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Part IV. Propagation of Error
Takashi Funakubo, Kazuo Nemoto
1986 Volume 30 Issue 3 Pages
531-544
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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When we study articulator movement and mandibular movement, we usually regard them as the rigid body movements. Now we attach some targets to an articulator and observe their three-dimensional displacements. Our observational data consist of X, Y and Z values of targets, and each value has an accidental error. When we correct these errors by the method of least squares, we can obtain the most probable values which make us to calculate a position and a displacement of the rigid body as observational results.
In this article, in the first place, we indicate accidental errors in our observational data by the use of formulae from (2) to (5). Secondary, we investigate theoretically how to propagate these errors to standard errors of observational results according to law of the propagation of errors (formulae from (6) to (21)). Using the variance and covariance matrix, which is obtained when we correct accidental errors by the method of least squares, we can easily calculate these standard errors (formulae from (22) to (28)). Lastly, we show concretely how to calculate standard errors when we correct accidental errors by the indirect conditional observation of the method of least squares (formulae from (29) to (50)). We also point out that we can calculate standard errors of observational results by the use of the direct conditional observation and the indirect observation of the method of least squares to correct accidental errors.
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Upper left second premolar
Dae Gyun Choi
1986 Volume 30 Issue 3 Pages
545-559
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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An abutment-tooth preparation with a full cast crown was done on the upper left second Premolar using Home position (H. P.) which, among the seating-posture during treatments, strictly specifies the relative relations of the dentist and patient. And measurement and examination of the prepared tooth form were made and the following conclusion was obtained:
1. The reduced extent of occlusal surface was excessively large at the buccal and lingual cusps while the minimum value was obtained at the central fossa area.
2. As for the reduced extent of axial surface, that at the buccal surface was half the value at other positions.
3. The reduced extent of subgingiva was excessively small at the buccal and lingual surfaces and at distobuccal line angle, with the value at the buccal surface, in particular, being about half as much.
4. The taper of axial surface showed high intensity at the distal surface in a treatment by any dentists. Consequently, a tooth which was given an abutment-tooth preparation tended to be reduced in such a way as to lean toward the mesio-buccal and distal-surface directions.
5. The time needed for the abutment-tooth preparation was about 11 minutes, 70% of which, or about 8 minutes, was accounted for by the operation of air-turbine. The most time-consuming work was the alteration and polishing.
6. The abutment-tooth preparation by the Home position system has almost achieved its goal in that it enabled even reduction of abutment-tooth. So, clinically, the H. P. system seems to be a method that can be highly evaluated.
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Kazunari Watanabe
1986 Volume 30 Issue 3 Pages
560-574
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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In order to investigate the nature of fatigue of dental porcelain, bending tests and fatigue bending tests were carried out using test pieces of glass, dental porcelain (enamel, dentin, core porcelain), laminated dental porcelain. These tests were performed in the air (the relative humidity was 50%) and in the water.
As the results of bending tests and fatigue bending tests, the evaluated values in the water were inferior to those in the air.
The strength of core porcelain was superior to that of any other porcelain but inferior to that of glass in bending tests. In addition, core porcelain was stronger than any other porcelain and glass from the viewpoint of fatigue.
The strength of laminated porcelain was inferior to that of core porcelain and superior to those of enamel, dentin porcelain in bending tests. Moreover laminated porcelain was more influenced by fatigue than any other porcelain: the lower the applied load became, the less the difference between laminated and enamel porcelain in number of cycles became.
The test pieces which were strong in bending tests were not necessarily strong in fatigue bending tests. This result suggests that the investigation of fatigue of dental porcelain is important.
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I: Clinical Figures in the First Examination
Ryoko Nishiyama, Naoto Ukita, Kazuhiro Tsuga, Tadahiko Takatori, Eisak ...
