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Tensile Strength of Presoldered Joints of Gold, Palladium and Nickel-Chromium Alloy Soldered by Forcused Energy of Infrared
Masayuki Tomomatsu, Yoshiyuki Hagiwara, Yuji Honda, Hiromi Ohsawa, Shi ...
1991 Volume 35 Issue 4 Pages
627-631
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The purpose of this study was to compare the difference of the tensile strength of presoldered joints between the infrared soldering and the torch soldering with regard to Au-Pt, Pd-Cu and Ni-Cr alloy.
The conclusions were obtained as follows:
1. No significant difference of the tensile strength of presoldered joints were obtained between the infrared soldering and the torch soldering respectively in Au-Pt, Pd-Cu alloy. In Ni-Cr alloy, the tensile strength of presoldered joints presoldered by the infrared soldering was statistically stronger than the torch soldering (α=0.05). However, the revised tensile strength of both soldering in the alloy were similar.
It was suggested that porosity might be one of critical factors on the tensile strength of presoldered joints.
2. Comparing porosity ratio of presoldered joints between the infrared soldering and the torch soldering, no significant difference were obtained respectively in Au-Pt and Pd-Cu alloy. In Ni-Cr alloy, porosity ratio of the infrared soldering was one-third as much as the torch soldering.
It had to be recomended that the infrared soldering should be employed when Ni-Cr alloy was used.
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Tomohiro Sakonaka, Fumitaka Takeshita, Hideki Akedo, Keizo Morimoto, T ...
1991 Volume 35 Issue 4 Pages
632-635
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The mobility of Sumicikon and IMZ implants, which had been kept unloaded more than 3 months for healing and were clinically judged to get the bony contact, were studied using Periotest
®. For comparison, we observed the mobility of both implants in the plaster.
The results were obtained as follows:
1. The periotest value of each implant was not different in the type, and the mean value of the mobility of Sumicikon implants was-5.2 and that of IMZ implants was -2.1 in the plaster.
2. The periotest value of Sumicikon implants was +1.5 (n=10) in jaw bone, and that of IMZ implants were +3.1 (n=9).
3. It was considered that Periotest
® was useful to estimate the condition of the implants in the jaw bone.
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Changes of α-motoneuron Activity of Masseter Muscle
Yukihiro Yoshida
1991 Volume 35 Issue 4 Pages
636-645
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The purpose of this study is to investigate the relationship between the incisal opening and the amplitude of the jaw-jerk reflex in the human beings.
The findings were summerized as follows;
1. The amplitudes of jaw-jerk reflexes were decreased according to the increase of incisal opening.
2. In all subjects, jaw-jerk reflexes were not evoked at mostly maximum jaw opened.
3. The regression lines between the amplitudes of the reflex and the displacements of the incisor elicited by the chin tapping at the different jaw openings suggest two different ways of the decreases of the reflex amplitude. The first is the increase of the threshold of the jaw-jerk reflex circuit and the second is the decrease of the sensitivity of the reflex circuit. The considerable mechanism for these changes of the reflex circuit are as follows;
a. The membrane potential changes of α-motoneurons, that is depolarization or hyperpolarization.
b. The change of muscle spindles sensitivity which is controlled by γ-motoneuron activity.
c. Primary afferent depolarization could change the efficiency of the synaptic transmission from Ia afferents to α-motoneurons.
These findings suggest that the increase of occlusal vertical dimension by such as occlusal splints for temporomandibular joint disoders could lead the relaxation of jaw-closing muscles and susseedingly doctors are able to improve the occlusion of the patients easier.
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Noriyuki Waguri
1991 Volume 35 Issue 4 Pages
646-657
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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This examination employed continuously configured cephalometric laminagraphs of right and left T. M. J. with computer operated superposition.
I also examined condylar movement from the intercuspal position (i. p.) to retruded contact position (r. c. p.) in the sagittal plane.
The results were as follows:
1. The direction of movement of the condyle from the i. p. to r. c. p. was 182.88±76.56° at the condylar top (C. T.), and 187.01±69.80° at the condylar center (C. C.). In most cases, the movement was backward or upper backward, whereas it was dispersed to almost all direction.
