Using 62 plaster dental models, we determined midpoints of the incisal ridge of the incisors (I1_R, I1_L, I2_R & I2_L), cusp tips of the canines (C_R & C_L), summits of buccal cusps of the premolars (P1_R, P1_L, P2_R & P2_L), summits of mesiobuccal cusps of the molars (M1_R, M1_L, M2_R & M2_L) and the midpoint A of line (I1_R-I1_L). Point B is defined as the intersection of the vertical line from point A with the line (M2_R-M2_L). Point E is the intersection of (A-B) with (C_R-C_L). We evaluated protrusion of the canines, curvature of the anterior teeth, length-to-width ratio of the dental arch, and degree of roundness of the arch. Six items were summarized into three essential principal components. We also determined the relation of the contour and position of line (P1-P2-M1-M2) to line (P1-M2). The results indicated that 60% of the maxillary dentitions had round-square arches; square arches showed a small value for protrusion of the canines; round arches were characteristic by a small degree of arch roundness; and round V-shaped arches had large values for curvature of the anterior teeth.

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We examined the production of viscous material using clinical strains isolated from severe odontogenic infections. Bacteria were isolated for all cases, and the average number ofisolates was 2.1×10^7CFU/mL. Although anaerobes predominated in all cases, the viscous material producers were, for the most part, from the facultatives. All cases contained bacteria thatproduced viscous material, the most prominent being Peptostreptococcus sp. (26%), Prevotella intermedia/nigrescens (18%), Streptococcus oralis (16%) and Fusobacterium nucleatum (8%).S. oralis in particular was more viscous than the other species, with an average viscosity of 3.32 mPa・s. S. oralis produced a viscous extracellular material that appeared under electron mi-croscopy to have fibrous-like structures. These results indicate that strong viscous material from bacteria such as S. oralis may be important in biofilm production and in the exacerbation of odontogenic infections.

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We investigated the healing process in the periosteum after experimental flap surgery in beagle dogs by focusing on morphological changes of the microvasculature. We examined gingivo-periosteal vascular plexus specimens collected from around the maxillary anterior teeth, and used a light microscope (LM) and transmission electron microscope (TEM) to histologically observe changes 3, 5, 7, 14, 21 and 28 days after the operation. Similarly, we observed vascular corrosion cast specimens of the gingivo-periosteum, into which acrylic resin had been injected, using a scanning electron microscope (SEM). The results showed that the vigorous vascularization that occurred in the periosteum as a reaction to the flap surgery, provided an important basis for the subsequent healing process. Further, we confirmed that the morphology of the gingivo-periosteal vascular plexus changed in accordance with the function of osteogenic cells, and contributed to regeneration of the periodontal tissue.

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We investigated the capacity of the quantitative light-induced fluorescence technique (QLF) to detect and quantify white spot lesions in vivo. Sixty-five white spot lesions in 65 patients with a mean age of 20.3±8.3 were selected by visual inspection during oral examination and the lesions were evaluated using a QLF technique. The QLF images were saved at the initial visit and were compared with images done one year later. This allowed us to quantify remineralization and/or demineralization for that period. The image of each white spot lesion was analyzed for four parameters. The average depth of the lesion was measured as the average of fluorescence loss (ΔF, %). The maximum depth of the lesion was measured as the maximum fluorescence loss (ΔMax, %). The lesion size (S, mm^2) and mineral loss (ΔQ, %×mm^2) were also measured for each white spot lesion. Based on our findings, we concluded that QLF is suitable for the early clinical detection and diagnosis of dental caries.

