Complete dentures were provided for the patient who had undergone the dreadging method for the treatment of large ameloblastoma.
The patient's masticatory function was evaluated periodically by observing mandibular movements during chewing peanuts, analyzing masticatory rhythm, and through a questionnaire listing 35 different foods. Also, the sensory threshold of the mucous membrane was checked at a number of locations on the alveolar ridge.
As the result of those evaluations, the dentures were shown to have been worn succesfully for up to 12 months. The patient was satisfied in both function and aesthetics. The sensory threshold was higher than the average of the normal control group.

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The purpose of this series of studies is to search for an effective gypsum hardener. In the present study, we picked up a new gypsum hardener, Plaster Aid^®. This hardener was applicated to two kinds of dental stones and the effectiveness was examined mechanically and dimensionally. In addition, the influence of soaking in water was also studied.
The following results were obtained.
1. Compressive strength, surface hardness and marginal strength of die stones after application of the gypsum hardener increased 1.5-2.0 times than those before application. After soaking in water, both compressive strength and surface hardness decreased, but the specimens applicated with the gyspum hardener were less influenced.
2. Surface accuracy of Plastone-L after application increased, and that of Vel-mix Stone decreased.
3. Film thickness of Plaster Aid^® was so thin that dimensional change of stone dies could not be detected.

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It is said that ultrasonic energy is effective in reducing retentive forces of dowels cemented to root canals. However, it is still not clear to what degree the retentive forces actually become reduced. Therefore, we started to measure retentive forces of dowels after applying of ultrasonic vibration. In this study, four kinds of cement, zinc-phosphate cement, carboxylate cement, glassionomer cement, adhesive resin cement, were used.
Results were as follows:
1. The retentive forces of dowels become 1/3-1/2 values after 3min. Ultrasonic vibration, except when the adhesive resin cement was used. Glassionomer cement showed the highest reduction rate, and zinc-phosphate cement and carboxylate cement followed it. Adhesive resin cement indicated the lowest reduction rate.
2. Until the first 1.5min. vibration, the reduction rate of glassionomer cement was actually lower than that of zinc-phosphate cement and carboxylate cement. Glassionomer cement could be considerably resist until the occurrence of the initial crack of cement, but after that the destruction would progress very quickly.
3. Dowels cemented with zinc-phosphate cement could be easily removed by adding 5-10 min. vibration with an aid of some auxiliary tools.

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The aim of this study is to clarify the microbial constitution of denture plaque with the adoption of the anaerobic glove box system. Anaerobic incubation of the samples taken from five edentulous patients (74-80 yr-old) always gave a higher recovery than aerobic one, suggesting that conditions in the plaque were anaerobic. Of total 185 isolates, 90 (49%) were obligate anaerobes, and the predominant bacteria were among Veillonella (23%), Bifidobacterium (7%), Lactobacillus (5%), Actinomyces (5%) and Eubacterium (3%). Among facultative isolates (51%), Streptococcus (31%) and Lactobacillus
(16%) were common. No strains of Candida were isolated. The bacterial composition of denture plaque was somewhat different from that of plaque on teeth.

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The purpose of this study was to estimate the occlusal contact area of completedenture wearers. The subjects were 72 patients, treated 5-10 years ago at students' clinic of the Tsurumi University, School of Dental Medicine. The occlusal contact area was measured with white-silicone.
Results
1. The average of the occlusal contact area including thinner white-silicone film than 50μm was 30.3 mm².
2. For the occlusal contact area, there was not significant difference between porcelain and resin artificial teeth.
3. Comparing with each masticatory side, there was not significant difference for the occlusal contact area.
4. Comparing with each progressing years, the occlusal contact area was the largest in 9 and 7 years of wearing period.
5. The occlusal contacts in anterior segment were observed in 33.3%.
6. Comparing the measured value of occlusal contact area with 5 years and 10 years wearing
period, there was not significant difference in each patient.7. There was significant difference in the occlusal contact area between the group that hamade a diagnosis to renew dentures and not.

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To clarify the dietary intake of full denture wearers, a hundred and ten wearers with upper and lower full denture were investigated by the questionnaire on the acceptability for chewing.
The following results were obtained.
1. The difficulty of chewing a hundred kinds of foods were determined numerically (0 to 100).
2. A table including twenty kinds of foods for full denture wearers was set up to scorerize the chewing ability of each wearer.
3. The score of chewing ability was well related to the acceptability for chewing function.

