The Journal of Japanese Society of Stomatognathic Function
Online ISSN : 1883-986X
Print ISSN : 1340-9085
ISSN-L : 1340-9085
Volume 2, Issue 2
Displaying 1-16 of 16 articles from this issue
  • —Effects of Surface Anesthesia of Lips on Jaw Movement in Chewing—
    Hiromasa Sasaki, Yukihiro Fujita, Kazuo Toda, Kunimichi Soma
    1996 Volume 2 Issue 2 Pages 83-90
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    In order to verify whether touch or pressure lip sensation between upper and lower lips plays a role in the regulation of mastication, we investigated the jaw movement of eight adult male subjects pre- and post- surface anesthesia of the lips. We used chewing gum and requested the subjects to masticate thirty strokes, first on the left side and then on the right. We recorded the jaw movement with the MKG (Model K-5) and devided each stage into the following classes: Stage 1 was pre-anesthesia, stage 2 was just after anesthesia, stage 3, 4, 5 and 6 were ten, twenty, thirty and forty minutes post-anesthesia respectively. Maximum opening distance, maximum lateral moved distance, and cycle time of each stroke were measured. The mean value of each stage was calculated and the changes were then compared and examined. A trend appeared with the change of maximum opening distance and the stages was observed in eight subjects showing a tendency to decrease to the minimum in stage 2 or 3 post-anesthesia, in both left and right gum mastication, and gradually increase to the pre-anesthesia value. There is a strong possibility that touch or pressure lip sensation between upper and lower lips takes parts in the regulation of the mandibular opening size during human mastication.
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  • Amane Miura, Yoshinori Hattori, Keiichi Sasaki, Makoto Watanabe, Yasuo ...
    1996 Volume 2 Issue 2 Pages 91-100
    Published: January 31, 1996
    Released on J-STAGE: December 10, 2010
    JOURNAL FREE ACCESS
    In order to develop an automatic contour extraction procedure of the cortical bone surfaces of the condyle and glenoid fossa of temporomandibular joint (TMJ) from Magnetic Resonance Images (MRI), a series of image processing techniques were applied to TMJ-MRI and the resulting images were evaluated. A TMJ in a healthy male was imaged on a 0.5 T system MRVectra (GE Yokogawa Medical System, Tokyo), with a 9 cm diameter surface radio frequency receiver coil in sagittal plane. A spoiled GRASS (SPGR) sequence with a 51 msec repetition time (TR) and a 12 msec echo time (TE) was used to obtain a series of 30 contiguous, 1 mm sections in sagittal plane. With a field of view of 6.5 cm by 13 cm and a resolution of 128 by 256, pixel sizes of 0.5mm by 0.5mm were measured and provided for image processing. Region segmentation using thresholding was employed for extracting the region of the condyle and fossa consisting of the cortical bone. As a threshold selection method, mean adjacent-pixel number method was applied in each slice, because the strength of the MR signal in each of serial slices were different due to the distance from the surface coil. This method provided appropriate threshold values to obtain adequate binary images of the cortical bone region, irrespective of the proportion of cortical bone areas in the slices. However, the binary images, in which the condyle and fossa formed a connected component, were observed because of low signal to noise ratio of the original images. Here intraarticular space between the condyle and fossa, with a width of at least 1 pixel, was presumed based on the anatomical structure of TMJ. Thus, a binary image of the presumed intraarticular space was obtained using thresholding and thinning on the image treated with low pass filtering technique and utilized to lose connectivity of the condyle and fossa. Smoothing for binary images was then performed to extract the contour of the condyle and fossa, respectively. The region of the intraarticular space derived from the slice was processed with thinning and used to disconnect the condyle and fossa in the adjacent slices. Then the smoothing for the contour extraction was repeated in the adjacent slices. Resulting images of the contour of the condyle and fossa in each slice well coincided with the manual traces of those structures by experienced dentists. The resulting 2-D images were reconstructed to 3-D images by means of 3-D visualization program (AVS Inc., USA) on graphic workstation. The reconstructed 3-D images represented the anatomical characteristics of TMJ region. These results indicate that the contour extraction method investigated in this study was appropriate to extract the cortical bone surfaces of TMJ structure from MRI.