2. The distance of movement the condyle from the i. p. to the r. c. p. was 0.47±0.29mm at the C. T., and 0.46±0.29mm at the C. C.
3. The closest distance between the posterior wall of the articular fossa and condyle was 2.35±0.72mm at the i. p. and 2.09±0.70mm at the r. c
4. The similar trend of C. T. and C. C. in the moving direction toward r. c. p. was noted in 70% of all cases.
5. In the inclination of the movement from the baseline, 93% of all cases were within±3.0°, and all cases were within±4.0°. This bodily movement was involved in most cases of the behavior of condyle toward r. c. p.
6. A significant difference was noted between left and right sides at the C. T. and C. C. with the level of significance being at 5%. Because no correlation was found, there is no similarity in the leftward and rightward directions.
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Part 1. New Solid Measuring Method and Occlusion at Intercuspal Position
Yoshihiro Tanaka
1991 Volume 35 Issue 4 Pages
658-670
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The occlusions of premolars and molars were measured at the intercuspal position of 20 normal natural dentitions (average age: 24.5 years old).
Taking the interocclusal record of the upper and lower molars, a plane figure was constructed by using the “Superposed rubber pattern method”.
It was the method in which the interocclusal record was sliced perpendicularly to the Camper's plane. The sliced patterns were then traced and a plane figure was graphed by superposing each traced figures.
The whole area in the unilateral lower four molars, the five different areas divided the intraocclusal distance, and the intraocclusal cubic volumes were measured, respectively.
The results were as follows:
1. In the whole area the average value was 318.31 mm
2.
2. The average values were 136.47 mm
2, 57.02 mm
2, 50.12 mm
2, and 74.72 mm
2 in each of the areas of the intraocclusal distance over 2.0 mm, the from 2.0 mm to 1. 0 mm, the from 1.0mm to 0.5 mm, and the under 0.5mm, respectively.
3. The average value was 21.44 mm
2 in the area of the intraocclusal distance under 0.05 mm.
4. The intraocclusal cubic volume was measured by applying the Simpson's rule. The average value was 289.78 mm
3.
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Yasunobu Takahashi, Mikiya Kishimoto, Takashi Nokubi, Yoshihiko Okuno
1991 Volume 35 Issue 4 Pages
671-674
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The 559 patients who visited our prosthodontic clinic during one year (1988) were evaluated for their general complications by collating informations gathered with a questionnaire and a physical examination. Our research indicated that 76.6% of the elderly patients (over 65 year-old) suffered from multiple diseases and that their major health problem was a circulatory disease. It was suggested that attention to general complications and following intraoral findings, especially in the elderly patients, was necessary to be paid before the prosthodontic treatment.
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Influence of Self-curing Resin for Crown
Keizo Iwai, Shigeru Kataoka, Yoshihiro Takahashi, Haruo Miyazaki, Mits ...
1991 Volume 35 Issue 4 Pages
675-680
Published: August 01, 1991
Released on J-STAGE: November 26, 2010
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Temporary cements are sold by many companies for use in cementing provisional prosthodontic appliance. However, as there is usually a color difference between temporary cements and resin temporary crowns, the color of the semi-transparent resin is often affected by the temporary cement, making it difficult to make a good color match.
In this study, we made photoelectric colorimetrical measurements of the colors of self-curing resin and eighteen kinds of temporary cements using a CIE L*a*b* color system, and we evaluated the change of color after application of each cement to resin.
The results were as follows;
1. The color of resin temporary crowns was affected by all the temporary cements.
2. Although all the temporary cements differed in color from each other, the colors of three of the temporary cements, Neodyne α, Hy-Bond temporary cement (soft) and Impression paste, differed especially from the rest.
