Purpose: The Oral Health Impact Profile (OHIP) is a measure of oral health related to quality of life and was developed in Australia but is being used increasingly in other countries. The original English version of OHIP was translated into Japanese in order to validate the translated questionnaire for use among populations in Japan.
Methods: A study was therefore undertaken to compare answers for the original version with those for the translated version. Data were collected from 39 bilinguals in Japan, using both English and Japanese versions of the questionnaire. The translated validity of the OHIP was analyzed by means of coincidence rate and A. coefficient.
Results: The mean of the coincidence rate was 0.75 for functional limitation, 0.76 for physical pain, 0.69 for psychological discomfort, 0.79 for physical disability, 0.77 for psychological disability, 0.90 for social disability and 0.85 for handicap. Forty-one items out of 49 had a A coefficient (index assessed symmetry) of more than 0.4. Cronbach's a of the original OHIP subscales ranged from 0.76 to 0.90 and those of the translated OHIP subscales ranged from 0.77 to 0.89, suggesting that the internal consistency of most subscales in the two versions were almost similar. Spearman's rank correlation in 7 subscales between the two versions ranged from 0.83 to 0.92 (p <0.001), which showed significant correlation, suggesting that the OHIP was acceptable across the two countries.
Conclusions: Although it is important to replicate these findings in other populations of different ages, the findings suggest that the Japanese version of the OHIP has good reliability and translated validity.

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Purpose: The purpose of this study was to clarify whether an experimental occlusal interference was recognized in the brain as stress.
Methods: 11-week-old male Wistar rats were used. They were divided into four groups: the control group, the immobilization stress group, the water immobilization stress group and the occlusal interference group, and each group consisted of six rats. Blood was sampled after the stress stimulation, and the concentration of corticosterone in blood was analyzed. In situ hybridization was then performed, and the expression of c-fos mRNA in the brain was observed. The eight regions of observation were amygdaloid, piriform cortex, hippocampus, cigulate cortex, paraventricular nucleus of the hypothalamus, locus coeruleus, raphe magnus nucleus, and central gray.
Results: c-fos mRNA positive cells were found in the eight regions of the brain, though the experimental occlusal interference group was different in the degree of c-fos mRNA expression in comparison with the two immobilization stress groups. Also, differences in right and left brain hemisphere of the c-fos mRNA positive cells were found in amygdaloid and piriform cortex of the occlusal interference group. The concentration of corticosterone in blood was high in the water immobilization stress group, the immobilization stress group, the occlusal interference group and the control group in this order.
Conclusions: The response caused by the experimental occlusal interference was clearly manifested as stress.

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Purpose: The aim of this study was to clarify the effect of an experimental occlusal interference on the brain function by the dipole tracing method.
Methods: Seven patients with healthy dentate were selected. Electromyograms (EMG) from the masseter and posterior temporal muscles and electroencephalograms (EEG) were simultaneously recorded and analyzed before and after clenching. The location of electric current sources was estimated by the dipole tracing method. In addition, evaluation by visual analogue scale (VAS) questionnaires consisting of five comfort parameters was also done. Four-session experiments-the control (Cont), just after and 2 days later after wearing the interference (JAR and 2 DL), and after removing the interference (AR)-were carried out.
Results: On JAR and 2 DL, VAS values increased and masticatory muscle activity decreased significantly, and both of them recovered by removing the interference.After clenching, %α in EEG decreased, and %α significantly increased compared with the control. Based on these findings, the sources of dipole were estimated in near amygdala, hippocampus, and thalamanus on JAR and 2 DL. The sources estimated in near amygdala disappeared on AR.
Conclusions: The experimental occlusal interference affected sensory evaluation, masticatory muscles, and EEGs and the localization of the dipoles estimated. It is suggested that the source of dipole localization had caused the emotional change.

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Purpose: The objective of this study was to clarify a suitable porcelain-fused alloy for Konus-Telescope dentures.
Methods: Two kinds of gold alloy (Degunorm and Degudent LTG), Pd-based alloy (KIK-WING) and Co-Cr alloy (DENTITAN) were investigated in this study. As the porcelains for veneer, special low-fused porcelain for gold alloys and conventional porcelain for the other alloys were used. Using a metal die formed with a shoulder shape, an outer crown specimen for the fitting test was cast using each alloy. The cast crown was replaced on the master die, then the vertical gaps between the die and margin of the cast crown were measured. The gap was measured every firing step for the porcelain veneer. The durability of each porcelain-fused crown was evaluated by a hammering test.
Results: The vertical gap of each alloy in the fitting test was slightly larger compared with that of the cast; DENTITAN and KIK-WING showed significantly greater vertical gaps (p<0.05), but Degunorm and Degudent LTG showed no significant difference. The vertical gap after the completion of fusion was largest for DENTITAN and significantly different from all the other alloys (p<0.05), and a significant difference was observed between Degunorm and KIK-WING (p<0.05). In the repeated hammering test, both multi-purpose gold alloys (Degunorm and Degudent LTG) showed good durability.
Conclusions: These results suggested that multi-purpose gold alloys are more suitable for Konus-Telescope dentures than the other metals tested in this study.

