The present study was conducted to investigate the efficacy of surface modification methods for precious metal alloys, including Adlloy surface modification method, Type I, and Type II tin electroplating methods. The structures of modified surface having an effect on the adhesive ability of 4-META heat-curing resin and Au-Ag-Pd alloy were analyzed by ESCA in order to discuss the relationship between the surface structure and the adhesiveness.
The modified surfaces of the alloy showing high shear bond strength were composed of a flat pane covered with a Ga₂O₃ layer by the Adlloy method and jagged grains covered with SnO layer by the Type II tin electroplating method. On the other hand, the modified surface of the alloy with the Type I tin electroplating method showed no efficacy of adhesion and was composed of polygonal grains covered with an SnO₂ layer.
It was suggested that the differences of adhesiveness depended on the kind of oxide compounds promoted by each modification methods.

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This study revealed how phonetically the prosthetic palatal plate is configured from the viewpoint of Saaty's Analytic Hierarchy Process as Fazzy decision theory. Ten male adults, aged 23-26, with normal teeth alignment and occlusion, and normal auditory system were selected as the subjects. Experimental palatal plates, 2mm thick, were morphologically designed into five types of outline formation such as full palatal (P1), anterior three quarters (P2), anterior one half (P3), and anterior one quarter (P4) plate. Sound samples were recorded by Digital Audio Tape-Corder and analyzed by Voice Recognizing System. Data was transformed into the matrix of “Weighted Recognition Score (WRS)”, and calculated by Analytic Hierarchy Process. Prosthetically effective conclusions were as follows: In application of voice recognition system for evaluating prosthetic fablication, WRS were found to be effective and useful. As for the high score order of the plate evaluation in recognition, P3 was the best on [p], [t], [b], [s], [dz], [n], and [r], and P2 was the best on [m] and [k]. From the viewpoint of AHP comprehensive decisions, P3 was the best form and P1 was the worst form for speech production.

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The purpose of this study was to investigate the relation between the horizontal mandibular position and bulging in the temporal muscle region in edentulous cases.
In the experiment, 6 edentulous patients were required to clench at the tapping point and horizontally deviated mandibular position. At each mandibular position, the amount of bulging was measured.
In case of anteroposterior deviation, the amount of bulging tended to be greater at the tapping point than the anteroposteriorly deviated mandibular position. In case of the maximum length of the tapping area being less than 1.0mm, the amount of bulging at 0.6mm anteriorly deviated mandibular position was larger than the amount of bulging at the tapping point. In case of lateral deviation, the bulging tended to be greater and tended to start earlier on the deviated side than the opposite side. In case of the maximum width of the tapping area being less than 0.5mm, the value of the difference in the starting time of bulging between the right and the left sides at 0.4mm lateral deviated mandibular position was larger than the value of the difference in the starting time of bulging between the right and the left sides at the tapping point.

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The following results were obtained when experiments on the dynamic characteristics of the bony palate of anesthetized adult Japanese monkeys that had been stabilized in an standing position were carried out. Electrical stimulus was applied bilaterally to the centers of the masseter and temporalis muscles and the animals were made to occlude with their anterior or posterior teeth on either hard food, soft food, or sticks of various thicknesses.
Among the bones of the bony palate, compared with occlusion without food, there was a tendency for the principal strains to become greater in the maxillopalatine process on the working side when chewing on the anterior teeth, and in the horizontal lamina of the bony palate on any teeth when chewing. Furthermore, since the directions of the principal strains were similar to those when occluding without food, stresses may readily be concentrated. Compared with occlusion without food, the strains during occlusion on hard food or on sticks on the non-working side were very small, and in addition, there was a marked change in the direction of the principal strain. Therefore, it was concluded that the median and transverse palatine sutures ingeniously buffer the strains propagated from the working side.

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The purpose of this study was to investigate the characteristics of the path of chewing movement in patients with osseointegrated implants.
Chewing movement was recorded and analyzed by Sirognathograph Analyzing System III. Seventy patients with osseointegrated implants and 100 subjects with natural teeth were selected for this study.
The results were as follows:
1. Distribution of the patterns of chewing movement
1) Distribution of the patterns of chewing movement in patients with osseointegrated implants were different from those in subjects with natural teeth, but both groups had many of the same patterns of chewing movement.
2) Distribution of the patterns of chewing movement in patients with osseointegrated implant of full bridges, over dentures, and partial bridges differed.
2. The causes of the abnormal patterns of chewing movement
Abnormal patterns of chewing movement were mainly caused by access holes in osseointegrated implant of full bridges, abnormal occlusal planes in over dentures, and abnormal natural teeth in partial bridges.

