Mandibular movement occurs during chewing, speech and swallowing functionally or during bruxism and clenching parafunctionally. Further, the occlusal facet is caused by functional mandibular movement and parafunctional mandibular movement. However, it is not defined to what extent the occlusal facet is within the range of functional mandibular movement. The purpose of this study was to examine the extent of functional tooth grinding in chewing mandibular movement. One hundred dental students were used in this study, and the portion of correspondence of path of chewing and lateral border movement was measured using Sirognathograph Analyzing System III. As a result, some subjects had a large corresponding portion of path of chewing mandibular movement and path of lateral border movement. The extent of functional tooth grinding in chewing movement has been considered to be small near the centric occlusion, however, the results suggested that a large portion of the grinding surface was used by functional mandibular movement.

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Ninety male Wistar rats were divided when 45 weeks old, into ten groups, the solid diet group, the soft diet group (fed powder diet containing the same components as solid one), the molarless group (all molars were removed when 45 weeks old and then fed powder diet), the low calcium solid diet group (fed solid diet low in calcium-deficient in vitamin D), the molarless with low calcium diet group (all molars were removed when 45 weeks old and then fed powder diet low in calcium-deficient in vitamin D). When 50 and 75 weeks old, measurements of bone mineral density (BMD) was performed by the image analyzing system in addition to observation by light microscopy of the condyles.
The results were as follows:
1. The molarless with low calcium diet group when 75 weeks old had a significantly lower BMD value of the condyle than all other groups (p<0.01).
2. As for the solid diet group, age-related disorder of cell arrangement and decrease in the number of cells at cartilaginous layer, and thinning of the hypertrophic layer of the condyle were observed. As for the molarless group, it was found that the stratified structure was disordered at the cartilaginous layer and the trabeculars decreased in the number and thickness were observed. As for the low calcium solid diet group and the molarless with low calcium diet group, inhibition of calcification was observed at the subcartilaginous layer was observed.

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The difference in color tone between adhesive resin cement used for bonding of all-ceramic restorations and trial cement used for trial, as well as the influence on color tone of restorations when the cement was present were studied. Further, using these data, it was attempted to assess the validity of the value of 2.0, which has been used as the reference for the color difference (ΔE^*ab) heretofore.
The conclusions were as follows:
1. It was only the specimen of Opaque White which showed a color difference (ΔE*ab) of 2.0 or less in the value of L^*a^*b^* between adhesive resin cement and trial cement. As for the other types of cement, the value was as high as 2.81 to 5.34, showing that color tones were different.
2. Color difference (ΔE*ab) of the value of L^*a^*b^* of the combined specimen of abutment, cement, and ceramic showed a value of 2.0 or lower in all combinations.
3. As the result of a visual comparison test, in case of translucent ceramic, it was found that the use of the value of 2.0 as the reference (criterion) for color difference (ΔE^*ab) was appropriate.

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Denture dynamics of the free-end saddle RPD (Removable Partial Dentures) should be made as low as possible in order to restore the stable occlusal contacts and protect both supporting tissues of abutments and residual ridges. Denture dynamics were directly affected by the connecting rigidity between the abutments and the denture saddles.
In this study, the denture base supporting load ratio was analyzed in relation to the connecting rigidity in patients.
Materials and Methods
1. Layered leaf springs were utilized to measure displacement.
2. Total occlusal load and denture sharing load were continuously measured when the connecting rigidity between the abutment and the denture saddle was changed.
3. Denture sharing load to total occlusal force was calculated and analyzed.
Results
1. Continuous change of connecting rigidity was realized using layered leaf springs as connecting components of distal extension RPD.
2. The more rigid the connection was, the less the denture base sharing load was.
3. Denture base sharing load was associated with the increase in total occlusal load when the connecting rigidity was low.
4. Denture base sharing load ratio to total occlusal load hardly showed any change when the connecting rigidity was over a certain level.
Conclusion
Connecting rigidity between abutments and denture saddle of distal extension RPD has a close relationship to the occlusal force distribution between abutments and residual ridges.