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Purpose: This study observed the daily change of the stress response caused by experimental occlusal interference.
Methods: 11-week-old male Wistar rats were used and divided into two groups: the control group and the occlusal interference group. Each group consisted of 36 rats. Six-session experiments were carried out over a period of 14 days. The concentration of corticosterone in blood was analyzed.
Applying in situ hybridization, the stress-induced c-fos mRNA in the brain was observed. The regions of observation in the brain were amygdaloid, piriform cortex, hippocampus, cingulate cortex, paraventricular nucleus of hypothalamus, locus coeruleus, raphe magnus nucleus, and central gray.
Results: Compared with the control group, c-fos mRNA expressions increased significantly in the occlusal interference group throughout the observation period. c-fos mRNA expressions were consistently manifested in the regions of the input system of the brain, and c-fos mRNA expressions in the regions of the output system of the brain adapted to the exprimental occlusal interference stress. The concentration of corticosterone in blood adapted to stress by experimental occlusal interference.
Conclusions: The stress caused by experimental occlusal interference is a stress with physical and psychological factors, and the stress responss did not disappear when the experimental occlusal interference was worn.

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Purpose: The discoloration of cast Ag-Pd-Au clasps has frequently been observed. This in vivo study investigated the effect of heat treatment on discoloration of cast clasps.
Methods: 10patients who had highly discolored clasps were selected as subjects. Cast clasps were conventionally cast using Ag-Pd-Au alloy (Ag: 46.0 mass%, Pd: 20.0 mass%, Au: 12.0 mass%). After casting, heat treatment was performed as follows: 1) Heated at 800°C for 1hour and quenched in water. 2) Heated at 800°C for 1hour and air cooled. As a control, cast clasps without heat treatment were used. After evaluating the luminance of the cast clasps, the removable partial dentures were delivered to 10patients. The luminance of the clasps was also measured after 6 months and after 1 year.
Results: Before delivery, the cast clasps with and without heat treatment both showed a luminance higher than 1, 000cd/m2.The luminance after 6months was decreased to the range from 1/5 to 1/8 of the first values. After 1year, luminance had decreased to that from 1/7to 1/12 in all clasps. The luminance of the water quenched clasps 6 months and 1 year after delivery was significantly higher than that of the air-cooled clasps and the control clasps.
Conclusions: Although there were significant differences in the luminance among the heat treated group and the control, the luminance was markedly decreased in all conditions after delivery. Heat treatment might thus have little effect for high discoloration subjects.

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Purpose: We investigated the effect of an occlusal splint on motor evoked potentials (MEPs) of fatigued masseter muscle using transcranial magnetic stimulation (TMS).
Methods: A double-cone coil driven by a MAGSTIM model 200 magnetic stimulator was placed over the right temporal area of 10 volunteers who reported no history, signs or symptoms of myofascial pain or arthralgia. The stimulus intensity was 50% maximum output of the MAGSTIM. We compared the MEPs in the volunteers while they were performing continuous voluntary contraction without an occlusal splint, with a 2.0-mm-high splint (Splint I), or with a 10-mm-high splint (Splint II). Each volunteer was assigned three conditions in random order. The volunteers were instructed to establish 50% maximum voluntary contraction without a splint. Root MEPs (R-MEPs) of the ipsilateral masseter muscle with short latency (about 3.0 ms) and cortex MEPs (C-MEPs) of the contralateral masseter with long latency (about 7.0ms) were measured. The data were analyzed using repeated measures two-way ANOVA. P values less than 0.05 were considered significant. The software package SPSS Ver. 11.0 J was used.
Results: There were no changes in the latency of the R-MEPs or the C-MEPs during the experiment. The amplitudes of both MEPs decreased during continuous voluntary contraction under each condition (p<0.01). The decrease in amplitude tended to be greater for C-MEPs than for R-MEPs without splint. There were no differences between the other conditions. The ratio between the amplitudes of the C-MEPs and the R-MEPs (C-MEPs/R-MEPs) decreased during continuous voluntary contraction without splint (p<0.05). There were no changes in the other conditions.
Conclusions: The occlusal splint reduced reflex inhibition of peripheral feedback into the motor neuron of the masseter muscle during fatigue.

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Purpose: We are developing an SA treatment that precipitates highly crystalline hydroxyapatite (HAP) on the surface of commercially pure titanium by using discharge anodic oxidation and hydrothermal treatment. It has been reported that SA treatment has an excellent bone conduction capacity. In order for a filled oral implant to maintain its function, it is necessary to examine HAP crystal transformation. In this study, we analyzed HAP crystal transformation in a solubility test by using SEM, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS).
Methods: An SA treatment pure titanium disk was soaked for 1, 7, and 14 days in 0.9% NaCl (pH6.0) and in Tris-Hcl (pH 7.4). Samples before and after immersion were analyzed for HAP crystal transformation by SEM, XRD, and XPS.
Results: HAP crystals were partially dissolved when immersed for 14 days in 0.9% NaCl solution. XRD analysis showed no changes before and after immersion in the detected materials (Ti, Ti02, Calcium acetate monohydrate, a-tricalcium phosphate, HAP, CaTiO). XPS analysis revealed that after immersion, HAP crystals have a greater tendency for solubility of binding energy of P and Ca in HAP crystals, than that after immersion for 1 day.
Conclusions: When assumed habitat of souring using 0.9% NaCl solution, decomposition was recognized by one part of configuration of alteration and HAP crystal internal energy, and the attribute did not receive influence. On the other hand, the internal energy of HAP crystals changed in Tris-Hcl solution, but the configuration and attributes of the HAP crystals were not affected. Accordingly, HAP crystals precipitated SA treatment was thought to be in stable condition at the organism internal environment.

