To find EMG-intrinsic factors properly reflecting different modes of mandibular movement, the power spectrum from EMG of the masticatory muscles was examined. The unitduration for power-spectral analysis was 64 ms. In tooth-tapping and gum-chewing, sampling at one stroke of one unit-duration, which starts at the EMG-burst appearance next to a silent period, was repeated ten times ; in clenching, ten segments in a large burst were sampled as ten unit-durations. Bite-force at clenching was regulated to three different degrees, minimum, medium and maximum.
The frequency at 80% of the cumulative power, F 80, in the 180-strokes/min tapping was significantly higher than F 80 in slower tappings examined (60 and 90 strokes/min). Similar frequency comparison differentiated functions of each side of masticatory muscles in uni-lateral gum-chewing. F 80 correlated highly with bandwidth covering from 50 to 80% of the cumulative power, B 50-80, under clenching with the minimum bite-force, the correlation coefficient being 0.928 for right and left masseter and 0.976 for the temporalis. Under the maximum bite-forceclenching, F 50 correlated highly with B 20-50: the correlation coefficient, 0.956 for both sides of the masseter; 0.926 for the temporalis.
These solid correlations between EMG-intrinsic functions and mandibule-movement modes could expand to distinguish various conditions of mandibular dysfunction.

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The purpose of this study is to mesure the three dimentional distotions and displacements in the Non-precious (Ni-Cr) ceramometal fixed bridge using the pre-soldered method.
Following conclusions were obtained as a results.
1. During the Pre-soldering stage, the distotion of soldered bridge frame (the potion was made with one-piece cast method) are minimal.
2. During the Pre-soldering stage, the curve of fixed bridge frame was slight opened on horizontal plane, but on the vertical displacement was larger than others.

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The relationship between the body balance laterally and the gnathodysfunction we often doubted through daily clinic.
The purpose of this study was to investigate the relationship between the morphological balance, and the functional balance of the body and the stomatognathic function.
Subjects of this study were composed of fiftynine young adults. The following items were examined on the subjects;
1. The distribution of the center of gravity position.
2. The difference of the height among both shoulder.
3. Dominant habitual masticating side.
In addition the jaw movement on chewing and the electromyograms of the bilateral masseter and temporal muscles during clenching were simultaneously recorded from three subjects.
The results obtained were as bellows;
1. A slight relationships were found between left and/or right dominancy and habitualmasticating side, and between posture and habitual masticating side were found.
2. Masseter muscles activity was inclined to increase in habitual masticating side.

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Internal voids in impression material are troublesome in clinical practice because they influence reproducibility of details and physical property of impression material. However, distribution and area of fine internal voids have been rarely measured quantitatively in many studies concerning them.
Therefore, we attempted to measure internal voids by digital image analyzer which has been used for quantitative analysis in dental studies recently. Measurement accuracy of device, treatment method to clear the margin of internal voids and influence of rotating original image on video input were investigated.
On calibration and video input, enlargement of original image with a zoom up lens was effective in improvement of measurement accuracy. Deviation of the examined value depended on position of CRT monitor was less than 1%. Catalyst of Bite-checker (GC Dental Industrial Corp.), used as a treatment material of internal voids, made the margin of internal voids the most clear compared to four other. It was necesary to adapt the mean of six measurements by rotating the original image 60 degrees each in order to make negligible the variation of directional dependence of video input.
From the above results, by direct input of specimen information into the digital image analyzer, measurement became fast and simple, and reproducibility and objectivity of the examined value were excellent in comparison with other measuring methods.

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The present study is concerned with the evaluation of adhesive bonding between the hard resin teeth and the denture base resin. Several denture teeth which included the porcelain teeth, the conventional acrylic teeth and the cross-linked hard resin teeth were used and completed the partial denture as usual. The gaps appeared after thermal cycling were investigated and compared each other.
We conclude that the conventional acrylic teeth showed better adhesive bonding than the hard resin teeth to the denture base resin. The use of stone-resin separator gave worse influence, however the results were improved in the case of using adhesive agents.