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Osteogenesis promotion during bone repair following placement of an endosseous implant may reduce the time required for initial implant fixation, permitting early seating of the superstructure. Prosthodontically, this may provide significant benefits by promoting early restoration of the occlusion.
Pulsing electromagnetic fields (PEMFs) were applied to the oral implants of 9 adult male Japanese white rabbits (experimental group), and 9 unstimulated rabbits were used as controls. Implants were inserted into bilateral femurs. PEMFs were applied at a magnetic intensity of 0.2mT, a pulse width of 25μEsec, and a pulse frequency of 100Hz. The duration of stimulation was 8 hours per day. The rabbits were sacrificed at 1, 2, or 4 weeks after implantation. The results were analyzed using a basic fuchsin-methylene blue double stain, contact microradiography, fluorescent labeling, and computer image analysis.
The experimental group showed a tendency to increase new bone formation compared to the control group one week after implantation. This tendency became significant by 2 weeks after implantation. Promotion of osteogenesis did not significantly differ from that seen in the control group 4 weeks after implantation. These findings showed that PEMFs are effective for promoting new bone formation during the early stages after implantation.

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The purpose of this study was to investigate the biomechanical causes of hydroxyapatite (HA) coated blade implant fracture. The results of three-dimensional Finite Element Analysis (3 D-FEA) indicated that the cause of these fractures was the connection of osseointegrated implant and tooth with a poor periodontal condition.

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The Nikon Corporation was able to further improve the surface characteristic of titanium by developing a hydroxyapatite (HA) film on an anodic oxide layer of pure titanium implant (SA treatment). The HA film was composed of an electolytic solution containing Ca and P that underwent anodic oxidation followed by hydrothermal treatment in high pressure steam. This study was conducted to investigate how SA treated implants affect the surrounding bone tissue by analyzing them under an electron probe X-ray microanalyzer (EPMA).
HA plasma sprayed pure titanium implants, titanium plasma sprayed pure titanium implants, and SA treated titanium plasma sprayed pure titanium implants were implanted in the mandibles of beagles. After four weeks, the surrounding bone tissues were analyzed according to the distribution of Ca and P by EPMA.
The results showed that newly-formed bone had a relatively lower density of Ca and P than the existing bone for all dogs. Titanium plasma sprayed pure titanium implants without SA treatment were found to have less geographical distribution for both Ca and P. The Ca/P ratio showed no significant differences among them, indicating that SA treatment increased the biocompatibility of titanium implants by allowing them to induce more newly-formed bone quantity.

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Free-end saddle removable partial denture is an alternative to prevailing implant prostheses to restore the lost occlusal function. Occlusal stress distribution in free-end saddle RPD has been discussed by many prosthodontists. This problem of stress distribution must be recognized because of further application of free-end saddle RPD, realizing the limitation of its use. In this study, stress distribution in both abutment teeth and residual ridges were measured, analyzed, and discussed.
The results were as follows:
1. Selection of retainers influenced the occlusal force distribution even in the same free-end saddle condition.
2. Occlusal force distribution in the free-end saddle was closely related to the connecting rigidity of the selected retainer. The higher the connecting rigidity was, the less the denture sharing load was.
3. Abutment tooth mobility did not show any difference among the three different retainers assessed.
4. Mucosal support was suggested to be important for sharing the occlusal force applied in even the rigid telescope retainer under various conditions.

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Laminate veneer restorations for discolorations of light (L), medium (M), and heavy (H) degree, T I and OII type IPS Empress with varying light transmission, were employed with varying thicknesses of 0.5, 0.8 and 1.0mm, and the effect of different colors of adhesive resin cement on tooth color was investigated.
The conclusions were as follows:
1. For T I, when the target color was A 2, the color appearance was improved at 1.0mm; Yellow Brown (YB) was selected for M and H at 0.8mm and YB for H.
Color appearance was not improved regardless of the choice of cement in any of the discolored samples when the thickness was 0.5mm. When the target color was B 2, no color appearance was improved by any type of cement in any discolored sample.
2. For OII, at 0.5mm and 0.8mm when the target color was A 2, YB was selected for all descolored samples; at 1.0mm, YB was selected for M and H in which color improvement was identified. Color improvement was identified when the target color was B 2. At 0.8mm, Medium Opaque (MO) was selected for L. At 1.0mm, Opaque White (OW) and MO were selected for the same.
3. When A 2 was the target color, YB was selected for OII. When B 2 was the target color, OH was selected along with an opaque cement with a lower Value (L*) than YB, such as OW or MO. It was found that the color appearance was satisfactory and that OII was usable in laminate veneer restorations of discolored teeth.

