The Journal of Japanese Society of Stomatognathic Function
Online ISSN : 1883-986X
Print ISSN : 1340-9085
ISSN-L : 1340-9085
Volume 9, Issue 2
Displaying 1-19 of 19 articles from this issue
  • [in Japanese]
    2003 Volume 9 Issue 2 Pages 133-140
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Katsunari Hiraba
    2003 Volume 9 Issue 2 Pages 141-151
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    Electromyographic (EMG) activities of the superior (SUP) and inferior heads (INF) of the lateral pterygoid muscle (LPT) were recorded in humans during voluntary stepwise changes in biting force and jaw-position which were adopted to exclude the effects of acceleration and velocity of jaw movements on the muscle activity. The SUP behaved like a jaw closing muscle and showed characteristic activity in relation to the biting force. It showed considerable amount of background activity ( 5 -32% of the maximum) even in the intercuspal position without teeth-clenching, and reached a nearly maximum activity at relatively lower biting force levels than the jaw closing muscles during increment of the biting force. Stretch reflexes were found in the SUP, the function of which could be to stabilize the condyle against the biting force that pulls the condyle posteriorly. This notion was verified by examining the biomechanics on the temporomandibular joint. The complex movements of the mandibular condyle in a sagittal plane was decomposed into displacement in the antero-posterior direction (Ac) and angle of rotation (RAc) around a kinesiological specific point on the condyle. In relation to Ac, each head of the LPT showed quite a similar behavior to each other in all types of jaw movements across all subjects. Working ranges of the muscle activ-ities were almost constant (Ac < 3 mm for the SUP and Ac > 3 mm for the INF) . The amount of EMG activity of the SUP changed in inverse proportion to Ac showing a hyperbola-like relation, whereas that of the INF changed rather linearly. The EMG amplitude of the SUP showed a quasi-linear inverse relation with RAc in the hinge movement during which the condyle rotated with no movement in antero-posterior direction. This finding suggests that the SUP controls the angular relationship between the articular disk and the condyle. On the other hand, the position of the disk in relation to the maxilla, not to the condyle, is controlled indirectly by the INF, because the disk is attached to the condyle by tendinous ligaments.
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  • Masato Taira
    2003 Volume 9 Issue 2 Pages 153-165
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    In 1980, Prof. Per Roland in Stockholm succeeded in visualization of the human brain activity by majoring regional cerebral blood flow, and this technique have developed afterwards into Positron Emission Tomography (PET) studies. For the PET research, however, incidental facilities such as a radioisotope facility and a cyclotron are needed; only few groups could proceed the research. In the nineties, new functional brain imaging technique using MRI (fMRI) has developed and a large number of researchers came to engage in functional brain imaging of human. The fMRI research is relatively easy to conduct and has many advantages as compared with other imaging methods. However, there are also many issues to be considered to get sophisticated results. In this review, I introduce the techniques of fMRI and discuss the possibility of fMRI study in the dental research field based on our preliminary data.
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  • Yasuhiro Tanaka, Tatsuya Shinogaya
    2003 Volume 9 Issue 2 Pages 167-175
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The purpose of this study was to make a standard of occlusal load center (OLC) from a standpoint of muscle activity when it was used for the evaluation of occlusal support in prosthodontic treatment. The experimental occlusal contact was set by using lower splint which was divided into 9 pieces of anterior block, right and left premolar and molar blocks. The bite force and EMG of right and left masseter and temporalis muscles were recorded from 8 normal subjects with complete dentition during maximal clenching. The occlusal stops were gradually increased by exchanging the premolar and molar pieces of splint so as to keep the shortened dental arch concept. The relations of the location of OLC, bite force and EMG among 15 kinds of occlusal conditions were investigated. Conclusions were as follows,
    1. The location of OLC was significantly different among 15 kinds of occlusal conditions, and the difference of occlusal condition was clearly distinguished by the OLC. Thus OLC was supposed to be a useful parameter for the evaluation of occlusal contact.
    2. The bite force and integrated EMG were gradually increased with the increase of occlusal stops. In the comparison with the occlusal conditon of full splint, the bite force of the other occlusal conditions had significant difference except for the occlusal condition without a unilateral second molar piece. The integrated EMG in the occlusal condition with the pieces of second premolar bilaterally had no significant difference. These findings suggested that muscle activity was more affected by the distribution than by the number of occlusal stops.
    3. The standard area of OLC for the evaluation of occlusal support in prosthodontic treatment was elliptic in shape. Its antero-posterior center was almost the same as the center of the second premolar and its right-left center was almost the same as Palatine Raphe. The range of ellipse distributed antero-posteriorly from the mesial contact point of first premolar to the distal contact point of first molar, and transversely between the center of lateral incisor.
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  • Part III : The Relation between the Main Occluding Area and the Tooth Fracture of the Inlay-restored Tooth
    Hitoshi Kato, Hiroyuki Miura, Shigeo Hasegawa, Keiichi Yoshida, Yoshih ...
    2003 Volume 9 Issue 2 Pages 177-184
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    In order to clear the functional force loading on the occlusal surface, we explored the relation between the main occluding area and tooth fracture of an inlay-restored tooth. From the observation of 44 cases the following conclusions were obtained:
    1. Tooth fracture of an inlay-restored tooth could be classified into two types: fracture at the margin of the inlay (margin fracture), and fracture extending over the cusp (cusp fracture) .
    2 . In many cases, tooth fracture occurred at the functional cusp and coincided with the main occluding area; therefore, the main cause of the fracture could be recognized as mastication on the main occluding area.
    3 . Care must be taken to the main occluding area when restoring.
