This study was conducted using X-ray photoelectron spectroscopy (ESCA) with an argon ion etching system to determine the chemical composition of the surface of dental enamel after fluoride treatment. The enamel surface was treated for four minutes with sodium fluoride (NaF) or acidulated phosphate fluoride (APF) which was adjusted to a fluoride concentration to 9,000 ppm. F-treated enamels were measured in a depth profile (surface to 0.3 μm depth) with wide scanning for qualitative analysis and narrow scannings for quantitative analysis of calcium (Ca), phosphorus (P), oxygen (O), fluoride (F), carbon (C) and nitrogen (N) for quantitative analysis. ESCA analysis showed that Ca, P, C and O were present from the surface to 11th layer (0.3 μm) of the untreated enamel, however, N was only in the surface and 2nd layers. The Ca/P ratio for each layer of untreated enamel (1.44) was lower than the stoichiometric value (1.67) of hydroxyapatite. It is suggested that the subsurface pellicle forms from the surface to 60 nm depth. When enamel was treated with fluoride solutions, the F peak was detected in the wide scanning spectra of both of enamel treated with NaF and APF. The results of Ca/P, O/P and F/Ca ratios showed that fluorapatite was produced on the enamel surface by the NaF treatment, while CaF₂ was produced by the APF treatment. Futhermore, this CaF₂ had a somewhat low ratio of F/Ca and induced a P compound as compared with pure CaF₂2. These results showed that this CaF₂ is not pure, but rather CaF₂-like materials.
Based on these results, it is suggested that ESCA may be used to analyze the depth profile of chemical composition of enamel, especially, in the nm depth range, and to detect fluoride compounds which are produced on the enamel surface.

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We investigated the ability of the sessile drop method (SDM) to measure the contact angle as compared with the gonionic and interferometric method (GM and IM) and to determine thermodynamically the surface characteristics of human dental enamel from the contact angle. Glass with both hydrophilic or hydrophobic surfaces were employed as standards. The enamel surfaces were treated with 2% NaF, APF or 8% SnF₂ solutions. The other enamel surfaces were irradiated with CO₂ or YAG laser.
The results of the contact angle measurements on the glass standard samples indicated that the SDM was useful method for both hydrophilic and hydrophobic surface compared with GM or IM. The contact angle of untreated enamel was 62.8°±8.6°. The measured contact angle by SDM indicated that the enamel surface treated with NaF or APF solution became more hydrophilic, while SnF₂ treatment became more hydrophobic than the untreated enamel. Furthermore, the enamel surface exposed to CO₂ and YAG laser irradiation also became hydrophobic.
Based on these results, it is suggested that the SDM is useful method for measuring contact angle and F treatment and laser irradiation can alter the surface characteristics.

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We attempted to find a method for the identification of children who would be at high risk for caries in the permanent dentition. We devised and examined the validity of a screening test based on the dmft, number of permanent teeth, and DMFT obtained during the child's first year in elementary school. The subjects were 382 children who entered elementary school in 1980, 1981 and 1982. We divided the high caries risk children into six groups having DMFT scores of ≧4, ≧5, ≧6, ≧7, ≧8 and ≧9 when they reached the sixth grade.
The DMFT index for all sixth graders was 4.05±2.65. Either dmft or DMFT in the first grade were good predictors for identifying high caries risk children, who were defined to have a DMFT score of 5 or greater. Combining above mentioned three criteria provided better predictability in identifying the true negative children in the sixth grade.

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I investigated the chemotactic response of fibroblasts to root surface components in wound healing following flap surgery. In order to investigate the effect of the most chemoattractive components on cell migration, I also studied the invasiveness of gingival fibroblasts into collagen gels containing components and other growth factors. Cell cultures were established from monkey gingival connective tissues, alveolar bone, periodontal ligaments, and rat calvariae. The root surface components were obtained from the teeth extracted 4, 7, 10 and 14 days after surgery. The chemotactic response was quantified by an in vitro assay using a 48 well microchemotaxis chamber. Deep cementum components produced the maximum chemotactic response. The chemotactic response to deep cementum components increased at days 4 and 7, but decreased at 10 days after surgery. Deep cementum components at day 7 also facilitated invasion of gingival fibroblasts as well as platelet derived growth factor (PDGF) and transforming growth factor-β (TGF-β). These results suggest that cementum components influence chemotactic migration of these cells in the initial stages of wound healing and that cementum plays an important role in periodontal regeneration.

