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[in Japanese]
1989 Volume 33 Issue 2 Pages
245-250
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
JOURNAL
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Part 1. The relations between the denture retention and the atmospheric pressure
Kiyoshi Takesako, Takayuki Nunoi, Yoshiyuki Koreeda, Takayuki Hiroyasu ...
1989 Volume 33 Issue 2 Pages
251-263
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Dynamics of atmospheric pressure under the maxillary complete denture, and their relations with the denture retention influenced by the factors such as the denture seating force, the saliva viscosity and the postdamming, were investigated on the simulation models.
The following results were obtained.
1. The atmospheric pressure under the denture became higher than the external one by the denture insertion, and increased during the denture seating, and decreased by the removing force of denture and furthermore became lower than external one by continuous application of its force, and at all became equal to the external one when the denture separated from the basal seat.
2. Greater seating force brought about greater positive pressure and less negative pressure.
3. Higher viscosity of saliva and the postdamming brought about greater positive and negative pressures.
4. Both of greater seating force and higher viscosity of saliva brought about greater retentive force.
5. The postdamming was useful for the maxillary posterior border seal.
6. The atmospheric pressure under the denture base seems not to relate directly to the maxillary denture retention in the static condition but to reveal the status of peripheral seal.
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Koichiro Ueda, Takahiro Ishizaki, Nobuo Iwauchi, Masanori Miyata, Yosh ...
1989 Volume 33 Issue 2 Pages
264-269
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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A questionare about the dental treatment for visiting patients at Welfare center for the aged people.
Nowadays, 11 percent of the population is over 65 in Japan. According to the Minister of Health and Welfare's Population Projection for Japan, it will grow to 20% at the beginning of the 21st century. Problems concerning old people will become some of Japan's biggest challenges.
In that situations, the dental treatments for visiting aged patients will become more important.
Then, authors sent out a questionare about it on aged people who have no need of anyone's assistances in their home lives. And we examined concrete countermeasures and problems about the dental treatments for visiting patients.
The findings were as follows:
1. Even the aged people who have no need of anyone's assistances in their home lives, they hope much carrying out the dental treatments for visiting them.
2. The dental treatments for visiting aged patients have some problems. But it will become one of the most important way to supply their demand for dental treatments, in spite of their latent requirements, a lot of old people give up to undergo dental treatments.
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Niichiro Amano, Shunsuke Andoh, Hiroki Matsuoka, Motonobu Hashimoto, M ...
1989 Volume 33 Issue 2 Pages
270-282
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Surface EMG activities in the masseter muscle were recorded from 8 healthy men with normal permanent dentition during habitual chewing of a small cube of synthetic cellulose sponge which had absorbed distilled water. Three parameters of chewing rhythm, viz., cycle time, duration, and interval, were shown as the respective averages of 40 measurements of the EMG traces of a masticatory series of 42 consecutive chewing strokes. Twenty-five recording sessions, in each of which the above masticatory series were repeated 10 times in a day with a 5 minutes' recess between each series, were performed on a subject during continuous 25 days. The amount of scatter in the distribution of 25 cycle time values was great at the 1st masticatory series, gradually decreased to reach a node relatively free from the dispersion at the 5th series, and then gradually increased from the 6th to 10th series. The same phenomenon was observed in all 8 subjects, although there was a small difference among them in the number of the series where the node was apparent. The average of 5 cycle time values was used to compare in the same subject the effect of chewing the cellulose sponge which had absorbed one of the 4 basic taste solutions with the effect of chewing that which had absorbed dis tilled water. The average value while chewing the sponge which had absorbed 1 M saccharose was significanty lower in the subjects who obtained a relatively large average value during distilled water spongechewing, whereas it was significantly greater in those who obtained a relatively small average value while chewing the sponge which had absorbed distilled water. The other 3 taste stimuli induced a significant increase in the average value in most subjects.
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The Relation between Ceramics Materials and Abutment Materials
Hajime Suzuki, Yoshiaki Hata
1989 Volume 33 Issue 2 Pages
283-293
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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This investigation was carried out to evaluate the alteration of stress distribution on ceramics crowns by each combination of ceramics crown materials and abutment materials.
