We examined the ability to form biofilm of 74 clinical isolates of black-pigmented Gram-negative anaerobic rods isolated from periodontitis lesions based on their capacity to produce viscous materials in culture media as most biofilm-forming bacteria do. Two strains, designated as OD 1-2 and OD 1-16, were obtained and identified as Prevotell intermedia by using the API-ZYM system, 16 S rRNA sequencing and DNA-DNA hybridization. Scanning electron microscopy revealed that both strains had dense meshwork-like structures around their cells which are typical cell surface structures for biofilm-forming bacteria. Chemical analyses of the viscous material isolated from culture supernatants of strain OD 1-16 showed that they contained neutral sugars (791.7μg/mg), uronic acid (27.7μg/mg), and amino-sugar (13.7μg/mg), with mannose constituting 82% of the polysaccharide. As compared to strain ATCC 25611, which was a type strain for Prevotell intermedia and was non-producing of EPS, strain OD 1-16 showed higher activities for inducing abscess formation in mice. Further, strain OD 1-16, but not ATCC 25611, showed resistance against phagocytosis by human neutrophils. Combining this with findings from our previous studies, these results suggest that Prevotella intermedia might achieve the capacity to produce large amounts of exopolysaccharide, consisting primarily of mannose, and that they might play a key role in the development of biofilm infections in the oral cavity.

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We isolated a spore-forming Gram-positive aerobic rod (strain N38) from a persistent periapical lesion that was identified as Bacillus subtilis using an API system, 16S rRNA sequencing, and DNA-DNA hybridization. Scanning electron microscopy revealed that this strain had dense mesh-like structures on the cell surface, which is typical of biofilm-forming bacteria. The PgcA gene, an important gene for exopolysaccharide production in B. subtilis, was detected in strain N38 by the polymerase chain reaction method. Also, proteinase K did not affect the mesh-like structures around the cells of strain N38, indicating that these structures may be composed of exopolysaccharide. We compared the susceptibility of strain N38 to anti-microbial agents with the susceptibility of ATCC 6051, which is a type strain of B. subtilis. Both strains showed the same sensitivity to ampicillin, cefalexin, minocycline, erythromycin, ofloxacin, cefteram and vancomycin. These results suggest that the ability of B. subtilis to persist in a periapical periodontitis lesion depends on biofilm formation, but not on antibiotic resistance.

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We investigated the influence of post cure heating on the flexure strength of the prosthetic composite resins GRADIA, SOLIDEX, Epricord, ARTGLASS, Sculpture, Targis and ESTENIA. Specimens were fabricated either with light curing only or with light curing and post cure heating. Four specimens were fabricated with each of the materials. Three-point bending tests were performed at a crosshead speed of 0.5mm/min and a span length of 20mm. The data were analyzed using two-way analysis of variance (ANOVA). Incorporation of post cure heating resulted in a statistically significantly higher flexure strength compared with light curing only for all of the products. There was no interaction between curing condition and product. ESTENIA had the greatest flexure strength, followed by Targis, ARTGLASS, Sculpture, GRADIA, Epricord and SOLIDEX in that order. Flexure strength of all of the products was improved by post cure heating after light curing.

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Electromyography (EMG) has long been used for the objective evaluation of muscule function. However, no clear activity pattern has been established for EMG during normal mandibular function. We attempted to determine an index of EMG muscular activity patterns in the lateral pterygoid muscle. Mandibular movements of the bilateral lateral pterygoid muscles were simultaneously recorded with their electromyographs in healthy subjects who had no orthognathic abnormalities in the jaw or oral system. We examined anteroposterior movement (AP) and opening and closing (OC) of the mandible. In addition the subjects were instructed to move their mandibles horizontally and vertically for 40 seconds to the rhythm of a metronome at 0.5, 0.65, and 0.8Hz. The muscular activity per unit time was calculated from the integrated value of muscular activity for a single back and forth movement. AP displacement, OC displacement, and mean muscular activities during AP and OC movements were calculated for each subject, and the ratios of EMG activity during OC and AP movements were calculated and compared. The OC/AP ratio was approximately 1 in healthy subjects, indicating that muscular activity of the lateral pterygoid muscle during AP and OC movements were similar in healthy subjects.

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We used dynamic magnetic resonance imaging (MRI) to analyze the velocity and excursion of the condyle and articular disk during mouth opening and closing. These parameters were compared between individuals with clicking sounds in the temporomandibular joint (TMD group, n=6) and those with no abnormalities in the joint (normal group, n=7). We used a Signa Horizon LX[○!R] (1.5 Tesla, GE Inc., Wisconsin, USA) at fast SPGR, 7.7/1.4 ms TR/TE, 8mm thickness, and 40 sec duration. Each subject was instructed to open as widely as possible and then to close over a period of 40 seconds, during which time we measured the velocity and excursion of the condyle and articular disk. The degree of anterior displacement of the articular disk was quantified in the TMD patients. Compared with normal subjects, the degree of variance in movement velocity for opening and closing movements was significantly greater for the TMD patients. These findings suggest that dynamic MRI is useful for observing and quantifying the dynamics of the articular disk and that the degree of fluctuation in the velocity of articular disk movement is significantly greater for patients with clicking sounds.