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  • Chiaki Satoh, Yoshinori Hattori, Makoto Watanabe
    1996 Volume 2 Issue 2 Pages 101-109
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    Recently, a bite force measurement using a pressure sensitive sheet which enables us to measure the bite force quantitatively at multiple bite points on the dental arch was developed. Clarifying bite force distribution in normal subjects would provide a useful guidance for occlusal examination and diagnosis. In this study, we investigated bite force distribution on intercuspal clenching in normal subjects and relationships among the clenching level, bite force distribution and masticatory muscle activities.
    Four healthy subjects with normal dentition were used in this study. Bite forces on each mandibular tooth and masticatory muscles' EMGs were recorded simultaneously on intercuspal clenchings with various levels of magnitude. The bite force was measured by using the pressure sensitive sheet“Dental Prescale 50H, type R” (Fuji Photo Film, Co., Japan) and the specially designed image scaner“Occluzer FPD-703” (Fuji Photo Film, Co., Japan) . Bite force distribution was defined as the proportion of bite force on each mandibular tooth to the total bite force. EMGs were recorded from bilateral masseter, anterior and posterior temporal muscles. These were then integrated and provided for analysis.
    As the results, the proportion of bite force on each tooth was almost constant irrespective of the magnitude of total bite force, when the clenching level was moderate and more of voluntary clencning in each subject. The proportion of bite force was higher on the tooth located more posteriorly in the dental arch. The highest proportion was found on the second molar in all subjects. However, the bite force proportion of the same named tooth was different among the subjects. The bite forces showed symmetrical distribution bilaterally on the dental arches.
    Relationship between the total bite force and integrated EMG activity of each muscle was different among the muscles, and also among the subjects.
    These results indicate that the bite force distribution on the dental arch was constant irrespective of the clenching magnitude and masticatory muscle activities, and that there were common characteristics in the bite force distribution in normal subjects. The bite force distribution by this measurement would contribute to evaluate the occlusion as a objective parameter.
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  • Yoshinori Hattori, Chiaki Satoh, Makoto Watanabe
    1996 Volume 2 Issue 2 Pages 111-117
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    This study aimed to clarify the normal pattern of bite force distribution on the dental arch during maximum voluntary clenching at intercuspal position. Bite force was measured in forty two normal dentate subjects using pressure sensitive film, “Dental Prescale 50H, type R” (Fuji Photo Film, Co.) . Bite force distribution was expressed as a percentage of bite force on each tooth to the total force. The symmetry of bite force distribution was investigated using asymmetry index, which was defined as a percentage of the difference between the right and left side bite forces to the sum (|R-L|/ (R+L) x100 [%] ) . Measured bite force ranged from 205 to 1, 963 N (mean±S.D.: 879±388 N) . The distribution of bite force was characterized by posteriorly increasing forces, and the force reached to the peak at the second molar irrespective of the presence of the third molar occlusal contacts. However, the bite force distribution on anterior teeth was smaller in the subjects with contacts at the third molar than in the subjects without contacts. Mean asymmetry index of the bite force distribution was 9.3±6.7 % in all subjects, that showed symmetrical distribution of bite force. Asymmetry index was smaller in the subjects with contacts in the third molars than in the subjects without contact. The patterns of bite force on dental arches, presented in this study, are useful for the clinical application of bite force measurement in occlusal diagnosis.
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  • Hitoshi Kato, Yuzuru Furuki, Shigeo Hasegawa
    1996 Volume 2 Issue 2 Pages 119-127
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    In order to locate the area which crushes hard food, subjects were asked to clench freely a temporary sotpping as a test food placed on their tongues. As a clenching area in dental arch for each subject was constant through five trials, the area was named the main occluding area in mastication.