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Crossliked plastic denture teeth have been used clinicaly in order to improve the poor wear resistance of conventional acrylic denture teeth. We suggest that highly crosslinked denture teeth are possibly disadvantaged compared with conventional ones, when considering the adhesion to denture base and impact resistance. The purpose of this study is to evaluate the impact resistance of crosslinked and conventional plastic denture teeth and porcelain teeth. The impactions were given repeatedly to the central fossae of the artificial teeth with the impact test machine. The thickness were 1.4, 1.0 and 0.4mm. The numbers prior to fracture were read as the impact resistance.
The results of the impact tests showed the highly crosslinked denture teeth became weak according to decrease of thickness but they showed the same toughness as the conventional ones when they were thicker than 1.4mm.
It was evident that the denture base resin beneath the artificial teeth plays the role of shock absorber against the impaction.

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Tongue movement of complete denture wearers was examined for/s/and/&int/by meansof dynamic palatography. The data as well as those changes with day were compared with those of normal speaking subjects with natural dentition.
1. Tongue ofcomplete denture wearers contacted with the hard palate sooner than that of the normal speaking subjects did, but the timing of forming maximum constriction at the anterior part of the hard palate was the same, whereas the timing of releasing the maximum constriction was later in the former.
2. Tongue movement of complete denture wearers was subjected to be under the influence of the adjacent vowel in both temporal and spatial aspects, particularly at the on-gride of the fricative.
3. The tongue-palate contact patterns for the maximum constriction had specific left-right asymmetries in each subject, which showed no significantchanges with day.
4. Tongue movement of complete denture wearers showed specific temporal asymmetries in each subject which didn't change with day, and tongue moved slightly at the midtime of the frication, the tongue tended to move awayfrom contact.
5. Variability of tongue-palate contact patterns for the maximum constriction became smaller with day, which can be used to estimate the degreeof speech adaptation to the denture.

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Five testfoods, kamaboko, raisin, peanuts, beefjerky and a piece of chewing gum (control), were used to investigate the characteristics in masticatory movements.During unilateralmastication of each food, surface EMGs from the bilateral masseter (Mm) and posteriortemporal (Tp) muscles were recorded simultaneous with MKGmotions in twenty normal subjects.
The swallowing threshold of each food were also obtained.
The results obtained were as follows:
The swallowing threshold did not differ significantly among the test foods.
The harder and/or morefibrous the food was, the longer occluding phase time and the wider chewing vectors in MKG were seen.
Also, early onset of the chewing side Tp and increased activities in EMGs in the chewing side Mm were seen.
Chewing rhythmicity was higher in soft gum and raisin, and lower in kamaboko, peanuts and beefjerky.
In conclusion, it might be supeculated that the masticatory movement of softgum and raisin would be controlled more peripherally, while the other test foodsrather centrally.

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The purpose of this study is to compare the tensile strength of Ni-Cr base metalpresoldered joints, soldered by focused energy of infra-red (Infra-red soldering) with torch soldering technique. The results indicate the following.
1. The tensile strength of presoldered joints, soldered by Infra-red soldering isstatistically stronger than presoldered joints, soldered by torch soldering (α =0.01).
2. In case of torch soldering joints, porosities appeared to have a greater tendency than Infra-red soldering joints. Torch soldering joints porosities are seven times as many as the other.
3. Correct tensile strength (Maximum Load: Kg/Sectional area of specimen-Porosityarea: mm²) of presoldered joints, solderedby both method are similar.
It means that, tensile strength is correlate closely with certainly soldering area.