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The purpose of this study was to fabricate all-ceramic crbwn with a target color. The color of all-ceramic crown was analyzed by measuring the color of all-ceramic specimens made by the refractory model technique (G-Cera), and lost wax technique (IPS Empress). The ceramometal specimen was used for the target color. The color of all-ceramic specimens was measured with a small area colorimeter by translucent and reflecting methods and evaluated by the CIE L^* a^* b^* color system.
The results were as follows:
1. The color of each system was different, though the same shade of porcelain was used. Both systems showed lower L^* and higher b^* than the target color.
2. The layer of enamel porcelain had an influence on the L* value, and the layer of dentine porcelain had an influence on the L^* and b^* values.
3. The system using the layering technique had greater changeability of colors than the system using the lost wax technique.
4. It can be concluded that the luminous value must be adjusted after reproducing the yellowness to fabricate all-ceramic crown with the target color.

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The purpose of this study was to investigate the histocompatibility of a bone graft cement, obtained by kneading an equimolar mixture of tetracalcium phosphate and dicalcium phosphate dihydrate with 35% citric acid solution (containing 0.5% gelatin, P/L 2.0; Te/DCPD). High-density hydroxyapatite granules (HAP, particle size: 300-500 μm) were used as a control.
Three holes, 5 mm in depth and 5 mm in diameter, were drilled at 10 mm intervals on the corpus of the tibia of mature beagles. Te/DCPD was shaped into a cylinder (5mm in height and 5 mm in diameter), and implanted into one hole. HAP was implanted into the 2nd hole, and the 3rd one was used as a sham operation. The implants were removed at 2, 12, and 24 weeks after implantation, and then all specimens regardless of decalcification were processed for routine microscopic examination. The results were as follows:
At 2 weeks, Te/DCPD and HAP did not induce an inflammatory reaction in periphery bone marrow tissue, and Te/DCPD was in direct contacted with new bone tissue. At 24 weeks, Te/DCPD was absorbed peripherally, and new bone tissue had replaced the absorbed portion.
It was concluded that Te/DCPD may be useful as a bone graft cement as well as HAP, because it was biodegradable and replaced gently by new bone tissue.

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Although a lot of artificial posterior tooth positioning techniques have been proposed, correlation between complete denture stability and posterior tooth position during mastication has not yet been clarified.
This study was conducted to analyze the behavior of complete maxillary dentures that have two posterior tooth positions by the simulation method. Three-dimensional mobility of these dentures was measured during biting two sizes of simulated foods on centric and eccentric positions. One of two artificial posterior teeth arrangements was based on the alveolar crest (A-denture) and the other was in a neutral zone of muscular activity (N-denture).
The results were as follows:
1. The working side point of two complete maxillary dentures moved downward, forward, and outward when they were loaded on one side.
2. The mobility of complete maxillary dentures was changed by posterior tooth position, simulated food size, mandibular position, and tooth contact on the balancing side.
3. When biting thick food, there was no tooth contact on the balancing side. In this condition, the mobility of A-denture was less than that of N-denture.
4. When biting thin food, there was tooth contact on the balancing side. This contact limited the mobility of two dentures. In this condition, however, the mobility of N-denture was less than that of A-denture.