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Nitrides used in this experiment are BN, AIN and Si3N4. First, we studied wettability between nitrides and molten Au-Ag-Pd alloy (composition Au: 12 wt%, Ag: 45 wt%, Cu: 18 wt%, Pd: 20 wt%, Bal.: 5 wt%; melting point: 930°c).
Secondly, we studied feasibility of nitrides as coating materials for wax patterns, that is, Au-Ag-Pd alloy was cast after painting wax patterns with coating material of nitrides. The temperature of mold was 700°C, and an argon arc vacuum-pressure casting machine was used. Surfaces of casted material were investigated using a scanning electron microscope, X-ray diffractometer and surface roughness analyzer.
Results were summarized as follows;
1. The nitrides little wetted molten Au-Ag-Pd alloy.
2. The color of the cast surface coated BN was purple with a dash of red, and this was derived from Cu²O.
3. The dense coating layer of BN inhibited formation of CuO on the cast surface and reduced the surface roughness of the cast.
4. The cast surface coated the nitrides had less clinging than uncoated one, and this indicated that its cleansability was improved.

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The new ceramic material (Olympus Castable Ceramics, O. C. C.) was developed for the purpose of fabricating castable crowns.
In order to get the optimum characteristics, its basic composition and the condition of heat treatment for crystalization, the thermal and mechanical properties and the biological tests were investigated.
The following results were obtained:
1. O. C. C. is mainly composed of Li₂O, MgO, ZnO, TiO₂, Na₂SiF₆, Al₂O₃ and SiO₂ and also includes ZrO₂, Y₂O₃ and a little amount of metal oxides as the stain.
2. The condition for heat treatment is as follows:
a) As casted O. C. C. is heated to 750°Cin one hour.
b) Maintain at 750°C for two hours.
c) Raise the temperature to 900°C at the rate of 3.3°C/min.
3. Main precipitated crystals are Mica (NaMg₃ (Si₃AlO₁₀) F₂) and β-spodumene (Li₂0, Al₂O
3, 4 SiO₂).
4. O. C. C. has high resistance especially to bending strength (2, 800 kg/cm2 at 950°C). The Vickers Hardness Number of O. C. C. is 360-420, which is similar to enamel.
5. Fracture toughness (K1C) of O. C. C. is 2.5-3.0 which is simillar to Al₂O₃ ceramics.
6. Thermal impact resistance was 36 times larger than that of the human enamel.
7. O. C. C. showed excellent chemical durability and no harmful ions leached out in elution test.
8. No abnormalities were found in any biological test.
From above results, it can be concluded that O. C. C. has many favorable properties as a new type of restorative material for future use.

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In case of laser welding of same metals, the mechanical properties of weld show a little difference from that of base metal. This article discribes metallurgical studies on several factors which affect mechanical properties of laser weld. In order to study about rapid thermal hysteresis, the changes of the age hardening curves in various solution treatment and of ageing temperature and time, a difference between fusion zone and base metal using X-ray diffractometer, thermal hysteresis around fusion zone, the change of metal component by evaporation and metallographic structure of fusion zone were examined. Additionally, the studies on the appearance of blowhole and crack, and on the area of heat affected zone were performed.
Ageing curve of Ag-Pd-Cu-Au alloy varied with solution treatment temperature. The fusion zone by laser irradiation was one supersaturated solid solution, while solution treated base metal precipitated into two solid phases. The increase in temperature around the fusion zone was restricted only in very narrow area, and no heat affected zone was found. In fusion zone, silver component was decreased. Crack regarded as stress corroision crack and blow hole appeared in the weld.

