• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.411-426
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• 2005

The purpose of this study was to investigate the effects of occlusal condition and clenching level on the mandibular torque rotational movement. For this study, healthy 14 men without any symptoms and signs of temporomandibular disorders were selected. Mandibular torque rotational movement was observed in each circumstance of combination of three occlusal conditions such as natural dentition, with wafer of 3.6 mm thickness, and wafer with resin stop of 14 mm thickness total during hard biting of bite stick at maximum voluntary contraction(MVC) and 50% of MVC level of surface EMG activity of masseter muscle. Electromyographic activity and mandibular torque rotational movement were observed using BioEMG and BioEGN in $BioPak^{(R)}$ system. Each biting movement in each circumstance was composed of clenching one time and hard biting of wooden stick two times. The observed items were opening distance, velocity and amount of torque rotational movement in mandibular movement, and the data were statistically processed with $SPSS^{(R)}$ windows (ver.10.0). The results of this study were as follows: 1. There were no differences in the mandibular movement distance between those value in both biting sides, and between those in both clenching forces, but the mandibular velocity showed a different results by clenching force. For the amount of torque rotational movement, there were no difference in the value of the frontal plane but some significant difference was in the value of the horizontal plane by biting side. 2. The mandibular movement distance and the mandibular velocity in both planes were higher by maximum voluntary contraction than those by half maximum voluntary contraction, and amount of torque rotational movement in the horizontal plane was also increased by maximum voluntary contraction. 3. The opening distance in both planes were decreased with the increase of vertical dimension of occlusion, namely, by the occlusal appliances, and this pattern was also showed in the mandibular velocity in case of hard biting by maximum voluntary contraction. However, the amount of torque rotational movement were not different by the increase of vertical dimension of occlusion. 4. The value of angle and distance of the torque rotational movement in the hard biting of wooden stick were generally higher than those in the clenching without wooden stick in both planes without regard to occlusal conditions and/or clenching forces.

• Journal of Oral Medicine and Pain
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• v.25 no.4
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• pp.383-394
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• 2000

This study was performed to investigate the effect of change of body posture on the rest position and the rotational torque movement of the mandible. Thirty dental students without any signs and symptoms of temporomandibular disorders and with natural dentition were selected for this study. Cervical inclination and the amount of the mandibular movement on protrusion, on left and right excursion, and on tapping in three body postures such as sitting position, supine position without pillow, and supine position with pillow were measured by goniometer, Cervical-Range-of-$Motion^{(R)}$, and mandibular tracking device, $BioEGN^{(R)}$ with $Rotate!^{(R)}$ program. The data obtained were classified and processed according to body posture and type of lateral guidance with SPSS windows program and the results were as follows: 1. There was significant difference among the three cervical inclinations by body postures. 2. Comparison of mandibular rest positions among body postures showed significant difference only for lateral distance in frontal plane, but comparison between before and after swallowing showed significant difference except for the lateral distance, vice versa. 3. Distance and amount of the rotational torque movement on protrusion and/or lateral excursions didn't show any difference by body posture. But by both body posture and lateral guidance type, there were slightly significant difference for some items. 4. A significant difference was shown for the rotational torque movement in frontal plane on tapping by body postures, for the lateral distance in frontal plane on sitting position by lateral guidance type, and for the rotational torque movement in frontal plane by both body posture and lateral guidance type.

• Journal of Oral Medicine and Pain
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• v.23 no.2
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• pp.143-155
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• 1998

This study was performed to investigate the factor that might affect mandibualr body rotation. For the study, 115 patients with temporomandibular disorders and 35 dental students without angy signs and symptoms of temporomandibular disorders were randomly selected as the patient group and the contreol group, respectively. Preferred chewing side, Angle' classification, lateral guidance pattern, and affected side were clinically recorded, and the amount of Mandibular body rotational torque movement was measured in wide opening and closure, in right and left excursion with vertical and lateral distance in frontal plane, right and left rotational angel in horizontal and in frontal plane. Masticatory muscle activity of anteriorocclusal contact pattern on maximal hard biting were also observed synchronously with BioEMG and T-Scan , respectively. The observed items were muscle activity of anterior temporalis and superficial masseter, and tooth contact status related to contact number, force, duration, and occlusal unbalance between right and left arch. The data collected were analyzed by SAS statistical program. The results of this study were as follows : 1. Mean value of vertical distance in frontal plane in wide opening and closure was more in control subjects than in patients, but there was no difference for rotational angle. In right excursion, rotational angles were greater in patient group than in control group. 2. Comparison among the subjects by preferred chewing side did not reveal any significant difference, but comparison among patients by affected side showed more rotational amount in bilaterally affected patients than in unilaterally affected patients. 3. Comparison among the subjects by Angle's classification or lateral guidance pattern revealed no difference. There was also no difference between preferred chewing side and contralateral side, and between affected side and contralateral side. 4. Positive correlation in madibular rotational torque movements were observed among vertical distance, total horizontal rotation angle, electromyographic activity of anterior temporalis, tooth contact number, and tooth contact force but total frontal rotation angle almost did not show any correlation with other variables except vertical distance.