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The purpose of this study was to examine effects of magnetizing, methods on attractive forces in disk-type model and crown-type model which consisted of two kinds of Fe-Pt magnetic alloys (Fe-39.5Pt-0.75 Nb (mole%), Fe-39.5 Pt-0.65 Nb-0.1Si (mole%)). In addition the surface roughness and adaptability of the inner surfaces were examined in the crown-type model.
The results were as follows:
1. Surface roughness (crown-type samples)
There was no significant difference between the alloys. As for the alloys, surface roughness was greater than that of the metal model.
2. Adaptability (crown-type samples)
The adaptability of the crown-type was loose. In order to keep the frictional forces as small as possible, the expansion of the investment was intentionally increased by the adjustment of the L/P ratio.
3. Attractive forces
1) Disk-type samples
The attractive force of the disk-type was large when magnetized at four-poles on a plane and the attractive force of a sample was 734 gf on the average.
2) Crown-type samples
The attractive force observed with crown-type (magnetized along the crown axis, Fe-39.5 Pt-0.65 Nb-0.1 Si (mole%)) showed 536 gf on the average. This value was sufficient for retaining removable crowns and bridges.

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CONDYLOCOMP LR 3 is mandibular movement measuring device characterized by six degrees of freedom and a light reflective mechanism. The measurement accuracy of this device was evaluated.
The results were as follows:
1. The sagittal plane was expanded 4.8% in the sagittal and 5.6% in the vertical directions, by moving the reflector anteroinferiorly (the measuring point was 2.5 mm anterior and 2.5 mm inferior to the coordinate point). Further, the measuring point was 5.0 mm anterior and 5.0 mm inferior to the coordinate point, and expansion was 3.6% in the sagittal and 4.0% in the vertical directions.
2. The sagittal plane was expanded 7.2% in the sagittal and 3.2% in the vertical directions, by moving the reflector internally 2.5 mm and anteroinferiorly (the measuring point was 2.5 mm anterior and 2.5 mm inferior to the coordinate point). Further, the measuring point was 5.0 mm anterior and 5.0 mm inferior to the coordinate point, and expansion was 7.4% in the sagittal and 4.3% in the vertical directions.
3. The horizontal plane was expanded 7.2% in the sagittal and reduced 9.2% in the horizontal directions, by moving the reflector internally 2.5 mm and anteroinferiorly (the measuring point was 2.5 mm anterior and 2.5 mm internally to the coordinate point). Further, the measuring point was 5.0 mm anterior and 5.0 mm internally to the coordinate point, and expansion was 10.2% in the sagittal and reduced 3.2% in the horizontal directions.

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It was reported that the pressure pain threshold (PPT) of masticatory muscle is useful in the diagnosis of muscle disorders. The difference between right and left sides of involved muscles was objectively judged. However, it could not determine the abnormal site because personal sensitivity to pain could not be measured. It was reported that the PPT of the styloid process gave a sign of personal sensitivity to pain. In this study, the styloid process site was added to the original masticatory muscle measurement sites, described in the previous report. The reference interval of each site was determined. Fifty-one volunteers (27 males and 24 females, mean age: 25.5 years) without muscle pain were used in this study.
The results were as follows:
1. The PPTs at all measurement points were different between sexes (p<0.01).
2. A significant difference was obtained in individuals of the PPT but not between the sides.
3. Significant correlation coefficients were obtained between the styloid process and all the other measurement points.
4. The reference range was determined using 95% confidence intervals.

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The purpose of this study was to investigate the effects of varying the thickness of IPS Empress and the color of the adhesive resin cement on metal core abutment by comparison and review.
The conclusions were as follows:
1. 1.0 mm Thickness
When a 1.0-mm thick crown specimen was adhered with each cement, the color difference of less than 2.0 when compared to the 1.0 mm standard color for AU tones were Opaque White (OW) of Variolink and XO (XO) of IMPERVA DUAL, and there were no cement types that were 2.0 and lower in PD tone.
2. 1.5 mm Thickness
When a 1.5-mm thick crown specimen was adhered with each cement, the color difference of less than 2.0 when compared to the 1.5 mm standard color for AU tones were OW, XO, Yellow Brown (YB) for LA cement, and YB for PD tone.
3. 2.0 mm Thickness
When a 2.0-mm thick crown specimen was adhered with each cement, the color difference of less than 2.0 when compared to the 2.0 mm standard color for AU tones were Yellow Universal (YU) and OW of Variolink, Translucent (TR) and YB of LA cement, TC (TC) and XO of Panavia 21, and OW, YB, and XO for PD tone.