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Primary testosterone and its derivatives are anabolic steroids that are used in the treatment of osteoporosis and Turner syndrome. They also enhance first-twitch muscle weight in female rats.
I evaluated the effect of an anabolic steroid on craniofacial growth and development in rats. One hundred and twenty 5-week-old female Sprague Dawley rats were divided into experimental and control groups. Rats in the experimental group were injected subcutaneously with 1 mg nandrolone phenylpropionate in the inter scapular region on alternate days, while those in the control group were injected with a vehicle, arachis oil. The rats were sacrificed by chloroform at 60 and 120 days of age.
Soft X-rays and cephalometric analysis showed that chronic administration of the anabolic steroid, nandrolone phenylpropionate, resulted in 1) about 20% increase in body weight, 2) an increase in total skull length, 3) elongation of the maxillary and mandibular incisors, 4) an increase in the depth of the anti-gonial notch, and 5) downward-forward growth of the viscerocranium against the neurocranium.
These results suggest that nandrolone phenylpropionate accelerates craniofacial growth and development in rats.

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I evaluated whether castable ceramics could be applied in clinical pedodontic practice. Wear tests were compared for castable ceramics, several other restorative materials, and deciduous tooth structure. Compressive fatigue tests were also carried out on these materials after repeated compressive loads. The wear volume of castable ceramics was closer to that of deciduous teeth than the other materials. The compressive fatigue strength of castable ceramics was greater than the maximum occlusal force in children, even after the ceramics had been subjected to 1,000,000 repeated compressive loads.

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We evaluated a new apparatus for testing the marginal toughness and wear resistance of dental restorative materials. We tested three types of composite resins (MFR, hybrid, and semi-hybrid) as well as an amalgam. The width of marginal fracture and wear volume were also evaluated. The width of marginal fracture test showed that the amalgam was the strongest, followed by the hybrid composite, semi-hybrid type, and the MFR type. The wear volume test showed that the amalgam was best, followed by the MFR composite, the semi-hybrid type, and the hybrid type. We concluded that this test apparatus was capable of evaluating the marginal toughness and wear resistance of restorative materials.

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Tooth brushing effectiveness is often very low in the elderly. In order to investigate the reasons for this and examine methods of elevating brushing effectiveness, we compared young adults and the elderly with respect to various characteristics of brushing movements that affect this effectiveness in the rolling and scrubbing methods. There is a marked decrease in muscle force, especially grip force, in the elderly compared with young adults. We found that the deterioration in brushing efficiency caused by this decrease in function can be corrected and the efficiency improved if the person practices while observing his brushing patterns on an oscilloscope.

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We attempted to devise a method for the early identification of children who would be at high risk for caries in the permanent dentition. We devised and examined the validity of a screening test based on the dmft, number of permanent teeth, and DMFT obtained during the child's first year in elementary school. It was found that although each factor alone did not provide a good predictor, by combining the three, we could accurately predict the DMFT for the child in the sixth grade.

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We investigated the ability of the sessile drop method (SDM) to determine the surface characteristics of human dental enamel. We found that the SDM was useful for measuring the contact angle of both hydrophilic and hydrophobic surfaces. The SDM indicated that the enamel surface treated with sodium fluoride or acidulated phosphate fluoride solutions became hydrophilic, while stannous fluoride treatment made it hydrophobic. Furthermore, the enamel surface exposed to laser irradiation also became hydrophobic.

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This study was conducted using X-ray photoelectron spectroscopy (ESCA) with an argon ion etching system to determine the chemical composition of the surface of dental enamel treated for four minutes with either a sodium fluoride (NaF) or acidulated phosphate fluoride (APF) solution, each with a fluoride concentration of 9,000ppm. We found that the NaF treatment produced fluorapatite in the surface layer of enamel, while the APF treatment produced calcium fluoride.

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I purified outer membrane proteins (OMPs) of Porphyromonas gingivalis and examined their immunological activities for leukocytes. The OMPs were purified from P. gingivalis 381. SDS-PAGE analysis revealed that P. gingivalis had two main OMPs of 40kDa and 53kDa. Antibodies to both of these proteins have been observed in the sera of patients with adult periodontitis. I found that both had chemotactic activity for human monocytes and both stimulated chemotactic activity for leukocytes in cultures when they were applied to lymphocytes. However, when they were applied to macrophages, chemotactic activity appeared only in the culture stimulated with the 40kDa OMP.

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I examined the relation between the development of periapical lesions and the immune response. Key-hole limpet hemocyanin (KLH) emulsified with Freund's complete adjuvant or KLH-coupled polystyrene beads was injected as antigen into the root canals of rat mandibular first molars. The possible involvement of cell-mediated immune response and of antibody production were examined. The lesions were examined histopathologically and immunohistochemically. Although lymphocyte proliferation was not demonstrated, antibodies were produced. Also, no involvement of immune responses could be observed in the experimental periapical granulomas.