Analyzing the stress distribution by the finite element methods, a two-dimensional model of jacket crown preparation was designed on lower first premolar, and restored it by ceramics crown. Under four loading conditions, the tensile stress distributions on the ceramics crown were analyzed to evaluate the relations between three kinds of ceramics crown, which were an aluminous porcelain jacket crown, a feldspathic porcelain jacket crown and an Olympus castable ceramics (O. C. C.) crown, and three kinds of abutment which were a natural tooth, a gold cast core and a composite resin core. And following results were obtained:
1. When the abutment was a natural tooth, the tensile stresses were apt to occur all over the ceramics crown and these magnitude were increased in proportion to the hight of Young's modulus of the ceramics materials.
2. When the abutment was a gold cast core or a composite resin core, the tensile stresses were produced only at the loading side of the ceramics crown, and the magnitude of stress were little affected by the type of core materials.
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Part 2. Comparison between Normal Subjects and Craniomandibular Disorder Patients
Hisashi Hori
1989 Volume 33 Issue 2 Pages
294-302
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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During fatiguing clenching, power spectrum in the surface electromyogram decrease to the lower frequency. The phenomenon has been expected to indicate the fatiguing condition. However, the underlying mechanism between the muscle fatigue and the power spectrum shift is still unclear. Therefor, it may be difficult to employ the spectrum shift for the diagnostic process.
The aim of this paper was to clarify the mechanism in the power spectrum shift and to find a possible parameter for diagnostic process. The shift in the mean power frequency (MPF) was observed during fatiguing clenching and the successive recovery period from a normal group (n=47) and a craniomandibular disorder patient group (n=46).
The results suggested that the power spectrum shift during the fatiguing clenching might be due to a reflex inhibition at the motoneuron level. From the comparison between the normal group and the dysfunctional group, there was larger difference in the normalized absolute MPF values between the right and left muscles. Also the larger variance was seen during the fatiguing process and the recovery process in the dysfunctional group than in the normal group.
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Part 2. A Relationship between Grinding Movement in Chewing-Like Empty Jaw Movement and Occlusal Form of Molar
Tooru Mizuno
1989 Volume 33 Issue 2 Pages
303-312
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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The purpose of this study is to clarify the relationship between the occlusal form of a molar and mandibular movement. For this purpose I measured the occlusal form of the upper first molar, and the 3-dimensional movement of the lower first molar during the grinding movement in chewing-similar to empty jaw movement.
In this study the following three parameters were analyzed.;(1) the distance between the upper and lower first molars in the lateral occlusal position, (2) the inclination of the cuspslope, and (3) the inclination of the lower first molar path.
Results were follows: 1) On the working side, the inclination of the cusp-slope is closely connected to that of the path, 2) On the non-working side, the correlation between the inclination of the cusp-slope, and that of the path was so weak, as to be statistically insignificant. 3) The distance between the molars tended to increase as the inclination of the path steepened. This tendency was marked on the non-working side.
The results mentioned above proved that, in cases with steeper anterior guidance, the upper and lower first molars disclude more on both the working and non-working sides. On the working side, however, the steeper cusp-slope prevents excessive disclusion of molars.
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Shinichi Ukon, Tetsuo Matsuura, Toshihiro Ogata, Koichi Akagi, Tomoji ...
1989 Volume 33 Issue 2 Pages
313-322
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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McLean and Sced have reported (J Dent Res, 56: 1067-1069, 1977) a procedure for a reinforcement of the porcelain jacket crown, which improved the resistance to a fracture as a result of inhibiting the propagation of cracks into brittle materials, so called the twin foil technique. The pourpose of this study is to evaluate the clinical application of this technique.
The FEM analysis revealed that the same magnitude of surface tensile stress and no difference of the stress pattern were observed between porcelain jacket crowns constructed with a conventional and the twin foil technique. As the internal tensile stress concentrated in a platinum matrix of the twin foil technique, the stress distribution in a core layer reduced to about 20-35% compared to that of the conventional technique. This is explained by the mechanical and chemical bonds between a platinum matrix and a core porcelain and also by extreme high young's ratio of platinum. We can assume the simular finding from the fractography of the conventional porcelain jacket crown. But contrary above results, no significant differences of the strength were observed in both the presence and the absence of a platinum matrix in the fracture test.
From the fact describe above, we may conclude that the tin coated platinum matrix contributes slightly to the strengthening of the porcelain jackt crown.
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Part 1. Muscle Activity during Tapping Movement
Takashi Nokubi, Minoru Yoshida, Takashi Morimitsu, Tadashi Nagashima, ...