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This study was conducted to improve the efficiency of the polishing procedure for various prosthetic appliances by using a newly-developed centrifugal shooting type polishing system.
This apparatus has a specific structure for shooting the polishing particles using centrifugal force. The polishing particles consist of an elastic body as a core and layer of polishing material adhering to that core. The apparatus does not bounce off the polishing surface but slides along it.
Two kinds of denture base materials (Co-Cr alloy and denture base resin) were investigated in this study. Polishing for each sample was performed at five different shooting angles of the polishing particles and in five different polishing times, respectively. The surface texture of these samples was investigated with a surface texture measuring apparatus. The results were as follows:
1. Satisfactory surface roughness was obtained when the shooting angle was less than 45°.
2. It took 3 to 10 minutes for Co-Cr samples and 1/2 to 3 minutes for resin samples to improve surface roughness.
3. It was suggested that the surface of various dental materials could be polished using the same polishing particles by converting the shooting velocity of particles.

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The electrolyzed acidic water is the water obtained from the anode by adding a small amount of salt to the water supply. Electrolyzed acidic water, when in vitro, shows a strong germicidal power in a short time against various bacteria including oral bacteria, but when it is under the existence of blood or an organic substance, its germicidal power attenuates.
Therefore, there is still doubt about its effect during oral use.
In this study, to apply the electrolyzed acidic water was used to irrigate the periodontal pocket. The results were as follows:
1. When the periodontal pocket was irrigated by using sterile distilled water, no significant change was found in the total number of cultured bacteria and of black pigmented anaerobic cells between before and after irrigation.
2. When the periodontal pocket was irrigated by using electrolyzed acidic water, the number of cultured bacteria and of black pigmented anaerobic cells decreased significantly after irrigation.
3. It was found that the decrease in the number of cells after irrigation with electrolyzed acidic water was due to the manifestation of the germicidal power of electrolyzed acidic water.

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An investigation on the effects of fatigue in the masticatory muscles on the articulatory and the masticatory movements was made from the aspect of movement changes in the perioral soft tissues. Ten healthy males were used as the subjects. They were asked to pronounce the five Japanese vowels through articulatory and masticatory movements before and after clenching for 30 sec at the maximum strength correlated between the two functional movements in each subject. The results suggested that articulatory movement could be utilized for the diagnosis of jaw function.

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The purpose of this study was to investigate the accuracy of interocclusal recording addition-type silicone rubber impression materials that reproduced intercuspation on mounting stone casts. A bridge type reference model, which could not maintain stable intercuspation without interocclusal records, was selected. The reference model was mounted on an articulator. Interocclusal records were taken on the reference model. The reference model could be separated from the articulator when interocclusal records were measured. For interocclusal records which were made from PRESIDENT JET BITE, EXABITE, Stat·BR, BITESIL, MEMOSIL, and MUSHPRINT between the upper and lower reference models, the occlusal heights of the reference model on the left molar of the abutment side, anterior teeth, and right molar were measured using an IP-Checker. In addition, the relationship of the reproducibility of intercuspation and the mechanical properties of materials was studied.
The results were as follows:
1. The occlusal height on the left molar was high; the occlusal height on the anterior teeth and the rightmolar were unchanged or low when the recording range was on the abutments. The occlusal height on the left molar and the anterior teeth were high; the occlusal height on the right molar was unchanged when the recording range was 1/3 of the dentition.
2. The reproducibility of intercuspation of the interocclusal recording addition-type silicone rubber impression materials was excellent; however, MEMOSIL was inferior to the other materials. The occlusal height on the anterior teeth was greatly influenced by the recording range when BITESIL and MEMOSIL were used.
3. It was surmised that the reproducibility of intercuspation was influenced by the compression set and the dimensional change of the interocclusal recording addition-type silicone rubber impression materials.