    From observations on the main occluding area of 24 subjects, the following conclusions were obtained:
    1. Most subjects had the main occluding area which was the same as occluding area between the lingual cusp inner incline of maxillary first molar and the buccal cusp inner incline of mandibular first molar.
    2. The main occluding area coincided with the area which had the closest occlusal relation at intercuspal position.
    3. The main occluding area changed to aproximal tooth or the other area bucco-lingually on the same tooth depending on changing occlusal relation at intercuspal position.
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  • Takahiro Ogawa, Kiyoshi Koyano, Keita Sumiyoshi, Tsuneo Suetsugu, Hiro ...
    1996 Volume 2 Issue 2 Pages 129-133
    Published: January 31, 1996
    Released on J-STAGE: December 10, 2010
    JOURNAL FREE ACCESS
    As a step to deepen our knowledge of masticatory biomechanics and to obtain functional background in a clinical situation, the purpose of this study was to investigate the relationship between the occlusal plane and masticatory movement. The masticatory movement and the inclination of the occlusal plane in the sagittal plane were measured on 41 normal young adults using the 6 degrees of freedom mandibular movement analyzing system and the 3-dimensional digitizer, respectively. There was a significant correlation between the inclination of the occlusal plane and the direction of the masticatory closing path outside the intercuspal range, and the occlusal plane and the masticatory closing path were consistent in maintaining at an almost perpendicular relationship with each other, regardless of the variation of the inclination of the occlusal plane. The correlation between them was confirmed by the finding that the amount of the balancing-side condylar translation during masticatory closure was also correlated with the inclination of the occlusal plane. The inclination of the occlusal plane has been identified as one of the contributing factors to masticatory movement by the present result, and this could serve as the functional background for the significance of the occlusal plane.
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  • Eiji Takayanagi, Takashi Kato, Yasuo Tamura, Sadahiro Yoshida
    1996 Volume 2 Issue 2 Pages 135-139
    Published: January 31, 1996
    Released on J-STAGE: December 10, 2010
    JOURNAL FREE ACCESS
    To evaluate masticatory muscle activity bilaterally during submaximal clenching, an asymmetry index (A.I.) has been recently introduced by Naeije et.al. However the characteristics of A.I. both in the temporal and masseter muscle activity have not been cleared yet. Therefore in the present study, the influence of clenching efforts and occlusal positions on the A.I. of the temporal and masseter muscles was investigated.
    Fourty healthy subjects with normal occlusion (Aged 20 to 37 yrs.) were asked to clench at 50 percent of the maximum voluntary clenching (MVC) level of the masseter muscles at 5 different clenching tasks as follows: (1) clenching in the intercuspal position (ICP), (2) intentional vertical clenching on the right and left side in the ICP (Int.VR and VL), (3) lateral shift clenching to the right and leftt side (Lat.R and L) . Bite checks were obtained in ICP and Lat. R and L, with green bite wax, and the number of post-canine tooth contacts were calculated bilaterally.
    Results were as follows; As to the temporal muscle, the A.I. of the ipsilateral side changed positively as compared with the contralateral side in all subjects. However, three patterns were recognized in the masseter muscle A.I., by evaluating the predominancy of the ipsi- and contralateral side activity at Int. VR and VL, and Lat. R and L. A positive correlation was recognized between the A.I. value of the masseter muscle and the asymmetry of tooth contact number both in the ICP and Lat. R and L, while it was not found in the temporal muscle. These results suggested that the A.I. values were related to the clenching direction and occlusal positions in the temporal musle, but related to the number of post-canine tooth contacts in the masseter muscle.
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  • Takayoshi Hiruma, Takeshi Suganuma, Masahiko Funato, Akiyuki Shinya, R ...