1989 Volume 33 Issue 2 Pages
323-336
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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The purpose of this study is to examine the influence of the insertion of bite plane on masticatory muscle activity during tapping movement, and find out useful parameters for examination and diagnosis of stomatognathic dysfunction. The subjects in this study were twenty normal subjects with intact dentition and no signs of mandibular dysfunction as the control group, and twelve subjects with unilateral temporomandibular joint pain during jaw opening or closing movement as the patient group.
Electromyographic activity in the bilateral anterior temporal and masseter muscles and mandibular movement using the Mandibular Kinesiograph were recorded simultaneously during tapping movement. The usefulness of the 61 items used in this study was evaluated.
The results were summarized as follows:
1. In the patient group, a significant correlation between the jaw opening degree during tapping movement and the maximal jaw opening one without pain was recognized.
2. The total muscle activity in the patient group decreased significantly by the insertion of the bite plane.
3. Many subjects of the patient group showed a significant difference between the right and left activity of each muscle.
4. A significant difference between the two groups was found in the duration of muscle activity before and after Silent period, those coefficients of variation and the difference between those durations of the right and left muscle activity.
This study suggests that the above factors are very useful parameters for examination and diagnosis of temporomandibular joint dysfunction.
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Part II. The Forms and Locations of Indirect Retainers used for Cross Arch Stabilizations
Masayasu Saito
1989 Volume 33 Issue 2 Pages
337-351
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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The purpose of this experimental study is to investigate and evaluate characteristic movements of the denture bases and the abutment teeth, when the forms and locations of the indirect retainers used for the cross arch stabilization are altered.
The results are as follows:
1. Under the vertical forces, the increases of abutment tooth excursion and denture base movement are observed, when the fulcrum line crosses the “loading axis” at nearly right angle.
2. When the vertical forces are applied, the displacements of abutment tooth and denture base with two indirect retainers are more reduction than that with one.
3. The distances between two indirect retainers used for cross arch stabilization increase, the less displacements of abutment tooth and denture base are.
4. When the partial denture has only one indirect retainer used for the cross arch stabilization, it is important that the positive rest is located on the anterior tooth and the indirect retainer is placed on as distal tooth as possible.
5. If the occlusal forces are supported by the residual ridge, it may be better designs that the positive rest is located on the anterior tooth and the Akers clasp with mesial rest or the double Akers clasp is located on the premolars.
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Taizo Omae, Shunji Inoue, Osamu Saito, Hiroji Ishii, Shouichi Ishigaki ...
1989 Volume 33 Issue 2 Pages
352-358
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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The purpose of this study is to reveal the relationship between the head position, and the neck and head muscles. At 4 head positions, the activities of masseter, anterior temporal, anterior digastric, sternocleidomastoid and trapezius muscle of ten normal subjects standing straight were investigated electromyographically with surface electrodes during voluntary maximal clenching in centric occlusion. Head positions were right tilting, left tilting, up-right and natural head position.
The results obtained were as follows;
1. During head tilting, the activities of anterior digastric and sternocleidomastoid muscle on the tilting side were increased, the activities of masseter and trapezius muscle on the opposite side of the tilting side were increased, the activity of the anterior temporal muscle did not vary from the activity during up-right head position.
2. During natural head position, only the activity of sternocleidomastoid muscle on the natural tilting side was increased.
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The Unanatomical artificial teeth for Fixed Bridge
Yoshihiro Furuta, Masataka Shibuya, Yasumasa Kazama, Hiroto Iijima, Yo ...
1989 Volume 33 Issue 2 Pages
359-368
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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With a view to research the effect of the crown form, we made the unanatomical artificial teeth and some doctors to do the abutment tooth preparation with full cast crowns for the maxillar left fixed prosthodontics three-unit bridge in random position. After that, following are the results of a study made on the influence to the prepared tooth form. The prepared teeth are the second premolar and the second molar (The “second premolar” is abbreviated to “5” and the “second molar” is abbreviated to “7”).
1. The reductions of occlusal surface was excessively larger at 5 and 7 buccal cusp regions, while it was excessively smaller at central groove area.
2. The reductions of axial surface and subgingival area were excessively smaller at 5 and 7.
3. As for the degree of axial taper, its was steeper toward the buccal and distal surfaces at 5 and 7.
4. As for the relative degree of axial taper, it get the largest in degree on both sides between 5 medial surface and 7 distal surface.
The results of this experiment are similar to the results that used anatomical artificial teeth. These results are affected by the operating posture.
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Part 1. Methods for Analyzing the Denture Dynamics of Free-end-Saddle
Yoshimasa Igarashi
1989 Volume 33 Issue 2 Pages
369-375
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Excess denture movement during function may cause to jeopardize the resorption of the residual ridges and the mechanical trauma on the abutments in the partially dentate mouth.