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We investigated the in vivo use of the quantitative light-induced fluorescence (QLF) technique to assess caries risk of white spot lesions over a one-year follow-up period. Sixty five white spot lesions in 65 patients with a mean age of 20.3±8.3 years were selected by visual inspection during oral examination. The lesions were evaluated using the QLF technique at the start of the examination and at 3, 6 and 12 months. Four QLF parameters were analyzed from each white spot lesion image. The average lesion depth was measured as the average of fluorescence loss (ΔF, %). The maximum lesion depth was measured as the maximum fluorescence loss (ΔMax, %). The lesion size (S, mm^2) and mineral loss (ΔQ, %×mm^2) were also measured. The results indicated that QLF could be used to monitor caries risk of a white spot lesions and to determine whether a white spot lesion had progressed, been arrested or regressed during the one-year period. Based on these results we concluded that QLF is a suitable clinical technique for caries risk assessment at the white spot lesion stage.

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We examined how jaw deformities affected personality in males and females using the MINI psychology analysis method Ver 6.0 with patients who visited the Orthodontic Department of Osaka Dental University between 1999 to 2002. We studied 19 males between the ages of 18 and 27 years with a median are of 22, and 27 females between the ages of 18 and 39 years with a median age of 23. The results for the two genders were compared. Males had siginificantly higher scores than people without jaw deformities for Hy (hysteria), Pd (psychopathic deviation), and Pa (paranoia). However, no siginificant difference were observed in the females. We concluded the jaw deformity might be associated with mental disorder in males.

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We attempted to clarify the morphological interrelationship of the area postrema (AP; the vomiting center), the lateral hypothalamic area (LHA; the feeding center) and the hypothalamic suprachiasmatic nucleus (SCN; the center of circadian rhythm), concentrating on vomiting and feeding behavior. The chemoreceptor trigger zone for vomiting is located in the AP, which is composed of neurons, astrocytes, and fenestrated sinusoidal capillaries. We investigated the morphology of these structures and discussed their relationship to vomiting. Immunohistochemistry was employed for these investigations in the AP of male Wister rats. Glial fibrillary acidic protein (GFAP) and vimentin were used to examine astrocytes, and tyrosine hydroxylase (TH) for neurons. Alkaline phosphatase histochemistry was employed for the sinusoidal capillaries. GFAP-positive astrocytes were shown over the entire AP, indicating a strong morphological relationship between astrocytic processes, TH-positive nerve endings and sinusoidal capillaries. Other authors have stated that SCN, LHA and AP are connected through the paraventricular nucleus (PVN) by nerve fibers. They suggested that vomit triggering information from AP, light information from SCN, and feeding behavior information from LHA may be projected into PVN, playing a role in the formation of feeding behavior patterns. Our results confirmed these findings.

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The most effective and efficient way to regenerate lost tissue is to use tissue factors that act on the targeted tissues during histogenesis. Revealing the types of tissue factors responsible for or related to the formation of cementum and the periodontal ligament (PDL) during periodontal regeneration is an extremely important subject. To discover the specific factors involved with the PDL, we produced a monoclonal antibody (MoAb) against PDL using periodontal tissue as the antigen. Various rat tissues were immunostained for the MoAb. The MoAb reacted with the PDL, connective tissue under the oral gingival epithelium, connective tissue beneath the epithelia covering the maxilla and mandible, and the connective tissue of the femoral surface. However, this MoAb did not stain the deeper connective tissue of the gingiva, oral gingival sulcular epithelium, buccal mucosa, or connective tissue on the surface of the maxilla facing the nasal cavity. It also did not stain, muscle, nerve, blood vessels, bone marrow, pulp, dentin or cementum. We concluded that this MoAb is a useful tool for investigating PDL regeneration.

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There are many diseases associated with hard tissue formation in the oral cavity. The hard tissues are derived from bone-like tissue, from cementum-like tissue and by simple calcification. It is important to distinguish the type of hard tissue to determine the classification and biological characterization of the disease. We immunostained disease specimens associated with hard tissues using a monoclonal antibody (MoAb) against human cementum using the Envision method. In normal tissue this MoAb produced a positive reaction in cementum and periodontium, and a negative reaction in bone. In cemento-osseous lesions, some regions produced a positive reaction while others were negative. The former tissue seemed to be cementum-like, while the latter seemed bone-like. These results indicate that this MoAb is useful for differentiating cemento-osseous lesions. Use of this MoAb provides new insights into the nature of these lesions.

