We investigate an adequate method for clinical application of a laboratory-made stud attachment reported formerly. This study was taken to know effects of kinds of metal alloys used for this attachment on its fatigue. 4 kinds of alloys and 14 kinds of assemblies were selected for the male casts (undercut of 0.25mm) and the female wrought wires (diameter of 0.8mm) of 5mm and 7mm length. 10, 000 cycles of engaging and disengaging induced different fatigue in relation to respective characteristics of alloys.
The results:
1. Initial retentive force in Co-Cr female is approximately 1.6 times amounts of the one in Pt-Au and 14K female which is approximately 1.1-1.2 times amounts of the one in Pd-Ag female. The initial retentive force in 7mm length is approximately 1/2 amounts of the one in 5mm length.
2. Abrasion of male, deformation of female and strain hardening of male and female affect on the consequent decrease in retentive force.
3. Strain hardening seems to induce decrease in abrasion of male and decrease in flexibility of female.
4. Decrease in retentive force is caused mainly by abrasion of male.

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The purpose of this study was to investigate the relationship of lips to maxillary anterior teeth of normal dentulous subjects. This relationship will help to determine proper functional and aesthetical anterior tooth arrangement for prosthesis.
Seven selected pointts were placed on the surface of lips and three points were placed on the labial surface of the anterior teeth of 96 subjects.
The coordinates of these points were surveyed with incisal point and maxillary cuspid as the origin by 35mm nonmetric SLR camera as a three dimensional measurement system.
The findings were as follows:
1. When the incisal point was taken as the origin of the three dimensional coordinates, the coordinates of labrale superius were (-0.2, 12.7, 10.1mm), the coordinates of labrale inferius were (-0.2, -7.1, 11.3mm).
2. When the each maxillary cuspid point was taken as the origin of the three dimensional coordinates, the coordinates of the left corner of the mouth were (-5.8, -5.4, 4.4mm), and the right corner of the mouth were (6.1, -4.8, 4.3mm).
3. In the X-coordinate, the shift of cuspid point and the ala of the nose was on the average 0.3mm on the right side and -0.7mm on the left side. When viewed from the frontal aspect these two points were almost coincidental.
4. The mean measurement of distance between cuspid points was 39.1mm, and the average distance between the corners of the mouth was 51.2mm. These two measurements showed a significant correlation.

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We tried to embed HY-preparation with the zinc oxide eugenol cement as the base material to the inner surface of denture base to which the abutment might contact. We reported that it was useful to prevent caries of the overdenture abutment teeth. But we anticipated solubility of the embedded HY-preparation might gradually decrease.
In this study we measured the F-ion solubility in the HY-preparation and examined the gradual change of its solubility in vitro, and examined clinically the caries activity of five subjects with overdenture and obtained the following results.
1) The F-solubility in both distilled water and artificial saliva almost had the same increasing tendency.
2) The F-solubility of the preparation, with zinc oxide eugenol cement in powder-liquid ratio of 6: 1 and 12: 1, had almost the same increasing tendency.
3) The solubility of HY-preparation to artificial saliva per day was larger in the early stage and gradually decreased thereafter, but after 24 weeks the solubility was almost nil. The solubility period of R2-group with larger surface area was longer than that of R1-group.
4) We examined clinically caries activity with the Cariostat. It was lower after 3 months than on the time we had embedded the HY-preparation in the cavity.

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The space of soldering gap was considered as one of the factors that affect the fitness accuracy of the soldering bridge. Three-unit posterior straight bridge was assembled by soldering with the second premolar and molar as abutments and the first molar as a pontic on the right mandible. The soldering gaps were made in three kinds; 50μm, 150μm, 300μm. The threedimensional distortion of both abutments to the pontic was measured, and the displacement and distortion as well as vectors were examined. The results are obtained as follows:
1. The direction of displacement showed a similar tendency even when the space of the gapwas changed.
2. Both the displacement quantity and S. D. values were smaller when the space was narrower, and a bridge with a wider space showed larger S. D. values.
3. As to the distortion, the occlusal surface was bent throughout the bridge and the distortion was observed in the direction of the cervical of the tooth. The S. D. value of the distortion was larger when the space was wider.
4. In terms of vectors, both the displacement quantity and the S. D. values were large when the space was 300μm. It is therefore suggested that the displacement quantity is difficult to be controlled when the soldering gap is too wide.