A removable partial denture (R. P. D.'s) should be so constructed that the artificial teeth on the denture base will be stabilized in their spatial position by way of the compensatory support due to the remaining abutments and the residual ridges.
In this pilot study, the ordinary denture movement, that is the denture dynamics in function of the free end saddle R. P. D.'s was measured in the test denture assembly. The denture dynamics was assessed in two ways: The displacement sensors revealed the vertical and the horizontal movement of the denture base during function. They were based on the field magnetic effect and with good lineality. Tiny accerelometer was attached to the denture base to detect the accerelation during function. Ordinary mastication was not interefered by both methods. The Author has already reported the palpation test for diagnosing the denture dynamics of the free end saddles in clinics. This method was discussed objectively against the accerelometry on fifty patients. Two methods have revealed the good coincidence with each other to detect the dynamics of the free end saddles.
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Part 2. Effects of Zinc Deficiency on Rats Oral Mucosa
Shouichi Yoshida
1989 Volume 33 Issue 2 Pages
376-390
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Histopathological and ultrastructural changes due to a zinc low diet were investigated in buccal, palatal and tongue mucosa of male 15 weeks rats of Sprague Dawley.
Experimental rats were fed with zinc low diet (1.3 ppm Zn) for 16 weeks. After 16 weeks, experimental rats were then kept on zinc-sufficient diet (50 ppm Zn) for 4 weeks during recovery experiment.
Results were as follows:
1. Zinc concentrations of serum and submandibular gland were decreased significantly (P<0.01) from 2 to 16 weeks respectively. Hair zinc concentrations did not show any significant changes until 4 weeks. But after 8 weeks, those values were lowered significantly (P<0.01). Those zinc concentrations were increased gradually after recovery experiment.
2. Hyperparakeratosis were consistent findings in buccal mucosa, ventral surface and interpapillary mucosa of tongue. Keratohyaline granules in those areas diminished in both size and number. Tonofilaments and ribosomes were increased in cells of granular layer, but did not associated with those granules closely.
3. Hyperparakeratosis were rarely seen in palatal mucosa and filiform papilla of tongue in the experimental rats. Marked hyperorthokeratosis was seen in filiform papilla, and eosinophilic granules in cells of granular layer were increased in both size and number. These granules were closely associated with tonofibrils.
4. These pathological changes were restored to normal after recovery experiment at 2 weeks.
The present results show that zinc deficiency may impede the process of physiological keratinization of oral mucosa in various degrees. It is suggested that zinc deficiency may have a serious consequence on the oral mucosa in its tolerance.
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Tatsuya Inaba, Hidetoshi Takada, Hironobu Sato
1989 Volume 33 Issue 2 Pages
391-394
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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SmCo
5 magnets and ferromagnetic alloy, which were recently developed, have been used to the removable prosthesis, but are not used to the fixed one.
We have applied them as a retainer to the bridge pontic with the removable plate.
This pontic have following advantage:
1. It is easy to clean and to alter the pontic lower area attached to the alveolar tissue.
2. It is a simple apparatus.
Here we propound 2 typical cases with fine result.
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Part 2
Tadashi Nakaminami, Taizou Omae, Masamitsu Akanishi, Takao Maruyama
1989 Volume 33 Issue 2 Pages
395-400
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Various kinds of mind stress are prevalent in our society today. Especially, in the current society, number of patients who suffered from mind stress have been increased. And to our interest, many of them tended to show dysfunction in stomatognathic system. We have reported in the previous report that psychosomatic factors not only occlusal factors played an important role in the function of stomatognathic system.
If the stomatognathic dysfunction patients were treated without the care of psychosomatic factors, effect of the treatment may sometimes be resulted in slow or uncertain cure. So we must analyze the psychosomatic condition of the patients in order to diagnose and treat them effectively.
Therefore we studied the relationship between the psychosomatic factors and the social condition such as age, sex, type of job, marital status. The personality test was done among the general patients, who belonged to three different companies, using a questionare such as CMI test in regard to general patients.
The results indicated that the difference of social condition developed different tendency in psychosomatic condition. This suggestion that psychosomatic factors must be taken care in order to diagnose and treat the patients.
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a mandibular non-reconstructed case
Takumi Tanaka, Yoshitaka Yuasa, Takahiko Ikeda, Shoji Sitozawa, Hideto ...