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The purpose of this study is to analyze, using CIELAB color system, the range ofgingival color variables in healthy gingiva of the maxillary incisor region.
Results indicated:
1. Color differences (dE) among the bilateral attached andmarginal gingiva of the incisor and lateral incisor regions were under 2.0. However, the attached and marginal gingiva of the canine regions were about 2.88 and2.45 respectively. The papillary gingiva was over 2.0 in each region.
2. Compared to the incisor region, an increase in chromaticness and hue a*, b* with a decrease in lightness was observed in the attached, marginal, and papillary gingiva of the lateral incisor and canine region. The range in dE was from 2.28 to 3.36. In the attached and papillary gingiva, dE between the incisor and canine region was significantly bigger than the incisor and lateral incisor region.
3.Decrease in chromaticness, lightness, and hue a*, b* was observed from the marginal to papillary gingiva, and dE was from 3.13 to 3.71 with a high being in theincisor region.4. Increase in chromaticness and hue a*, b* with a slight decreasein lightness was observed from the attached to marginal gingiva, and dE was from2.25 to 2.75.

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The purpose of this study is to investigate the effects of inflammation on the color variable contents of the marginal gingiva and to analyze its relationship to capillary areas, from the standpoint of gingival transmission.
Transmissionof a clinically healthy marginal gingiva was examined using two black and white colored chips, and measuring the gingival color of the inflammed areas. Furthermore, the subepithelial capillaries were photographed with the oral biomicroscope.
Results showed inflammation to cause a decrease in lightness and hue b*variable, and an increase in chroma and hue a* variable. The color elements which showed a strong correlation to dE were in the order of da*, dL*, and db* respectively. This relationship was most evident among the high transmissional gingiva. In addition, the relationship of dE to increase in capillary area varied in accordance to gingival transmission.
In conclusion, a certain pattern among the color variables and elements which showed a high correlation to dE was observed. Furthermore, it can be concluded that gingival transmission is an important item in evaluating the effects of inflammation on the color variables of marginal gingiva.

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One hundred temporomandibular joints of 50 adults with normal occlusion were studied using a cephalometric laminagraph“Sectograph”.
The results were as follows:
1. The mean depth of the mandibular fossa was 8.7 mm; the anteroposterior length, 19.0mm; the anteroposterior length of the frontal area of the mandibular fossa, 10.3 mm; the anteroposterior distance at the middle level of the depth of the mandibular fossa, 10.8 mm. The frontal area of the mandibular fossa was 41.7 mm²; the rear area, 51.1 mm².
2. The salient width of the sigmoid curve of the frontal wall was 2.0 mm; the upper curve, 0.8 mm; the lower curve; 1.2 mm.
3. The inclination of the frontal wall to Frankfort horizontal line was 40.4° the rear wall, 35.2°. The radius of the circumference on the upper curve of the frontal wall was 5.6 mm; the lower curve, 8.1 mm
4. The salient width of the rear wall was 0.8 mm. The radius of the circumference on the rear wall was 11.6 mm.5. The anteroposterior width of the condyle was 9.5 mm, the width of the frontal region of the condyle divided by the condylar top, 3.8 mm.
6. This study established the standard size of T. M. J. in the sagittal plane, and makes possible the detection of abnormalities. It also established the basis of mean-value articulator.

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Fracture of an acrylic denture base has been a problem for all dentists and dental laboratory technicians.
We have previously reported that the most effective reinforcement could be obtained when athin metal plate were affixed to the tensile side of acrylic resin with an adhesive resin.
In this paper, we report the effect of a swaged metal plate reinforcement of maxillary denture.
The results were as follows:
1. When a load was applied to the molar region of maxillary complete denture, the incisal papillae and posterior palatal area of denture base were the region of tensile strain, and labial and central palatal area were the region of compressive strain.
2. The strain was reduced if the metal plate was affixed to the polishing side of the anterior palatal area of denture base.
3. The reinforcement to the denture base resulted in 36 percent to 58 percent decrease in tensile strain in the incisal papillae area, and in 90 percent to 93 percent decrease in compressive strain in the plicae palatine area.
From these results, we conclude that the metal plate reinforcement is an effective technique for improvement of the flexural rigidity.

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The purpose of this study was to compare the dimensional accuracy of thermoplastic impression material Adaptol with that of other impression materials by computer simulation. The impression materials used for comparison with Adaptol were polysulfide rubber base and irreversible hydrocolloid impression material. To investigate the accuracy of impression material, master model and standard plaster model which adapted accurately to master model were used in this study. After taking impression of m ster model with each kind of impression material, stone casts were made. Then the contour of stone casts and the standard plaster model were measured with profile projector and the data of the measurement were recorded with personal computer. Vertical displacements by placing the standard plaster model on stone casts were measured with personal computer. The following results were obtained.
Adaptol indicated same degree of accuracy with polysulfide rubber base impression material and indicated better accuracy than irreversible hydrocolloid impression material.