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With a view to clinically applying the Visible Light Curing Denture Base resin, the authors have conducted a series of basic studies. As a result, it has been concluded that some compositional improvements will be required of this resin because of such shortcomings as its amine smell and bitter taste. The authors, therefore, trially produced Visible Light Curing Denture Base resin by combining the monomers, sold on the market, in various ways. As for the monomers used in this experiment, the authors produced a mixture by first adding to the monomer sold on the market a combination of Cyclophosphazene monomer {4PN-(TF)₂-(EMA)₆} as a new type of dental monomer, and then further adding the PMMA polymer and the filler.
In the course of the studies made this time, the authors also trially produced a compound based on the composition of this resin. This compound, which possesses a large flow, was produced as relining material. A comparative study was then made of this compound and the Dentsply Triad VLC Direct Reline Material, which had recently been put on sale, with regard to the physical properties and fitness.
As a result of such comparative studies, it was found that the trially-produced relining material, as compared with the Triad, showed good values with regard to its mechanical property. As to the fitness, no gap was observed between the palate and the cast in the deepest part of the palatal cavity.

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The evaluation of the masticatory function as a whole is important in diagnosingTMJ dysfunction and in judging the effectiveness of various prosthetic treatments.
As a simple method to evaluate the masticatory function in complete denture wearers, the types of foods that can be eaten commonly by patients are often asked at the dental chair side.
In this respect, it is hoped to have more accurate and objective method. Thus, as the first step, choosing of an appropriate list of foods is necessary.
In this study, a questionnaire with a listing of 170 different types of foods was used. 30 complete denture wearers were asked to select an answer from the four categories (Ο-can be eaten, Χ-cannot be eaten, Δ-do not eat because I dislike it, _??_-have not eaten since wearing of denture) to each type of food.
The result suggests that the further considerations of food texture (hardness, viscosity, elasticity, adhesiveness), the cooking methods, and likes and dislikes should be included in making the test food list for the evaluation of the masticatory function.

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The titanium blade-vent implant coated with HAP·alumina, by the plasma-sprayed technique, were clinically applied for 30 patients.
Chronological assessments of them were given for 3 to 9 months after implantation; mobility of implant, pain after implantation, status of gingival tissue, bone resorption, bite force, etc.
The results certified that this type of implant had very good initial fixation in human jaw, and can be satisfactorily applied to daily clinic of implantology.

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Full balanced occlusion and lingualized occlusion of the upper and lower complete dentures were studied about deformation using a model programs of long term exercise of denture under similar conditions in vivo.
Deformation of the denture was analyzed by strain gauges placed on the middle line of the denture base after three hundred thousand times of lateral gliding movement in water at 37°C. The lateral gliding excursion was tested at three different distances (0, 0.5, 2.0mm).
This study showed that tensile strain in the centric occlusion and compressive strain during lateral gliding excursion occured at the central area of the dentures. The proportional increase of maxmum shear strain was brought about by the increase of lateral gliding excursions. The data suggested therefore that quality, thickness, and reinforcement of denture must be carefully designed if long lateral gliding excursion is needed.
With respect to two types of occlusions, lingualized occlusion was found to give less deformation and better distribution of stress as compared to full balanced occlusion at any length of duty time tested.
In conclusion, these results proved that the lingualized occlusion is superior to full balanced occlusion in terms of deformation and stress distribution.

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Previous studies have shown that SmCo₅ magnets can be used for overdenture retainer and that 3 different types of magnetic attachments are developed. One of the most significant merits of these magnetic attachments is that they can be available for prosthetically hopeless teeth-teeth with bone loss or large mobility. We have successfully used these magnetic attachments in more than 35 hopeless teeth for periods of up to 7 years. Here we introduce 3 typical cases among them. Radiographs of abutment teeth applied with magnetic attachments show alveolar bone improvement and this is to clear the usefullness of magnetic attachment.

