Current advances in computer technologies have afforded dentists precision ways to examine occlusal contacts and muscle function. Recently, two separate computer technologies have been synchronized together, so that an operator can record their separate diagnostic data simultaneously. The two systems are: the T Scan II Occlusal Analysis System and the Biopak Electromyography Recording System. The simultaneous recording and playback capacity of these two computer systems allows the operator to analyze and correlate specific occlusal moments to specific electromyographic changes that result from these occlusal moments. This synchronization provides unparalleled evidence of the effect occlusal contact arrangement has on muscle function. Therefore, the occlusal condition of an inserted dental prosthesis or the occlusal scheme of the natural teeth (before and after corrective occlusal adjustments) can be readily evaluated, documented, and quantified for both, quality of occlusal parameters and muscle activity and the responses to the quality of the occlusal condition. This article describes their synchronization and illustrates their use in performing precision occlusal adjustment procedures on two patients: one who demonstrates occlusal disharmony while exhibiting the signs and symptoms of chronic myofascial pain dysfunction syndrome, and the other who had extensive restorative work accomplished but exhibits occlusal discomfort post-operatively.

Combining Technologies: A Computerized Occlusal Analysis System Synchronized with a Computerized Electromyography System

The purpose of this study was to measure the performance of a new design of occlusal sensor, the high definition (HD) sensor, and directly compare this sensor to the previous design. This new HD sensor design has increased active recording area by 33%, and decreased inactive recording area by 50% as compared to the previous design (G3). This was accomplished by determining the force reproduction variability for repeated occlusal closures on the same sensor for a sampling of sensors from both designs. Thirty (30) G3 and 30 HD sensors were consistently positioned and loaded 24 times between articulated epoxy casts by a Pneumatic Occlusal Force Simulator. Their force reproduction consistency was measured as an electronic voltage drop across six occlusal contacts that were consistently located on all sensors. The force variability of the two sensor designs was determined by comparing the consistency of the voltage drops across the six occlusal contacts. An analysis of variance was employed to determine the variability of force reproduction over multiple closures across six occlusal contact regions. For five of the six contacts, the G3 sensor mean variances, were significantly larger (p < 0.05) than those of the HD sensor. The within sensor variability of the HD sensor was significantly less than that of the G3 sensor. Within the limitations of this study, the HD sensor exhibited less variable force reproduction than the G3 sensor for at least 20 in-laboratory loading cycles.

A force reproduction analysis of two recording sensors of a computerized occlusal analysis system.

The purpose of this study was to determine if a statistically significant reduction in muscle activity (p 0.4 sec/excursion) is shortened to <0.4 sec/excursion with the Immediate Complete Anterior Guidance Development (ICAGD) enameloplasty. Forty-five symptomatic, fully informed subjects (29 female, 16 male) had their right and left disclusion times recorded with T-Scan III, while simultaneously, the bilateral masseter and anterior temporalis muscle activity was recorded electromyographically with BioEMG III (n=180 muscles). This recording was done twice, once pretreatment and again posttreatment (same day) after undergoing the ICAGD enameloplasty on the same day without changing electrodes. The Student's paired t-test was utilized to detect any significant change in the muscle activity levels between the pre- and posttreatment lateral excursive muscle contractions. Highly significant reductions were found in all four muscles' activities after shortening the pretreatment prolonged disclusion time to less than 0.4 seconds (p<0.0014); after Bonferroni correction (p<0.006). When properly performed, such that the posttreatment disclusion time is <0.4 sec/excursion, the ICAGD enameloplasty predictably reduces excursive muscle activity levels in the bilateral anterior temporalis and masseter muscles. Excursive muscle hyperactivity can be a source of lactic acid accumulation, muscular ischemia, and chronic myalgic temporomandibular joint dysfunction (TMD) symptoms. The ICAGD enameloplasty significantly reduces excursive muscle contractions after completion of the first ICAGD treatment session.

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Masseter and temporalis excursive hyperactivity decreased by measured anterior guidance development.

Background: All disciplines of dentistry require that clinicians assess the articulation of the teeth/prosthesis with respect to simultaneous contacts, bite force and timing.Aims: This article intends to describe the advantages and limitations of the data acquired when using a computerized occlusal analysis as a dynamic occlusal indicator.Methodology: A search of the literature was completed (Medline, PubMed) using the keywords occlusion, occlusal registration, computerized occlusal analysis and T-Scan for dental.Results: According to the evidence available, the computerized occlusal analysis system is the only occlusal indicator that demonstrates the ability to provide quantifiable force and time variance in a real-time window from the initial tooth contact into maximum intercuspation.Conclusion: The reported advantages to accurately indicate occlusal contacts make the computerized occlusal analysis system a better occlusal indicator when compared with other non-digital convention indicator mater...

Computerized occlusal analysis as an alternative occlusal indicator

Simultaneous recording of excursive function and muscle activity on 62 MPDS patients demonstrated that reducing prolonged disclusion time (14 seconds per excursion) to short disclusion time (041 seconds per excursion) created a therapeutic effect such that within one month’s time following treatment, there was an observed increase in the maximal clenching capacity of the masseter and temporalis muscles This clinical treatment effect appears to be the result of decreased ischemia in these same muscles resultant from minimizing the time posterior teeth compress their periodontal ligament mechanoreceptors as these teeth are engaged and disengaged during excursive function

The effect of disclusion time reduction on maximal clench muscle activity levels.

Seven women patients at Tufts University School of Dental Medicine were evaluated for the subjective symptoms of a myofascial pain dysfunction. Each patient was evaluated by an occlusal analysis of the T-Scan computer to determine posterior disclusion time during excursive movements, and EMG analysis of the masseter and temporalis muscles. Each patient was then treated occlusally by developing immediate complete anterior guidance. This adjustment process involved the removal of all lateral and protrusive interferences prior to habitual closure adjustments. No attempt was made to retrude the mandible in centric relation, and splints were not used to deprogram the musculature before adjustment. In this study, protrusive movements and interferences were not examined, and there was no control group. Posttreatment EMG and T-Scan computer analyses revealed that by shortening disclusion times to less than 0.5 second in any lateral excursions, muscle function returned to normal in all seven patients in approximately 1 month's time. A direct correlation seemed to exist between contractile muscle activity and disclusion time. Lengthy disclusion time leads to excessive muscle activity that introduces spasm and fatigue of the masseter and temporal muscles. These results indicated that a partial explanation of the etiology of MPDS may be the time the molars and nonworking premolars remain in contact during excursive movements--a phenomenon termed "disclusion time."

Electromyographic and computer analyses of patients suffering from chronic myofascial pain-dysfunction syndrome: before and after treatment with immediate complete anterior guidance development.

N.R. Wright

Papers

Electromyographic and computer analyses of patients suffering from chronic myofascial pain-dysfunction syndrome: before and after treatment with immediate complete anterior guidance development.