In this paper in order to analyze the stress distribution on human dry skull through a thermoelastic stress imaging method the observation patterns was compared with those of strain gage method and discussed. As a result, the following conclusions have been reached:
1. The thermoelastic stress imaging method allowed the measurement of the mandibular stress distribution upon positioning the bone similar to the in vivo mechanism.
2. It was found that stess distribution pattern through the thermoelastic stress imaging method was similar to those through the strain gage method.
3. It was considered that the thermoelastic stress imaging method was useless for measuring transverse stress or shearing stress.
4. It was possible to make up for defects of each of these by using both the thermoelastic stress imaging method and the strain gage method in combination.
These results showed that the thermoelastic stress imaging method may have an analyzing ability under the condition that is closer to the actual natural state than conventional methods.

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Under two conditions considering the direction and activities of the mastication muscle, we investigated the strain distribution on the loading or unloading side of mandible in cases where the loads were applied to the first premolar and first molar.
1. At the loading points, the amount of compressive strain directly below the first premolar tooth was larger than that directly below the first molar tooth.
2. In the external surface ranging from the ramus mandible to linear oblique mandible, the tensil strain was recognized, and the amount loaded at the first premolar tooth was found to be larger than at the first molar.
3. In the external surface of mandibular notch, the amount of strain was, when a hard force loading was applied, larger on the loaded side, as well as it was larger when a force loading was applied to the first premolar than when applied to the first molar.

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In order to clarify changes in the inner surface of posterior resin crowns in response to polymerization, changes in the contour of the inner surfaces of these crowns (1.0, 1.5 and 2.0 mm in thickness) under conditions of light polymerization or light and heat polymerization (heat polymerization) were determined by a three-dimensional measurement system, and changes with light polymerization were compared with those of heat polymerization. The results are summarized as follows:
1. Under conditions of both light and heat polymerization, the inner surface shrank at all measurement sites and the amount of shrinkage with heat polymerization was greater than that with light polymerization.
2. Under conditions of both light and heat polymerization, the amount of shrinkage was decreased in the region ranging from the occlusal surface to the dental neck, showing a claviform pattern. This tendency was marked under the light polymerization condition.
3. Dimensional changes were observed, i.e., -16μm with light polymerization and -28μm with heat polymerizaiton, at a site 6 mm from the occlusal surface, -11μm with light polymerization and -30μm with heat polymerizaiton at a site 8 mm from the occlusal surface, and -8μm with light polymerization and -27μm with heat polymerization at the dental neck. There were significant differences in dimensional changes between light and heat polymerization at the site near the dental neck on the axial wall.
4. When the thickness of the resin crown was 1.0, 1.5 or 2.0mm, the inner surface shrank at all of measurement sites. With the increase in thickness, the amount of constriction was increased.
5. When the thickness of the resin crown was 1.0 or 1.5mm, the amount of shrinkage was decreased in the region ranging from the occlusal surface to the dental neck, showing a claviform pattern. When the thickness was 2.0mm, the amount of shrinkage was almost fixed. The ten-dency to form a claviform pattern with the 1.0mm-thick crown was greater than that with the 1.5 mm-thick crown.
6. There were significant differences in all dimensional changes except height, at all measurement sites on the axial wall, between the 1.0mm-and 1.5 mm-thick crowns, and at all of measurement sites, except the occlusal surface, between the 1.0mm-and 2.0mm-thick crowns. There was a significant difference in the dimensional change of height between the 1.5mm-and 2.0mm-thick crowns.

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OXILYZER^®is a device to obtain acidic electrolyzed water from tap water. The purpose of this study was to examine to apply the electrolyzed water for dental region. To establish general rules for usage of acidic water (Aqua-oxidized water), the oxidation-reduction potential and chorine (·Cl)-concentration as factors germicidal effect, the efficiency to rinse the mouth and the germicidal effect against microorganisms were examined. Changes in the quality of Aqua-oxidized water the germicidal effect on some oral microorganisms and those with the passage of time on preseruative condition were also examined. The washing efficiency of alkaline water was measured simultaneosly.
The following results were obtained.
1. Aqua-oxidized water with pH below 2.7, O. R. P. over 970 my and the concentration of Clover 0.8 ppm had germicidal effect. Though the germicidal effect of Aqua-oxidized water was reduced by the existance of salivary protein, dilution the protein by rinsing the mouth for three times showed a sufficient germicidal effect on Streptococcus mutans and Candida albicans.
2. The germicidal activity of Aqua-oxidized water was reserved for one month when sealed and shaded in a dark container at 4°C.
3. The less the pH value, the more the solutional rate and the more the effect were obtained in the alkaline water.