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Using several brands of articulators, we examined the precision involved in the manipulation of them. We reported in the first study mainly about the vertical displacement of the upper frame as we adjusted articulators. In the second study, we investigated about lateral displacement. This time, we measured the anteroposterior displacement of the upper frame as we adjusted the “ Inclination of sagittal condyle path”(I. S. C. P) or the“ Inclination of sagittal incisal path”(I. S. I. P). And next, we measured the anteroposterior displacement, which is caused when we loaded statically to the center of the upper frame, or also measured the rest displacement after having removed the vertical load. We got these results. The rigidity or the precision of articulators should be taken into consideration, and we should adjust the I.S.C.P to 30° and the I.S.I.P to 0° as we mount a model. However we found error due to anteroposterior displacement during these adjustments after mounting a model. So we should take these things into consideration and use articulators in the clinic.

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The purpose of this study was to investigate the mean integral EMG level of the masseter muscle, which was obtained from the EMG biofeedback of the frontal muscle of those patients whom once had a case of mandibular dysfunction, and to use this as an effective means of treatment. Furthermore, the correlation between the psychological characteristics of mandibular dysfunction patients and EMG biofeedback of the frontal muscle were examined.
Results showed;
1. EMG biofeedback of the frontal muscle of a normal group to decrease in mean integral EMG level of the masseter muscle, indicating that it was controllable and a learned effect.
2. Patients whom once had a case of mandibular dysfunction also showed similar results, but its inhibitory effect was not to the extent of the normal group.
3. When patients were further divided into those having psychological problems and those who have not'a decrease in the mean integral EMG level of the masseter muscle after Biofeedback Training and a low and stable EMG level even before BFT that did not vary between and during the session were observed.
The findings above, thus suggest a clinical value for EMG biofeedback of the frontal muscle of mandibular dysfunction patients.

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The purpose of this paper is to investigate the chemical composition, the polymerization ability and the abrasion resistance of two brands (Isosit, Plastique) of thermo-setting resin for crown and bridge.
1. Isosit (Is) contained approximately 55 per cent of MFR type filler and 45 per cent of a comonomer (urethane dimethacrylate, 1, 3 butane dimethacrylate and 1, 10 decamethylene dimethacrylate).
2. The extent of polymerization (Ep) of experimental comonomers (Is′, Pl′) and composites (Is-E and Pl-E) which corresponded to Is and Pl was as follows:Is', P1'>Is-E, P1-E>Is, P1
3. There was no significant difference in Ep between Is group and Pl group.
4. The residual monomer was less than 4 per cent.
5. The efficiency of cross-linking (Ec) of two experimental comonomers was higher than those of the corresponding brands.
6. The Ep and Ec of the two brands cured by at the designated temperatures were slightly less than those cured by at 150°C
7. The amount of abrasive wear of all materials cured by DSC decreased with increase the Ep and Ec. And the cured products of experimental comonomers showed lower abrasive wear values than those of the two brands cured by DSC. The abrasive wear values of the two brands cured by specified polymerization apparatus were intermediate between the two groups as above mentioned.
8. The surface roughness of Pl group was slightly larger than that of Is group through the abrasive wear test.

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How functional occlusal pressure on teeth is relieved is unclear. Consequently this paper uses frequency analysis in an attempt to evaluate and compare the difference in dynamics between the tooth crown and root. Comparing these results with those obtained by linear level method as described in the previous paper leads to the following conclusions:
1. In both the crown and root the highest measured levels were 2-4 kHz vertically and 500 Hz-2 kHz horizontally.
2. A resonant tendency was observed at the crown rather than the root vertically and the root rather than the crown horizontally in the highest measured levels.
3. The difference in dynamics between the tooth crown and root can be determined by either the frequency analysis method or the linear level method.
4. In multirooted teeth, the peak spectrum moved to the lower frequency band after the root separation.

