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 disorder. 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
|•||American Academy of Craniomandibular Disorders -Guidelines for Evaluation, Diagnosis and Management. Quintessence Publishing, 1990.|
|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.|
|•||Bell, WE. Clinical Management of Temporomandibular Disorders Yearbook Medical Publishers, Chicago/London, 1986.|
|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.|
|•||Bessette, R.W.: Role of Madibular Tracking in Temporomandibular Joint Surgery. Oral and Maxillofacial Surgery Clinics of North America 1989 1:205-220.|
|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.|
|•||Bigelow, W C., Slagle, WF., Chase, D. C. : Evaluation of Internal Derangement ofTMJ With Mandibular Kinesiography/Arthrography AADR Abstract, 1983:675|
|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.|
|•||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.|
|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.|
|•||Kuwahara, 7: Effective Malocclusion in Mandibular Movements During Speech. IADR Abstract, 1991.|
|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.|
|•||Michler, L., Bakke, M, MoIler, E.: Graphic Assessment of Natural Mandibular Movements. J Craniomandib Disorders Fac & Oral Pain, 1987,.1: 97 -114.|
|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.|
|•||Mongini, F., Tempia-Valenta, G.: A Graphic and Statistical Analysis of Chewing Movements in Function and Dysfunction. J Craniomandib Prac 1984,’2: 126-134.|
|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.|
|•||Mongini, F., Tempia-Valenta, G. and Conserva, E.: Habitual Mastication in Dysfunction: A Computer-BasedAnalysis. .I: ProsthetDent, April 1989,.61:484-494.|
|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.|
|•||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.|
|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.|
|•||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.|
|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.|
|•||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.|
|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.|
|•||Throckmorton, G.S., et.al. : The Functional Changes Following Surgical Treatment for Hemifacial Microsomia. USDA Abstract. 1991.|
|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.|