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Stress analysis concerning the mechanical effects of cracks in roots on the tooth structure of the crack tips in the abutment tooth on the upper central incisor with a cemented dowel, depending upon the difference of the crack position and the conditions of supporting bone, in case where the tooth axis was loaded from the lingual side to the cracks at 45° was conducted by means of the two-dimensional finite element method. Further, effects of the cracks in roots on root fracture were examined by calculating the crack tip stress intensity factors K, for the opening mode and for the in-plane shear mode.
The following results were obtained:
1. The larger vertical cracks on the side around the dowel in the loaded lingual side become, when the loss of supporting bone is great and the dowel surface is configuration-threaded, the more liable are the cracks in roots to spread during the opening mode.
2. Parallel cracks on the side of the apex of the dowel are more liable to appear during the opening mode than during the in-plane shear mode, and there is little difference among the forms of the dowel.

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The purpose of this study was to inyestigate the effect of the periodontal sensation of canine teeth on lateral movement and masticatory movement in man. The mandibular movements of 20 healthy subjects were measured using Kyushu University 3-D movement analyzing system, before and after local anesthesia to upper and lower canine teeth.
The results were as follows.
1. The lateral movement was very stable before and after anesthesia. The stability was not affected by the periodontal sensation.
2. The chewing pattern and the chewing cycle did not alter before and after anesthesia.
3. In the group which showed small lateral displacement of the chewing path, the masticatory movement was not affected by the anesthesia.
4. In the group which showed large lateral displacement of the chewing path, the masticatory movement was not altered by the anesthesia.
5. In the group which showed intermediate lateral displacement, the amount of lateral displacement and gliding length in mastication increased after anesthesia. The amount after anesthesia was equal to that of the large lateral displacement group.
It was suggested that the lateral limitation existed in masticatory movement and the periodontal sensation of canine teeth controlled the amount of lateral displacement of mastication.

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This study was to investigate the stress distribution in the peripheral bone tissue of the post of the blade type implant under changing various bending positions by using two-dimensional finite element method analysis and the following conclusions were obtained: 1) As the bending position of the post of the implant being away from the cortical bone surface, maximum principal compressive strength value and its range were decreased. 2) In the relation of the implant body and its peripheral supporting tissue, stresses concentrated at the cortical bone in the bone contact condition. 3) In the relation of the implant body and its peripheral supporting tissue, stresses concentrated at the fibrosis tissue intermediating condition. Moreover these stresses spreaded from the cortical bone to the cancellous bone area. Therefore the design which must be bent the post of the implant, the bending portion should be away from the cortical bone surface.

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We examined the relation between the tooth guide in lateral excursion and habitual chewing side. Out of the 90 subjects studied, 45 had a chewing side preference (habitual chewing group), 19 preferring the right side and 26 preferring the left side. 32 subjects were randomly selected as the control from the subjects without chewing side preference. The data of working side guidance and balancing contacts in those groups were evaluated by principal component analysis. The following results are obtained:
1. In the control group, the working side guidance by cuspid and premolars was predominantly observed compared with that in the habitual chewing group.
2. The M-type guide of the cuspid was observed on both sides in the control group, while that in habitual chewing group was more predominant on the habitual side than on the opposite side.
3. The balancing contacts were considered to be influenced when the working side guidance was not confirmed clearly. The habitual chewing side may be the side with less balancing contact on the working side in mastication.
4. The features of tooth guide in lateral excursion had some similarities between the subjects with right/left TMJ symptoms and right/left chewing group. The above suggests TMJ symptoms may appear on the habitual chewing side.

