Our previous report appearing as Snow white (Shofu : the conventional phosphatebonded investment for casting plates) was impossible to apply to a heat-shock method because the mold would explode. In this study we tried to find suitable firing and casting conditions for this investment under a heat-shock procedure. At first we found that the decreasing temperature of heat shock could prevent the mold from expanding. Because we couldn't obtain sound castings from a mold fired at 700°C, we investigated an increase in the soaking time and the firing temperature. We were then able to successfully fabricate the sound Co-Cr full denture plates from the mold that was heat shocked at 700°C for 10 min followed by a secondary heating to 1,000°C with soaking for 30 min. We can conclude that the two-stage heat-shock procedure is available for fabricating a sound Co-Cr casting denture by using conventional phosphate-bonded investments.

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The possibility of fabricating Co-Cr casting plates by using a heat-shock method with conventional phosphate-bonded investments was investigated. Commercial phosphatebonded investments (Snow white, Univest nonprecious : Shofu) were investigated. A block of a duplicated model was prepared by using each powder mixed with its specific colloidal silica solution. A sheet of wax pattern with 0.5 mm thick on the model was secondarily invested by slurry mixed with water, colloidal silica solution, and their mixture. After 30 min on investing, the mold was put into the furnace preheated at 800°C and kept there for 30 min. Only the mold prepared from Univest mixed with water was available for casting after the heat-shock treatment. Other molds exploded in the furnace or received cracks after the treatment.The Co-Cr castings obtained from the available molds were not obviously sound because of insufficient firing. These results suggested that we might fabricate Co-Cr casting plates by using a heat-shock method with conventional phosphate-bonded investments, but we need further investigations to find suitable conditions for this method.

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We have been developing a dental CAD/CAM system to fabricate dental restorations automatically with computer assistance. We already developed the first and second versions of a compact CAD/CAM machine that contained both a digitizer and machinery. In our system, a laser digitizer digitizes the surface of the stone model of an abutment. In previous studies the width of the abutment's shoulder appeared to affect digitizing accuracy. In this study, the effect of the proximal teeth on the accuracy of the abutments shoulder margin was investigated in detail. Since the results indicated that accuracy decreased when the distance between the abutment and the proximal tooth was less than 2mm, we need to prepare a practical countermeasure to eliminate the effect of a proximal tooth.

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We have been developing a dental CAD/CAM system for fabricating crowns automatically. We have already developed a compact machine containing both a digitizing apparatus and a machining apparatus. Previous studies using a simple model for digitizing should that the adjacent tooth influenced the accuracy on the axial wall and the margin area on the abutment. In this study, a stone model of the standard abutment with a clinical taper and shoulder margin was digitized on the second version of the CAD/CAM machine with different digitizing conditions. Ceramic crowns were fabricated from a block by machining with a CAM procedure followed by their being cemented to abutments. Cement thickness measured on different spots appeared should that the accuracy on the transitional part on the shoulder to the axis of the wall increased when the digitizing model was separated from the adjacent teeth. Furthermore, the accuracy of the crown increased with the decrease of the digitizing pitch. Accurate crowns with a cement thickness designed on the CAD process were available when the digitizing pitch was 180μm. Therefore we can fabricate ceramic crowns with clinically acceptable accuracy by using a second version of the developed CAD/CAM machine.

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For exerting a disinfectant effect, electrolyzed strong acidic water should maintain such properties as the oxidation-reduction potential being 970 mV or greater, the concentration of active chlorine gas 0.8 ppm or higher, and pH 2.7 or less. It was found that when fresh samples of electrolyzed strong acidic water are stored in a tightly closed container that protects them from light, no change occurred in 2 weeks and its disinfectant efficacy did not change for about 1 month if the storing temperature was kept as about 4°C. Since salivary proteins largely affect the property of electrolyzed strong acidic water in its oral use, it is necessary to minimize the weakening of the oxidation-reduction potential and the concentration of active chlorine gas by increasing frequency of mouthwashing. Despite the presence of salivary proteins at ordinary concentrations, electrolyzed strong acidic water showed excellent disinfectant effects not only on Streptococcus mutans, a bacterial species relating most closely to dental caries, but also on Candida albicans, a main fungus species forming denture plaques.

