The purpose of this study is to establish an index in adjustment of occlusal height of a cast crown by the silicone-black method.
Firstly, occlusal contact area in dentition was measured when occlusal height and proximal contacts of the molar tooth were varied. Secondly, validity of this index was investigated in adjustment of occlusal height of a cast crown.
The results obtained were as follows:
1) In case that any the second premolar, the first molar, or the second molar was an abutment tooth, occlusal contacts of the mesial tooth close to them came into being only when occlusal height of a crown was made high less than 100μm.
2) In case that any the first premolar was an abutment tooth, occlusal contacts of a contralateral one came into being only when occlusal height of a crown was made high less than 100μm.
3) It was found that phenomena of 1) and 2) were an useful index in adjustment of occlusal height of a crown.

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One hundred temporomandibular joints of 50 adults with normal occulusion were studied using a cephalometric laminagraph “Sectograph”.
The results were follows:
1. There were significant correlations of anteroposterior length, vertical range and area between the mandibular fossa and the effective condylar region. Therefore, the mandibular fossa and the condyle on intercuspidated position were assumed to be similar in shape.
2. Concerning the condylar position on intercuspidated position.
1) The shortest distance between the frontal wall of the mandibular fossa and the condyle was 2.1mm, and the shortest distance between the rear wall and the condyle was 2.4mm. Therefore, the condyle is closer to the frontal wall.
2) The frontal sectional area between the mandibular fossa and the condyle was 27.3mm2, and the rear sectional area was 29.4mm2. Judging from the sectional area, the condyle is located roughly near the center or the mandibular fossa.
3) The highest point of the mandibular fossa being made as a datum, the condylar top was 3.4mm lower and 0.4mm posterior. Therefore, the condylar top is located slightly posterior.
3. This study makes possible the estimation of the proper mandibular position for prosthetic treatment such as occlusal reconstruction. It also established data for diagnosis on T.M.J. disease.

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The right upper first molar was prepared as a test tooth for the outside abutment for a full cast crown in the random position (R. P.). The characteristics of the reduction and the total amount of time required for the preparation of the abutment were examined. In comparison with the results obtained in the home position (H.P.) by Ishizuka, the following results were obtained.
1. In terms of the effect of R. P. and H. P. on the form of the abutment, a significant difference from the indicated degree was noticed in the taper degree, particularly on the axial surface; the imaginary crown axis was inclined to the distal proximal side in R. P. and inclined to the mesial proximal side in H. P.
2. In comparison with the time required for the preparation of the abutment between R. P. and H.P., no large difference was noticed in the time of operation and the total time of the air turbine, while the time of non-operation in R. P. was about 1/2 of that in H. P.; the ratio of nonoperation time to total time in R. P. was about 1/2 of that in H. P.

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The right lower first molar is prepared for the outside abutment for a full cast crown in the random position (R. P.). In order to clarify the possible effect on the abutment form, the amount of reduction of the abutment was measured. In comparison with the results obtained in the home position (H. P.) by Koizumi, the following results were obtained.
1. A significant difference in the effect on the abutment, resulting from a difference in position between R. P. and H. P. was noticed in the taper degrees, especially on the axial surface; the imaginary crown axis was inclined to the distal proximal side, in the opposite direction from that in H. P.
2. In comparison with the time required for the preparation of the abutment between R.P.and H.P., no significant difference was noticed in the time of operation or in the non-operatingtime of the air turbine.

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Clinico-statistical observation of 87 patients with TMJ and muscle dysfunction whovisited the Ist Department of Prosthetic Dentistry, Univ. Hospital attached to the Facultyof Dentistry Kyushu University during 10 years and a half from April 1977 untill September 1987was studied.
The results were as follows;
1. The number of patients suffering from this disease tends to increase every year, and inlast 5 years this increment was remarkable.
2. Female was 4.8 times more than male. The patients in fifties (26.4%) was most of alland the next was in thirties (21.9%). Then the distribution showed double-curve.
3. On suffered side, left side was a little more than right side, but there was no significantdifference.
4. The incitation was prosthetic treatment in 40.2% of all and in 35.6% was unknown.
5. Initial symptoms and the chief complaint, the single symptoms was more than many onesand the pain of TMJ was the most usual symptoms.
6. In present symptoms, the pain was recognized in 60.9%, the noise in 59.8% and thedifficulty of opening the mouth in 33.3%.