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We tried to duplicate the shape of occlusal surface of artificial tooth using the CAD/CAM technique and to replace the occlusal surface of the plastic tooth of denture with gold alloy.
The present CAD/CAM system was composed of the three-dimensional shape measurement system (XYZAX PA 400 A, Tokyo Seimitsu Co. Ltd.), the personal computer (PC 98, NEC), and the computer aided engraving machine (CAMM-2, Roland D. G.).
The contour of occlusal surface of the molar artificial tooth was measured by stepping at 0.5mm intervals. Measured points were interpolated with the spline function to obtain as smooth a surface as possible. Those data were used to cut a methacrylic plate to a pattern of occlusal surface (acrylic pattern). To examine the accuracy of duplication, the space between the acrylic pattern and the plaster core of the artificial tooth was evaluated. The space was represented as the thickness of silicone rubber and measured by using the optical magnifier (Profile projector V-12, Nikon). The thickness ranged from 70μm to 290μm. It was suggested that a CAD/CAM system like the present one is useful to duplicate the occlusal surface of an artificial tooth.
More accurate duplication requires some improvements in the intervals of measuring the contour and cutting the acrylic plate.

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The aim of this study was to investigate the characteristics of masking porcelain for laminate veneer restorations.
In this experiment, three brands of masking porcelain were used. Transmission and reflection on the background (standard white board and discolored teeth color resin board) were measured.
The following conclusions were obtained.
1. Lights transparented through a thickness of 3.0 mm for Cosmotech and 2.0 mm for Clapearl and Lamina.
2. The color of background (standard white board and resin board) had great influence on reflection within a thickness of 1.0 mm.
3. At clinical thickness of masking porcelain, a value of a^*was similar to that of normal teeth, while values of L^*and b^*were higher than the that of normal teeth.

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The purpose of this study was to investigate the physical properties of Co-Cr alloys containing 0-10% titanium. The results were as follows: The solid and liquid temperature fell, the specific gravity decreased and the oxidation was repressed with addition of titanium. The value of Vickers hardness increased with addition of 4% upward titanium. The maximum contraverse strength value was shown in 4% titanium alloy. The maximum tensile stregnth value was shown in 6% titanium alloy. The maximum elongation value was shown in 2% titanium alloy.

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The purpose of this study was to examine the polymerization method suitable for the microwave-curing type denture base resin depending on the adaptability and physical properties of the resin while varing microwave irradiation conditions.
Under condition of microwave irradiation at 500 W, the resin was exposed to themicrowave for 2, 3, 4 and 5 minutes. And also under condition at 90 W, the resin was exposed to the microwave for 10, 15, 20, and 25 minutes. Irradiation was directed to mucosal side, occlusal side, and both sides. For two-stage polymerization, irradiation was first carried out at 90 W for 13 minutes and then at 500 W for 1.5 minutes from the mucosal side.
The results were as follows:
1. Better adaptability was obtained by irradiation at 90 W and two-stage polymerization than irradiation at 500 W.
2. Surface roughness of the resin was smoother in irradiation at 90 W and two-stage polymerization than irradiation at 500 W.
3. Irradiation at 500 W and two-stage polymerization produced high transverse strength and Knoop hardness than irradiation at 90 W.
4. Fewer internal poroes were observed with irradiation at 90 W and two-stage polymerization than irradiation at 500 W.
5. Low residual monomer was obtained by irradiation at 500 W and two-stage polymerization than irradiation at 90 W.

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The number of oral symptoms caused by psychosomatic disorder or nervous disorder seems to increase these days. It is necessary for dentists to examine psychologically aspect. The purpose of this study was to investigate the relation with oral symptoms and dental phobia between psychological factors. The questionnaire was given to two-hundred and sixty-six subjects (male: 108, female: 158). The questionnaire was composed of two psychological tests (MMPI Alexithymia Scale and State-Trait Anxiety Inventory) and oral examinations based on dental psychosomatic classification by Uchida and dental phobia examinations by Dental Fear Survey, etc.
The results were as follows:
1. It was suggested that alexithymia has a correlation with pains of temporomandibular joints, lack of adaptability of dentures and disturbance of mouth opening.
2. It was suggested that State-Anxiety has a correlation with dental phobia, pains of temporomandibular joints, sounds of temporomandibular joints, ringing in the ears, hypersensitivity of teeth and bruxism.
3. It was suggested that Trait-Anxiety has a correlation with dental phobia, a sense of incongruity of temporomandibular joints or oral incongruity and lack of adaptability of crowns and bridges.