3. Opotow Temporary cements, Propack, and Nogenol Temporary Cement showed the greatest color-difference values.
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Yasuo Kohsaka, Mitsuo Kato, Ting Jiang, Tadamasa Goto, Minoru Ai
1991 Volume 35 Issue 4 Pages
681-688
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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In order to investigate masticatory function and influence on remaining tissue by wearing denture, 13 patients with removable free-end denture were observed longitudinally up to one year after initial insertion. Masticatory function was evaluated by measuring the crushed peanut particles remaining on 10 mesh sieve and biting force, and the influence on remaining tissue was estimated by measuring tooth mobility.
The findings were as follows:
1. Weight decrease of the particles with time showed an improvement of chewing ability.
2. From the variation of particle size distribution, patients without occlusal contact with antagonist (OCA) showed the lowest chewing ability at first, and then improved gradually.
3. The longitudinal alteration of maximum biting force showed two-phases. That rapidly increased in the first month and then slowed down. The biting force was stronger in order of bilateral denture case, unilateral case with OCA, and case without OCA.
4. In denture case without OCA and bilateral case with OCA, the tooth mobility increased in insertion of denture, but came to decrease 3 month later. In unilateral denture case with OCA, however, the tooth mobility did not increase until 3 month. Continuous increase of tooth mobility was almost never observed.
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Comparison of Dental Color Analyzer (Nakagawa) and Color Analyzer (Hitachi) on the Color of Vita Porcelain
Tomoko Murakami, Yoshihiro Terada, Kenichi Minamihara, Ryoichi Ikono
1991 Volume 35 Issue 4 Pages
689-699
Published: August 01, 1991
Released on J-STAGE: November 26, 2010
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Recently, shade matching between the teeth and dental porcelain has been investigated in the field of esthetic dentistry.
This study compared two types of spectrocolorimeters, a precise machine (HITACHI color analyzer 607) and simple machine (Dental color analyzer), for studying the color of Vita dental porcelain.
Our conclusions are as follows:
1. X, Y, Z values of porcelain after baking dentin were larger than those after baking enamel in the case of using color analyzer 607, while X, Y, Z values using Dental color analyzer recorded reverse order.
2. CIE color coordinates of porcelain after baking enamel were approached a neutral point.
3. It was difficult to decide color of C shade in the case of using Dental color analyzer.
4. CIE a*b* color coordinates recorded lower values after baking enamel than after baking dentin.
5. Dental color analyzer has high reliability and usability.
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Toshihiro Ogata, Tomoji Matsuura, Yoshizo Okamoto, Takashi Horibe
1991 Volume 35 Issue 4 Pages
700-707
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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To use titanium alloys with excellent properties as prosthetic materials, the amount of the oxide film produced after firing and its physical properties, which have major effects on their binding with porcelain, were studied in pure titanium and Ti-6Al-4V alloy.
The following results were obtained:
1. The amount of the oxide film was related to conditions of firing. It was greater as the rate of the increase in the temperature was slower, the duration of firing was longer, and the final firing temperature was higher.
2. The color of the oxide film was also related to conditions of firing. Pure titanium became whiter, and Ti-6Al-4V alloy became browner, as the amount of film produced was greater.
3. The hardness was similarly related to the amount of film produced. The materials were harder as the film was thicker.
4. At 1, 000°C the expansion rate of Ti-6Al-4V alloy was about twice that of pure titanium. The coefficient of expansion of the alloy was also slightly greater at 200-700°C. Pure titanium has a transition point near 885°C at which the crystalline structure changes from α-phase to β-phase, but this transition point was not observed in Ti-6Al-4V alloy.
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Naokatsu Ueda, Naoji Yuba, Masahiro Tanaka, Tohru Tokunaga, Wataru Kaw ...
1991 Volume 35 Issue 4 Pages
708-714
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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This study was made to investigate the correlation between masticatory laterality, handedness and footedness in 1287 volunteers.
The results obtained were as follows:
1. Right-biased chewing behaviour was slightly predominant in comparison with the other side.
2. Handedness and footedness had no significant correlation with masticatory laterality.
3. It was showed that oral diseases and the treatments mainly motivated to be conscious of masticatory laterality. Dental caries, toothache and missing teeth tended to be determinant factors of acquired masticatory laterality.
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Masanori Mizui, Fumikazu Nabeshima, Masakazu Hirayama, Masahiro Yanagi ...
