I determined physico-chemically and electro-chemically the surface characterization of synthetic hydroxyapatite (HAp) and dental enamel treated with fluorosurfactant (FSA), and the resulting adsorption of protein. The HAp was treated with the FSA that had four different types of polar hydrophilic radicals (anionic, nonionic, amphoteric and cationic).
     The surface characterizations of the FSA-treated HAp were analyzed for several parameters: surface tension, zeta potential, surface chemical composition and contact angle. The results indicated that treatment of FSA resulted in surface alterations of HAp and dental enamel. In particular, the contact angles of dental enamel treated with anionic or nonionic FSA indicated a slight increase in hydrophobicity compared with untreated dental enamel, while treatments with amphoteric or cationic FSA significantly increased hydrophobicity of the dental enamel surface.
     The adsorption of protein (HSA, CA and PR) on the surface of HAp treated with FSA was analyzed quantitatively by zeta potential. The adsorption decreased with treatment of anionic FSA, nonionic FSA and cationic FSA (DS-202), and was not influenced by treatment with amphoteric FSA and cationic FSA (Lodyne and Zonyl).
     These results indicate that the adsorption of protein to the sorbent is greatly influenced by the hydrophobicity of the sorbent surface.

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     I investigated the clinical implications of the masseteric evoked electromyography (EMG) method. The masseteric jaw jerk reflex and silent period (SP) were studied using an electrode array. The response varied with location and contraction level of masseter muscles. The latency period for the jaw jerk reflex was the same on both sides. I also investigated the relationship between the masseteric nerve and muscles, using electrical stimulation from the skin at the mandibular notch. I observed the M-wave, which is the so-called distal motor latency (DML). The M-wave peaks propagated from the motor end-plate. Although the muscle fiber conduction velocity (MFCV) decreased with fatigue, the DML did not change over time.
      It is suggested that the evoked EMG, e.g. bilateral jaw jerk reflexes, MFCV and DML, are useful parameters for estimating nerve and muscle conditions.

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     Using histochemical methods, we studied the changes in transforming growth factor-β (TGF-β) caused by tooth movement. TGF-β is a peptide growth factor which is abundant in bone and acts on osteoblasts and osteoclasts.
      Male Wistar rats weighing about 200 g were killed at 6, 12, 18 and 24 hours, and 3, 7 and 14 days after initiation of tooth movement, and paraffin sections 6μm in thickness were cut from the left maxillary molars. Sections from the right molars were used as controls. The sections were stained by the immunohistochemical (LSAB) method and H.E. staining. Examination was concentrated on the periodontal tissue mesial to the mesial root of the first molar.
      TGF-β-immunoreactivity was found in the periodontal ligament. There was strong TGF-β-immunoreactivity in multinuclear osteoclast cells in the ruffled border at 12, 18, and 24 hours after tooth movement, there was also strong TGF-β-immunoreactivity at the bone edge at 12 hours after tooth movement, and strong TGF-β-immunoreactivity in blood vessels at 24 hours. Strong TGF-β-immunoreactivity was also observed in new bone after initiation of tooth movement.
      These results suggest that TGF-β is a factor in controlling bone resorption and formation resulting from tooth movement.

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     We compared the deformation of maxillary complete dentures polymerized under conventional water bath curing and four different conditions of microwave irradiation.
      In the regions where there artificial teeth, there was considerable deformation in the dentures polymerized by microwave irradiation due to large anterior/posterior shrinkage and small lateral shrinkage. However, there was little deformation in the dentures polymerized by conventional water bath curing.
      In the alveolar ridge region, the deformation varied with conditions of microwave irradiation. There was little deformation in the dentures polymerized by three minutes of irradiation from the mucosal side. However, there was considerable deformation in the dentures polymerized by three minutes of irradiation from the occlusal surface side due to large anterior/posterior shrinkage. And there was considerable deformation in the dentures polymerized by conventional water bath curing.
      In the denture border region, the deformation varied with conditions of microwave irradiation. There was little deformation in the dentures polymerized by three minutes of irradiation from the mucosal side. However, there was considerable deformation in the dentures polymerized by three minutes of irradiation from the occlusal surface side due to movement of the denture border around the canine. There was also considerable deformation in the dentures polymerized by conventional water bath curing due to movement of the denture border around the canine and maxillary tuberosity.
      All of the dentures shrank. However, the shrinkage decreased between 7 and 30 days after polymerization by storage in water at 37℃.
      The weight of the dentures decreased one day after polymerization, then increased for the next 30 days by storage in water at 37℃.
      These results suggest that in regions where there are artificial teeth, the deformation of the dentures polymerized by microwave irradiation is larger than that of dentures polymerized by conventional water bath curing. In the mucosal regions, polymerization by microwave irradiation from the mucosal side produces a decrease in deformation.