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Correlation between movements of the mandible and hand in response to auditory signals were studied to obtain basic data on motor skills in the orofacial structures and upper extremities.
Ten dentulous young adults were asked to make tapping movements of the mandible or hand in synchronization with auditory signals generated at regular intervals of 1.3 time/sec.
Light-emitting markers that could be recorded as shining points when illuminated by a cold spotlight were used to monitor the orofacial and hand movements. This system provided trajectory data for the menton (Me) and fingertips (Ft). The subjects' hand or facial markers were recorded on videotape by two highspeed TV cameras from two perspectives, i. e., frontally and laterally, during a series of 20 tappings. The videotape of hand or facial recordings were then reproduced on high-speed video and fed into an image processor (Image Data ID-8000, nac Co.) that automatically tracked the movements of each marker.
The frame numbers of the opening/closing or up/down phases of each stroke were identified by sweep drawings of the up/down movements. Then the trajectory of each monitored point was computed using a three-dimensional (3 D) analyzer (Movias 3 D, nac Co.) with reference to the following parameters: total length of the trajectory from start to finish (TL); distance between the start and finish of the trajectory (SL); ratio of TL to SL (TL/SL); volume of the rectangular solid encompassing the entire trajectory (cubic range); and the mean of the 3 D angles created by differences in the direction of the preceding and subsequent trajectories for each measured time point (TH).
The following results were obtained. Although the range of movement for the Ft was approximately 8 times greater than that for the Me, the time lag between the auditory signal and Ft movement was significantly smaller (p<0.01) than that between the signal and Me movement. The TL and TL/SL of the Me and Ft during the closing/down phase were significantly smaller than during the opening/up phase. Similarly, the TH of the Ft during the down phase was significantly smaller (p<0.05) than during the up phase. These results indicated that the trajectories of the closing/down phase are smoother and more convergent than those of the opening/up phase (TL, p<0.01; TL/SL of the Ft, p<0.05).

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This study was carried out to examine the changes in chewing pattern during mastication of chewing gum with four hard materials. Each hard material was granular but varied in size and hardness. Recording and analysis of chewing movement was performed in 9 males and 6 females without stomatognathic dysfunction by using Sirognathograph Analyzing System III.
The results were as follows:
1. The typical changes in the chewing pattern were classified into two groups:
1) the terminal position of mastication when contacting or crushing a hard material coincided with the inherent terminal position.
2) the terminal position of mastication did not coincide with the inherent terminal position.
2. The process of mastication of the testing gum with a hard material was divided into five phases by changes in chewing patterns.
3. The changes in chewing patterns were different among the hard materials.

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A new mandibular positioner for quantitative analysis of mandibular bone resorption by rotational panoramic. radiography enabled measurement of the mandibular corpus height. The purpose of this study was to investigate the effect of positioning for edentulous mandible by rotational panoramic radiography.
Five dry mandibles were used in this study, and each mandible was tilted up to 30° using the mandibular positioner. Metal tubes were set vertically to the crest of the mandibular corpus of another mandible. The angle of mandibular plane and the angle of inclination of metal tubes were measured using rotational panoramic radiograms.
There was a high correlation between the actual size and the measurement by rotational panoramic radiogram.
It was possible that the mandibular corpus height was measured within 15° about the inclination of standard metal tubes. This study indicates that the angle measurements of mandibular plane and of the standard metal tubes on rotational panoramic radiogram were useful for accurate positioning.

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The up-and-down head mobility during repetitive jaw open-close movement with (jaw tapping) and without tooth contact were studied in ten healthy participants. The accelerometers were attached to the forehead and the mentum, and the direction of their mobilities were observed around the onsets of jaw open-close movement. The results were as follows:
1. During the jaw tapping movement, forehead mobilities in the opposite direction to the ones of the mentum were observed in 94.0% of the strokes around the onset of jaw open movement, and in 96.5% at the beginning of jaw close movement.
2. In the jaw open-close movement without tooth contact, the incidence of the forehead and mentum mobilities opposite to each other were significantly lower than those in the jaw tapping movement, and the same-directed mobilities thereof were observed with increasing frequency (p<0.0001).
3. It was suggested that the jaw open-close movement is accompanied by the head mobility and there would be functional relations between the mobilities of the head and the mandible, but their coordination pattern depends on the type of jaw movement.

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This study was conducted to examine the influence of changing the location of guidance teeth on the movements of the condyles during simulated parafunctional unilateral clenching.
Two healthy adults volunteered for this study. To simulate bruxist behaviour, they were asked to perform maximal clenching in a lateral edge to edge position with onlay-like metal guidances that increased by 10 degrees the inclination of the lateral excursions, but did not change at all the vertical dimension in intercuspal position.
A 6-degree-of-freedom jaw movement measurement system was used to record 3-dimensionally the condylar movements.
When the contact point of the anterior guidance was moved posteriorly along the arch from canine to second molar, the trajectory of working condyle movement was an antero-superior one up to the first premolar; but from the first molar this trajectory changed dramatically to an inferior one during unilateral clenching. All the trajectories of nonworking condyle movement were superior during unilateral clenching.
In consideration of the movements of the working condyle during eccentric movement in a parafunctional environment, the results suggested that the location of guidance teeth should be relegated to the anterior region of the working side.

