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KMID : 0362419800180010073
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Journal of Korean Academy of Prosthodontics
1980 Volume.18 No. 1 p.73 ~ p.86
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An experimental study on the positional relations of centric relation, centric occlusion and myo-co, and free-way space using Mandibular Kinesiograph and Myo-monitor
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Chung Chae-Heon
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Abstract
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Recently, the controversy continues as to whether maximum intercuspation of teeth should occur at the terminal hinge position (the condylar theory)or at the myo-co(the neuromuscular theory). There is also much controversy regarding the antero-posterior position of myo-co. The object of this study was to measure and compare with the positional relations of centric relation, centric occlusion and myo-co, and free-way space using Mandibular Kinesiograph and Myo-monitor in the 40 subjects without stomatognathic problems. Mandibular Kinesiograph (M.K.G.) was originally conceived as a research instrument to track mandibular movement and position. As its use in research progressed, its great diagnostic value became apparent in case by case. And Myo-monitor was developed as a means of applying the neuromuscular approach to occlusion. Thus the Myo-monitor technique is an intra-systemic approach to occlusal positioning using patient’s own musculature, and Myo-monitor is used to relax the musculature by a light myopulse induced electronically.
From this experiment, the following results were obtained. 1. The adaptive free-way space before muscle relaxation was an average of 1.6±0.60㎜, and the true free-way space after muscle relaxation using Myo-monitor was an average of 2.4±0.74㎜. 2. It took an average of 25±3.11 minutes to relax the mandibular musculature by Myo-monitor and administration of 5㎎. Diazepam and an average of 38±4.73 minutes by Myo-monitor without administration of Diazepam. 3. Myo-co existed anterior to centric occlusion, with an average of 0.53±0.31㎜, and centric relation existed posterior to centric occlusion, with an average of 0.57±0.58㎜ before muscle relaxation and with an average of 0.57±0.43㎜ after muscle relaxation. 4. Centric relation coincided with centric occlusion in 5 of 40 subjects(12.5%), and posterior to centric occlusion in the rest of cases(87.5%). 5. Myo-co existed anterior to centric occlusion in 38 of 40 subjects (95%), except 1 subject that coincided with centric occlusion and 1 subject that existed posterior to centric occlusion. 6. Myo-co and centric relation existed inferior to centric occlusion and the lateral displacement was various with individual difference. 7. The total displacement from centric occlusion to centric relation was an average of 0.74±0.64㎜ before muscle relaxation, and an average of 0.68±0.53㎜ after muscle relaxation, and the total displacement from centric occlusion to myo-co was an average of 1.07±0.58㎜.
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