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The purpose of this study was to find a means to prevent the adhesion of carboxylate temporary cements to the abutment teeth and an easy way to remove the cements stuck to the dentin surface.
At first, the effect of tannin-fluoride component in cements on adherence to abutment teeth was examined, and carboxylate cements showed strong stickiness with and without tannin-fluoride. Then experimental solvents for carboxylate temporary cement were manufactured and the removing ability of stuck cement to dentin was evaluated. Shear bond strengths of adhesive resin cements to the dentin surface treated with the trial solvent of 2.5% ammonia solution were measured. Ammonia solution showed excellent removing ability and had little influence on shear bond strength of adhesive resin cements. The treated dentin surface showed almost no change in micromorphological characteristics.
The results suggested that ammonia solution is a practical solvent for carboxylate temporary cements.

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This study was performed to investigate sequential vascular dynamics during bone regeneration by electrical stimulation.
Osseous defects (∅ 1.8 mm) were created in adult male Wistar rat femur. Osseous defects of groups A and B were covered with nonpoling or poling VDF/TrFE film, and osseous defects that received no film served as the control group. After 3, 5, 7, and 14 days, the vascularization was evaluated by SEM of the vascular corrosion cast and LM of transparent preparations by India ink injection. The results were as follows:
Osseous defects of the control group were supplied with elongation and anastomosis of newly-formed vasculature which derived from periosteum and bone marrow. Newly-formed vasculature in osseous defects of groups A and B derived from bone marrow. In group B, the diameter and density of newly-formed vasculature increased in each experimental period, although the vascularization was delayed in group A. A newly-formed vasculature elongated to osseous defect with a small angle of branches.
It was concluded that electrical stimulation activated the vascularization and provided the change of the vascular architecture that influenced the direction of bone formation within the experimental period.

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A new porcelain fused to a metal system consisting of a universal gold alloy and a low-firing porcelain for veneering was introduced with the idea that it is possible to fabricate all prosthetic appliances using only one alloy. However, the properties and bonding mechanism of this system have not been clarified. In this study, the bonding characteristics of the universal alloy and its porcelain were investigated. Three systems of the universal alloy and its porcelain and two conventional porcelain fusing to metal systems were selected. The bonding strengths were measured by a shear bond test; fractured surfaces after the bond test and the interface between the alloy and the porcelain were observed using a scanning microscope and analyzed with an electric probe micro analyzer. The bonding strengths of the universal alloys ranged from 13.7 to 21.4 MPa. Moreover, porcelain segments remained on all fractured surfaces after the bond test and a tight interface between the alloy and the porcelain of the sectioned specimen was observed. The results suggested that usage of two universal alloys similar to a conventional porcelain fused to metal alloy is possible.

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前号42巻2号 (平成10年4月) の目次 (和文・英文) および201ページの著者名に誤りがありました. （誤）新庄文明 Douglas B. Berky Fumiaki Shinsho and Douglas B. Berky （正）新庄文明 Douglas B. Berkey Fumiaki Shinsho and Douglas B. Berkey

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第99回日本補綴歯科学会学術大会抄録集 (平成10年5月) 16ページ, 112ページ (P-4-10) の演者に誤りがありました. （誤）梅原亜紀,野首孝祠,沖山誠司,安井栄 Umehara A, Nokubi T, Okiyama S, Yasui S （正）沖山誠司,梅原亜紀,安井栄,野首孝祠 Okiyama S,Umehara A,Yasui S,Nokubi T

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第99回日本補綴歯科学会学術大会抄録集 (平成10年5月) 16ページ, 112ページ (P-4-10) の演者に誤りがありました. （誤）梅原亜紀,野首孝祠,沖山誠司,安井栄 Umehara A, Nokubi T, Okiyama S, Yasui S （正）沖山誠司,梅原亜紀,安井栄,野首孝祠 Okiyama S,Umehara A,Yasui S,Nokubi T

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