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The purpose of this study is to estimate the change of the intermaxillary distance of the intercuspation on the molar followed with the variation of the occlusal contacts and the occlusal force.
Fifteen subjects with normal occlusion were organized into the following three groups:(1) The complete dentition group;(2) The double crown at the first molar group;(3) The first molar missing group.
Using IP-checker and EMG activity, the variation of the molar intermaxillary distance on the occasion of changing the occlusal contact and the occlusal force were measured.
The following results were obtained.
1. The intermaxillary distance of the molar intercuspation was affected by the variation of the EMG activity (occlusal force).
2. The change of the intermaxillary distance under the occlusal force was very different between the disappearance of the occlusal contacts as to the bridge included the last tooth and that of the first molar.
3. For this reason, the bite taking of bridge must be investigated from the new point of view.

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The objective of this study was to examine the kinetics of mesenchymal cells derived from the periosteum to apatite particles with autoradiographical evaluation using tritiated thymidine. A circular hole 4.5mm in diameter was made in each rat's parietal bone. Apatite particles were implanted on one side as the experimental group, while the other was left empty as the control group. 1.0μCi/gram body weight of tritiated thymidine was injected intraperitoneally 1 hour before the rats were sacrificed, and 12 rats were sacrificed from 6 hours to 28 days after operation. On the other group, to clarify cell differentiation of labeled cells, 3.0μCi/gram body weight of tritiated thymidine was injected intraperitoneally at 4 days afterthe operation and sacrificed at 28 days after the operation. Percentage of population labeling gave a highest value at 2 days after operation at each measured area, and was slightly higher inthe experimental group than in the control. The labeled cells were mainly seen close to some cells but away fromthe bone surface and the apatite particles. From the results of long term labeling, the labeled cells were seen in the newly formed bone around the apatite particles and in the area where there was no bone formation, the labeled cells were seen in the surface of the apatite particles. From these results, it is suggested that bone formation at the surface of the apatite particles originated from the osteoprogenitor cell in the mesenchymal cells which is derived from the periosteum differentiated to osteoblasts.

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It was the purpose of this investigation to study the general stress distribution in the abutment teeth and their supporting tissues of a semi-fixed or a fixed bridge, which was connected with the tilted second molar and second premolar, using three-dimensional photoelastic stress analysis technique.
The following conclusions were obtained;
1. The tilted second molar's supporting tissues were subjected to the mesial stresses of the fixed bridge under load. While they were subjected to the nearly axial stresses of the semi-fixed bridge.
2. The second premolar's supporting tissues were subjected to the mesial stresses in relation to the second molar of the semi-fixed bridge under load.
3. The stress concentrations, which were seen in the cavity floor and distal wall of the tilted molar in the fixed bridge, were favorably altered by the placement of the semi-fixed bridge under load.
4. In the second premolar, there was no difference in the stress distribution between the semi-fixed and the fixed bridge.

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The purpose of this study was to compare pressure sensory mechanisms associated with implant dentures with both natural teeth abutments and implant abutments which have no periodontal membrane. With the von Frey feather stimulation technique we measured axial tactile sensibility of fourteen subjects with a total of nineteen implant dentures and compared results with those obtained from thirteen conventional bridges, four splinted mandibular posterior teeth, and all splinted mandibular teeth in ten normal subjects. We also measured the tactile sensibility of other prosthetic appliances in subjects with implant dentures.
For the fixed conventional bridge, the minimum tactile sensibility was 9.7 g, maximum was 21.4 g, and the mean was 13.5 g; for the four splinted teeth the minimum tactile sensibility was 7.6 g, maximum was 12.0 g, and the mean was 9.5 g. When all mandibular teeth were splinted the minimum tactile sensibility was 9.7 g, maximum was 12.0 g, and the mean was 10.2 g. Value obtained for the implant denture minimum tactile sensibility were 7.6 g, and the maximum was over 119.9 g. Twelve of the implant dentures of the nineteen tested had the same tactile sensibility as the conventional bridges. In seven of the eight subjects with an implant denture and another prosthetic appliance there was no difference in tactile sensibility between the implant denture and the other appliance.
These results suggest that when the tactile sensibility associated with an implant denture is measured, overall sensation created by the prosthesis must be considered in addition to local stimulation caused by the implants.

