frequently Asked Questions

🔹 What does computerized mandibular scanning measure that conventional examination cannot?

CMS records the actual three-dimensional path the mandible follows during opening, closing, swallowing, chewing, and rest — accurate to 0.1mm, in real time, across the complete arc of mandibular motion. Conventional examination observes the mandible visually as the patient opens and closes; the clinician notes deviation, range, and obvious abnormalities. What conventional examination cannot capture is the quantitative trajectory itself — the precise three-dimensional path, the velocity profile, the symmetry between opening and closing, the AV ratio that documents retrusive drift. A clinician watching a patient open their jaw can see roughly straight or roughly deviated; CMS measures exactly how much, in which dimension, with what velocity, and how reproducibly across multiple trials. This is the dimension of clinical reality CMS makes visible — the precise mechanical relationship the mandible is operating in, captured in a way that allows pre and post treatment comparison.

🔹 Why is CMS the foundation of accurate occlusal diagnosis?

Because the bite registration on which restorative dentistry depends is only as accurate as the jaw position from which it is taken. When a patient is registered for a crown, a denture, an orthotic, or any restorative procedure, the clinician is capturing a specific mandibular position in time. If that position has been imposed by occlusal interferences, chronic muscle compensation, or guarded musculature, the registration encodes those compromises into whatever is built from it. CMS is the instrument that documents the trajectory the mandible is actually following — and by extension, the trajectory it should be following once optimized. Without CMS, the clinician is registering a position by feel and assumption. With CMS, the clinician is registering a position that has been objectively documented as physiologic. This is the methodological foundation of GNM dentistry.

🔹 What does CMS reveal that MRI and cone beam CT cannot?

Where MRI shows static anatomy, CMS shows dynamic function. MRI and cone beam CT capture the anatomical state of the joint, the condyle, and surrounding structures at the moment of imaging — but the patient is not actively functioning during the scan. CMS records what the mandible is doing during real movement: opening trajectory, closing trajectory, lateral excursions, swallow patterns, chewing cycles, rest position. These functional dimensions do not appear on MRI or CBCT because static imaging cannot record them. Both modalities are essential. Neither replaces the other. CMS and static imaging together — alongside K7 sEMG and ESG — provide the complete diagnostic picture the GNM clinician needs to understand how the patient’s mandibular system is actually behaving in clinical reality.

🔹 How does CMS verify whether GNM orthotic treatment is actually working?

By recording Scan 2 mandibular trajectory before orthotic delivery (pre-treatment) and Scan 7 mandibular trajectory after GNM orthotic optimization (post-treatment) — and comparing the trajectories objectively. Pre-treatment scans typically show retrusive drift (high AV ratio), lateral deviation on opening, restricted range, and aberrant velocity profiles. Post-treatment scans show whether the trajectory has normalized — straightened path, reduced AV ratio, symmetric velocity, and physiologic range of motion. A change in mandibular trajectory documents that the mechanical relationship between the upper and lower jaws has been altered, not that the patient feels better. This is not subjective improvement reported by the patient. It is the geometric evidence that the orthotic has restored a physiologic closing path. Without CMS, treatment outcomes are described. With CMS, they are measured.

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.

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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

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