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Recently patients demand their esthetics on their dentition more severely. Dentists have to reveal natural color on their metal ceramic restorations in limited thickness. The purpose of this investigation is to spectrophotometrically evaluate the effects by varying opaque thickness and shade.
Conclusion: 1. The masking effects by only opaque porcelain were adequate on all samples of 0.3 mm opaque thickness. Some were adequate and the others were inadequate on samples of 0.2 mm opaque thickness.
They were inadequate on all samples of 0.1 mm opaque thickness.
2. CIE Lab color coordinates of each opaque material were not so characteristic as they were told up to date.
3. The color of A 1 (D 3), B 1 and C 1 opaque materials was alike.

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Sixty subjects (42 subjects with dentures and 18 subjects without dentures) were participated in this study. Crevicular fluid flow (Periotron unit: GCF), gingival index (GI), plaque index (PH) and probing depth (PD) of 209 marginal gingiva around natural and crowned abutment teeth were measured to evaluate gingival condition.
The following results were obtained.
1. The GI, PII and PD in subjects with dentures were higher than those in subjects without dentures. The GCF in subjects with dentures was inclined to be high comparing with those in subjects without dentures.
2. The GCF, GI and PD of crowned teeth in the subjects with dentures were higher than those of natural teeth. On the other hand, the GCF, GI and PD of crowned teeth in the subjects without dentures were almost equal to those of natural teeth.
3. The coefficient of correlation between GCF and other indices (GI, PII, PD) were+0.66 (p<0.01), +0.38 (p<0.01) and+0.38 (p<0.01), respectively.

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The functional behavior of removable partial denture is destined to be transmitted directly to the abutment tooth as a stress via clasp because of most of its retention being dependent upon the clasp retainer. Therefore, the influence of the clasp on the behavior of the abutment tooth is supposed to be more important according to its designs.
Thus, using a bend strain measuring system according to 2 gauge Active-Active method developed previously by the Author and 4 kinds of clasp with a high applicability to cases of distal extention, the Author examined, on experimental models, possible difference horizontal stress on the abutment tooth according clasp designs.
The results are as follows:
1. Both clasp of Supra-bulge type with distal rest and Infra-bulge type with mesial rest exerted respectively to make the abutment tooth incline distolingually.
2. It was showed that the horizontal stress put on the abutment tooth reduced Aker's clasp, Wire combination clasp, Kratochvil I-bar clasp and Krol I-bar clasp in turn, and for the Infra-bulge type clasp was smaller than for Supra-bulge type clasp.

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When the occlusal force was applied to the bridge on molar region, accompanied with a defect of the supporting tissue of abutment tooth, which ranged from 0 to 2/3 of the root length, possible change in the stress distribution occurring in the residual supporting tissue was analytically examined using two-dimensional finite element method. Furthermore, radicular tooth accompanied with various defects of the supporting tissue was simulated by a two-dimensional and a three-dimensional models and was analyzed using two-dimensional and three-dimensional finite elemnet methods.
The following information was obtained:
1. The stress of the mesial supporting tissue of the most anterior abutment tooth increased most with a larger defect of the supporting tissue of the abutment tooth.
2. Additional abutment tooth was effective for the stress relief of the adjacent abutment tooth.
3. When the defect of the supporting tissue of the most posterior abutment tooth exceeds 2/3of the root, no difference in stress distribution of the supporting tissue was found between intension bridging and free end bridging with extraction.
4. Comparison of the analytical results of the two-dimensional and three-dimensional models revealed the approximation of stress values in the vicinity of root apex and largestress of the three-dimensional model in nearer approach to the dental neck.

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Simple excision of the epulis fissuratum results in loss of sulcus dept hand scar formation, hence the peripheral seal of full denture are obstructed. In order to avoid these condition, lyophilized porcine skin or dermis were used to excised surface for wound dressing, and treatment dentures were inserted one week after the operation which act as a splint maintaining sulcus depth. Furthermore, occlusal correction, which included to restore an optimal vertical dimension of occlusion of the old dentures, and correction of the extent of the tissue coverage by the old denture base were accomplished by modifying the old (treatment) dentures.
Consequently, it seems that loss of sulcus depth and scar formation were reduced. The ridge relation was improved, and this improvement faciliated the eventual registration of the jaw relation.
In broad lesion, it is difficult to correct the extent of tissue coverage by the resin bordermolding materials. Therefore, the extent of tissue coverage of old dentures without lesion by the impression technique before operation, and refitting the excised surface by instant chairside reline technique after the operation, it may be useful for the resolution of this difficulty.