1986 Volume 30 Issue 3 Pages
575-580
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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An attempt was done to evaluate clinical figures in the first examination of mandibular dysfunction patients with two or more symptoms of temporomandibular joint (TMJ) pain, TMJ sounds and limitation of mandibular movement followed by no organic change in the TMJ. The results were as follows:
1. A great prevalence of female was seen and the ratio of female/male was 9 to 1.
2. In age distribution, the patients of 10 years old to 19 and 20 to 29 were predominant.
3. Most patients were treated by restorative therapies and few of them had experiences of several general diseases.
4. Evaluating the chief complaints associated with the first symptoms, TMJ pain was much predominant in comparison with TMJ sounds.
5. Clinical symptoms were expressed by TMJ pain, TMJ sounds and limitation of mandibular movement with other symptoms as headache, neck and shoulder pain and ear symptoms.
6. Most patients had natural dentitions. Premature contacts were seen in centric relation in all patients and more than half of them had occlusal interferences in eccentric relations.
7. The remarkable presence of oppressive pains in masticatory muscles was observed. The finding that factors which might be associated with muscle tensions were seen in many patients suggest the correlation between mandibular dysfunction and muscle hyperactivity.
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With Special Reference to the Mandibular Left First Molar
Yoshinori Nameta
1986 Volume 30 Issue 3 Pages
581-596
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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In our laboratory, we have been studying the reduction tendency seen when the fullcast crown preparation is done on a patient in “Home Position” which, among the various “Random Position” methods, particularly enables a dentist to approach his patient in a stable posture. Up to now, we have been studying this subject and have published a number of reports on the results of our studies conducted with regard to the upper left and right molars and lower right first molar. This time, the authors, in addition to using the results of their previous studies as reported, have had the full-cast crown preparation done by Home Position Dentistry with regard to the lower left first molar as well and made a quantitative analysis of the reduction tendency of abutment tooth. As a result of these analysis and examination, the following conclusion was obtained:
When the preparation was full-cast crown was done for the lower left first molar on a patient in the Home Position, a tendency was invariably noted, the same as in the case of preparation for the lower right first molar, of the preparation being done in such a way as to tip toward the direction of approach by the dentist to the patient. In that it enables even preparation of abutment-tooth, the Home Position has almost attained its objective and, especially in view of the fact that it is a system suited to the gross reduction which is an overall reduction, the Home Position may be regarded as a system that can clinically be given a high evaluation.
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Akinobu Tsue
1986 Volume 30 Issue 3 Pages
597-614
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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Notable distortion and displacement of the ceramometal fixed bridge frame occur in presoldering and degassing phases through laboratory procedures. In porcelain-fused-to-precious-metal crown, heat treatment before grinding is said to prevent marginal distortion. There is no research, however, on this heat treatment to make ceramometal fixed bridges or to assemble them by pre-sol dering.
The author studied the heat treatment effects on distortion and displacement of ceramometal fixed bridges compared with ones not treated by heat. The frames were measured three-dimensional deviations after the indexing for the heat treatment, pre-soldering, surface grinding of the frame, degassing, opaque porcelain firing, body-incisor porcelain firing and glazing.
The results were as follous:
1. In pre-soldering and degassing phases, the heat-treated frames produced significantly smaller distortion and displacement than not heat-treated ones.
2. In opaque porcelain firing, body-incisor porcelain firing and glazing phases, the heat-treated frameworks were not significantly different from ones not treated by heat.
3. It was therefore explicated that the heat treatment before grinding is the effective method of producing ceramometal bridges in decreasing distortion and displacement expected in labolatory procedures.
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Junichi Mega
1986 Volume 30 Issue 3 Pages
615-627
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The close association between restorations with ill-fitting margin (especially overhanging margin) and periodontal disease has been accepted as a common opinion by the dental profession. The purpose of this study was to survey the subgingival microflora in patients treated with fixed prosthetic appliance. Subjects were divided into three groups (H group: periodontal health, G group: gingivitis, P group: periodontitis) by the clinical parameters of the periodontal tissue. The results indicated the changes of the subgingival microflora in every group, that is, G group had a significantly higher level of genus
Actinomyces (0.05≥P>0.01) and a lower level of genus
Streptococcus (0.01≥P>0.001), whereas P group had a significantly higher level of genus
Bacteroides (P≤0.001) and a lower level of genus
Streptococcus (P≤0.001) than H group. The present study suggests that overhanging margin is one of the factors causing the microbial succession in subgingival microflora. This fact should be noted as iatrogenic factor in the prosthetic treatment by the dental profession.