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This study was carried out to investigate the effect of“anterior diskdisplacement with reduction”to chewing movement with the expectation that the analysis of chewing movements could deliver new aids for diagnosing the state of TMJ. 11 patients with reciprocal click and 10 normal subjects were selected. Right side chewing and left side chewing were recorded using Sirognathograph Analysing System and frontal projection of chewing movements were observed. The conclusion was summerized as follows.
1. The group of patients with reciprocal click could be divided into chewing click (+) group and chewing click (-) group. Chewing click (+) group showed significantly (p<0.05) earlier opening click compared with chewing click (-) group.
2. Chewing click was observed only in non-symptomatic side chewing. The bigger test food was, the higher the frequency of chewing click became.
3. Normal subject group showed patterns with convex opening path but without deviation to non-chewing side.
4. Chewick click (+) group characteristically showed eight-shaped patters with sigmoid opening path. Chewing click (-) group showed two characteristic patterns. One is with concave opening path but without deviation to non-chewing side, and the other is with convex opening path and with deviation to non-chewing side.

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The purpose of this research was to determine optimal specimen size for Pull-Out Test and to determine the bonding strength of adhesive resin cements to the metal (SUS 304). Three experiment were carried out using Panavia EX (PE) and Superbond C&B (SB).
The following results were obtained.
1. Breaking load increased with increasing length of the adhesive surface, and there was a significantly chose correlation between the length of the adhesive surface and breaking load in the specimen of a 10 mm in diameter.
2. The bond strength of PE was not influenced by the length of the adhesive surface when the diameter was 10 mm, whereas bond strength decreased with increasing length of adhesive surface when the diameter of SB was 6 mm.
3. The photoelasticity experiment revealed no difference in stress distribution, shear stress and the maximum stress between PE and SB.
4. The diameter of the specimen had an influence on the stress distribution and maximum stress. The specimen of 10 mm in diameter showed a shear stress distributed up tothe superior region of the adhesive surface and maximum stress was a small value.

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Four different types of methods for testing adhesives for binding to 18-8 stainless steel (SUS 304) were performed using two kinds of dental adhesives, Panavia EX (PE) and Superbond C & B (SB), and the coefficient of variation (CV%) of the values determined and the destructive mode were compared among the testing methods.
Furthermore, using the Type III method with high reproducibility that produced a lower coefficient of variation and surface destruction among the above testing methods, the effect of surface treatment on the bond strength was studied, and the following results were obtained.
1. When the bond strength was compared according to the coefficient of variation, it was low for both PE and SB when testing method Type III or IV was used, revealing that they produced little variation.
2. Evaluation of the effect of surface treatment using method Type III which induced surface destruction revealed that the bond strength of PE was increased by ca. 50% by sand-blast treatment or silane-coupling treatment, and that Sn-electro deposition had no effect.
3. There was no difference in the bond strength of SB due to sand-blasting or silanecoupling treatment as forms of surface treatment, but the strength was decreased by Sn-electro deposition.

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Since the effects of bioactive glass on host defence mechanisms in the oral region are still unknown, we investigated the in vitro effects of bioactive glass on lymphocyte functions, particularly lipopolysaccharide (LPS)-induced responses.
Spleen cells were cultured with mitogen (LPS, lipid A-associated protein or phytohemagglutinin-P) on the surface of bioactive glass and other experimental materials (Al2O3 ceramic, Hydroxyapatite, Silica glass) underlaid in a 96-well multiplate. The effects of materials on lymphocyte functions were evaluated by three parameters, i. e., mitogen induced enhancement of 3H-thymidine uptake, and LPS-induced increment of IgM producing cells and augmentation of polyclonal IgM production. Results were as follows;
1. Three mitogens increased 3H-thymidine uptake by spleen cells with dose dependency. Bioactive glass reduced the mitogen-induced uptake of 3H-thymidine by spleen cells. Bioactive glass was found to be most effective in response to LPS among the three mitogens.
2. Number of polyclonal IgM producing cells was increased depending upon the dose of LPS. Bioactive glass inhibited the LPS-induced increase of the number of polyclonal IgM producing cells.
3. However, bioactive glass was found to enhance LPS-induced production of polyclonal IgM-antibody.
These results suggest that bioactive glass, when closely cultured with lymphocytes, suppresses mitogen-induced proliferation of lymphocytes, but enhances LPS-induced production of polyclonal IgM-antibody.