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The functional appliance is widely used in orthodontic practice for treating patients with skeletal problems. We treated 29 patients (18 males and 11 females, average age 11.6 years) who had Angle Class II division 1 malocclusion using the function regulator II. Cephalograms taken before and after treatment were traced and analyzed. Five esthetic indices were used to evaluate soft tissue profile changes in the patients. Most of the indices tended to normal values and the soft tissue profile of the patients were improved after the functional treatment. However, individual changes differed and second stage treatment was still required for some patients. Early function regulator treatment reduces the need for second phase treatment, reduces the difficulty of late treatment, and shortens the period of late treatment. It is considered on efficient method of treatment.

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We attempted to determine whether enamel matrix derivative (EMD) affects the quality of bone repair around titanium implants. Screw-shaped pure titanium implants were inserted in both tibia of beagle dogs with approximately 0.1mL of EMD gel. Removal torque strengths were measured at 3, 6, 9 and 12 weeks post-insertion. Higher removal torque strengths were achieved for the implants with EMD gel compared to the controls at 3, 6 and 9 weeks postinsertion. These results may indicate that EMD contributes to strengthening the interface between implant and bone, thus promoting the establishment of osseointegration at an earlier stage.

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Regional cerebral venous infarction was induced in rabbits to assess the degree of resulting cerebral edema and changes in autoregulation of cerebral blood flow. The specific gravity of cerebral tissues was lower three hours after induction of infarction than it was before. The ratio of decrease in cerebral blood flow to the decrease in mean arterial pressure after exsanguination was greater in animals with infarction than in those without. These findings suggest that loss of autoregulation of cerebral blood flow is caused by an increase in the difference in hydrostatic pressure between the cerebral and surrounding tissues, which results in cerebral edema, as well as by disruption of the cerebral vascular endothelium.

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We studied dental arch forms using 62 maxillary and 53 mandibular casts having normal dentition and occlusion selected from 396 pairs of standardized dental study models. We determined reference points on the dental arch and analyzed seven items used for differentiation of arch forms. Six of the selected items were summarized into three principal components for evaluation. We found that most of the maxillary and mandibular arches were round-square in shape. The first component, which represents the curvature of the anterior teeth, showed significant differences between round V-shaped arches and other arch types. We concluded that there was greater variety in the maxillary arches than in the mandibular arches.

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I investigated the bone regeneration process using bovine periosteal cells by examining the effect of ascorbic acid, mRNA expression of specific markers and the ultrastructure of osteoblasts. Cells cultured in ascorbic acid, had a three-dimensional structure at a concentration of 50μg/mL ascorbic acid, but not at concentrations of 10μg/mL or 0μg/mL. mRNA expression of type 1 collagen, osteocalcin and alkaline phosphatase were observed after three weeks. These results seem to indicate that the three-dimensional structure of cells and differentiation into osteoblast-like cells are important in the bone regeneration process.

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We explored the possibility of local inflammation as the mechanism responsible for the Chronic Constriction Injury (CCI) model. Local inflammation induces the release of several algogenic substances and causes pain. It is thought that nitric oxide (NO), a free radical, causes pain. We administered a free radical scavenger to a CCI model and analyzed the reactions of neuropathic pain through behavioral and histological studies. We found that the free radical scavenger did not inhibit neuropathic pain.

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We evaluated the occlusal contacts in the intercuspal position between natural teeth and prostheses with no stress absorbing elements that were placed on osseointegrated implants. Using this information, we investigated how to best create occlusal contacts on the prostheses with opposing teeth. The number and area of occlusal contacts increased with increases in occlusal force both on the natural teeth and on the prostheses. However, the location of the occlusal contacts remained the same in both healthy dentulous subjects and in those with prostheses. We think this probably occurred because of displacement of the opposing teeth and strain on the supporting tissue that occurred regardless of the presence of stress absorbing elements. We concluded that a harmonious intercuspal position with natural teeth could be established by imparting appropriate occlusal contacts on the prostheses regardless of the presence of stress absorbing elements.

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I identified viscous-material-producing facultative anaerobic Gram-negative rods that were isolated from a therapy-resistant apical periodontitis lesion as Escherichia hermannii strains. I named them E. hermannii strains 11-1 to 6. These bacteria were surrounded by mesh-like structures which are typical of biofilm-forming bacteria. The culture medium of strain 11-2 had the highest viscosity of the six strains. When I purified exopolysaccharide (EPS) from this culture medium and analyzed its chemical composition, I found it consisted primarily of polysaccharide that contained 80% mannose. Susceptibilities of these strains to anti-microbial agents did not show any particular pattern. My data suggests that E. hermannii, a transient bacterium in the oral cavity, might form biofilm in the periapical region and cause therapy-resistant apical periodontitis.

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Human gingival fibroblasts and epithelial cells were cultured on the surface of composite resin to investigate the influence of restorative materials on gingival tissue. Composite resins were either immersed in PBS for three days or not subjected to immersion. The specimens were then either polished with #600 or #10000 SiC abrasive paper, and some of them were not polished. Cell growth was determined using the MTS assay. ELISA assay was used to determine fibronectin and vitronectin on the resin surface, and the expression of integrin β_1. We concluded that cell growth on the surface of immersed or polished composite resin was greater than non-immersed or non-polished specimens, respectively.

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