1991 Volume 35 Issue 4 Pages
715-722
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The occlusal contacts patterns which were given on prosthetic works while mandibular lateral translation had been classified into cuspid protected occlusion, group functioned occlusion and full balanced occlusion. However, there were not consensus about occlusal contacts near intercuspal position at the initial stage of lateral excursion.
In this study, we used one of the software of T-Scan system, Force Movie
®, and recorded continuously occlusal contacts during left and right lateral movements in 12 normal subjects with complete dentition.
Cuspid protected occlusion was found in 11 sides (45.8%), group functioned occlusion in 10 sides (41.7%) and full balanced occlusion in 3 sides (12.5%).
All subjects had balancing side contacts in molars near the intercuspal position, with working side contacts at the same time.
These results indicated that Force Movie
® was easily able to show occlusal contacts during lateral excursion, and all subjects showed similar contacts pattern in the vicinity of intercuspal position.
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Especially, Biological Aactivity of Periodontal Ligament
Hideki Takizawa
1991 Volume 35 Issue 4 Pages
723-737
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The object of tooth transplantation and replantation is to rehavilitate the oral function, however, it's not common because of its difficality to preserve teeth for long term period.
The purpose of this study is to evalute the preservation of teeth for long time, and to investigate effects of different presevating solutions (SS-solution, physiological-saline, Eu-ro-Collins-solution, UW-solution and D-MEM). SS-solution and physiological-saline are storaged in-60°C and other solutions storaged in 4°C according as their manuals. Tooth are preserved from 3 hours to 4 weeks.
To revaluate the efficancy of solutions, all frozed-storage cases (SS-solution and DDS
1) were showed strong degeneration of fibroblast in periodontal ligament from 3rd hours preservation. Degenerations were appeared at 6th hours in Euro-Co-llins case, 24th hours in DDS
2case, 2nd weeks in UW case, and 24 th hours in D-MEM case in non-frozen cold storage cases.
In tissue culuture, frozen storage cases appeared no evidence of biolosical activity, and other solutions had been kept biological-activity for 24th hours in Euro-Collins solution, 1st week in DDS
2, 2nd weeks in UW solution and D-MEM. Especially use of UW-solution in non-fro-zen cold teeth storage is most effective method, because cells appeared firstest and cell-growth-rate are obviously found higher than the other solutions.
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Kazuhiro Kobayashi, Keiichi Iwanami, Takumi Ogawa, Hayato Kida, Tetsui ...
1991 Volume 35 Issue 4 Pages
738-744
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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It was found in the last study that ultrasonic energy is effective in reducing retentive forces of dowels.
In this study, we actually removaled 147 dowels cemented in the mouths.
The results were as follows:
1. Out of 147 cases, 146 cases (99%) were successful to remove dowels with ultrasonic energy, which would be effective in reducing retentive forces.
2. Removal was successful within 5 minutes in 91 cases (62%).
3. 18 cases (12%) of patients expressed discomforts during or after applying the ultrasonic energy, but they didn't continue but faded away immediately.
4. In 10 cases of successful removal, the ultrasonic apparatus was not used at all.
5. Removal was successful within 30 minutes in 112 cases (83%).
6. Cement layer was interfacially broken in 75 cases (51%).
7. By the followup study of 57 cases, 2 cases indicated unpleasantness but no cases exhibited percussion pain, spontaneous pain and occlusal pain.
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Opposing Maxillary Complete dentures
Soni Kim
1991 Volume 35 Issue 4 Pages
745-756
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The purpose of this study is to evaluate restoration of masticatory function from the physiological point of view in the application of the cone crown telescope dentures with lower Kennedy Class I.
Recently, Cone crown telescopes used to a considerable extend for good retainer to maintain abutment teeth satisfactorily and no resorption of edenturous ridge.
Five subjects, upper edentulous and lower Kennedy Class I Case, were selected and restorated by complete dentures on maxillary and cone crown telescope dentures on mandibles. Masticating function was observed at three objects as follows, electromyography (EMG) with muscle of mastication, biting force and masticatory efficiency.