    1996 Volume 2 Issue 2 Pages 141-149
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The purpose of this study was to determine an optimal projection method in order to obtain reformatted sagittal CT images (CT) for condylar position measurements and to estimate the accuracy of the measurements.
    Three human dried skulls (6TMJs) were employed in this study. The reformatted sagittal CT images and the sagittal tomograms (TG) were compared for evaluating the accuracy of the condylar position measurements. Impressions of the joint space were obtained in order to estimate the actual dimensions. The CTs, TGs and impressions were measured with a profile projector. The errors, differences between the values from the impressions and the values from CTs and TGs, were calculated.
    The reformatted sagittal CT images of 40TMJs in 20patients were also observed for clinical evaluation.
    The results were as follows:
    1) The reformatted CT images from the coronal scan projected at 90°, 80°or 70°to the F-H plane clearly depicted the condyle and fossa.
    2) The mean measurement error on the CTs was 0.1mm and that on the TGs was 0.25mm.
    3) The measurement error on the TG in one of 6 TMJs was especially great while the measurement errors on the TGs in the other 5 TMJs were of the same range of the CTs. Therefore, there ma a considerable number of errors in the measurement on the TGs in the case of particular morphological types of joints.
    4) The reformatted sagittal CT images from the coronal scan of 28 TMJs were clearly depicted the condyle and fossa in the same manner as the dried skulls.
    These results suggest that the sagittal CT reformatted from the coronal scan is useful for accurate measurement of the condylar position and clinical application on all types of TMJs.
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  • Toshiaki Kido, Atsusi Watabe, Shoji Kohno, Naoko Igarashi, Koh Kaneda
    1996 Volume 2 Issue 2 Pages 151-157
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The main objective of mastication is not only to grind and crush foodstuff but also to form a swallowable food bolus. Though much research has been done regarding masticatory mandibular movements and the stages of deglutition, we believe that a thorough study of mastication should include an analysis of the flow of crushed food on the occlusal surface; which since has not yet been reported became the objective of this study.
    Four young adults, fully dentate, with good occlusal relations, and unrestored dentitions were selected as subjects. The interocclusal clearance between upper and lower first molars during functional lateral excursion and the behavior of food following crushing were examined in all subjects.
    Results.
    1) The occlusal clearance between the mesiopalatal section of the upper first molars and their opposing teeth increased more rapidly than in any other section
    2) As masticatory strokes increased in frequency, small particles of food accumulated in the lingual side.
    From these results, we implied that food flows in a mesiolingual direction on the occlusal surface after being crushed. To confirm it, we observed the flow of food using two experimental telescopic crowns. One was casted with the characteristic molar anatomy whilst the other one was made without buccal cusps. After comparing food behavior with these two crowns, we observed that the flow of food changed accordingly; possibly as a result of lowering the ability to regulate the flow of food that normal occlusal configuration posseses.
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  • Takeshi Matsuyama, Shoji Kohno, Yoshiaki Arai, Keisuke Ikeda, Hidetosh ...
    1996 Volume 2 Issue 2 Pages 159-165
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    Masticatory movements are rhythmical movements carried out by the coordinated activity of masticatory muscles, head and neck muscles, lingual muscles and intra-oral soft tissues. It has been reported that changes in head posture affect stomatognathic functions. Therefore it is hypothesized that the head is moving rhythmically simultaneous with mandibular movements during mastication.
    The purpose of this study was to observe the head movement and to investigate the coordination between movements of the head and the mandible. We used a system that tracks head and mandibular movements at the same time, and simultaneously recorded bilateral electromyographic signals from Masseter and Sternocleidomastoid muscles. During the experiment the subjects' head was not restrained. Three male adults who have no craniomandibular dysfunctions were selected. The task was to chew unilaterally a piece of chewing gum.