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In order to develop a system whereby facial form could be expressed quantitatively, we studied scans taken with a non-contact three-dimensional system (VIVID 900, Minolta, Japan). When we compared a person's face at rest with that when his teeth were occluded, we found that there was a significant difference between the left and right sides (p<0.05). This difference was primarily caused by the masseter muscles. Based on these results, we concluded that our system could be used to quantitatively analyze the human face.

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We investigated the use of digital image analysis to objectively evaluate the condition of marginal gingiva. Digital images were taken of the gingiva of 25 subjects using a special CCD camera with various magnifications. The subjects had been requested not to brush for three days. Five parameters were analyzed: hue, lightness, saturation, three-dimensional image, and amount of microvasculature. We found that this apparatus could be useful for the objective evaluation of gingiva because changes could be expressed quantitatively.

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We investigated the detection and analysis of dental plaque using quantitative light-induced fluorescence (QLF). The QLF examination of the digital image of dental plaque was used to calculate the detected area (Area), the average red-fluorescence intensity (AR ave) and the maximum red-fluorescence intensity (AR max) in 10 healthy volunteers who refrained from tooth brushing for three days. Each of the three parameters increased at a different rate for the three days. We concluded that the QLF examination can distinguish and quantify the three parameters, and evaluate the rate of dental plaque formation.

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We evaluated how exposure of the pharyngeal mucous membrane in rabbits to carbon dioxide (662) affects the negative pressure airway reflex (NPAR) using the activity of the genioglossal muscle as an index of NPAR. Exposure of the pharyngeal cavity to air containing 1096 CO2 significantly inhibited NPAR, while treatment with methazolamide (MZ) prevented inhibition of NPAR caused by CO_2 exposure. The magnitude of decrease in pH in the pharyngeal submucosa that resulted from CO_2 exposure was smaller in animals with MZ treatment than in those without. These results suggest that inhibition of NPAR by CO_2 exposure may be associated with change in the pH of the pharyngeal tissues.

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We investigated how factors such as the dental mirror and surgical gloves affected precise finger manipulations using a high-speed cutting simulator that we developed. The simulator recreates the minute movements of the airturbine handpiece (ATM) during high-speed operation, although there is no actual cutting. Eight dentists were requested to stably move the ATM on the simulator and to control the operating force using less than 80 grams of force with direct vision, using a mirror, and with direct vision using surgical gloves. The forces and movement of the ATM were evaluated. We found that dentists who used indirect vision in daily practice were able to precisely control the ATM with a mirror.

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We investigated how film thickness (FT) and thermal stress affects the tensile bond strength (IBS) of resin cements to dentin. The resin cements used were Superbond C&B (SB) and Panavia Fluoro Cement (PF). FT was standardized by using a spacer with a hole in it placed on the polished surface of bovine dentin. A resin inlay was bonded with cement to the dentin surface with the spacer in place. The thickness of the spacers were 25, 50, 100, 350 and 1000 μm. TBS was measured after the apparatus was subjected to thermal stress cycling 10,000 times. The thickness of the spacer had no significant effect on TBS for SB. However, there was a significant decrease in TBS for PF at 1000 μm.

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We investigated the effect (in vitro) of ZrO_2, Si_3N_4 and TiN on the activity of the human osteoblast-like cells, Saos-2. The initial cell attachment of ZrO_2 and Si_3N_4, as evaluated by the methylthiazole sulfate test, was greater than that of TiN, which was the same as that of the control. The viability after 72 hr of culture with ZrO_2 was the same as that of the control, but greater than that with Si_3N_4 or TiN. The average ALP, as assayed by the release of p-nitrophenol from p-nitrophenylphosphate, was greater for the three ceramics than for that of the control. Although the collagen type I mRNA expression level was also greater for the three ceramics than for that of the control, only the difference between TiN and the control was significant. The results of this study lead us to conclude that the three ceramics did not disturb cellular activity.