And then the results were compared to the conditions wearing last dentures in every subject, and to 10 natural dentitions.
In all subjects, comparing last dentures, rehabilitation in EMG was observed after 4 weeks from insertion and maintained, biting force was increased progressively after 1 week with time.
In 3 subjects, masticatory efficiency recuperated after 4 weeks from insertion and the rests, recuperated after 8 weeks.
Five subjects were the same level in masticatory rhythms and biting forces comparing to 10 natural dentitions, but were unfavorably in masticatory efficiency.
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Yuichi Higuchi, Yoshimichi Gonda
1991 Volume 35 Issue 4 Pages
757-764
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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Although glycosaminoglycans are thought to play an important role in the alleviation of stresses and as a lubricant in the temporomandibular joint, their localization is unclear.
The following information was obtained when the condition of the heads of the mandible of SD rats were histochemically investigated and histopathological examinations were carried out.
Histopathological findings: The head of the mandible is completely covered by cartilage, and is made up of 4 layers which are the fibrous, proliferating, mature cell, and hypertrophic zones.
The fibrous zone is a perichondrium made up of collagen fibers, and the proliferating zone is formed from regularly arranged squamous chondrocytes.
The chondrocytes of the mature cell zone are circular in shape, and there are cartilage lacunae. Ossification is seen in the hypertrophic zone. The bone matrix and cavum medullare are adjacent to the hypertrophic zone.
Histochemical findings: A very strong metachromasie reaction is seen through out the cartilage at 5 weeks of age, which reaction is especially strong in the hypertrophic zone and the lower layer of the mature cell zone. In regions of the bone matrix, there was an overall weakening of the reaction with age.
The types of glycosaminoglycans observed at 5, 15, and 25 weeks were hyaluronic acid and chondroitin sulfate A/C.
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Masahiro Aida, Hideo Kanaya, Taira Kobayashi, Keiji Utsugizaki, Yoshiz ...
1991 Volume 35 Issue 4 Pages
765-771
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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Here is investigated the adhesiveness of one liquid type silane coupling agent. For the experiment, following materials are used: Cosmotech porcelain primer, Laminabond porcelain primer, Optec silane coupling agent, and Clearfil porcelain bond.
The opal porcelain or the masking porcelain surface was polished with # 1000 paper and randomly classified as one of the following three conditions: 1) non etching, 2) phosphoric acid etching, 3) hydrofluoric acid etching. Then the porcelain surface was treated with each porcelain primer. The Laminabond composite paste was applied on the treated surface and cured by photo irradiation. The shear bond strengths between the composite and the porcelain were measured after one day immersion in 37°C water, or 10, 000 thermocycles between 4°C and 60.°C
There was no difference between the adhesion of composite to the opal porcelain and to the masking porcelain. The Laminabond porcelain primer and Optec silane coupling agent gave high bond strengths of 150-200 kgf/cm
2on the non etching surface. Mechanical effects by the hydrofluoric acid etching did not contribute to the adhesion.
The bond strengths after 10, 000 thermocycles remarkably decreased in all kinds of porcelain primer tested here.
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tress Analysis by the Finite Element Method
Mikako Aoki, Tsukasa Shioyama, Tetsuo Yamamori, Izumi Sasajima, Akihik ...
1991 Volume 35 Issue 4 Pages
772-778
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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Bioactive glass is a new form of dental implant material which has the ability to combine with bone, and various research and tests have been undertaken to strengthen its range of clinical application.
The purpose of this study is to analyze the stress distribution of bioactive glass by the finite element method, and to compare its results with a natural tooth model.
The results obtained were as follows:
1. The displacement showed the natural tooth model to be larger than the implant model.
2. The stress distribution showed the natural tooth model to be similar to that of the implant model. However, as the implant model showed the most stress to be on the side where the direction of the force was applied, the natual tooth model showed just as much stress on the opposite side as well.
3. The displacement and stress distribution varied according to the direction and area of the applied force. Displacement of the natual tooth was the least when force was applied toward the axial direction of the tooth, and increased as the angle of force applied varied. However, no dis-placement of the implant model was observed when the force was applied within 30° of the axial direction, but increased drastically beyond that point.
