Studies on Masticatory Force and E.M.G. of Difference from Border Forms of Complete Dentures

It has been considered that the occlusal aspects of artificial molar teeth, occlusal types, forms and sizes of denture bases are the significant factors, which have direct effects masticatory function of complete denture wearers. According to the serial studies at our department, it is defined that the difference of occlusal forms and occlusal of complete dentures have influence on the masticatory function of complete denture wearers, especially masticatory force and electromyography (EMG).As regarding the effect of the difference in border forms and sizes of complete dentures on the masticatory function, it has been analyzed that using the bite force by Moriya and Okane, using the EMG by Nakano, using the masticatory performance ratio and EMG by Sasaki, using the masticatory performance ratio and the activity of masseter by Yanagida and using the masticatory performance ratio by Kapur and so on.However, there are little studies about the effect of difference in border forms of molar ragion of mandibular complete denture on masticatory function. Then, the author make the following plane to examine about these problems. Two different complete dentures are fabricated. The form and size of the control complete dentures are defined by the functional impression, the subjects are trimed at bilateral buccal shelves, retromylohyoid spaces and retromolar pads. Using these complete dentures, the author examines the masticatory forces and EMG used the semicondoctor element.The outline of the discussion about these studies as follows;1. About the masticatory and antagonic force in various foods, such as peanuts, ham and takuan. The measured values of the control complete denture are the same level with the subject complete denture when the patient masticate peanuts, the control is higher when the patient masticate ham and the control is lower when the patient masticate takuan.2. Concerning the masticatory rhythm and the swallowing pattern in various foods, the duration and a ratio of the duration during electric discharge period on masticatory force for the control complete denture are larger than that of the subject complete denture, and the interval and the cycle for the control are smaller than the subject. On the other hand, the duration, the cycle and a ratio of the duration during electlic discharge period on EMG for the control are smaller than the subject, and the interval for the control are smaller than the subject except ham.3. The integrated masticatory forces in various foods for the control are larger than that of the subject.4. The activities of masticatory muscles in masticating various foods for the control, are smaller than that of the subject.5. The activities of masticatory muscles which are needed for the integrated masticatory force unit and the antagonistic force unit in masticating various foods for the control, are smaller than that of the subject.6. The masticatory force and integrated masticatory force per unit area of complete denture base in masticating various foods the control, are smaller than that of the subject.