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In Reference to the Bond Strength
Masaru Tomono
1986 Volume 30 Issue 3 Pages
628-637
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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A study was made as to how the bond strength in the agar-alginate combined impression technique is affected by the variations in such factors as the length of time left alone, the W/P ratio and the temperature of the combining water with regard to the alginate impression material on the one part and the length of time left alone, the temperature maintained and the number of times of boiling with regard to the agar impression material on the other. As a result, the following conclusions were obtained.
1. As regards the alginate impression material, the bond strength was found to decrease with the elapse of time it is left alone after combination. There was no increase or decrease effect of the W/P ratio, and an increase in bond strength was noted when the temperature of the water in which the materials were combined was low.
2. As regards the agar impression material, the bond strength decreased with the elapse of time the material was left alone after combination. The result was good when the temperature was maintained at 60°C, while the number of times of boiling was found to give no effect.
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Yasuhiro Nakamura, Toshiya Kuwabara, Takahiro Mizumori, Takao Kuwahara ...
1986 Volume 30 Issue 3 Pages
638-645
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The purpose of this article is to investigate the effect of the restoration of single tooth by crown on chewing movement. Chewing movement was recorded and analyzed by Sirognathograph Analyzing System on 12 subjects both on restored side chewing and on contralateral side chewing, with the restoration and without the restoration.
The result showed there were no common evident difference among those experimental circumstances in all subjects. However, there were several parameters which might be affected among those circumstances in individuals. The parameters were the lateral deviation of closing path and the duration of occluding phase in the restored side chewing and the lateral deviation of closing path near intercuspal position and the duration of occluding phase in the contralateral side chewing.
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Hiroshi Murakami, Kyoichi Hashimoto
1986 Volume 30 Issue 3 Pages
646-651
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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During the observation of progress after the insertion of removable dentures, the patient presented voluntary and active reports (16 times) with various complaints for 4 months. The consideration of the reports were as follows.
1. Reports were 41 sheets of B5 size paper (7 times).
2. Reports by the postal cards were 9 times.
3. There were 32 complaints altogether in the reports.
4. Pain grade was made into a table by 1-15 steps.
5. Pain place was certainly made into the figures in the oral statement.
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Examination Using Spectroradiometry
Toshiki Ichiwata
1986 Volume 30 Issue 3 Pages
652-664
Published: June 01, 1986
Released on J-STAGE: November 26, 2010
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Detailed measurements of the color of the maxillary anterior teeth of young men and women were examined in CIE1976 (La*b*) Color Space by using the spectroradiometer (Photo Research Co., Pritchard Model 1980B) to clarify color of the natural teeth. As a result, the following conclusions were obtained.
1. The spectral distribution range under Illuminant D65 was as follows: L*(metric lightness) 52.3-80.3, Cab*(metric chroma) 2.9-28.1 and Hab°(metric hue-angle) 55.2-94.3°.
2. As for the differences by type of tooth, they were as follows:
With regard to L*, at the middle, central incisor>lateral incisor>canine.
With regard to Cab*, at the middle, canine>central incisor-alateral incisor.
With regard to Hab°, at the middle, central incisor>lateral incisor≡acanine.
3. As to the difference by region, regarding L* apart from the fact that no significant difference was observe in women's canine between the cervical and the middle, middle>cervical≡aincisal in both men and women.
With regard to Cab*, cervical>middle>incisal.
With regard to Hab°, incisal*amiddle>cervical.