    Results were as follows;
    1. During tapping movements, the maxillary incisor point moved vertically and rhythmically. This movement occured at the same time with vertical movement of the mandibular incisor point. The lateral movement of the maxillary incisor point was very slight.
    2. During masticatory movements, the head made lateral cyclic movements cooperatively to the lateral component of the mandibular movement.
    3. This cooperative movements were observed frequently in the early stage of mastication.
    4. Lateral cyclic movements of the head showed a time delay of approximately 170-190msec from those of the mandible.
    So we conclude that the head produces vertical and lateral cyclic movements cooperative to those of the mandible during mastication. It is possibly brought about by the coordinated activity of masticatory and neck muscles.
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  • Yoshiei Munakata, Mitsuru Tsuji
    1996 Volume 2 Issue 2 Pages 167-171
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The relationship between the location of the nerve fascicle in the infraorbital nerve trunk and the location of the corresponding receptive field in the facial area was analyzed in cats anesthetized with pentobarbital sodium. The receptive field of each fascicle was confirmed by the evoked action potentials. The nose and the area below the eyelid were often innervated by the same fascicle. On the contrary, the upper lip and the corner of the mouth were innervated by an individual fascicle respectively. The fascicles located in the medial part of the infraorbital nerve trunk innervate the nose and the area below the eyelid. The fascicles located in the central and the lateral parts of the trunk innervate the upper lip, the vibrissae and the corner of the mouth. These findings suggest that there are two groups of fascicles, each corresponding to the sensory inputs from the different areas of the facial skin.
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  • Mari Ogawa, Takahiro Ogawa, Kiyoshi Koyano, Miwa Tsukiyama, Yoshihiro ...
    1996 Volume 2 Issue 2 Pages 173-178
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The purpose of this study was to examine whether there is any correlation between tooth guidance and masticatory movements in different chewing patterns. Masticatory movements and lateral movements were measured on 33 normal young adults using the 3-dimensional Mandibular Movement Analyzing System in six-degrees of freedom. The tooth guidance (TG) was evaluated as the inclination of the incisal path during the lateral movements. The shapes of the incisal masticatory paths were divided into four types of masticatory patterns, which were normal type (Type I ), reverse type (Type II ), and two cross types (Type III and IV) . The pattern of Type III was the envelope that had the closing path in working-side area relative to the opening path within the intercuspal range, and that of Type IV the one that had the opening path in working-side area relative to the closing path. The variables to analyze the masticatory movements were closing angle of the incisal path (MA) at 0.5 mm and 5.0 mm closing level below the inter-cuspal position. The mean value of MA in each pattern was calculated on each subject. The results were as follows:
    1. There were significant conelations between TG and MA at 0.5mm closing level (r=0.46, p<0.01) and no significant correlation at 5.0mm closing level in Type I.
    2. There were no significant correlations at 0.5mm and 5.0mm closing level in Type II.
    3. There were no significant correlations at 0.5mm and 5.0mm closing level in Type III.
    4. There were significant correlations at 0.5mm and 5.0mm closing level in Type IV. (0.5mm level, r=0.85, p<0.05, 5.0mm level, r=0.93, p<0.01)
    It is suggested that the relation between tooth guidance and masticatory movements varies according to the type of masticatory pattern.
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  • Young Hoon Yoon, Takaaki Yamamoto, Tohru Imai, Shinji Nakamura
    1996 Volume 2 Issue 2 Pages 179-187
    Published: January 31, 1996
    Released on J-STAGE: December 10, 2010
    JOURNAL FREE ACCESS
    The purpose of this study was to investigate the relationship between the occlusal stability and the masseter muscle activity in cleft lip and palate patients. Eighteen subjects were selected and divided into 6 groups; children and adults with normal occlusion as normal child group and normal adult group, cleft lip and/or palate child patients and adult patients without constricted upper arch at initial examination as child non-constricted arch group and adult non-constricted arch group, cleft lip and/or palate child patients and adult patients with constricted upper arch at initial examination as child constricted arch group and improved constricted arch group. The occlusal stability of posterior teeth was evaluated by calculating the occlusal stability index, and the masseter muscle activity was measured with the 9 channel EMG analyzing system in the subjects. And also, their symmetries were estimated by the asymmetry index.