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  • Toshikazu Ishikawa, Shinji Iyama, Yoshihiro Tsukiyama, Kiyoshi Koyano
    2003 Volume 9 Issue 2 Pages 185-190
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    The influences of head and body posture on physiologic rest position, range of functional movements and initial tooth contact have previously been reported. The purpose of this study was to investigate whether the posture of the body can be modified by alterations in the stomatognathic system. Postural sway was assessed in 8 healthy subjects. We recorded the subjects' center of gravity (CG) during natural standing in physiologic rest position (with eyes open or closed), while biting on one sheet of occlusal registration paper without clenching on the left and the right sides (with eyes closed) . The dominant side of the velocity vector of CG (DSVV) was determined by comparing the total value of magnitudes in right and left ingredients of the velocity vector. In each subject, the DSVV coincided with the side for which the subject presented a smaller value of total sway length of center of gravity (LNG) . The LNG values with eyes open were significantly smaller than those with eyes closed. The LNG values obtained when subjects were biting on the occlusal registration paper placed on the ipsilateral side to the DSVV were significantly smaller than those obtained when they were biting on the contralateral side to the DSVV. The results suggest that there could be a dominant side for the CG in normal subjects and this condition might be more stabilized with biting on the ipsilateral side of DSVV.
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  • Hiroshi Shiga, Yoshinori Kobayashi, Kunihisa Nakajima, Masaoki Yokoyam ...
    2003 Volume 9 Issue 2 Pages 191-195
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
    In order to investigate the reliability of the occlusal force displayed on the dental prescale system, 5 different magnitudes of pressure were applied on the dental prescale and the displayed colored area and the occlusal forces displayed on the dental prescale system were analyzed.
    Two types of pressurizer, pressurizer A, a column with a square surface of a side of 1 mm and a surface area of 1 mm2, and pressurizer B, a column with a circular surface area of 1 mm2 were attached to the pressure device. Then for each type of pressurizer 5 different magnitudes of forces, 20, 40, 60, 80, and 100N were applied onto the dental prescale. For analysis the colored surface area created by the two pressurizers were calculated and compared among the pressurizing forces. Then the occlusal forces recorded on the dental prescale were measured by the Occluser (FPD703, Fuji film) and the relationship between occlusal forces and pressurizing forces was investigated for both pressurizer A and B. Also the occlusal force obtained under the application of each pressure was compared between the two pressurizers.
    When pressures of 20 to 100N were applied each colored area on the dental prescale showed the shape of the pressurizer. Every surface area was close to 1 mm2 and no significant difference was found between the pressurizing forces (F=1.306, p>0.05) . The occlusal forces displayed on the dental prescale system for both pressurizer A and B increased as the pressurizing force increased and a significantly positive correlation was statistically found between the two (pressurizer A; r=0.991, p<0.01, pressurizer B; r=0.990, p<0.01) . The occlusal forces displayed on the dental prescale system for both pressurizers A and B had similar values and no significant difference was found between the two. Also the occlusal forces showed on the dental prescale system for pressurizers A and B were close to the theoretical values for pressures between 20N and 80N and was smaller than the theoretical value for 100N.
    From these results it was concluded that the dental prescale system can measure the occlusal forces within the range of pressure 20 to 80N exclusive of 100N with high accuracy.
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  • Katsunari Hiraba
    2003 Volume 9 Issue 2 Pages 198-199
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Teruaki Ishikawa, Mariko Kitamura, Masanori Nakano, Keisuke Nishigawa, ...
    2003 Volume 9 Issue 2 Pages 200-201
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Toshikazu Ishikawa, Shinji Iyama, Yoshihiro Tsukiyama, Kiyoshi Koyano
    2003 Volume 9 Issue 2 Pages 202-203
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Ichiro Okayasu, Yoshiaki Yamada, Shoji Kohno, Noriaki Yoshida, Takeyas ...
    2003 Volume 9 Issue 2 Pages 204-205
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Soshi Hanawa, Akito Tsuboi, Makoto Watanabe, Tetsuji Inai, Keiichi Sas ...
    2003 Volume 9 Issue 2 Pages 206-207
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • —study of the intermaxillary axis model—
    Yukiko Kori, Kimiko Yamaguchi, Yuko Kitaoka, Mizuho Nishino
    2003 Volume 9 Issue 2 Pages 208-209
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • —Comparison between No Bone Change Group and Bone Change Group—
    Akiko Hosogai, Shoji Kohno, Kazuhiro Yamada, Toyohiko Hayashi, Hiroshi ...
    2003 Volume 9 Issue 2 Pages 210-212
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Kei Kubo, Tetsuo Kawata, Toru Ogawa, Makoto Watanabe, Keiichi Sasaki
    2003 Volume 9 Issue 2 Pages 214-215
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • —Comparison between Children and Adults—
    Seiko Miura, Zenzo Miwa, Hideyo Iijima, Yuzo Takagi
    2003 Volume 9 Issue 2 Pages 216-217
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Masayuki Kurose, Kensuke Yamamura, Makoto Inoue, Makiko Noguchi, Sajji ...
    2003 Volume 9 Issue 2 Pages 218-219
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Yasuharu SHONAI, Hiroshi SHIGA, Yoshinori KOBAYASHI, Ichiro ARAKAWA, M ...
    2003 Volume 9 Issue 2 Pages 222-223
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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  • Wataru Honma, Shoji Kohno, Yuki Mukawa, Koh Kaneda, Akiko Hosogai, Har ...
    2003 Volume 9 Issue 2 Pages 224-225
    Published: April 25, 2003
    Released on J-STAGE: October 13, 2010
    JOURNAL FREE ACCESS
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