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 What
is Electrognathography?
Computerized jaw tracking is another important diagnostic
and treatment tool. Using a small, powerful magnet stuck to
the gums below the lower front teeth, movements of the jaw
can be measured with unprecedented accuracy. The jaw tracker
can be combined with the JVA to provide the most comprehensive
diagnostic and treatment information available today.
 How
does it work?
Jaw Tracking (Electrognathography) equipment offers the ability
to track the jaw movements three dimensionally to record the
point of dysfunction so it can be corrected. A headset is
placed on the patient and with a magnet inside their lower
front teeth, a recording of the lower jaw movement is made.
Jaw tracking is a completely non-invasive technique.
In Support of the Efficacy of Jaw
Tracking
Clinical and research experts agree, unanimously, that restrictions,
limitations, and deviations in jaw movement are classic signs
of TMJ dysfunction. More than 40 research studies have employed
a jaw tracker to validate and document these restrictions,
and to record normal mandibular function following treatment.
Annotated Bibliography in Support
of Jaw Tracking
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American
Academy of Craniomandibular Disorders -Guidelines for Evaluation,
Diagnosis and Management. Quintessence Publishing, 1990.
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Evaluation
of mandibular patters is recommended as diagnostic criteria for all
classifications of temporomandibular joint disorders. These disordes
are characterized by restrictions, deviations, and limitations of these
patters, including range of motion, frontal deviations, limited lateral
extrusion, etc. |
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Bell, WE. Clinical Management of Temporomandibular Disorders Yearbook Medical Publishers, Chicago/London, 1986.
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Restrictions,
deviations, limitations in jaw movement are important diagnostic
criteria for TMD. Any restriction of jaw movement should be noted in
either joing as related to opening, protrusion, and lateral excursion,
and deviations of the midline incisal path should be graphed. |
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Bessette,
R.W.: Role of Madibular Tracking in Temporomandibular Joint Surgery.
Oral and Maxillofacial Surgery Clinics of North America 1989 1:205-220.
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Pattern
of anterior to posterior opening in patients with specific types of
internal derangements is distictly different than asymptomatic
controls. In addition, maximal opening and closing velocities during
function are significatly reduced in patiens with TMJ symptoms. The
sagittal and velocity parameters return to normal following surgery. |
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Bigelow,
W C., Slagle, WF., Chase, D. C. : Evaluation of Internal Derangement
ofTMJ With Mandibular Kinesiography/Arthrography AADR Abstract,
1983:675
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Patients
with arthrographic diagnosis of internal derangement without reduction
demonstrate jaw tracking traces of impaired vertical opening deviation
towards the effected side and characteristic irregularities in the
velocity tracing. Patients with reduction show only deviation to the
effected side. Evaluation of their pattern appeared to be a reliable
means to diagnose internal derangement of the TMJ. |
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Clark,
G.T., Seligman, D.A., Solberg, WK., Pullinger, A.G.: Guidelinesfor the
Examination and Diagnosis of Temporomandibular Disorders. J
Craniomandib Disord Facial Oral Pain 19893:7-14.
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In
physical examination for TM disorders, measurement and recording of
mandibular motion should be completed for opening, lateral and
protrusive movements. The quality and symmetry of jaw movement should
be noted and diagrammed. |
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Kuwahara, 7: Effective Malocclusion in Mandibular Movements During Speech. IADR Abstract, 1991.
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The
mandibular movements during speech were evaluated in a patient group,
with diagnosed malocclusion, and a control group. Significant
differences were found in the envelope of motion and path of motor
movement, displayed by jaw tracking, between the patient group and
controls. |
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Michler,
L., Bakke, M, MoIler, E.: Graphic Assessment of Natural Mandibular
Movements. J Craniomandib Disorders Fac & Oral Pain, 1987,.1: 97
-114.
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A
magnetic jaw tracker was used to track mandibular movements during
resting, posture, swallowing, speech, chewing, and maximal openings.
The method proved to be efficient in assessing the functional response
to individual occlusal characteristics as well as the effectiveness of
treatment, such as correction of malocclusion and reconstructions,
involving increase in vertical dimension and re- establishing posterior
support. |
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Mongini,
F., Tempia-Valenta, G.: A Graphic and Statistical Analysis of Chewing
Movements in Function and Dysfunction. J Craniomandib Prac 1984,'2:
126-134.
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To
study the statistical difference between functional and dysfunctional
chewing, a group of subjects with good masticatory function was
compared with subjects with dysfunction of the stomatognathic system.
Statistically significant differences were found using a magnetic jaw
tracker between the movements of these two groups. |
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Mongini,
F., Tempia-Valenta, G. and Conserva, E.: Habitual Mastication in
Dysfunction: A Computer-BasedAnalysis. .I: ProsthetDent, April
1989,.61:484-494.
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Mandibular
movements and electromyographic activity of the elevator muscles were
recorded during three chewing sequences in 86 dysfunctional
individuals. It was found that in dysfunctional patients, 1) the normal
symmetrical and balanced distribution in chewing cycles is lost and the
movements are more restricted; and 2) EMG data showed marked
alterations with a tendency to reduce or suppress the isometric phase
of contraction during closing in the temporomandibular joint patients. |
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Nielson,
I.L., Marcel, 7:, Chun, D., and Miller, A.J: Patterns of Mandibular
Movements in Subjects with CraniomandibularDisorders. J ProsthetDent,
February 1990:63:202- 217.
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Using
a jaw tracker, mandibular movements were evaluated for border and
function movements in 24 normals and 26 patients with muscle pain
associated with a craniomandibular disorder. The patient group
demonstrated asymmetry in the length of laterotrusive movements,
unequallaterotrusive excursions, and asymmetrical nonparallel movement
patterns for mandibular protrusion and retrusion. |
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Roberts,
C.A., Tallents, R.H, Espeland, MA,: MandibularRangeofMotion Versus
Arthrographic Diagnosis of the Temporomandibular Joint. Oral Surg, Oral
Med, Oral Path 1985 60:3,'pp. 244-251.
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The
range of mandibular movements has been correlated with arthrographic
fmdings of the temporomandibular joint in 205 patients. Abnormalities
of meniscns position in function have been found to influence
mandibular movements in characteristic patterns. However, these altered
movements alone are insufficient for a definitive clinical diagnosis of
the specific type of internal derangement of the temporomandibular
joint. |
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Talley,
R.L., Murphy, G.J:, Smith, S.D., Baylin, MA., Haden, J:L.: Standards/or
the History, Examination, Diagnosis, and Treatment o/Temporomandibular
Disorders (TMD): A Position Paper o/the American Academy o/ Head, Neck,
Facial Pain and TMlOrthopedics. JCraniomandib Prac 1990;8:60-77.
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Because
of its precise accuracy, the jaw tracker allows objective measurement
of movements which could only be estimated before. This instrumentation
is extremely valuable for initial patient evaluations, as well as for
monitoring treatment results. |
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Throckmorton, G.S., et.al. : The Functional Changes Following Surgical Treatment for Hemifacial Microsomia. USDA Abstract. 1991.
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Jaw
tracking was used to determine how surgical treatment effects the
function of hemifacial microsomia patients. By measuring range of
motion, lateral excursion, extrusion, and mastication, it was
determined that surgical treatment had improved mandibular range of
motion in these subjects. |
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