    The results were as follows:
    1) The occlusal stability index and the masseter muscle activity in the child constricted arch group were lower than those of normal child group and child non-constricted arch group. Also, the child constricted arch group showed higher value of asymmetry index than other groups.
    2) A strong positive correlation between the occlusal stability index and the masseter muscle activity were admitted in the child groups (r=0.96) .
    3) The masseter muscle activity of the child constricted arch group was increased and the asymmetry index was reduced after wearing an occlusal splint for 10 days.
    4) Comparing the child subjects with adult subjects, the occlusal stability index and the masseter muscle activity of the adults were higher than those of children.
    Especially, the occlusal stability index and the masseter muscle activity were eminently ameliorated in improved constricted arch group. We think this result is due to the improvement of the stability of posterior teeth after orthodontic treatment.
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  • Tetsuya Gocho, Tohru Kiryu, Yoshiaki Yamada, Yoshiaki Saitoh
    1996 Volume 2 Issue 2 Pages 189-193
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    Various aspects of physical function of living beings have been solved because of recent advances in physiology. Many studies of living beings have been made in the engineering field as well. In this study, we analyzed the relation between the muscle activities and the information from the sensory receptors during chewing by the spectrum analysis. Trigeminal mesencephalic nucleus activities, myoelectric signals of masticatory muscle and jaw movements were recorded in freely moving rabbits during chewing, and analyzed by the bispectrum method. Taking the time-varying behavior of masseter muscle activity into account, there is a difference of spectrum between an opening stroke and a closing stroke. It seemed that the results were reflected in the functional differences of muscle spindle activity.
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  • Naoya Sorihashi, Yoshio Matsumoto, Shigekazu Takahara, Mari Shinohara, ...
    1996 Volume 2 Issue 2 Pages 195-200
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The purpose of this study was to investigate the relationship between mandibular rotation and mandibular incisal position during chewing movements.
    Measurement of mandibular movements during mastication was made using the Sirognathograph Analyzing System in 25 normal subjects.
    The rotation around the anteroposterior axis and lateral axis of the mandible and the lateral deviation exhibited high correlation at each vertical dimension except 1-2mm level. The rotation around the anteroposterior axis and the lateral deviation exhibited no correlation at 1-2mm level.
    It is suggested that measuring mandibular rotation is important to comprehend detailed mandible movements during mastication.
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  • 1. Effects of repeated opening movements
    Kazuhiro Tsuga, Jun Yamauchi, Shuji Tanaka, Masakazu Desaki, [in Japan ...
    1996 Volume 2 Issue 2 Pages 201-206
    Published: January 31, 1996
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The aim of this study was to investigate the effect of repeated border movement on motional area of mandible. Eight male dentists (25-33 yr. old) were asked to open their mouths via (i) habitual (ii) anterior border (iii) right and (iv) left border path of mandibular movements from maximal intercuspal position, and close freely to the starting position except (ii), when they closed via posterior border. After the recording of each of the 4 movements in order without visual feedback, they repeated this sequence of movements 10 times with visual feedback followed by the display of a jaw tracking device (Shofu co. ltd., MM-JI-E) simultaneously showing their mandibular movement of lower incisal points. Including the last one sequence recorded without visual feedback, 12 sequences were recorded for each subject. The pathways and range of motions of lower incisal, right and left condylar points were compared according to repetition.
    The range of maximal opening was expanded in 7 subjects in accordance with repetition of sequence and they were correlated with the range of condyle movement in one or both sides. The range of hinge movement during closing via posterior closing path was also expanded in 5 subjects in accordance with the repetition of sequence.
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