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Brefeldin-A (BFA) is a specific and potent inhibitor of the intracellular transport of clathlin-uncoated transitional vesicles from the cisterns of rough-surfaced endoplasmic reticulum (RER) to the Golgi complex. We have examined the effects of BFA on ultrastructure and absorptive function of cultured osteoclasts. In control cultures, osteoclasts were structurally characterized by development of broad ruffled borders and clear zones racing the co-cultured dentin slices. Many resorption lacunae were formed on these slices. In BFA-treated cultures, osteoclasts lacked the ruffled borders and the Golgi complex. The RER cisterns were markedly dilated. BFA treatment significantly inhibited formation of resorption lacunae onco-cultured dentin slices. But the formation of clear zones and the adhesion of osteoclasts to dentine slices were not obstructed by BFA. These results suggest that the formation of the osteoclast ruffled borders is closely associated with the protein transport from the RER cisterns to the Golgi complex, and osteoclastic bone resorption is remarkably reduced by inhibiting intracellular protein transport. Therefore, this experimental system is useful to examine the functions and the transport pathways of various protein molecules in osteoclasts.

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A DNA fragment in the dextranase gene of Streptococcus salivarius was amplified by polymerase chain reaction, labeled with digoxigenin, and offered for a DNA probe. The specificity and the sensitivity of the probe were examined by hybridization analysis with the DNA of oral streptococcal species. The probe specifically hybridized to S. salivarius and was able to detect 1 ng of genomic DNA purified from S. salivarius JCM5705. Furthermore, the probe could differentiate S. salivarius isolates from other dextranase-producing oral streptococci. These results suggest that the probe is a useful tool for the detection and identification of S. salivarius.

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The purpose of this study was to investigate the 3-D shape of the vocal tract during /i/ production in patients with tongue and mouth floor resection by comparing Magnetic Resonance Imaging (MRI) data with acoustic data. The advantages of this procedure are the use of dental crown plates and stable landmarks. We report on the stability and reproducibility of this technique and functional areas of the vocal tract in five normal subjects. In this study, 10 patients with the tongue and mouth floor resections were measured and compared with 5 normal subjects.
MRI slices were obtained at 5 mm intervals from the central incisor to measure (1) change of functional area on the palate, (2) the location of narrowest section, (3) area functions at three locations on the palate, and (4) vocal tract shape. Spectral peak frequencies of F1 and F2 from 300 to 500 Hz and from 1,500 to 3,000 Hz were measured.
The following results were obtained.
1) Parameters in the normal range exhibited the following characteristics : (1) stable change, (2) the narrowest portion was centrally located on the palate, (3) functional area should be close to normal range, and (4) vocal tract shape was a symmetrical flat elipse.
2) The acoustic features of widely resected patients were (1) higher Fl than normal, (2) two peaks in the 1,500 to 3,000 Hz range, and (3) lower F2 than normal.
In conclusion, these factors are suggested to be important considerations in obtaining favorable speech function, indicating the importance of sufficient reconstruction of the anterior and posterior portions of the tongue.

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Recent studies have showed that anatase-type TiO₂ irradiated with UV acquired additional effects such as wettability, decontamination, and antibacterial effect. In this study we examined whether UV-irradiation to anatase-type anodized Ti plate induced wettability and antibacterial effect and discussed their relationship, using both the experimentally prepared and commercial anodized Ti plates. Wettability on the oxidized Ti plate increased in an irradiation time-dependent manner and reached the plateau at continuous irradiation for 24 h.The wettability on the Ti plate acquired, however, was quickly reduced to the original level after UV-irradiation was stopped, implying that continuous UV-irradiation was needed to keep a highly wettable surface. In contrast, the antibacterial effect on the oxidized Ti plate was not inducible by UV-irradiation even when the surface was highly wettable. These results suggest that no relationship existed between wettability and antibacterial effect on the anatase-type oxidized Ti plate with UV-irradiation.

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In the clinical, growth suppression in a cleft palate patient caused by postoperative scar tissue after the palatoplasty. Recently, the metabolism pattern of the normal palatal mucosa reports a difference in comparison with the scar tissue in collagen cross-link and conformer. This fact indicates the importance of leading the collagen of the scar tissue, which exists for the palate to the normal condition, to stimulate growth of the normal maxilla. However, the research that revealed metabolism activity of the collagen included for palatal mucosa and growth of the maxilla is limited, and the elucidation is urgent. It was then made that the relevance to maxilla lateral growth and collagen metabolism existing for palatal mucosa of the normal rat was clarified as the first step of purpose in this study. The retrieval was observed by the change of the gelatinase activity, which is concerned in metabolism activity of the collagen, using histological observation by morphological evaluation and H-E staining of the rat maxillary dentition, Film in situ zymography method (the FIZ method). The following was obtained after each relevance was examined.
1. With aging, the dentition width described by the increase curve equal to the body weight. Especially, it was indicated to be the growth middle point of a 15-week-old rat nearly in puberty almost. And though the start of the growth of the dentition width was later than that of the body weight, it became a similar growth rate after 11 weeks-old rat.
2. With the aging was a narrowing of the midpalatal suture division cartilage layer.
3. Gelatinase activity of the palatal mucosa was highest at either week-old in the epithelium.The high activity was recognized in the connective tissue division in nerve and blood vessel circumference. Moreover, the activity of epiphysis circumference bone in the midpalatal suture division was highest in a 4-week-old rat, and it lowered afterward time-dependent. In an 11-week-old rat it could not be recognized.
These findings suggested that gelatinase activity, which is collagen metabolism activity, was changed with the growth of the maxilla, and it was proven that the change was obvious in the midpalatal suture.