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In this study we investigated the effect of two different dentin pretreatments on the retention of prefabricated posts and on the microleakage of the composite resin cores.
The dentin surfaces of both post space and root face of extracted human single-rooted teeth were treated with either 1) 37% phosphoric acid solution or 2) 37% phosphoric acid solution and then 10% sodium hypochlorite solution. Then, a prefabricated post (AD Post®, Kuraray Co.) was cemented with an adhesive resin cement (Panavia EX®, Kuraray Co.) after application of dentin bonding agent (Clearfil New Bond®, Kuraray Co.). And a composite resin core was built up with light-cured composite resin (Clearfil Photo Core®, Kuraray Co.).
The retention of prefabricated posts was measured after one day immersion into 37°C water, 5, 000 times and 10, 000 times of thermalcycles between 4° and 60°C of water bath. The microleakage was measured after 2, 500 times of thermalcycles between 4° and 60°C in 0.2% aqueous solution of basic fuchsin dye.
The results obtained indicated that phosphoric acid etching was ineffective both on the retention and on the marginal sealing of posts and composite resin cores. Meanwhile, removing of the collagen layer exposed by phosphoric acid etching (30 s) with sodium hypochlorite solution (60 s or 120 s) effectively increased adhesive strength of the adhesive resin to dentin, i. e. the retention of prefabricated posts significantly increased and the microleakage of the composite resin cores was significantly reduced.
These results were supported by SEM observation of interface between adhesive resin and dentin.

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The initial histopathological change in denture supporting tissue caused by covering with denture base without mechanical pressure for the palate of a rat was studied.
The purpose of this study was to reveal the relationship between the histopathological changes and three causative factors: non-pressure contact of denture base with palatal tissue, lack of physiological stimulation and lack of self-cleaning for palatal tissue.
The experimental denture base was designed to contact the palatal tissue of rat without any mechanical pressure and to transmit no occlusal force to the denture supporting tissue. The palatal tissue was examined histopathologically 4, 7, 10 and 14 days after the insertion of the denture base.
From the results of this study, it was revealed that non-pressure contact of denture base with palatal tissue and lack of physiological stimulation would not cause any inflammatory change or bone resorption in the denture supporting tissues except for the transient slight proliferative reaction in the epithelial ridges. Lack of self-cleaning for palatal tissue, on the contrary, was revealed to cause deformation of some epithelial ridges, decrease of the thickness of lamina propria mucosae in places and bone resorption.

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The objective of this research was to study the kinematical characteristics of the mandibular movement using a new method of analysis of jaw movements with six degrees of freedom. The full range of mandibular positions at the incisal point were recorded accurately by a digital type jaw movement analyzer. The results were as follows:
1. The three-dimensional movement space model was produced with 11, 620 jaw position data both at the incisal and condylar points.
2. The Z-value, which determines the upper and lower width of jaw movement space, was regarded as a useful parameter to represent the kinematical characteristics of the mandible.
3. The jaw movement characteristic curve for the Z-value showed a singular point at the condyle.
4. The condylar point was the most important point used to represent the mechanisms of mandibular movements in three dimensions.

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When a denture with plate is applied to recover the stomatognathic functions for prosthetic treatment, the plate can be a factor which causes new functional failures. However, the failures are often reduced or disappear gradually with time. This study was made to investigate how the failures of phonation and mastication caused by the experimental palatal plate (anterior/posterior plate) are reduced or disappear as days go by and the study was made in terms of the “fluctuation” of the standard deviations of speech time duration and chewing path. It was concluded that both standard deviations increased after insertion of the palatal plate but as time passed they approached those before insertion. The larger value (0.77) of the first canonical correlation coefficients obtained from the canonical correlation analysis between both standard deviations fall once after insertion of the plate, but as time passed the value for the anterior plates approached it before insertion at 14 days after insertion, the value for the posterior plates did not.

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The occlusal contacts are closely related with the stress distribution on the supporting tissue in complete denture wearers.
The aim of this study was to analyze the relation of the occlusal contacts to the stress distribution pattern on the supporting tissue under the lower complete denture. For this purpose, a three-dimensional finite element model was constructed with occlusion rim and residual ridge mucosa. The stress distribution was calculated with a computer under different loading conditions.
The results were as follows:
1. The stress distribution on the supporting tissue was uniform and the denture base settled perpendicular to the occlusal plane when the sum of the occlusal forces and vectors were localized near the center of the denture base.
2. The stress distribution on the supporting tissue was significantly altered and the denture base was displaced with rotation when the location of the sum of the occlusal force was on points moved antero-posteriorly or laterally.
3. The stress distribution on the supporting tissue by using the finite element method was similar to that obtained by using pressure sensors.