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Basic Characteristics of Resin Preparations Made an Experimental Basis
Tomotaka Takeda, Kenji Fukushi, Kazuhiko Kadena, Rika Yokoi, Hisashi H ...
1991 Volume 35 Issue 4 Pages
779-788
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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As additional application of occlusal surface resin in antificial resin tooth of denture during use, splint and temporary restoration. All require materials which can be easily and properly applied. The authors tentatively made several preparations of visible light-curing tooth crown resin using cyclophosphazene monomer on an experimental basis, because this monomer has neither odor nor taste. We determined basic characteristics of these preparations and their adhesive strength to a resin teeth, and the results were compared with those seen in 2 commercially-available materials. As a result, the following results were obtained.
1. As for mechanical characteristics, the preparation containing an organic composition filler and that containing a large amount of U-2 TH as a comonomer showed large bending strength, and the preparation containing a large amount of cyclophosphazene monomer and that containing an organic composition filler had great compressive strength as well as large Rockwell hardness.
2. Preparations of these 3 types all showed a relatively large contact angle.
3. Satisfactory wear resistance was observed in preparations with large compression strength and hardness. The preparation containing an organic composition filler disclosed especially good results.
4. Our preparations all demonstrated smaller impact resistance than the commerciallyavailable material B.
5. The preparation containing an organic composition filler showed the greatest adhesive strength, and the other 2 preparations showed the same as or even greater adhesive strength than the 2 commercially-available materials.
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Measurements of the Japanese bucco-lingual Breadth of the Dentulous Alveolar Process
Syuichi Nomura, Junichi Miura, Yasuhiro Kaneko, Toshiyuki Hoshino, Kiy ...
1991 Volume 35 Issue 4 Pages
789-793
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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This study aims to applicate the Biometric impression trays for Japanese edentulous patients. A hundred (fifity males and fifity females) Japanese bucco-lingual breadth (BLB) s of the dentulous alveolar process were measured on maxillary study casts by the three dimensional coordinate measuring machine.
Results:
1. Average measurements (mm) and standard deviations (mm) were as follows. Central incisor; 5.7±1.15, canine 7.5±1.41, first premolar 10.7±1.07, second premolar 11.4±1.37, first molar 13.4±1.25 and second molar 12.3±1.33.
2. Japanese average measurements were 0.5-1.0mm smaller in incisor and canine region, but 0.6-0.8 larger in premolar and molar region as compared with figures of Scottish that Watt had reported.
3. Biometric tray of which design is based on the average BLB measurements will become a concrete guide to the breadth of the flange of complete upper dentures for Japanese.
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Morphological and Immunofluorescent Studies
Takako Sakai, Mizuho Kido, Yoshihiro Terada, Keiichi Kawano, Yasuyoshi ...
1991 Volume 35 Issue 4 Pages
794-803
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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Morphological and immunofluorescent studies of age-dependent changes of the periodontal ligaments were performed in the lower first molars of mice ranging in age from 1 week to 80 weeks after birth. The alveolar bone which was completed by 20 weeks, was gradually decreased in amount and its surface bordered upon the periodontal ligament became irregular resulting in wavy appearance after 20 weeks postpartum. A space which was occupied by the periodontal ligament decreased in width with aging, probably because of deposition of newly formed cementum on the surface of the root. In addition, cells in the periodontal ligaments also became decreased in number with aging. Moreover, a interstitial space of each collagen fiber bundles enlarged.
The type I and type III collagens, and fibronectin were distributed in close association with the periodontal fibers. The immunoreactive products of the type III collagen was intensily deposited on the fiber bundles of periodontal ligament being close to the alveolar bone of mice ranging in age from 2 to 20 weeks after birth. This fact indicates that an active synthesis of type III collagen occured in this region. In mice of after 30 weeks postpartum, the junctional epithelium proliferated and migrated down to the apical side along the cementum resulting in deepening gingival pocket. The fibronectin was strongly stained on the external basement membrane of migrating junctional epithelium. This finding suggests that the fibronectin played an important role in the proliferation and migration of the junctional epithelium.