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We examined the effect of similar and dissimilar combinations of three precious dental alloys under dynamic extraction on metal release and cell viability. The amount of metal measured by inductively coupled plasma spectrometry in extracts of dissimilar combinations was greater than that of similar combinations. Only Cu and Zn were detected in the filtrates. Cell viability, as evaluated by L-929 mouse fibroblasts, of the dissimilar combinations was lower than that of the similar combinations. These findings indicate that dynamic contact between two alloys influences metal release and cellular response.

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We performed experimental flap surgery on the maxillary anterior region of beagle dogs to examine how it affected microcirculation, and investigated morphological changes in the microvasculature during the healing process. We observed the gingivo-periosteal vascular plexus histologically using a light microscope and a transmission electron microscope 3, 5, 7, 14, 21 and 28 days after the operation. Scanning electron microscopic examination was also done during the same time period using vascular corrosion cast specimens into which acrylic resin had been injected. Our results showed that vigorous vascularization in the periosteum was important in providing a basis for the healing process after periodontal surgery, and that the gingivo-periosteal vascular plexus contributed to the metabolism involved in repair of periodontal tissue.

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We evaluated the occlusal contacts in the intercuspal position between natural teeth and prostheses that have stress absorbing elements that have been placed on osseointegrated implants. Using this information, we investigated how to best create occlusal contacts on prostheses with opposing teeth. The number and area of occlusal contacts increased with occlusal force both on the natural teeth and on the prostheses. However, the location of the contacts remained the same in both the healthy dentulous subjects and those with prostheses. We think that these results probably occur because of displacement of opposing teeth, strain on their supporting tissue and displacement of the stress absorbing elements. We concluded that a harmonious intercuspal position with natural teeth can be established by imparting appropriate occlusal contacts on the prostheses.

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We investigated the influence of the shape of fiber-reinforced composite (FRC) on the flexure strength of bridges. Four different FRC shapes were fabricated with laminating hybrid composite resin (n=5). Flexure strength was determined by mechanical loading on the center of the pontic using a universal testing machine. Both enlarging the width of the FRC from 3 mm to 6 mm, and bending the FRC apically increased the flexure strength by about 400 N respectively (p<0.01). We found that it is desirable to enlarge the width of the FRC and to bend the FRC apically when using this material for making a bridge.

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We analyzed the three-dimensional occlusal force vectors during intercuspation in normal adults. Silicone occlusal registration and pressure-sensitive sheets were recorded for ten subjects during clenching with medium force and maximum force. A non-contact, three-dimensional measuring device digitized the silicone occlusal registration. Occlusal forces were measured using pressure-sensitive sheets. After the occlusal contact position had been identified, the three-dimensional occlusal force pattern was synthesized from the data. The contact points, contact areas, resultant forces and moments for the molars were significantly different from those for the premolars. The inclination of resultant forces were almost vertical to the occlusal plane in the frontal and sagittal view. There was also a significant difference in the contact points, contact areas, resultant forces and moments when clenching with medium force was compared with clenching with maximum force. However, there was no consistant tendency in the inclination of the resultant forces.

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Nociceptive neurons responding both to tooth pulp (TP) stimulation and to mesencephalic reticular formation (MRF) stimulation were recorded from the nucleus centralis lateralis (CL) of the thalamic intralaminar nuclei in cats anesthetized with urethane and chloralose. We investigated the effect of the cervical vagus nerve (CVN) stimulation on response of CL neurons to electrical stimulation of the TP and of the MRF. A total of 22 CL neurons responding both to MRF stimulation as well as to TP stimulation were obtained. In 9 of 22 neurons, electrical stimulation of the CVN inhibited responses of CL neurons to TP stimulation. However, the CVN stimulation had no effect on responses to electrical stimulation of the MRF. These results suggest that vagal afferents can activate the descending antinociceptive system that acts on the lower brainstem, and that there is no ascending pain suppression system acting on the CL that is controlled by vagal afferent input.

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