1989 Volume 33 Issue 2 Pages
401-408
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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One of the most consistently frustrating areas of maxillofacial rehabilitation is the treatment of patients who have had radical cancer surgery of the tongue, floor of the mouth, and mandible.
The patient described in this report, was a 66-year-old man who had squamous cell carcinoma of the right jaw. The right body of the mandible distal to the right cuspid was resected, and this part of the mandible was not reconstructed. For this mandibulectomy patient, we have treated with the removable partial denture using 30°teeth and TS telescope crown as retainer, registrating maxillomandibular relation with Gothic arch tracer and MKG. In addition, masticatory function in this patient was evaluated on tooth contact, tapping pattern, masticatory efficiency and rhythm of mastication.
Consequently, 4 to 8 weeks later, tapping pattern and centric occlusion was stabilized, and masticatory function was improved. We will continue to observe this case in long term.
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Application of Ceramco Opaque Porcelain
Yoshihiro Terada, Naoko Sugimura, Ryozo Hirayasu
1989 Volume 33 Issue 2 Pages
409-415
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Chromatic characteristics were compared between the porcelain fused metal substructures using a gold alloy and a nickel-chromium alloy with or without superficially sprayed with gold alloy.
From the stand point of the hiding efficiency for the metallic color of the substructure by opaque porcelain fusing, the gold alloy and the sprayed nickel-chromium alloy were superior to the nickel-chromium one as a metal for the porcelain-fused-to-metal crown.
The likeness in color of the gold alloy and the sprayed one was also shown.
As the conclusion, the application of wire explosion spraying technique which combines the advantages of the gold alloy and the nickel-chromium one appears to be quite useful for providing an excellent substructure for porcelain-fused crowns.
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Naoyuki Shinohara, Yoshito Minesaki, Noburou Mukoyoshi, Hidetoshi Mori ...
1989 Volume 33 Issue 2 Pages
416-421
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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On the assumption that the all ceramic crown was cemented on an abutment tooth, the effect of the cementing materials on the strength of the ceramic crown was analyzed using two-dimensional finite element technique.
The results obtained were as follows 1. When the compressive load was applied to the ceramics, the principal stress in the cementing material was compressive in the region of Young's modulus of the cementing materials 200-700 kg/mm
2, but was in tension beyond it.
2. When the tensile load was applied to the ceramics, the principal stress in the cementing material was in tension, and decreased as Young's modulus of the cementing materials decreased.
3. When the adhesive effect of the cementing material was investigated with examining the presence of the crack between the ceramics and the cementing material, the principal stress in the ceramics increased as the crack propagated.
4. The creation and propagation of the crack, the increase of the principal stress in the ceramics and the destruction of the ceramics were suggested.
5. When the analyzed results were compared with the mechanical properties of the cementing materials from the point of view of the breaking strength, it was considered that the adhesive resin cement was favorable as the cementing material of the ceramic crown. And the Young's modulus of the adhesive resin cement was about 400 kg/mm
2.
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Keiichiro Yuasa, Tadashi Chikatsune, Hiroshi Oohira, Akira Nakazawa, T ...
1989 Volume 33 Issue 2 Pages
422-428
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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Tooth mobility was measured with the use of a two-dimensional displacement measuring system. This small-sized system can measure the displacement both in the direction of the tooth axis and the buccolingual direction simultaneously with no contact. As test teeth, lower right first premolars with no clinical mobility were examined. The load was applied from the lingual to the buccal direction, to the vertical direction as well as from the buccal to the lingual direction.
The results obtained were as follows:
1. This system possesses sufficient accuracy and reproducibility for tooth mobility measurement (measurement range 500 μm, resolving power 1 μm).
2. Most of the load-displacement curves showed diphasic displacement.
3. As to the amount of displacement in the buccolingual direction, 3 of 8 cases showed greater values by the load in the buccal direction and the remaining 5 by the load in the lingual direction.
4. As to the displacement direction of loaded teeth, the lingual and buccal load displaced teeth to the lingual-coronal and buccal-radicular directions respectively. Teeth under the vertical load were displaced almost to the radicular and slightly to the buccal direction.
5. As to the direction of tooth displacement in relation to load directions, it appeared that the teeth not only rotated within the dental sockets but also indented or extruded into the dental sockets.
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Part 1. Measuring Procedure
Kouji Matsumoto, Tsuyoshi Sasagawa, Shin Komiyama, Yoshihiro Furuta, K ...