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     Occlusion management, which incorporates coordination of occlusal development and oral function, is an important theme in long-term dental care of children. We investigated the various types of occlusion for various ages, changes in occlusion with age, and longitudinal charges in occlusion. We also measured the occlusal force of caries-resistant children with normal occlusion and bite volume.
      The results were as follows:
1.  At 5 years of age the prevalence of caries was 50.5% in boys and 48.4% in girls. The deft indices were 2.47 and 2.31, respectively.
2.  The prevalence of normal occlusion was 70% at 1 year of age and 50% at 2 years. However, there was little change between 3 and 5 years. At 1 year of age the prevalences of deep overbite and maxillary protrusion were very low, although both increased with age. At age 1 year normal occlusion was most prevalent, followed by mandibular prognathism, which had a prevalence of 20%. However, the prevalence of mandibular prognathism decreased with age. The prevalences of edge-to-edge occlusion, anterior crossbite and anterior openbite were low for all ages.
3.  At all ages there were children for whom the type of occlusion changed and those for whom it did not.
4.  The longer the length of time for which the type of occlusion at 1 year of age was maintained, the less was the change in that type of occlusion.
5.  Occlusal force increased with age although considerable variations were seen among children of the same age. At any particular age, the lowest occlusal force was about 1/3 that of the highest.
6.  The thicknesses remaining after occluding into bite wax of 1 and 3 mm thickness decreased significantly with age.
      It was found that there are significant changes in the deciduous dentition with age. Since occlusion in the deciduous dentition can be unstable, it is important to monitor changes, even in children with normal occlusion and no caries.

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     The purpose of this study was to investigate the intercuspal dimensional changes in teeth caused by polymerization shrinkage and hygroscopic expansion of composites. Marks were made on the cusp tips of maxillary premolars with a mesioocclusaldistal (MOD) cavity by means of a Vickers microhardness tester, and the distance between the two marks was determined with a measuring microscope. A cylindrical cavity was prepared in an acrylic plate for determination of horizontal and vertical linear polymerization shrinkages. The cavity was filled with a composite resin, and four pieces of aluminum foil (100×200μm) were placed at 90° intervals around the periphery of the composite. The shrinkage was calculated by measuring the microscopic three dimensional changes in the foil before and after polymerization.
      The following experiments were undertaken.
1.  Vertical and horizontal polymerization shrinkages were measured for the four composites with different inorganic filler content, and different volumetric polymerization shrinkage.
2.  The composite with the highest polymerization shrinkage was chosen for investigating intercuspal contraction in maxillary premolars using a variety of MOD cavities.
3.   MOD cavities with proximal boxes were filled with four different composites. Intercuspal dimensional changes were measured before and after polymerization, and for the duration samples were kept in water.
      The following results were obtained.
1.  Intercuspal contraction increased with increased cavity depth, increased cavity width, and inclusion of proximal boxes.
2.  Although volumetric polymerization shrinkage of the four composites was not entirely proportional to horizontal shrinkage, it was proportional to vertical shrinkage. It was assumed that horizontal shrinkage of the low filler content composites was offset more by the flow of the resin than was the case for high filler content composites.
3.  Intercuspal contraction was proportional to horizontal shrinkage, while intercuspal expansion was proportional to hygroscopic expansion.
      We concluded that measurement of horizontal polymerization shrinkage of composites was important in understanding dimensional changes in restored teeth. The new measuring method was useful for long term observation of dimensional changes in teeth and restorative materials.