4. On the whole, no difference by sex was noted.
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Part 1. pH Value in Gingival Crevices and Periodontal Pockets
Shigeki Katayama, Makoto Kawae, Akihiko Shiba
1986 Volume 30 Issue 3 Pages
665-670
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The amount of gingival fluid increases with inflammation, sometimes in parallel to its severity. This may lead to the finding that the pH in gingival crevices and periodontal pockets varies depending on the extent and severity of the periodontal disease. In the present investigation, the hydrogen ion-sensitive field-effect transistor (HIS-FET), which is based on the structure of a gate-insulated field-effect transistor, was used to measure the gingival pH in 4 normal adults and 3 patients. The pH was measured at depth of 1 mm from the gingival margin on the surface of each tooth. The measurement was repeated 5 times.
The average values of pH ±S. D. in the buccal, lingual and interproximal crevices were 6.22±0.44, 6.79±0.39 and 6.13±0.54 respectively, and those in the periodontal pockets were 6.14±0.72, 6.44±0.48 and 6.07±0.65 respectively. Thus, periodontal pockets showed lower pH levels than normal crevices, and statistical evaluation showed a significant difference (p<0.05) on the lingual tooth surface. The average values of pH in lingual crevices were higher than those in the buccal and interproximal, and this was also the case for lingual periodontal pockets.
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Toshiaki Yamami, Atsushi Yamashita, Nobuyoshi Takeshita, Noriyuki Naga ...
1986 Volume 30 Issue 3 Pages
671-678
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The pulpal reactions of dog teeth were investigated after full coverage crowns were set with new dental adhesive resins, Super Bond C & B and Panavia EX. Elite Cement 100 and Durelon was used as control. Histopathological changes were examined according to the standard of ADA on 123 adult dog teeth at different periods of time after the setting of crowns. All of the materials satisfied the ADA standard. However, histopathological reactions changed with a lapse of time in a way different for each material. With all materials, acute inflammatory reactions of pulpal were observed after 1-3 days, though the reactions caused by the new resins were less severe than those caused by Elite Cement 100 and Durelon. The acute inflammatory reaction disappeared after 25-35 days except the teeth with Elite Cement 100, and the formation of reparative dentine was observed with all materials. The inflammatory reaction caused by Elite Cement 100 was not ob. served after 50-60 days, and the formation of reparative dentine became less remarkable with all materials. These results suggest that the effects of Super Bond C & B and Panavia EX on dental pulp were less harmful than those of usual setting materials.
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Makoto Segawa, Mutsuo Yamauchi, Hideyuki Higashi, Kazuyoshi Tsuboi, Jo ...
1986 Volume 30 Issue 3 Pages
679-683
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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Occlusal splint has gained wide-spread clinical application. Insertion of occlusal splint has been reported to exert a harmful effect on teeth or periodontal tissue. Great care should, therefore, be paid to the usage. The occlusal splint (Michigan University type) which is most frequently used covers a wide area of the palatal gingiva and this may result in damage to periodontal tissue. Using 10 volunteers, the occlusal splint was inserted on the maxilla for 3 weeks in succession to examine the degree of damage to the periodontal tissue at the labial, palatal and both proximal surfaces of maxillary anterior teeth using the bleeding index and gingival crevicular fluid volume (Periotron value). It was found that (1) from immediately after insertion, both the bleeding index and Periotron value increased markedly, demonstrating significantry high value after 3 weeks, (2) of changes in the Periotron value at various sites, a most distinguished change was noted on the proximal surface and (3) removal of the occlusal splint resulted in reduction of both the bleeding index and Periotron value, returning to the original value 2 weeks later.
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Equipment and ultrasonagraph
Ken'ichi Kobayashi, Tetsuya Suzuki, Masumi Kimura, Shinji Tanaka, Hiro ...