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Titanium can adhere to high polymer material through the oxidation coating. Therefore, it is expected that titanium will be applied to resin facing crown by the non-retention method. A suitable treatment of the titanium surface was investigated to obtain strong adhesion between titanium and resin. It was clarified that resin adhered firmly to the titanium surface treated with Al₂O₃ sandblasting for 45 sec/cm² and heating at 600°C for 60 min, and then the bond strength was shown for a long time. In this study, the influences of the heating time on the adhesive strength was investigated. Test specimens using three kinds of facing resins (Cesead II, Thermoresin LC II, and Solidex) were prepared, and the shear bond strength of resin to the treated titanium surface after thermal cycling was examined. In addition, the interface of titanium and resin was examined under the scanning electron microscope. The results were as follows:
Cesead II showed durable adhesive strength to the titanium surface treated with Al₂O₃ sandblasting for 45 sec/cm² and heating at 600°C for 45 min, and cohesive failure of opaque resin was observed on the titanium surface fractured after 20, 000 thermal cycles in the bond strength test.

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Mouthguards are effective means of protection against traumatic injury in the maxillofacial complex during sports. The thickness of the mouthguard material which is essential to provide shock absorption can also have side effects such as increase in vertical dimension and disturbance in speech.
The objective of our current study was to examine the possibility of utilizing newly developed high-shock absorption silicone material (α-Gel) for fabricating mouthguards to reduce their thickness. Shock absorption was tested with the accelometer on the testing machine and on two volunteer subjects. The results indicated that α-Gel is a promising material to reduce the thickness of mouthguards without losing shock absorption.

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The castable ceramic restorations have advantages on clinical applications. However the clinical strength of the restorations for long-term have yet to be fully investigated.
The purpose of this study was 1) to evaluate the clinical strength of the castable ceramic crown (OCC), 2) to estimate the cause of failure, and then to improve the clinical technique.
In this study, 65 single crowns (including 4 onlays to molar) were placed in 25 patients and observed for a 5-year follow-up.
The results were as follows:
1. Nineteen of 65 restorations fractured, chiped and hair-cracked.
2. The incidence of failure for molars, premolars, and anteriors was 39%(7/18), 25%(5/20), and 26%(7/27), respectively.
3. The mean period of these failure cases was 27.9 (±S. D. 9.7) months.
4. Kaplan-Meier's estimation revealed that the estimated mean time of success was 47 months andsuccessful probability of 3 years later was about 65%, and 5 years later was 45%.
The successful life time of OCC might be shorter than other restorations.

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The purpose of this study was to investigate the relationship between 1/f fluctuation spectrum in brain waves and state anxiety score constituting Japanese STAI.
As a result, the beginning frequency of brain waves significantly correlated with the state anxiety score.

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This study was conducted to determine the effectiveness of bonding material (Bonding Porcelain, Noritake), especially bond strength between pure titanium (KS 50, Kobe Steel Ltd.) and low-fusing porcelain (Super Porcelain TITAN, Noritake), and color stability. Specimens were made with three building conditions of porcelains: 1) firing only Opaque Porcelain, 2) firing Opaque Porcelain after firing Bonding Porcelain, and 3) firing compound of Bonding Porcelain and Opaque Porcelain. The bond strength was measured by the pull out method and color by the spectrophotometric method. When Bonding Porcelain was used, the bond strength was greater than when not used, and the difference between conditions 2 and 3 was not statistically significant. However, there was significant difference between conditions 2 and 3 in color. In condition 3, it was possible to mask the color of titanium. The results of this study indicated that the use of Bonding Porcelain affected the bond strength and color stability. It was suggested that porcelain fused to titanium crown could be applied to aesthetic restoration.

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In recent years, castable glass ceramics have been used clinically as material in crown and bridge restorations. Materials used in such restorations must be not only strong enough to withstand masticatory and biting forces but also aesthetically close to the color of natural teeth.
In order to establish a technique for enhancing the color reproducibility of castable glass ceramics, which is an essential factor for clinical application, the relationship between the amount of crystalline phase and total light transmission of the crystal was investigated. The results were as follows:
1. Castable glass ceramics showed a high degree of translucency. A crystallization temperature of 910°C was found to be the most appropriate for the amount of HAP crystal, which has a translucency close to that of enamel.
2. For enhancement of the color reproducibility of castable glass ceramics, consideration must be given not only to the color of the glass and the stain but also to the influence of the tooth substance and metal as well as the color of the cement.

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