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The cleaning ability of five denture cleansers using Candida adhered acrylic an fungicidal effect of each cleansers were studied.
The results obtained were as follows.
1. After treatment for seven hours with denture cleanser A, B, C or D, the percentage of remaining cells on the acrylic were 0.002, 0.6, 0.7 or 1.9%, respectivery. In the case of treatment with cleanser E, forty three per-cent of cells were still remained on the acrylic.
2. The time for sterilizing of 2.0×10³/m/ of C. albicans by cleanser A, B or C were 15, 30 and 45 min, respectively. Treatment with cleanser D needed five hours for sterilizing of C. albicans. After seven hours treatment with cleanser E, the number of survived cells were 3.2×10² cells/m/.

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The purpose of this study was to evaluate the effectiveness of the lingual bladed tooth in the practical use. The questionnaires were then sent to 36 patients wearing complete dentures with lingual bladed teeth.
The following results were obtained through the answers received from 23 among 36 patients and several recalled patients:
1. The lingual bladed tooth seemed to be effective for mastication, especially excellent in ability of cutting food.
2. By wearing the denture with lingual bladed teeth, crushing type of foods such as a piece of hard buiscuit and okoshi (millet-and rice cake), and shearing type of foods such as kamaboko (a piece of boiled fish paste), a piece of raw cuttlefish and abalone became to be masticated more easily, but type of sticky foods such as zouni (rice-cakes boiled in soup) and a piece of chewinggum were little effective.
3. Lingual bladed teeth seemed to be most suitable when the setting position of artificial teeth were decided through a neutral-zone technique, because they were arranged by the linguali zed occlusion.
4. The lingual bladed tooth seemed to exhibit more effectiveness in such patients who had good alveolar ridges and were given stable occlusions.
5. In patients who had poor ridges and unstable occlusions, it seemed that the lingual bladed tooth should not be used because of more frequent soreness in the patients.

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There are two types of cone and particle in hydroxyapatite ceramics implant (HAP) applied to the fresh extraction socket.
In this study it was investigated macroscopically, microscopically, radiologically and morphologically, which form of cone or particle is more effective to prevent the alveolar ridge from bone resorption. In the left and right premolar region of mandibular ridge in the same dogs, the ridges submerged cone type HAP (C-HAP) and particle type HAP (P-HAP) respectively were compared with the ridge which only tooth extraction (Ext) was done, and furthermore the ridges submerged C-HAP and P-HAP was compared each other.
The following results were obtained.
1) This HAP have biocompatibility with the bone. 2) The C-HAP was more effective to preserve the contour of the alveolar ridges than the P-HAP. 3) There were free particles from the bone near the alveolar crest in the ridges of the P-HAP, and the bone fracture at the alveolar crest brought about more frequently in ridges with the P-HAP than the ridges with C-HAP and Ext. 4) The bone fracture and the presence of the free particles of alveolar crest result in continuous bone resorption and more change in the contour of the ridge with P-HAP than with C-HAP.

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The purpose of this study is to quantitate the movement three-dimensionally and consecutively as well as to evaluate the stability of the maxillary complete denture during masticatory movements. Firstly, a system for measuring the amount of the movements of maxillary complete denture was developed. The detail of this system was reported previously.
Movements of maxillary complete denture of 5 edentulous patients during function were examined with this system. Factors affecting retention and stability of complete dentures were also investigated. The results were as follows:
1. During tapping movements, the denture moved upwards and forwards on the whole. The amount of denture movements in the incisal region was larger than that in themolar region.
2. During masticatory movements, the denture moved upwards and forwards on the chewing side, but downwards and backwards on the nonchewing side in the molar region. In the incisal region the denture moved upwards and towards nonchewing side.
3. It was possible to divide the periods of mastication into two parts in accordance with the change of the amount of denture movements.
4. Hard food made the denture rotate remarkably.
5. The denture movements were affected greatly by food-hardness, the jaw closing path and the shape of alveolar ridge. But the correlation between static retentional force and denture movements was not significant.

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