1989 Volume 33 Issue 2 Pages
429-437
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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1. The state of inclination and the change under various conditions of the imaginary axis of the tooth crown of upper jaw and lower jaw right and left first molar can be determined by the measuring apparatus and method of this study.
2.The measurement error of this method was not more than 0.1 degree. This value was sufficient for the purpose of this study.
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Part II. Influence of Difference in Palatal Depth and Amount of Load
Masatoshi Shimizu
1989 Volume 33 Issue 2 Pages
438-449
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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This author planned to clarify the influence of differences in palatal depth andthe amount of load on the bearing stress on the basal seat under this type of denture. He consequently investigated the effectiveness of a stress-sensor usable on curved areas, and using simulation models of upper maxillas with three different palatal depths, investigated the influence that different amounts of load onan artificial molar might have on bearing stress on the basal seat under the denture in terms of deformation and displacement (direction and quantity).
The findings can be summarized as follows,
Deformation and vertical and lateral displacement of dentures were influenced by differences in palatal depth and theamount of load. This discovery was useful for measuring the bearing stress on the basal seat under the denture.
The above results lead us to conclude that the supporting area of the basal seat under the denture for the upper maxilla wasmainly the alveolar ridge, and that the palatal side of the ridge could also become a supporting area when the palate grew smaller. this indicates that palatal depth is an important clinical clue for surmising the supporting area of the basal seat under the denture whose bearing stress must be reduced.
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Part I. Application of Optimization Method
Yoshinobu Maeda, Sadami Tsutsumi, Masatoshi Okada, Shigeru Idoji, Taka ...
1989 Volume 33 Issue 2 Pages
450-456
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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The purpose of this study was to simulate the process of bone resorption under removable denture bases. Two dimensional finite element models were prepared for the frontal section of a maxillary complete denture with its supporting mucosa and bone in the first molar region. Simulations were performed with the optimization program which could proportionally move the nodal points according to the stress level difference between the actual and the reference stress level.
By exerting loads on occlusal table of the model, the bone resorption progressed inthe similar manner to reported clinical observations. The location and magnitudeof the resorption were highly related to the location and direction of the loads.
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Ultrasound (Motion-mode) Evaluation
Toshihiro Hirai, Osamu Tanaka, Hisashi Koshino, Hidehito Takasaki, Yos ...
1989 Volume 33 Issue 2 Pages
457-465
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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In order to investigate tongue skill, upward and downward tongue movements with two constant frequencies were observed by using an ultrasound system in young and elderly adults. Upward and downward movements in accordance with a metronome were recorded by ultrasono recorder from the Motion-mode.
Movement rhythm andmovement velocity of the tongue were compaired in the two age groups.
The main findings were:
1. The ultrasound system with 5 MHz ultrasound convex transducer and Motion-mode observation produced clear traces of the tongue surfaces in the sagital plane during upward and downward movements.
2. Upward and downward movement rhythms in the elderly were more irregular than those of young adults.
3. Velocity of tongue upward and downward movements were statisticallydecreased in the elderly (p>0.01). Velocity did not clearly change if themovement speed was different in the elderly.
Results of this study revealed that oral motor behaviour in the elderly differed from that of young adults.
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Nobuyoshi Mishima, Hirofumi Yatani, Yasuhiro Kondo, Tomoko Yokoyama, A ...
1989 Volume 33 Issue 2 Pages
466-474
Published: April 01, 1989
Released on J-STAGE: August 10, 2010
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The authors devised a new handy apparatus for iontophoresis in order to prevent pulp irritation caused by tooth reduction. This study was intended to observe the ability of the device.
8% zinc chloride solution was iontophoresed in the dentin of extracted human and bovine teeth by the device. Then, the dye and microbial invasion tests were carried out to investigate how effectively it could seal the dentinal tubules.
The following conclusions were drawn:
1. By thezinc iontophoresis, the zinc briefly penetrated into the deep portion of the dentin.
2. The zinc iontophoresis by using the new device showed enough abilityto decrease the coloring and bacterial invasion into the dentin, although all ofthe dentinal tubules were not sealed.
3. The tensile strengths of an adhesive luting resin ' Panavia EX' to the bovine dentin decreased significantly by thezinc iontophoresis. This phenomenon could be partly due to the lack of resin tagformation into the dentinal tubules.
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1989 Volume 33 Issue 2 Pages
493a
Published: 1989
Released on J-STAGE: August 10, 2010
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1989 Volume 33 Issue 2 Pages
493b
Published: 1989
Released on J-STAGE: August 10, 2010
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