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I studied the difference of coronal bucco-lingual contours influenced self-cleansing effect by food and easiness in mecanical cleansing, using the teeth coloring matter, and got the following conclusion.
About self-cleansing effect by food.
1. From the bucco-lingual side point of view, the rate of removing the coloring matter was higher in functional cusp side than in non-functional cusp side.
2. From the form variety point of view, in functional cusp side, according to high of contour decreasing, the rate of removing the coloring matter was higher. On the other hand, in non-functional cusp side, the evident defference was not observed. And the coloring matter remained at the cervical part in every form.
3. Form the food variety point of view, the evident difference was observed; the rate of removing the coloring matter was highest in boiled pork, next raw cucumber, and was lower in kamaboko and bread.
About easiness in mechanical cleasing. From the form variety point of view, according to height of contour increasing, the rate of remaining the coloring matter was higher.

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An eighteen year old female patient with cleft lip and palate underwent prosthetic treatment using a partial denture. Examination of electromyography of masticatory muscles, mandibular movement, masticatory efficiency, and articulation test were conducted periodically concerning restoration of oral function after treatment.
1. Examination revealed no occurence of decay in abutment teeth or gingival inflammation, nor any other particular problems even one year after denture placement.
2. Analysis of electromyography revealed a periodic increase to the integral value for maximum clenching the first month but stabilized thereafter. The integral value for chewing varied only slightly. Chewing time decreased slightly and masticatory rhythm stabilized with time. Silent period duration showed little difference before and after treatment.
3. An increase in the speed of rapid opening and closing movement was noted. In the gothic arch, pre-treatment forward movement on the right side was improved and now occurs smoothly. Concerning chewing movement, the distance of sliding contact at closing phase for chewing on the right side decreased, and although a chewing pattern translation from grindertype to chopper-type developed.
4. Masticatory efficiency improved from the second week, but the value itself was considerably smaller than for persons with normal dentition.
5. In the articulation test, these was a significant increase from a pre-treatment 67.2% to a post-treatment 84.8% which after one year rose to 87.3%.

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The report reviews the color determination of gingiva by a new measuring system and the accuracy of the system. Pathological change of gingiva has been determined and evaluated by personal experience of the researcher's eye. Realizing this points, the authers commenced a study of this problem and recently successful result has been obtained.
Gingiva, as a soft tissue, is not only unsteady but also uneven on the surface. There are two possible solutions to the problem; in the first place, we must describe each datum exactly, and the second place, we must obtain the data repetitionary. A new measuring system which was used in this study is the best of the countermeasures answering the request. We also performed the fundamental experiment to determine whether assumption used in the standardization is good or not. In this research, the strongest correlation was observed between measuring distance and the data, the most reliable distance was 0.05mm from the tip to gingiva.

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In this paper we deal with artifical tooth arrangement arch and classification method of the arch. Data are from 160 cases of complete denture fabrication for the student exercise in 1986. Fourteen points were set up at the denture models, five on upper and nine on lower, and variables were established as a line and degree among the points. We also establised a space area and inter-dental space diameter not to correlate strongly among the variables. The variables were inputted in NEC Computer Data Base and analyzed. Tooth arrangement model swere classified into eight patterns in the form. Since artificial tooth arch has a complicated structure, its analysis requires a special technique and extreme care must be taken to it. Roughly speaking, arch form was divided into three types as might be suspected. The first type of cluster was ovalum arch from, the second was triangle and the third was round in shape. Distal space of the lower canine presented any special abnormality. No apparent relation was observed between arch form and instructer.

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Bonding of porcelain, quartz and alumina was investigated using a silane coupling agent and carboxylic monomers together with MMA-TBB resin. Using MMA-TBB resin, porcelain pretreated with 3-trimethoxysilylpropyl methacrylate and 4-methacryloxyethyl trimellitate anhydride showed bond strength above 30 MPa after 2, 000 thermocycles. Silane lined quartz and alumina bonded with carboxylic MMA-TBB resin showed adhesive durability. Silane coupling agent and carboxylic monomer seemed respectively to be effective for bonding the silicon derivative and aluminum compound which were the main components of the porcelain.

