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Biomedical subjects

K Fushima

Publications and source records attributed to K Fushima.

11 recordsLinked to original sources
PubMed2000

Asymmetry of masticatory muscle activity during the closing phase of mastication.

The purpose of this study was to investigate the asymmetry of masticatory muscle activity between working and nonworking sides in the closing phase during mastication. Fifty adult subjects displaying normal oral function and occlusion participated in this study. Electromyographic (EMG) activity of the anterior temporalis and the superficial masseter muscle were recorded during mastication, simultaneously with motion data of the mandible. EMG activities of elevator muscles and their Asymmetry Index (AI) were analyzed depending on the vertical deviation of the lower incisal point with a two mm gap from the intercuspal position (ICP). EMG activities of both the anterior temporalis and the masseter on the working side were significantly greater than those on the nonworking side. Masseter muscles tended to show greater AI than the anterior temporalis muscles. Thus, asymmetry of the elevator muscles during mastication was a common finding in normal subjects. The normal range of variability of EMG activity and AI was confirmed in each section.

Adult↗
PubMed2000

Mandibular helical axis pathways during mastication.

Condylar and incisor trajectories are often used for the study of mandibular movements. Condylar trajectories, however, depend on the location of the reference point and can be interpreted erroneously. In contrast, the helical axis analysis yields an unequivocal description of rigid body kinematics. The aim of this study was to analyze the mandibular helical axis during mastication. Seven subjects without signs and symptoms of craniomandibular disorders and with class I occlusion were recorded by means of the opto-electronic system Jaws-3D during unilateral mastication of bread cubes (2-cm side). The helical axis was computed every 14 ms with a rotation threshold of 1 . Parameters describing its spatial orientation and position relative to the condyles were calculated. The helical axis changed orientation and position more pronouncedly during the closing than during the opening phases of mastication. The orientation varied significantly from beginning to end of closing but not of opening, indicating less fluctuation of the helical axis on opening than on closing. Also, the distance dCP between helical axis and reference condylar point varied more significantly (p < 0.05) on the working than on the balancing side: On the working side, dCP decreased during both opening and closing, whereas on the balancing side, dCP increased only for closing. Furthermore, the helical axis pathway often showed a bowing ventrally to the balancing condyle, indicating that, during closing, the balancing condyle still translated backward while essentially only rotation occurred around the working condyle. Thus, the helical axis changed its position and orientation continuously during mastication.

Adult↗
PubMed1999

Facial asymmetry in temporomandibular joint disorders.

In order to investigate skeletal deviation in patients with internal derangement of the TMJ, facial asymmetry was examined by the frontal cephalogram and compared with a control group of asymptomatic subjects. It was demonstrated that mandibular lateral displacement in the patients was significantly greater than that in the controls. The degree of displacement was significantly related to the cant of the frontal occlusal plane and the frontal mandibular plane, indicating the reduced vertical dimension of the posterior occlusal level and the ramus height on the mandibular displaced side. It is concluded that facial asymmetry due to mandibular lateral displacement is a relatively common problem in patients with internal derangement of TMJ. The cant of the frontal occlusal plane seems to be an important occlusal characteristic related to temporomandibular joint dysfunction.

Adolescent↗
PubMed1999

Dental asymmetry in temporomandibular disorders.

In our previous study, it was reported that facial asymmetry due to mandibular lateral displacement (MLD) was significant in patients with temporomandibular disorders (TMD). In this study, dental asymmetry in TMD patients was investigated by means of PA cephalogram and study model. Lateral deviation of the midline of the mandibular occlusal table (PA-mid) and right-left difference of the molar relationship (Molar-Diff.) were examined, and their relationship with MLD was studied. PA-mid and Molar-Diff. were significantly correlated with MLD. In most cases, displaced side of the midline of the lower occlusal table was coincident with that of the mandibular skeletal midline. These results suggest that in TMD patients asymmetries in occlusal relationship of the midline of the mandibular teeth and molars were mainly due to a mandibular skeletal asymmetry and not merely due to a dental malposition on the alveolar basal bone. Many cases had a more distal occlusal relationship of the first molar on mandibular displaced side compared with that on the opposite side. A high incidence of Class II relationship was found (61.8% as a whole) and more remarkable on the mandibular displaced side. Midline discrepancy and right-left difference of the molar relationship seem to be important occlusal characteristics in patients with TMD.

Adolescent↗
PubMed1996

Significance of the cant of the posterior occlusal plane in class II division 1 malocclusions.