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Purpose: This study evaluated the discoloration of a new composite denture tooth containing reactive organic composite filler.
Methods: A new composite denture tooth, Duracross physio (DP), and four conventional composite denture teeth including Duracross (DC), Endura (ED), Duradent (DC), and Surpass (SP) were used. Two test specimen groups for each denture tooth were prepared: a no treatment group, and, a treatment group where teeth were subjected to laboratory procedures (heat-polymerization and polishing) to fabricate a denture.The completed specimens were immersed in 23°C distilled water for 7 days, and the treatment groups were then subjected to either 5, 000 or 10, 000 thermocycles (4°C to 60°C; dwell time 60s) before staining. The color differences (JE) were determined before and after the staining test that specimens were immersed in 0.1% curry solution at 100°C for 1 hour or 0.2% basic fuchsin solution for 20 minutes. The specimens stained in curry solution were then stored in distilled water for 3 days to evaluate the recovery of their color. All data (JE) were statistically analyzed with ANOVA and Fisher's PSLD test (p=0.05). The color changes and the surface textures were observed optically and electro-microscopically.
Results: For the no treatment group, DP exhibited the lowest JE value among teeth tested after either immersion in curry solution or storing in distilled water. For the treatment group, DP was discolored similar to other teeth after the curry staining test. However, JE of DP decreased to a lower value compared to other denture teeth by storing in distilled water. DP also showed a lower JE value than that of DD or SP after the staining test using fuchsin.
Conclusions: The new composite denture tooth was less susceptible to staining compared to the other composite denture teeth. Discoloration could be prevented if dentures are cleaned properly during use.

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Purpose: Composite denture teeth are frequently used for removable prostheses.Recently, it has been observed that composite denture teeth suffer from unexpected discoloration. The objective of this study was to determine the causal factors contributing to the discoloration. In this study, the effect of different laboratory procedures was examined.
Materials and Methods: Five commercially available composite denture tooth specimens were tested. The specimens were treated with a total of 12 combinations of experimental conditions: with or without burning by a gas torch; 3 different denture processing methods ; and with or without polishing. The treated denture tooth specimens were then submerged in coffee solution at 37°C for 60 hours. The color of the specimens was measured before and after immersing in the coffee solution. In addition, the surface hardness and roughness of each specimen were measured.
Results: The denture teeth with rougher and softer surface tended to change color. The burning treatment by a gas torch contributed to the discoloration of some specimens. There was no effect by the different denture processing methods.The polishing minimized the discoloration in all tested conditions. Two-way analysis of variance indicated that there was a significant difference in the combined effects of the polishing and the different composite denture teeth. Each denture tooth appeared to respond differently to the experimental treatments.
Conclusions: Within the limitation of the study, the following clinical processes may be recommended in order to prevent unexpected denture tooth discoloration: to include the composite denture teeth in the final polishing procedure;and to carefully avoid accidental burning by a gas torch during the festooning process depending on the kind of denture tooth.

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Purpose: The purpose of this study was to clarify the behavior of buccal and lingual muscles of subjects without stomatognathic dysfunction by analyzing muscle pressures.
Methods: Six male subjects (average age 27.1 0.7) without stomatognathic dysfunction participated in this study. Pressure-measuring pieces which were made of self-curing acrylic resin with sheet formed sensors (Custom button sensor, Nitta), were placed around the maxillary molar areas except occlusal surfaces. Muscle pressures exerted on the buccal and lingual surface areas of the maxillary first molar were recorded bilaterally during chewing. Mandibular movements were recorded simultaneously. Peak pressures and the number of peaks were compared between buccal and lingual, chewing side and non-chewing side, and changes during the course of chewing.
Results: The lingual peak pressure was significantly higher than the buccal peak pressure on the chewing side and non-chewing side. Not only was the buccal pressure on the chewing side significantly higher than that on the non-chewing side, but also the lingual pressure on the chewing side was significantly higher than that on the non-chewing side. Peaks were frequently seen from the final stage of the occluding phase to the middle stage of the opening phase and in the middle stage of the closing phase on the chewing side. During the final stage of course of chewing, the peak pressure on the buccal surface of the chewing side was significantly increased and the number of peaks on both buccal and lingual surfaces were significantly increased. However there was no change on the non-chewing side.
Conclusions: This study examined subjects without stomatognathic dysfunction, and indicated the coordination of buccal and lingual muscles of the chewing side during chewing in regard to muscle pressures.

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