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We studied how polymerization shrinkage and water sorption of composite resins produced dimensional changes in teeth. We determined the polymerization shrinkage and water sorption of four composite resins with different inorganic filler content. We also examined intercuspal dimensional changes in the teeth for various types of mesioocclusaldistal (MOD) cavity preparations. We found that dimensional changes increased together with increases in the cavity depth and/or width. The extent of the dimensional changes were dependent on polymerization shrinkage and water sorption of the composite resins. Water sorption expansion of the experimental composite resins could not compensate for polymerization shrinkage. Improvements in filling methods and cavity design are recommended to diminish residual stress in both the tooth and resin.

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In recent years there has been increased interest in odontoparallaxis in deciduous teeth. We examined the primate spaces, developmental spaces, and interdental spaces between the maxillary deciduous canine and first deciduous molar three consecutive times annually in 520 kindergarten pupils. We found that the incidence of spacing in the arch decreased with age. The incidence of primate spaces was greater in the maxilla than in the mandible, and decreased with age. Also, the incidence of interdental spaces between the maxillary deciduous canine and first deciduous molar tended to increase in both sexes between four and five years of age, and decreased between five and six. The incidence of developmental spaces was greater in children with primate spaces than in those without. In terms of chronological changes in spaces, of the three types, dentition that did not change was most common.

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We studied the changes caused by phospholipids (phosphatidylethanolamine (PE) and phosphatidyl-serine (PS)) in the physicochemical properties and hydrogen ion diffusion of glycoprotein. Six types of glycoprotein were injected into the sample port and hydrogen ion diffusion was measured. A fluorescent probe with 8-anilino-1-naphthalene sulfonate was used to determine changes in the hydrophobicity and surface potential of the above glycoprotein. The permeability of the glycoprotein membrane was inversely related to the concentration of phospholipids in the glycoprotein layer. It was found that permeability of glycoprotein associated with PS is lower than that of glycoprotein associated with PE. PS and PE had different hydrophobicity and surface potential. These findings suggest that phospholipids in the glycoprotein layers play an important role in retarding hydrogen ion diffusion, creating increased hydrophobicity and maintaining surface potential in the glycoprotein layer.

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We obtained average values for the Powell analysis of Japanese children using photographs of the profiles of 1,518 children between 6 and 17 years of age. We found no chronological changes in the nasofrontal angle, nasofacial angle, nasomental angle, mentocervical angle, nasolabial angle or subnasale-stomion/stomion-menton ratio. However, there were significant chronological changes in the base to dorsum ratio and nasion-subnasale/subnasale-menton ratio. By aesthetic evaluation of selected 276 profiles of adolescents between 16 and 17 years of age, we obtained ideal values for this group.

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We investigated and traced growth changes in the cranio-facial skeleton from childhood to adolescence in 15 boys and 14 girls between 10 and 15 years of age using Jarabak analysis, taking cephalometric radiographs once a year for six years. Average values and annual increments were obtained for the Jarabak analysis for this group of Japanese children. We found that the Japanese cranio-facial growth pattern either had a slight inclination from the straight downward type or tended to the counter-clock-wise growth type.

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The chewing paths of normal children, in particular those with deciduous dentition and with mixed dentition with four completely erupted permanent first molars, were analyzed and compared with those of normal adults. Compared with normal adults, the paths of children with both deciduous and mixed dentitions tended to have lower values for maximum opening distance, maximum anteroposterior movement, maximum opening velocity and maximum closingvelocity. However, maximum lateral movements in children with deciduous dentition were greater than in adults, although these values were similar for adults and children with mixed dentition.

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We investigated the effect of food characteristics on masticatory time. Jaw movements were recorded on a kinesiograph in 30 normal subjects and 15 patients with craniomandibular disorder(CMD). Cheese, boiled fish paste ("kamaboko"), pickled radishes ("takuan"), rice crackers ("senbei"), dried cuttlefish ("surume") and sticky candy ("gumi") were used as test foods. For both the normal subjects and CMD patients, the longest masticatory time was with dried cuttlefish, and the shortest was with cheese. Multiple regression analysis indicated that gumminess and volume affected masticatory time in both groups. High values for sensitivity and specificity indicated that mastication of a large volume of dried cuttlefish is a good test clinical examination and diagnosis of CMD patients.