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Toshio Hosoi, Yoshikazu Ishikawa, Tsutomu Okajima, Takashi Sagae, Ryui ...
1991 Volume 35 Issue 4 Pages
804-816
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The biting forces from integrated EMG and the pressure distributions at the denture basemucosal interface in three complete denture wearers were recorded simultaneously under the regular clenching condition. In order to measure the stress of the tissue bearing pressure, duplicated mandibular dentures containing six pressure sensors on basal surface were constructed. Integrated EMG and pressure distributions were measured at the same time and analyzed on time by using digital processing system. The conclusions as to the change of pressure distribution and calculating the biting force by proceeding occlusal adjustment were as follows:
1. It was possible that present method of calculating the biting force from integrated EMG and pressure distribution by pressure sensors could be used for complete denture wearers.
2. Before occlusal adjustment, it was recognized to dispersion of pressure distribution. But after occlusal adjustment, it was indicated to converge of pressure distribution.
3. After occlusal adjustment, adequate pressure distribution was transmitted directly to tissues under the denture base. Therefore, it was acknowledged that load supporting capacity and biting force had increased.
4. After occlusal adjustment, the activity of masseter and temporal muscles had become more active. It was recognized to coordination of four muscles.
5. The Measuring System which calculated the biting force from the integrated EMG and measured pressure distribution under the denture base was available to evaluate the denture functions in complete denture wearers.
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Takeshi Maruyama
1991 Volume 35 Issue 4 Pages
817-829
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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Occlusal contact must be in harmony with temporomandibular joint movement and musticatory muscle activity for healhy stomatognathic functions. Using normal subjects with healhy stomatognathic functions and occlusions, the following were measured at eccentric positions: occlusal contacts, inclination of incisal path and condylar path, EMG activities when subjects performed maximal clenching. And reductions of EMG activities when artificial canine guidance fitted for subjects were also measured.
The following results were obtained:
1. Inclination of lateral incisal path which projected on the sagital plane were different according to difference of the occlusal contacts.
2. There was no difference in inclination of lateral incisal path which projected on the horizontal plane and lateral condylar path according to difference of the occlusal contacts.
3. Different co-ordination patterns of the EMG activities were observed according to difference of the occlusal contacts, when subjects performed maximal clenching at lateral eccentric positions
4. The co-ordination patterns did not change much even after the artificial canine guidance was fitted.
5. These findings suggest that maximal clenching at lateral eccentric position might help us to dicide the anterior guidance.
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Tetsuya Fujimura, Eiichi Bando
1991 Volume 35 Issue 4 Pages
830-842
Published: August 01, 1991
Released on J-STAGE: August 10, 2010
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The purpose of this research is to develop a digital type jaw movement analyzer for studying human mandibular movement. This type of instrument has wide application in both research and clinical sciences.
The instrument with attached type sensor is fixed to the maxillary and mandibular arches allowing measurement of jaw movements with six degrees of freedom.
A description of the features of the newly developed instrument is as follows:
1. The measurement accuracy of jaw movement and maxillary arch target point is less than 170μm.
2. The jaw movement analyzer can collect data of mandibular position at a maximum of 6, 500 positions per second. Data processing is performed by online real time system in which a monitor displays jaw movement tracks.
3. The measuring instrument weighs 660g. The maxillary arch weighs 533 g and the mandibular arch 127g. This instruments allows all normal jaw function and therefore disturbances to stomatoghnatic system is minimal.
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1991 Volume 35 Issue 4 Pages
846a
Published: 1991
Released on J-STAGE: August 10, 2010
JOURNAL
FREE ACCESS
-
1991 Volume 35 Issue 4 Pages
846b
Published: 1991
Released on J-STAGE: August 10, 2010
JOURNAL
FREE ACCESS
-
1991 Volume 35 Issue 4 Pages
846c
Published: 1991
Released on J-STAGE: August 10, 2010
JOURNAL
FREE ACCESS