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An experimental study was undertaken to evaluate the effects of emotional stress to the stomatognathic functions on the mirror drawing test (MDT) which had been employed as a conflict producing situation. The experiments were carried out on ten human subjects having on average age of 26.7 years. None of the subjects had any clinically detectable abnormalities of the masticatory muscles or temporomandibular joints. Each subject performed the mirror drawing test. Then the MKG and EMGs of tapping movements were recorded nine times during the experiment. The EMGs recorded were from the masseter and anterior temporal muscles. Those were at rest (I) as control, just after the 1st MDT (II), just after the 2nd MDT (III) and just after the 3rd MDT (IV), all after a one minute rest interval respectively. Subsequently, the EMGs were recorded five times (V-IX) each after a two minute rest interval for ten minutes without MDT stress loading.
The results were as follows:
1. EMGs time parameters of ASPD (after silent period duration) and BD (burst duration) showed a tendency to be prolonged under stress loading.
2. EMGs time parameters of SPD (silent period duration) tended to decrease under stress loading.
3. The other EMGs time parameters of tapping movement did not show any significant changes.
4. CV (coefficient of variation) values of every EMGs time parameter tended to be higher under stress loading, especially in terms of SPD and ASPD.
5. CV values of the vertical velocity and mandibular opening on MKG tended to be higher under stress loading.
MDT stress loading was found to affect EMGs of tapping movement which is regarded to be a more rhythmical motion compared to other mandibular movements. These results suggest that emotional stress may influence the stomatognathic function.

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The trial visible light-curing relining resin, suitable for use when denture does not fit, and suitable also for marginal molding, is considered necessary to prepare a number of different types according to different occasions.
So, the author changed the biscosity of the relining material in three different stages of low, medium and highdegrees of biscosity, and using these samples, made test objects by means of light-curing polymerization. When the transverse strength, deflection, modulus of elasticity, rockwell hardness, waterworption and solubility of physical properties test objects were examined and the following conclusions were obtained:
1. Transverse strengh: 730-775kg/cm²
Deflection:(5.0kg) 2.0-2.2mm
(3.5kg) 1.0 mm
Elasticity: about 3.0-10⁴kg/cm²
2. Rockwell hardness: 64.8-69.1 (HRS)
3. Watersorption: 20-23μg/mm³
4. Solubility: 1.8-2.8μg/mm³
When the above-mentioned three points have been put together, it has been suggested that, since the physical properties of Type I, II and Type III after polymerization hardly deffered, their clinical application is feasible and theat, since their biscosity befor curing deffers, their clinical effects will be better than the conventional types of resin.

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Ion sputtering is a phenomenon in which ions or other high energy particles strike at a target electrode causing emission of atoms from the electrode. It takes placein a grow discharge in a relatively low vacuum chamber. We studied the application of this phenomenon to surface treatment of dental precious alloys for adhesion.
Nine pure metals were examined the aptitude as a target which was the source of metal oxide supply. As the result of adhesion endurance test, Cu target showed favorableadhesive strength, and following studies were conducted applying Cu target. In the next study to decide the optimum ion coating time, best result was obtained by 10 minutes treatment.
Type IV and Au-Ag-Pd alloys ion coated for 10 minutes with Cu target showed excellent adhesive durability in endurance test and after subjection to thermal cycling of 50, 000 times, adhesive strength of above 250 kgf/cm2 were maintained.