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I investigated the effects of storage conditions and type of tooth (human or bovine) on marginal leakage in coronal and cervical composite restorations. Coronal and cervical cavities were prepared in each tooth, which was then treated with one of two dentin bonding systems, and restored with composite resin. All specimens were then immersed in distilled water at 37℃. After either a penetration test or thermal cycle test in a dye solution, marginal leakage of the specimens was evaluated and the cavity margin was observed by scanning electron microscopy. Differences in storage conditions and type of tooth markedly influenced the degree of marginal leakage.

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Ameloblastomas were cultured to investigate their possible involvement in bone resorption. Bone resorption assays of calcium release from new bone mouse calvariae, osteoclast formation from bone marrow cultures and chemotaxis of mouse peritoneal macrophages were examined in four tumor cases. Conditioned tumor media demonstrated enhanced calcium release, while homogenates of the tumors themselves did not have a significant effect on calcium release. Some tumors increased the number of osteoclasts, while others activated the chemotaxis of macrophages. Conditioned media of monocytes and lymphocytes stimulated by some tumors enhanced bone resorption. These results suggest that ameloblastomas release soluble factors during their growth which directly and indirectly promote osteoclast recruitment and differentiation.

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I evaluated the effect of an anabolic steroid on craniofacial growth and development in rats. One-hundred twenty 5-week-old female Sprague Dawley rats were divided into experimental and control groups. Rats in the experimental group were injected subcutaneously with nandrolone phenylpropionate in the intra-scapular region on alternate days, while those in the control group were injected with the vehicle, arachis oil. The rats were sacrificed with chloroform at 60 and 120 days of age. Soft X-rays and cephalometric analysis showed that chronic administration of the anabolic steroid nandrolone phenylpropionate resulted in accerelated craniofacial growth and development in the rats.

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I examined the morphological features of attachment between various root surfaces and regenerated periodontal tissues following guided tissue regeneration (GTR). Experimental periodontitis was induced on the canines and incisors of 16 adult monkeys. During flap surgery, the root condition was modified by either root planing or curettage of the superficial cementum, with and without application of citric acid. Membranes (Millipore^[○!R] filters) were placed over the experimental teeth on the left side, while the contralateral teeth served as controls without membranes. The root surface condition determined the type of attachment, regardless of the migration of specific cells.

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I investigated the chemotactic response of fibroblasts to root surface components in wound healing following flap surgery. I also studied the invasiveness of gingival fibroblasts into collagen gels when chemoattractive components and other growth factors were incorporated. Cell cultures were established from monkey periodontal tissues and rat calvariae. The root surface components were obtained from teeth extracted at various intervals after surgery. Deep cementum components produced the greatest chemotactic response. Their response was increased at days 4 and 7, but decreased at day 10. Deep cementnm components at day 7 facilitated invasion of gingival fibroblasts as well as PDGF and TGF-β. These results suggest that cementum components influence chemotactic migration of these cells in the initial stages of wound healing.

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The collagen of Sprague-Dawley rat sagittal sutures was investigated to elucidate the effects of expansion forces on the restoration of connective tissue. After the rat sagittal sutures were expanded by optimum (70g) and excessive (220g) forces, they were retained for seven days. I measured the concentrations of total protein, DNA, collagen as hydroxyproline and the ratio of type III to type I collagen in the rat sagittal sutures, and observed the sutural morphology by light microscopy. Expansion of the sagittal suture by excessive force delayed restoration of the connective tissue with the collagen and new bone formation compared with expansion by optimum force.

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Formalin resistant monoclonal antibodies (MoAbs) against squamous cell carcinoma (SCC) were produced using as an immunogen deparaffinized tissue from formalin-fixed, paraffin-embedded block of human tongue carcinoma. Electrofusion (E) and polyethylene glycol fusion (P) were performed and three MoAbs (IgM, kappachain), E 8, P 53 and P 54 were isolated and characterized. E 8 and P 54 recognized the cytomembrane of various normal and neoplastic oral epithelial cells. The staining patterns of P 53 were similar to those of several keratin MoAbs, and immunoblotting assays showed multiple keratin bands of 40-68kDa. All three MoAbs reacted strongly with well differentiated SCC. These antibodies may provide pathologists with new insights into diagnostic markers.