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Following are the results of a study made on the influence to the prepared tooth form, when the abutment tooth preparation with full cast crowns are done for the Maxillar Left Fixed Prosthodontics three-unit bridge in Random Position. The prepared teeth arethe Second Premolar and the Second Molar (The“Second Premolar”is abbreviated to “5” and the “Second Molar”is abbreviated to “7”).
1. The reduced extent of occlusal surface was excessively large at 5 and 7 buccal cusps, while it was excessively small at Central grooves.
2. The reduced extent of axial surface was excessively small at 5 and 7 all surfaces.
3. The reduced extent of subgingiva tended to be shallower than the designated depth of 1.0mm at the all portions.
4. As for the degree of axial taper, its made steeper toward the buccal and distal surface both 5 and 7.
5. As for the relative degree of axial taper, it get the largest in degree on bothsides between5 medial surface and 7 distal surface.

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For this purpose, the stress distribution produced on the porcelain and resin cement layer of prosthetic porcelain laminate veneer crown on upper central incisor, under the different loads were applied to the normal coverage portion and the incisal edge portion at an angle of 45° or 0° to the tooth axis, were estimated in the present study with respect to the shape of the abutment tooth for the laminate veneer crown, by means of finite element method as well as model tests.
The results obtained were as follows:
1. When the load force was applied to the incisal edge of abutment tooth covered over the incisal edge by porcelain, the tensile stress in the porcelain and the maximum shear stress at resin cement layer were most distinct.
Furthermore load distribution was parrarel to the tooth axis, the highest tensile stress was produced in the porcelain.
2. The maximum shear stress at resin cement layer were dependented on the sites of the prosities in resin cement layer rather than the amount of them.
3. As for a model test, there was no risk of fracture of the porcelain under the load within 15 kg.

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The RPI bar clasping system devised by Kratochvil and Krol has been highly evaluated as a typical retainer of a lower extensional partial denture. However, since part of the approach arm, ranging from the junction with the skeleton to the distal end of an abutment tooth, is impacted at the denture base upon completion of the denture, the fulcrum of stress that is intended upon setting of the framework is removed to around the denture base and its vicinity, from which it is deduced that elasticity of the approach arm varies with the form of the denture base. To prevent changes in the elasticity, the Tubing method was devised and its effects were studied in experimental models. The clinical procedure was found to be very easy to handle, to be a practical method for improvement and to reduce markedly the physical effect of the denture base upon the clasp, having the following advantages as compared with the usual method:(1) it maintains reset of the arm to the designed position without any effect of the form of the denture base;(2) it induces a reduction in the lateral load to an abutment tooth;(3) it is partly helpful for reduction of metal fatigue of the clasp;(4) the feeling of the setting of denture is soft (according to a patient's impression).

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The Cera-Platin crown system using a special noble metal foil coping is well known as a new metal ceramic technique. We observed the effect of soldering and the micro configuration of the noble metal foil coping with a bunsen flame and a furnace using Renaissance Crown.
The results can be summarized as follows: I. There was no fusion, but only diffusion, with bunsen flames at 1, 000°C and 1, 050°C.
2. The pure gold layer fused, the pleats were soldered and a stable coping was formed in a bunsen flame at 1, 100°C.
3. In conclusion, there was little difference between the furnace and the bunsenflame with regard to soldering and the micro configuration of noble metal foil.

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Cephalometric laminagrams of T.M.J. under the mandibular movement were obtained “Sectograph”.
We researched the inclination on the condyle of the non-working side at the lateral movement.
At the lateral movement, the movement which the condyle of the non-working side was stipulated to the maximum eccentric position.
The subjects were one hundred temporomandibular joints of 50 adults with normal occlusion.
The results obtained were as follows.
1. The average of the horizontal condylar inclination at the lateral movement of the condylar top and center were between 45-47 degrees either mandibular lateral movement.
2. The correlation of the right and left side were not recognized at the small quantity of the lateral movement, but they were recognized strongly at the large quantity of the lateral movement.
3. Tendency of change in the translated inclination were divided four categories but, the condylar of the non-working side was engaged in bodily shift at the lateral movement.