1986 Volume 30 Issue 3 Pages
684-690
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The retention and the support of the complete denture depend upon the oral mucosa under the denture base in the edentulous state. In this respect the close examination of the oral mucosal tissue is a must for constructing prosthesis. The purpose of this study is to investigate the possibility of the application of an ultrasonic imaging equipment in correct diagnosis of the oral mucosal tissues. The equipment is composed of (1) an ultrasonic transducer, (2) an ultrasonic cell, and (3) a mechanical driving unit. The transducer generates ultrasonic waves of 20 MHz in frequency. The ultrasonic cell was equipped with a converting lens of 10 mm in focal length. The driving unit performs ultrasonic scanning three times a second. The resolution are 0.15 mm for distance and 0.27 mm for direction. The thickness of the oral mucosa can be measured at a unit of 0.1 mm by the electric caliper built-in. The ultrasonic tomogram of the oral tissues was displayed clearly on TV monitor. The contact pressure on scanning was 45.3 g/cm
2, small enough not to deform the tested mucosal tissue. The safety in clinical uses seemed to be assured in consideration of SPTA (20mW/cm
2). The ultrasonic imaging equipment satisfied the accuracy and the safety required for the oral uses with easy handling, and was evaluated to be applicable to diagnosis of the oral mucosa in preparing the edentulous prosthesis.
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Ikuhisa Maeno
1986 Volume 30 Issue 3 Pages
691-704
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The purpose of this study is to measure transmitted interproximal forces and to evaluate the contact relationships. Firstly, the development of a new measuring evice for forces between interproximal surfaces of teeth was aimed. Secondly, transmitted interproximal forces at the midline of maxilla were measured, employing the measuring device, when experimental separations were applied to interproximal areas between the central and the lateral incisor, between the lateral incisor and the cuspid, and between the cuspid and the bicuspid, respectively.
The following results were obtained:
1) The force transducer which was made by using piezo plastic film was very thin, and its thickness was 60 μm.
2) When the experimental separations were applied, the magnitude of transmitted interproximal forces increased. As the amount of separations increased, the magnitude of transmitted interproximal forces more increased.
3) Splinting a few teeth in the anterior segment increased the magnitude of the transmitted interproximal forces when the same amount of separations was applied.
From this study, it is suggested that the entire arch, consisting of all the teeth, may move in such a way that all teeth perform as a unit in a functioning whole.
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Seiki Imaoka
1986 Volume 30 Issue 3 Pages
705-718
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The present report discusses clinical application of our new simplified quantitative analysis method of masticatory efficiency by counting particles through a sieve system using patients with removable prostheses.
MATERIALS AND METHOD
1. Reversible and irreversible hydrocolloid impression material were used as the test materials.
2. As a basic investigation, 10 edentulous patients with removable prostheses and 5 persons with natural dentition were investigated.
3. Based on conclusion from test 1, and additional 25 edentulous subjects with removable prostheses, 5 with overlay dentures and 21 with removable partial dentures were analyzed.
RESULTS
1. By means of a size determining coefficiency, an arbitrary number of remaining 5 mesh particles was calculated. This method was found to be as effective as the gravimetric sieveanalysis on subjects with complete dentures.
2. The standard equation of natural dentition could not be applied to subjects with removable prostheses.
3. The standard equation of the subjects with complete dentures which are shown below could be applied on subjects with removable partial dentures.
Reversible hydrocolloid impression material:
Y=-1.060 X+32.844
Irreversible hydrocolloid impression material
Y=-1.287 X+41.992
(10 stroke chewing, 5 mesh sieve)
4. Masticatory efficiency of subjects with a few remained teeth and removable partial dentures on maxilla and mandible was almost the same as subjects with complete or overlay dentures.
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Part 2. The physical properties and fitness
Yoshihiro Aoyama, Takao Umi, Hiromi Gotoh, Takayuki Nakamura, Isao Kob ...
1986 Volume 30 Issue 3 Pages
719-723
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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Recently,
Visible light curing resin has been on the market. This type of resin has advantage that
troublesome technical process can be omitted and polymerization time can be greatly shortened in comparison with the conventional
heat curing resin. But, there are few research reports related to this resin. Then, in this study, we examined its
physical properties and fitness. As the results, it could be noted that hardness was changed by the visible light irradiation time. Furthermore, in the case of resin was separated and irradiated, gap between resin and mold was very small.