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We elucidated the effects of dynamic extraction on cytotoxicity and dissolution of metalic biomaterials under stress. The cytotoxicity and dissolution of gold alloy, three types of silver alloy, nickel-chrome alloy, and titanium were examined by gyrating them with alumina balls for seven days in distilled water, Ringer's solution, phosphate buffered saline, minimum essential medium (MEM), or MEM containing 0.4% albumin. The filtrate of the Ag-Sn-Zn alloy was cytotoxic in MEM and MEM containing 0.4% albumin, while the filtrates of the other metallic biomaterials were slightly cytotoxic. Dissolution of metallic biomaterials was increased by addition of amino acids and/or albumin. The wear debris of all the biomaterials except titanium was cytotoxic. It is essential to test biomaterials in simulated environments and to consider the effects of wear debris on the results.

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Using clinical strains isolated from subperiosteal abscesses, we examined the production of hydrolytic enzymes such as β-lactamase, DNase, hyaluronidase, chondrotin sulfatase, lipase, lecithinase, collagenase, trypsin, chymotrypsin, and viscous materials. Anaerobes predominated in those isolates. The proportions of β-lactamase, DNase, trypsin, and lecithinase producers were 18.4, 12.7, 6.0 and 5.1%, respectively. Other hydrolytic enzyme-active bacteria were found in less than 5% of all isolates. Black-pigmented Prevotella, especially P. intermedia, were the predominant β-lactamase, DNase, and lecithinase producers. We found that hydrolytic enzymes produced by various Prevotella may exert an important influence on the exacerbation of the periapical pathosis.

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We attempted to purify peritrichous fimbriae from Streptococcus oralis strain 2705. The fimbriae were purified by mechanical shearing, ammonium sulfate fractionation, and sucrose density gradient ultracentrifugation. Electron microscopy demonstrated the presence of dense masses of aggregated fimbriae. SDS-PAGE analysis revealed that the fimbriae consisted of a 16kDa protein. However, they were eluted at a void volume by Sepharose CL-6B gel filtration, suggesting the fimbriae are polymers of 16kDa monomer proteins. In colony immunoblotting, antiserum raised against the purified fimbriae reacted with strain 2705, but did not react with other peritrichous S. oralis or S. salivarius strains. This indicates that antigenically for different peritrichous fimbriae might exist in S. oralis.

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Using plate and broth methods, we screened human saliva and dental plaque constituents for their ability to produce β-lactamase, DNase, hyaluronidase, chondroitin sulfatase, lipase, lecithinase, collagenase, trypsin, chymotrypsin, and viscous materials. Strains freshly isolated from the saliva and dental plaque of healthy students were used in this experiment. DNase and β-lactamase activities were found in 4% of the isolates. Hyaluronidase, chondroitin sulfatase, lipase, lecithinase, collagenase and trypsin activities were found in less than 1%. Prevotella species were the predominant producers of DNase, β-lactamase, hyaluronidase, lecithinase, and chondroitin sulfatase. Trypsin producers were identified as Capnocytophaga and Porphyromonas gingivalis, while P. gingivalis was the only species producing collagenase. These results indicate that constituents of saliva or dental plaque have the potential to exacerbate odontogenic infections.

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Strains of Streptococcus salivarius and oralis with fimbriae examined for in vitro plaque formation and for adherence to hydroxyapatite (HA) and epithelial cells. The average adherence of S. salivarius to HA was 9.5×10^5 cells/cube, while the adherences for S. oralis with types A, D and E fimbriae were 1.7×16^6, 4.9×10^5 and 1.0×10^6 cel1s/cube, respectively. Significantly more S. salivarius than S. oralis cells were found adhering to human oral epithelial cells. However, S. salivarius strains which adhered well to HA tended to have low attachment with epithelial cells. No correlation was found between hydrophobicity and the adherence to HA and epithelial cells. S. salivarius had a greater capacity to form in vitro plaque than S. oralis. These results suggest that S. salivarius has a greater involvement in adhesion than S. oralis.

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We compared glycosaminoglycans (GAG) in the lamina propria, fatty zone and glandular zone of the submucosal layer of the palatal mucosa. The GAG were chemically analyzed, separated by electrophoresis, and the results obtained were compared. The GAG content of the lamina propria and the glandular zone was higher than that of the fatty zone. Four GAG, hyaluronic acid, dermatan sulfate, chondrotin sulfate and heparan sulfate, were found in the palatal mucosa. Each layer had all four components. Dermatan sulfate was the predominant GAG in the lamina propria and gladular zone, followed by hyaluronic acid. Hyaluronic acid was the predominatnt GAG in the fatty zone of the submucosal layer, followed by dermatan sulfate.

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[in Japanese]

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[in Japanese]

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