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We embedded tannin-fluoride preparation with the zinc oxide eugenol cement as the filling material to the inner surface of denture base to which the abutment might contact, and reported that it was useful to prevent caries of the overdenture abutment teeth. But we anticipated the weakness of mechanical strength of the denture.
In this study we produced autopolymerizing resin containing the preparation, and the F-ion solubility, setting time, Knoop Hardness, adhesive strength and compressive strength were measured. The following results were obtained:
1) The F-ion solubility was increased as the mixing ratio increased.
2) Setting time was increased as the mixing ratio increased.
3) The values of Knoop Hardness from 10 to 50% groups were lower than that of 0% group, and there was no statistical difference between the values from 10 to 50% groups.
4) The values of adhesive strength of mixing ratio from 10 to 30% groups showed almost the same value as that of 0% group.
5) The values of proportional limit of compressive strength of 10 and 20% groups showed almost the same value as that of 0% group.

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In order to evaluate masticatory efficiency easily, the method of appreciation of chewing ability was determined applying the particle analyzer by TV measuring system (PLAMSYSTEM). Ten subjects with normal dentition were tested. The test food was two grams weight of peanut. After 10 masticatory strokes, the crushed particles remaining on 10 mesh sieve were measured. The sieve-analysis represented particles as the equivalent of sphere, therefore, in this study, particle size distribution was analyzed by the equivalent of diameter.
1. The particle size distribution showed a peak at 2-2.5mm diameter. In a part of large particles, the number of particles exhibited rapid decrease, and the particles above 4mm were few.
2. In the particle weight distribution obtained by calculating from the size distribution, the chewing ability were divided into three patterns according to the difference of the distribution in a part of large particles.
3. With increase of masticatory strokes, large particles were crushed selectively.
4. The ability of food crushing was observed clearly in the particle weight distribution, especially in the part of large particles.

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Masseter muscle cross-sectional images obtained by X-Ray CT Scanning were studied to assist in diagnosis of the stomatognathic function and evaluation of various prosthetic treatments.
The cross-sectional images of the masseter muscle of the subjects at rest and clenching at the level of subnasal point (subnasasion) and the basis of the cranium (basis craniiexterna) were obtained with computed tomography. For the analysis, the masseter muscle images were divided into two parts, an anterior part and a posterior part by a line drawn through the most forward point of the mandible (ramus). The area and length of each part were measured for all the subjects. Differences between the young and the older subjects were assessed with Student's t-test for unpaired data, and the Paired t-test for paired data at rest and clenching.
The results were as follows.
1) The bucco-lingual width of the masseter muscle and the cross-sectional area was smaller (53-54%) in the older than in the young subjects (p<0.01).
2) At clenching, there were very few morphological changes in the masseter muscle in older subjects.
3) Compared to the rest state, the cross-sectional area of the masseter muscle decreased at clenching (p<0.01), especially in the posterior part of the masseter muscle in young subjects.

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For making apatite implant easy to use clinically and characteristics of apatite being bony-ankylotic surely exhibit, the implant was devised so as to consist of the root portion to be embedded completely in bone under periosteum at the first operation and the abutment portion to be cemented to the root portion after excising corresponding mucosa after bone healing. Developed 2-piece implant is formed of the root portion having both the dense apatite outer tube and titanium-made flanged inner tube, being attached to each other with finepowdered apatite filled-cement through heat polymerization, and the titanium-made abutment portion. 2-piece implants were implanted in adult dog lower jaw bone for two weeks, five months and ten months, respectively, for evaluation of the tissue around the root portion.
Result:
1. On almost apatite surfaces of root portion, bone formed, and after five months of implantation, root portion and jaw bone were in a state of being united.
2. It was found that both the slight resin cement existing between the titanium flange forming the root portion top surface and the apatite outer tube and the titanium flange were harmless to the around tissue and did not inhibit the bony ankylosis of apatite part.

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In developing the expert system for designing removable partial dentures, the construction and enlargement of data base are indispensable.
The object of this study was to report on the process of constructing the clinical data base and its function within the expert system.
The data base in the system consisted of three main parts. They are the knowledge data base obtained from human experts and text books, the clinical fact data base collected from the oral examination or from the clinical experiments and the graphic data base for graphic outputs. Following effects were suggested by using above mentioned data bases.
1) By using data bases, the execution of the expert system program became faster and more efficient.
2) The design suggested by the expert system is more likely to lead to reasonable and practical ones.
3) Many denture designs and data of clinical cases would be stored and readily used as references for practical and educational purposes.