• Journal of Oral Medicine and Pain
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• v.26 no.1
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• pp.59-73
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• 2001

This study was performed to investigate the effects of occlusal appliance on the mandibular position and the mandibular rotational torque movement during speech. For this study, 20 patients with temporomandibular disorders(TMDs) and 20 normal subjects without any signs and symptoms in the masticatory system were selected as the patient group and as the normal group, respectively. Biopak $system^{(R)}$(Bioresearch Inc., Milwaukee, USA) and a sentence of 'Sue is missing her house' were used for recording and for observing of speech pattern. There were five mandibular positions observed in this study, that is, mandibular rest position, 'ssi', 'her', 'ha', and 's' speech position. In each position, slant and A-P distance in sagittal plane, vertical distance and lateral distance in frontal plane were measured. Amount of the mandibular rotational torque movement were measured at 'her', 'ha' speech position and for all through speech movement. Centric relation splint(CRS) was placed in both groups, but anterior or posterior bite plane were placed in normal subjects only. Data collected were processed and analysed by SPSS windows program. The results of this study were as follows : 1. Mandibular positions in both groups were not different before adaptation, with CRS, and after removal, but total amount of the mandibular rotational torque movement was greater in patients. 2. Mandible was slightly placed anteriorly with CRS at 'her' and 'ha' speech position in patients, but was placed anteriorly at all the five positions in normal subjects. 3. Difference with type of occlusal appliance in normal subjects were noted only for vertical distance at 'ssi' and 'ha' speech position, and the distance with CRS were more than that with posterior bite plane. 4. Mandibular rotational torque movement at 'her' and 'ha' speech position was greater in patients, but the difference was disappeared after appliance removal. And the torque movement was greater at 'ha' speech position than that at 'her' speech position in frontal plane. It could be concluded that the adaptation of occlusal appliance showed a tendency to locate the mandible anteriorly during speech in both groups, but did not affect total mandibular rotational torque movement which was greater in patients.

• Journal of Oral Medicine and Pain
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• v.24 no.2
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• pp.207-217
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• 1999

This study was performed to investigate the effects of clutch adaptation on the mandibular rotational torque movement in normal people. 69 dental students were selected for the study. Their mean age were 23.6 years and they did not present any signs and symptoms of temporomandibular disorders. $BioEGN^{(R)}$ with $Rotate^{(R)}$ program was used to observe and record the amount of mandibular rotational torque on protrusion, on right excursion, on left excursion, and on comfortable wide opening movement. The natural tooth contact movement and the movement with clutch were performed in the above four each mandibular movement. Clutch was made by the method used in $Pantronic^{(R)}$ clutch fabrication. Distance of slant frontal which was translatory trajectory in frontal plane and degree of rotational torque in horizontal and in frontal plane were recorded. The data obtained were processed with SPSSWIN program and the results were as follows : 1. Distance of slant frontal in each mandibular movement generally increased with clutch. 2. Degree of rotational torque in horizontal and in frontal plane on protrusion and on lateral excursions did not increase with clutch, but the degree on wide opening increased with clutch. 3. Degree of rotational torque in horizontal plane on protrusion and on lateral excursions did not show any difference between right and left side, but the degree in frontal plane on protrusion and on lateral excursions showed significant difference between right and left side. 4. Total amount of rotational torque from right and left sides on protrusion and lateral excursions were not increased with clutch, but the degree on wide opening movement was increased with clutch. And in this case, degree in horizontal plane was larger than that in frontal plane. 5. Correlation between total amount of rotational torque in horizontal plane and that in frontal plane were highly significant on protrusion and on lateral excursions with or without clutch, but the significant correlation on wide opening without clutch became not significant with clutch.