In studying a group of fifty adult females with Class II division 1 malocclusion, it was evident that the skeletal problems of this malocclusion involved small, retruded mandibles accompanied by backward rotation. This skeletal pattern was considered to be influenced by the vertical dimension of the upper dentition in the buccal segment for mandibular function. The anterior and the posterior occlusal planes were examined to gain a detailed assessment of the relationship between the dental and the skeletal patterns. The findings indicated that the steep cant of the posterior occlusal plane was strongly correlated with the following: 1. Small, retruded mandible with backward rotation as the skeletal pattern. 2. Short vertical height of the upper second molars and distal inclination of the upper molars as the dental pattern. The increased vertical height of the lower second premolars was found to be related to backward rotation of mandible. In treating skeletal Class II malocclusions, this study indicated that control of the vertical dimension of the posterior teeth is extremely important.

Adolescent↗
PubMed1994

Horizontal condylar path in patients with disk displacement with reduction.

In 32 patients with disk displacement with reduction, the condylar path in the horizontal plane during opening and closing movements of the mandible were analyzed with a computerized axiograph. The horizontal condylar tracings during opening were divided into 15 types. There was no clear relationship between the types and clinical symptoms. The specific correspondence of the types were revealed between the right and left joint. In 21 of 32 patients, the condyle on one side deviated medially, while the contralateral condyle deviated laterally at maximum opening. In most of the patients showing medio-lateral condylar deviation at maximum opening, a straight condylar path was observed from the maximum opening to the position just before the closing click. In some of the patients, the type of horizontal condylar tracing during opening was related to the displacement pattern of the disk assessed by magnetic resonance imaging (MRI).

Adolescent↗
PubMed1989

[Incidence of temporomandibular joint disorders in patients with malocclusion].

In order to examine the relationship between the incidence of temporomandibular joint (TMJ) disorders and the occlusal problems, epidemiological surveys regarding the signs of TMJ disorders (joint noise, pain and disturbance of mandibular movement) were carried out to 149 untreated patients (54 males and 95 females) with malocclusion. The results indicated as follows: 1) Incidence of TMJ disorders was 33.6% of total samples, 27.8% of males and 36.8% of females. 2) In symptomatic subjects, the most frequent sign of TMJ disorders was joint noise (76.0%), the second was joint pain (68.0%) and the third was disturbance of mandibular movement (38.0%). 3) The incidence of TMJ disorders increased after 8 years of age, while it decreased slightly from 15 to 18 years of age and showed high frequency after 19 years of age. It was suggested that these changes were related with the occlusal configurations such as the exfoliation followed by the eruption of permanent successors or the eruption of the third molars. 4) Symmetrical anterior cross-bite malocclusion showed low incidence of TMJ disorders. In posterior cross-bite malocclusion and mandibular lateral displacement case, however, the signs of TMJ disorders were found frequently. These results suggested that the lateral shift of mandibular head in fossa may relate with the appearance of TMJ disorders.

Adolescent↗
PubMed1989

[Morphological feature and incidence of TMJ disorders in mandibular lateral displacement cases].

In the malocclusion with mandibular lateral displacement (MLD), it is difficult to establish the functional occlusion by orthodontic means. The careful diagnosis brings us to recognize that MLD condition is the rule rather than the exception. In order to examine the characteristics of the cranio-facial morphology in the cases with MLD, the posteroanterior cephalograms were analyzed. Furthermore, the incidence of temporomandibular joint (TMJ) disorders (joint sound and joint pain) were examined clinically. The results were as follows: 1) Occlusal plane and mandibular plane (the plane running through the anti-gonialnotch bilaterally) inclined superiorly toward the mandibular displaced side. 2) The position of mandibular head shifted to the opposite direction of the mandibular displaced side. 3) The symptoms of TMJ disorders were found in 65.0% of patients with MLD, and more frequently at the TMJ of mandibular displaced side. Considering the evidences, the symptoms of TMJ disorders were much detected and occlusal deviation was found in MLD, it is suggested that mandibular dysfunctions derived from occlusal problems relate to the appearance of MLD. Since both the mandibular plane and the occlusal plane revealed the similar changes in response to mandibular deviation, it is considered that the condition of MLD as skeletal problem may be induced by the functional lateral shift of mandibular position come from occlusal interference during growth period. The deviation of mandibular head may relate to the appearance of TMJ disorders in MLD. Therefore, it is important to recognize the adequate mandibular position prior to occlusal reconstruction, and the vertical dimension control of the occlusal plane is necessary for improving the condition of TMJ and establishing the functional occlusion in the cases with MLD.

Humans↗