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In selecting and arranging artificial teeth, it is necessary to consider the relationship between the tooth and lips. The relation of high and low lip line to incisal edge has been a standard for the selection and arrangement of artificial teeth. However, form and movements of lips are variable because of their softness and elasticity.
The purpose of our investigation was to evaluate movements of lips three-dimensionally (3 D). We used the 3 D Image Scanner (3 D-VMR-201: Unisn Inc.) for measuring the surface shape of the face. This machine was capable to measure surface shape at high speed without touching the object.
We recorded and measured the surface shape of lips in function (smile, pronunciation etc). The movements of the measuring points were calibrated in order to compare each data of the surface shapes in different functions among the dentate subjects. Further, we examine the influence of prosthetic appliance such as bite raising assuming prosthetic treatment for edentate subjects.
The following results were obtained:
1. In function times, upper lip moves rearwards and upwards. Lower lip moves rearwards and downwards. Lower lip movements were larger than those of upper lip.
2. The influence of bite raising appeared mainly in upper and lower lip, and those of changing labial surface position appeared in upper lip and both corners of the mouth.

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This study was to investigate the effects of carbon-fiber (CF) or aramid-fiber (AF) cloth application and surface treatment as a means of reinforcing the denture base to the palate of complete upper resin dentures. The CF or AF cloths were incorporated by being sandwiched between the acrylic resin.
The mechanical strength of specimens, such as transverse and tensile strengths, were measured and compared with the reinforced specimens and the plain acrylic resin specimens, and the following results were obtained:
1. The experiments show clearly that the strength of the reinforced acrylic resin specimens with CF or AF cloth is significantly greater than that of the plain acrylic resin specimens.
2. The transverse and tensile strengths of the reinforced acrylic resin containing CF-cloth were improved 11-12 percent and 24-31 percent, respectively, as compared with the plain denture base resin, in the case of the Bis-GMA+3 G or RIPDXY treatment.
3. The transverse and tensile strengths of the reinforced acrylic resin containing AF-cloth were improved 12 percent and 33 percent, respectively, as compared with the plain denture base resin, especially in the case of the RIPDXY treatment.

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Studies related to the Computer Color Matching (CCM) system were carried out from a clinical standpoint. The concept involved making a 3-layered porcelain sample by the CCM program and comparing its color to that of an objective porcelain sample which resembled the structure of the upper anterior tooth.
Points A and B dealt with measurements of the reflection rate of the enamel layer and the enamel+dentin stratified layer, respectively. Point C consisted of the enamel+dentin+opaque stratified layer, and points D and E consisted of the dentin+opaque layer.
Trial porcelain samples were baked according to these standards, and their color was analyzed and compared to the objective samples.
The results showed that the color of the CCM porcelain samples was almost identical to that of the target samples, and the color difference dE was within the range of 1.0-3.0 (CMC), indicating a high level of color reproducibility.

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The purpose of this study was to investigate the effect on the porosity development in three powder-liquid type reline materials on a simulation model.
The influence of the kinds of reline materials, mixing methods, L/P ratio, load timing and spillway were examined.
The results obtained were as follows:
1. Rebaron LC was the smallest on the number of porosities and percentage of porosity per unit area regardless of L/P ratio, followed by TOKUSO REBASE, Rebaron.
2. Method of the mechanical mixing with vacuum (VAC-MECH) decreased the number andpercentage of porosity. Using VAC-MECH was statistically significant by handmixing (HAND) and handmixing with vibrator (VIB), so VAC-MECH was effective for decreasing porosities.
3. When the monomer was decreased by 20%, the number and percentage of porosity by HAND increased in all reline materials.
4. When the load was added later, the number and percentage of porosity decreased by HAND.
5. On the model without a spillway, the percentage of porosity was tended to increase.
6. Porosities under 0.6 mm in diameter occupied over 80% in all reline materials.

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