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We evaluated the “ Periotest ^®” for prosthetic clinical application.Stability and reproducibility of measured value, effect of tapped points and strength of proximal contact on measured value, Periotest value of normal tooth, corelation between Periotestvalue and clinical tooth mobility were investgated.
Periotest values were stabilized during 20 times measurement. Although coefficient of variation of Periotest value measured in premolar and molar were larger than thatin incisor. Good reproducibility were observed in same day and different days. Tapped points and strength of proximal contact affected on Periotest value in incisor and premolar signifficantly. In Feriotest value of normal tooth, maxillaly and mandibular canine tooth were least value, andmandibular tooth were less value than maxillaly tooth. Coreration between Periotest valueand clinical tooth mobility were observed.
From above results, Periotest was useful disgnostic machine for dynamic periodontal condition with limitted use.

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The purpose of this study was to analyze the surface and centraltemperature of wax rims for recording neutral zone.
Three types of wax rim were used in this study. The width of them were 10 mm (sample S), 13 mm (sample M) and 15 mm (sample L). Temperature were measured with the following procedure. Wax rims were soaked into 47°C water for 3.0 minutes, 37°C water for 1.0 minute, then cooled in 10°C water for 2.0 minutes. This procedure was repeated three times. The surface and central temperature of wax rims were measured continuously by the thermosensor through all steps.
The results were obtained as follows:
1. In sample M and L, central temperature of wax rim was lower than surface temperature.
2. In sample S, cental temperature of wax rim was as high as surface temperature.

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The solubility of luting cements was investigated in an environment of flowing buffered solutions of organic acids, and experimental results were used to standardize the condition of buffered solutions of organic acids. Then the influence of the differences of zinc phosphate cement film thickness, liquid-powder ratio, and cement film thickness in the marginal area of full cast crown, etc., on the solubility of zinc phosphate cement were investigated.
The experimental results obtained were as follows:
1. The effects of citric acid on the solubility of cements were particularly remarkable. The cements tended to be most soluble in solutions with high molarity and with low pH. The solubility of glass ionomer cement was much less than those of zinc phosphate cement and polycarboxylate cement.
2. The difference of zinc phosphate cement film thickness slightly affected the depth of dissolution of cement. Of course, the thicker the cement film at the site of dissolution, the greater the space resulting from dissolution. Even with an increase of liquid-powder ratio, the solubility showed a slight decrease. The depth of dissolution of cement film decreased with the decrease of zinc phosphate cement film thickness in the marginal area.
3. Only in the area of the burnished margin of the crown and in the area of the suppcsed subgingival margin of the crown covered with artificial gum was there no dissolution of zinc phosphate cement film.

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The purpose of this study is to investigate the sensory mechanism in jaws that have received dental implants. These cases of course have no periodontal membrane. Withthe von Frey feather stimulation technique we measured tactile sensibility of 6 subjects with 9 endosseous implants and compared results with those obtained from the remaining natural teeth in these patients and natural teeth in corresponding locations in other patients. We also measured the tactile sensibility in patients with implants after infiltration of anesthesia at the mucous membrane surrounding implant and at the bone surrounding implant.
1. Minimum tactile sensibility in endosseous implant patients was 54.0g axially and 17.6g bucco-lingually. Maximum tactile sensibility was 119.9g. These measurements were much higher in both directions than the results from any of the measurements of natural teeth.
2. When anesthesia.was injected at the mucous membrane at the necks of the implants the results obtained were nearly unchanged from the unanesthetised implants, but with bone anesthetised, the tactile sensibility of the patients with implants incresed in all cases.
These results suggest that mechanorceptors in the tissues surrounding the endosseous impalnts are associated with the determination of tactile forces.

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Bacterial flora and number in early denture plaque were studied for the purpose of clarifying influence of denture base materials on them. Four kinds of denture base materials were set in oral cavities of subjects with normal dentition for 2, 12 and 24 hr. Plaque formed on the surface of materials was investigated bacteriologically and morphologically, and primarily consisted of facultative Gram positive cocci and rods. Bacterial flora and number were not influenced by the differences of materials. A scanning electron microscopic study showed characteristic flora and distribution of the adhered bacteria to setting time of materials, and such characteristics were uniformly observed in all materials.

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