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Kiyomi Ohno
1986 Volume 30 Issue 3 Pages
724-733
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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It is very important to make sure of the mechanical behaviors of fixed prosthetic appliances in order to design them. Fixed prosthetic appliances on premolar are simulated to analyse by thy two dimensional models.
Those models are divided into 105 curved isoparametric quadrilateral elements, loaded with a statically concentrated vertical 1.0 kg load at the occlusal surface, and numeically analysed by the finite element method.
The results obtained are as follows:
1) The sysmatic analyses of fixed prosthetic appliances are easily and exactely performed by the finite element method in place of the former experimental method.
2) The fixed points in the finite element method are considered on the boundary line between periodontal menbrane and alveolar bone.
3) The analytical values are affected by the material properties of periodontal menbrane. And, Young's moduli of periodontal menbrane have larger influence than poisson's raitos. The stresses of dentin in the model are small as Young's moduli are large.
4) The modeling of the neighbour teeth is able to analyze fixed prosthetic appliance in dental arce.
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Hidetoshi Takada, Hironobu Sato, Hiroyuki Fujii
1986 Volume 30 Issue 3 Pages
734-737
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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In order to improve an esthetic of the clasp denture, the labial clasp arm on the anterior abutment was tried to be shorten in length. Its fair effect was clinically exemplified by the partially edentulous patients. The significance of a guiding plane on the abutments and a cross-arch sprint by the denture was discussed. Finally, it was suggested that the Kennedy's Class III partial denture could be designated as to be the most indication for this application.
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Kazuyoshi Yoshimura, Takatoshi Onoe, Nagataka Nakamura, Eiko Mushimoto ...
1986 Volume 30 Issue 3 Pages
738-744
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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This study was undertaken to clarify the proportional distribution of bacterial flora in denture plaque in order to decide whether relationship between Candida and onset of denture stomatitis could be shown or not.
The results obtained were as follows:
1) The bacterial flora in denture plaque was predominated by facultative Gram positive cocci and rods. The flora in denture plaque was similar to a large extent to that in dental plaque excepted for the percentage of anaerobes.
2) The correlation between the degree of denture stomatitis and the viable counts of Candida could not be shown. The proportion of Candida in the total viable counts had a same tendency of that relationship. But positive correlation could be detected between the degree of denture stomatitis and the isolation frequency of Candida.
3) The proportion of Candida in the total viable counts on full denture was significantly greater than that on partial denture (0.01<P<0.05).
4) There was no major difference in the proportional distribution of flora between male and female or among the different age groups.
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Concerning the Effects of Complete Denture on Facial Contour
Akihiro Miwa
1986 Volume 30 Issue 3 Pages
745-765
Published: June 01, 1986
Released on J-STAGE: August 10, 2010
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The restoring, by means of denture prosthodontics, of the dento-facial morphology, which has been deformed as a result of the loss of teeth, is not only effective in recovering the lost functions but is also regarded as one of the important clinical problems yet to be solved. And the author believes that, as the first step in an argument about esthetics, it is essential to grasp, qualitatively, quantitatively and objectively, the changes brought about in the facial contour following the insertion of complete denture.
So, the author, using the moire topography, conducted this study for the purpose of making a comparative study of the changes made in dento-facial morphology after insertion of complete denture and the relationship between the denture and the facial contour.
As a result, some conciliatory action to respond to the changes in the upper lip following the insertion of the maxillary denture was observed in the lower lip, and the effects were found to consist largely of that of the maxillary denture, and the effect of the flanges was considerably larger. Furthermore, the changes in facial contour resulting from insertion of the denture were evident especially in the periphery of the upper lip but not so much in the lower portion. But it was suggested that the changes occurring to the lower jaw played an extremely important role in relation to the entire balance between the upper and the lower portions of the face and that those changes were vastly responsible for the recovery of the facial appearance.
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1986 Volume 30 Issue 3 Pages
785
Published: 1986
Released on J-STAGE: August 10, 2010
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