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I investigated morphometrical and histological changes in craniofacial growth after maxillary expansion. A total of 135 four-week old male Wistar rats were used in this experiment. Lateral expansion was applied to the maxillary incisors by a stainless steel helical loop that was activated for one week and then removed. The experimental animals were killed at 5, 8, 11 and 14 weeks of age and the skulls were resected. Morphological measurements and microscopic as well as microradiographic observations were carried out. Maxillary expansion affected not only the midpalatal suture, but also the sutures of the craniofacial complex. These results indicate that maxillary expansion creates changes in the direction of cranifofacial growth.

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Management of occlusion, which is one theme in the long-term dental care of children, must consider development of oral function. We investigated the occlusal force of caries-resistant children with normal occlusion using occlusal indicating wax, and followed their development. The occlusal force increased with age. The thickness of the wax after occlusion decreased with age. These finding suggest that occlusion of deciduous dentition changes over time. Without proper management, even normal, caries-free children may develop unstable occlusion.

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The paracellular transport of salivary components from the interstitial space to the lumen was examined using microperoxidase as a tracer, and the distribution of anionic sites on the lateral cell membrane associated with the tight junction were observed utilizing ruthenium red and cationized ferritin. In the substance P-stimulated gland, we found the permeability of the tight junction was increased and the tight junctional region became negatively charged when compared with the resting gland. There were also changes in the anionic sites on the lateral cell membrane in the resting gland and in the secretory stimulated gland.

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Age-related changes in cerebral hyaluronic acid (HA) and chondroitin sulfate (CS) in senescence-ac-celerated mice (SAM-P/8//Odu, P substrain) were determined and compared with those of controls (SAM-R/1//Odu, R substrain). The CS chain consisted mainly of ΔDi-4S, with ΔDi-0S and ΔDi-6S as minor components for all ages of both substrains. The amount of each of the unsaturated disaccharides was higher in the R substrain than in the P substrain mice for all ages. These results indicate that the qualitative and quantitative changes in cerebral CS and HA of the P substrain mice were already expressed at 7 weeks of age and may cause the physiological and functional alterations associated with senescence in the central nervous system.

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We recently isolated a few anaerobic gram-negative, black-pigmented rods from saliva and periapical lesions. Several of these isolates, although resembling Prevotella melaninogenica, P. denticola or P. loescheii in most of their phenotypic expression, were capable of producing indole, a biochemical characteristic atypical of the P. melaninogenica group. Enzyme patterns by the API ZYM system and protein bands on SDS-PAGE gels were useful in differentiating the above three Prevotella species from other black-pigmented Prevotella, and in differentiating P. loescheii from P. melaninogenica and P. denticola. We failed to find phenotypic characteristics for differentiating P. melaninogenica and P. denticola. DNA-DNA hybridization is thus necessary for identification of the two Prevotella species.

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We compared the oral distribution and pathogenic characteristics of two homology groups in Prevotella intermedia. Almost all of the strains presumptively identified by indole production and enzyme patterns belonged to the ATCC 25611 or 33563 groups of Prevotella intermedia. Bacterial strains of the 33563 group predominated in cases of periapical periodontitis and cellulitis, whereas the strains of the 25611 group were present in oral microbial flora. The amounts of both groups were the same for bacteria from periodontal pockets. No differences in pathogenic enzyme production were observed for the two groups. These results indicate that both homology groups in Prevotella intermedia are prevalent in the oral cavity.

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Fimbriae-positive streptococci isolated from buccal mucosa, supragingival plaque and saliva were identified and their adherence properties were examined. Based on DNA-DNA hybridization, all strains tested were identified as S. salivarius or S. oralis. S. salivarius cells were abundant in supragingival plaque and saliva, while S. oralis cells were predominant in buccal mucosa. Electron microscopic studies revealed that all strains of S. salivarius possess peritrichous fimbriae, and that fimbrial tufts are present on 50% of S. oralis. S. salivarius were more hydrophobic and had more capacity to adhere to human buccal epithelial cells and to form in vitro plaque than S. oralis, indicating that S. salivarius have more pathogenic potential than S. oralis.

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