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Part of the biting force is believed to be transmitted to the temporomandibular joint and cause interarticular pressure. In this paper, we shall examine bite-pressure during mastication and employ a method which estimates this pressure from mandibular displacement measured by the face-bow.
To ensure that interarticular pressure is accurately measured, mandibular displacement should only refer to this pressure. But previous studies have never mentioned this point. Its clarification required the following experimental conditions:(1) that the object bitten would not become deformed, (2) that the mandible would not bend, and (3) that tooth movement be prevented. Considering object size and location in normal crushing, we opted for the followings limitations:(1) that the object be located at the first molar, and (2) that the vertical dimension of the incisal point be less than 10 [mm].
We manufactured an intraoral appliance consisting of upper and lower metal clutches, which strictly limit tooth movement and mandibular bending. As an immovable object, a pivot was fixed to the clutch which satisfied the limitations referred to above. The experiments proved that the pivot moves a distance of less than 0.15 [mm] during clenching, which limits the accuracy of this method.

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The purpose of this study is to develop a rational fabricating system for determining retentive force of cast clasps. The radius of curvature of a circumferential clasp arm is considered to be one of the important factors affecting dynamical properties of cast clasps. In this study, a device for determining the radius of curvature and a computer system for Akers clasps and I-bar clasps were developed.
It was suggested to be very significant in partial denture designing, that the retentive force and the bending rigidity required according to various conditions around abutment teeth can be easily obtained by using a personal computer, and that the proper part of a commercially available clasp pattern required to fabricate cast clasps providing rational retentive forces can be determined in this system.

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Imprint culture from patients with denture stomatitis is a common method used to examine the relationship between localization of yeast colonies to inflammed mucosa area. However, this technique consists of problems such as;
1. negative effect on the growth of Candida due to the temperature of the agar.
2. the need of having to box the denture base.
3. difficultly of applying this technique to partial dentures.
Therefore, a modified imprint culture technique was developed to improve these problem.
The ability to detect Candida by the modified imprint culture technique was examined in regards to temperature of the agar. Results showed that this technique did not have such an important effect on the growth of Candida.
Thus, the modified imprint culture technique was found to have many advantages such as:
1. No influence by the temperature of the agar on the growth of Candida.
2. Easy application of this technique to partial dentures.
3. Easy aseptic handling.
4. No need of a boxing process on a denture base.
5. No reinforcements of the agar.
6. A shortened length in handling time.

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It is clinically well known that the secondary splinting is as effective as the primary splinting, using the konus-telescope crown. The purpose of this study is to investigate and to evaluate the displacement of the konus-telescope outer crown under the lateral loads of them, changing angles, heights and shapes of konus-telescope inner crowns.
The results were as follows:
1. The horizontal and vertical displacement of the outer crown were influenced by not so much the angle as the height of inner crown.
2. As for inner crown shape, the displacement of c.s.c. type outer crown was larger than that of konus-type.

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The tissue conditioner changes in its viscoelastic properties with time lapse after mixing. The purpose of this study was to investigate the flow of six commercial tissue conditioners (Coe-comfort, Hydro-cast, Shofu tissue conditioner, Soft-liner, Softone, Visco-gel) at 22±1°C by the parallel plate viscometer. The viscometer is to measure the spread radius of samples (a volume of 0.5cm³) between two parallel flat plates loaded by 1 kgf weight at 1, 10, 60, 100 seconds after loading had begun. Two types of measurements were taken. The first measurement consisted of mixing powder and liquid according to the manufacture's recommendations, loading the sample on the viscometer, and measurements taken at 3, 5, 7 minutes after mixing had begun. The second measurement consisted of mixing powder and liquid in three varieties of powder-liquid ratios, loading the sample on the viscometer, and measurements taken at 3 minutes after mixing had begun.
The findings were as follows;
1. Mixing powder and liquid according to the manufacture's recommendations, the spread radius decreased at 3 minutes in the following order: Hydro-cast, Shofu tissue conditioner, Viscogel, Coe-comfort, Soft-liner and Softone. The spread radius decreased at 5, 7 minutes in the following order: Hydro-cast, Visco-gel, Coe-comfort, Shofu tissue conditioner, Soft-liner and Softone.
2. As the powder-liquid ratio increased, all materials were more viscous. As the powderliquid ratio decreased, all materials were more fluid.

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