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The purpose of this study was to find out the prope time and degree of adjustment for removable partial dentures using konus retainers.
Experimental dentures were placed in 4 subjects and set to a height of 100μm. They were then measured for longitudinal and vertical displacement by a fixed microgap sensor placed within the oral cavity.
The results were as follows:
1) During a 7 day period, the vertical displacement was measured to be 71.5μm as an average.
2) A large displacement was observed in those dentures between the time of insertion to the 4th day.
The results of this study suggest that the denture using konus retainers was able to settle into proper position after a few days. It is thus advisable to allow a few days for readjustment after insertion.

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A method was designed to determine the mandibular positions during speech in which three phenomena, namely, -(1) the path of the mandibular jnovements, (2) the spectrogram of the voice, and (3) the voice sound-were simultaneously recorded on the same frame of 16mm motion picture films.
The method was applied to predict acceptable occlusal vertical dimention (O. V. D.) for a patient with mandibular prognathisrn before surgical correction.
The O. V. D. was gradually increased by setting resin blocks on the occlusal surface of the mandible.
At various O. V. D., the mandibular positions during pronunciation of/s, sh, m/were observed. As a result, it was found that the mandibular positions of each consonants were almost constant regardless of the difference in O. V. D. to some extent.
Within this range, the O. V. D. was increased and the mandibule was retruded to the esthetically ideal position by surgery.
Just before the operation, provisional bridges with guide pins and holes were cemented to keep predetermined intermaxillary relation during surgical retrusion of the mandible.
Two and six months after the operation, the mandibular movements during speech showed normal pattern and the precise intercuspal position was established.

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This study presented the visualizing method of occlusal contacts by means of the digital image processing system.
Silicone-black method was frequently used to examine transparent areas as occlusal contacts in clinic.
Silicone-black (Bitechecker, GC Co., Japan) had two images, which were transparent areas and teeth surfaces. Each image through CCD TV camera was memorized in the digital processing system. And then the new image was obtained that markings of occlusal contacts were superimposed on teeth surfaces.
This method makes it valuable to examine occlusal contacts in number, location, intensity and area.

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For the purpose of clarifying the relation between the retention and stability of the maxillary denture and proteins in palatine saliva, we have fractionated proteins in palatine saliva by means of 310% gradient SDS-PAGE method, and stained fractionated proteins including glycoproteins with silver.
Thirty four samples of palatine saliva showed 27 protein bands, and fifteen samples of palatine saliva showed 12 glycoprotein bands.
Estimated molecular weights of palatine saliva proteins were in a range from 33, 000 to over 1, 000, 000, while those of glycoproteins were in a range from 40, 000 to over 1, 000, 000. The glycoproteins which were thought to be most closely related to the retention and stability of the denture were clearly fractionated into 3 bands, and we named them bands a, b, d in order of their molecular weights.
In the protein bands which showed high percentage concentration were band a, b, d, 16b, 10.
In the glycoprotein bands which showed high percentage were band a, b, d, 9, 16b.
These six bands were thought to be major proteins conteined in palatine saliva.

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Laser welded material must have enough mechanical strength withstanding the biting impact and stress. In case of Ag-Pd-Cu-Au alloy, the mechanical properties proved to be changed by heat treatment. The heat treatment before and after welding influences the mechanical properties of welded material. The purpose of this study was to evaluate the influence of heat treatment for the mechanical properties of laser welded material.
Specimens, rolled sheets of 1.2mm thickness, were welded by a pulsed Nd: YAG laser, Test pieces were made of specimens with different heat treatment before and after welding, then tensile test and Vickers hardness test were performed.
The hardness of the weld by laser irradiation was higher than that of solution treated base metal. The tensile strength of the laser welded specimen was nearly equal to the solution treated base metal. And the welded specimen after ageing had nearly equal to or higher tensile strength than the soldered specimen. In the fractured surface of laser welding specimen by tensile test, the dimple showing the ductile fracture was observed.

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