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The purpose of this study was to investigate the changes of degradation activity of the extracellular matrix in mucosal scar tissue formed after palatoplasty in a cleft palate patient.
By using three-week-old Sprague-Dawley strain male rats, the distribution of the incidence of gelatinase activity in scar tissue after surgical stripping of palatal mucoperiosteum was evaluated. One, two, four, and eight weeks after surgical procedure, histological and enzymological changes were compared with the film in situ zymography method in each group.
From the results, at the first week after surgical operation the area stripped of mucoperiosteum consisted of immature granulation tissue with a saturation of inflammatory cells and high gelatinase activity was observed. A slight regeneration of epithelium with no gelatinase activity was found in this term.
After two weeks, gelatinase activity decreased with the subsidence of inflammatory cell saturation, and it was correlated with the degree of inflammatory changes. The epithelium was regenerated and gelatinase activity was found with the differentiation of epithelium cells.
After eight weeks, fibrous connective tissue with a few components of cells was observed. Compared with normal epithelium, no differences in structure, components of cells or gelatinase activity were found in this group. These findings suggested that the gelatinase activity in rat palatal mucosa was correlated with the degree of inflammatory changes during cicatrization.

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The purpose of this study was to grasp the substance of the effects of treatment with maxillary protraction and their changes in a term of six months to two years after treatment of patients with crossbite caused by an undergrowth of the nasomaxillary complex.
The objects of this study are seven unilateral cleft lip and palate patients treated with maxillary protraction by the same orthodontist in the Orthodontic Department of Showa University Dental Hospital.
The following three conclusions were reached after the analyses of lateral cephalograms of these patients before, immediately after, and during a term of six months to two years after treatment.
1. The improvement of the crossbite with this approach shows changes in the advancement of the nasomaxillary complex, in the clockwise rotation of the mandible and labial inclination of the upper alveolar segment, and in the counterclockwise rotation of the palatal plane.
2. Four of seven cases had reoccurring crossbite during an observations after treatment that was caused by a lingual inclination of the upper incisors and a counterclockwise rotation of the mandible.
3. It was shown that the maxillary protraction for a patient with a cleft palate during the deciduous dentition was effective in the improvement of skeletal and occlusal unbalance with more or less amounts of relapse.

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We carried out a survey for residents to learn the oral health condition of dependent elderly in a special nursing home opened at Ohta-ku, Tokyo, in 1998. Since then, we have conducted a home-visit dental treatment at the request of the nursing home.
The summary is as follows.
1. Twenty-seven residents, about a third of all residents, received dental treatment. They were a slightly younger group than the average resident.
2. All subjects had basic diseases. Circulatory diseases were more frequent, and degenerative brain diseases were found at a lower frequency in the subjects when compared with all residents.
3. Most common reasons for the treatment were related to dentures. Two cases that complained of ill-fitting dentures were treated more than 20 time because they were too difficult to treat in the nursing home.
4. The contents of our home-visit dental treatment mainly consisted of the adjustment and repair of dentures, medication, and oral hygiene instruction. Some cases, in which it was necessary to monitor vital signs or to make new dentures, were treated in our dental hospital because of the difficulty of managing or treating : them in the nursing home.

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The great majority of developmental cysts in the mandible are lined by stratified squamous epithelium. The presence of ciliated epithelium in such cysts is extremely rare. This case is a follicular cyst in the left molar region of the mandible of a 45-year old man. Marked ciliated epithelium and scattered mucous-producing cells are found in the lining epithelium of the cyst wall with mild inflammatory change, hemosiderosis, and focal cholesterin cleft formation.
In a clinicopathological study of developmental cysts in the mandible by review of cases from our files covering 5 years, ciliated epithelium was present in 6% of all. The cases lined by ciliated epithelium are follicular cysts. The male and female ratio is 3 : 1, and mean age is 30.8 years. Our results seem to show a young male predilection. The mechanism of occurrence of ciliated epithelium is still unclear, but it seems that metaplasia is due to inflammatory change.

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