Oxide film was obtained on a NiTi shape memory alloy by a chemical method. The influences of surface oxidation on the phase transformations and corrosion resistance were assessed. Light blue oxide film formed on the alloy was mainly composed of TiO₂. Differential scanning calorimetry(DSC) measurement displayed that the phase transformations was not affected by surface oxidation. Electrochemical tests indicated that the oxidized NiTi alloy showed better corrosion resistance than the non-oxidized one in the simulated body fluid. Scanning Electron Microscopy (SEM) revealed that lower pitting corrosion occurred for the oxidized NiTi alloy compared with the non-oxidized. The oxidized samples did not show any surface alterations except very small and homogeneously distributed pits were observed.

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The replacement of deciduous teeth by permanent teeth was an in vivo controlled physiological course. Odontoclast is the main functional cell involved the physiological root resorption of human primary teeth. TRAF6 is the key molecule in the signals regulation during the procedure of differentiation and maturity of osteolasts/odontoclasts. This experiment was to study the expression of TRAF6 in physiological root resorption of deciduous and permanent teeth. In addition, the effect of TRAF6 during the physiological root resorption of human deciduous teeth was also discussed. Permanent and deciduous teeth in physiological resorption period were decalcified, embedded and sliced. TRAF6 antibody and TRAF6 in situ hybridization agent were used to detect samples’ expression of TRAF6 protein and mRNA. Im-pro-plas 6.0 analytical system was used to measure the photodensity of odontoclasts, odontoblasts and dental pulp fibroblasts respectively between study and control group. It was observed that TRAF6 protein and mRNA of odontoclasts, odontoblasts and dental pulp fibroblasts existed in deciduous teeth with physiological resorption showing positive stained results. However, in permanent tooth, odontoclast was not observed and TRAF6 in odontoblast and dental pulp fibroblasts displayed negative. For the same cells of the two groups, t-test showed that p‹0.01. The optical density of the deciduous teeth odontoclasts was higher than that of the odontoblasts and dental pulp fibroblasts, P‹0.01; the odontoblasts and dental pulp fibroblasts showed no difference. TRAF6 activated the root resorption of deciduous teeth by participating in cellular differentiation and function.

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In the Wnt/β-catenin signaling pathway, Wnt signal is transmitted to glycogen synthase kinase-3β (GSK-3β) through Dishevelled (Dvl), GSK-3β activity is inhibited, β-catenin phosphorylation is inhibited by the inactive-type GSK-3β, and β-catenin is transferred to the nucleus where it interacts with lymphoid enhancing factor (LEF)/T-cell factor (TCF), a transcription factor, which is considered to induce and regulate gene expression. In tooth development, it has been reported that Wnt and LEF are expressed at the earliest stage and are related to tooth development, but there are few reports on the situation at a later stage, and there have been no reports on Dvl and GSK-3β. In this study, we immunohistochemically examined the distribution of factors related to the Wnt/β-catenin signaling pathway, Wnt10, Dvl, GSK-3β, p-GSK-3β (inactive GSK-3β), and β-catenin, using serial sections of rat first molar germ to investigate the role of the Wnt signaling pathway in tooth germ development and tooth morphogenesis. Immunostaining for anti-Wnt10, anti-Dvl, anti-GSK-3β, anti-p-GSK-3β, and anti-β-catenin showed positive reactions at the inner enamel epithelium of tooth germ and weakly positive reactions at the dental papilla cells in contact with the inner enamel epithelium at embryonic day 19. At 8 days after birth, immunostaining for every antibody showed positive reactions for preameloblasts and preodontoblasts and more clearly positive reactions for secretory ameloblasts and odontoblasts. These results suggest that Wnt10, Dvl, GSK-3β, p-GSK-3β, and β-catenin are distributed in inner enamel epithelium, secretory ameloblasts, and odontoblasts, and that the Wnt/β-catenin signaling pathway via Dvl and p-GSK-3β is involved in these cells. In addition, for each of the factors, differentiated secretory cells showed more clearly positive reactions than undifferentiated cells; therefore, we conclude that the Wnt10 signaling pathway may be involved in differentiation to ameloblasts and odontoblasts, as well as secretory functions of ameloblasts and odontoblasts.

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Interleukin-17 (IL-17) is a proinflammatory cytokine involved in autoimmune diseases such as rheumatoid arthritis (RA). IL-17 consists of six ligands that signal through five receptors (IL-17Rs). Serine proteinases, such as plasmin and plasminogen activators (PAs), as well as matrix metalloproteinases (MMPs) degrade the extracellular matrix during cartilage remodeling.In contrast, plasminogen activator inhibitor-1 (PAI-1), an endogenous inhibitor of PAs, forms a complex with PA to inhibit plasmin production. In the present study, we examined the effect of IL-17F on the plasminogen/plasmin pathway in cartilage using human articular chondrocytes. We evaluated the effects of IL-17F on the expression of tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), PAI-1, and cyclooxygenases (COXs), as well as on the production of prostaglandin E₂ (PGE₂). We also examined the indirect effects of PGE₂ on the above IL-17F-induced/reduced components using NS-398, a specific inhibitor of COX-2 activity. Cells were cultured with or without IL-17F in the presence or absence of NS-398 for up to 28 days. mRNA and protein expression levels of PAs, PAI-1, and COXs were determined using real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. PGE₂ production was determined by ELISA. The addition of IL-17F increased the expression of PAI-1 and COX-2, as well as the production of PGE₂, whereas uPA and COX-1 expression decreased and tPA expression was unaffected. NS-398 did not block the reducing/stimulating effects of IL-17F on the expression of COX-1 and COX-2. In contrast, NS-398 may be, in part, responsible for IL-17F-induced/reduced uPA and PAI-1 expression. Our results suggest that IL-17F suppresses the plasminogen/plasmin pathway by increasing PAI-1 expression and decreasing uPA expression in chondrocytes.

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The purpose of this study was to assess the antibacterial efficacy of incorporating catechins into 4-META/MMA-TBB resin against Streptococcus mutans and to measure the shear bond strength of a metal bracket bonded to enamel using catechin-incorporated with 5% 4-methacryloyloxyethyl trimellitate anhydride (4-META)/methyl methacrylate (MMA)-tri-n-butyl borane (TBB) resin (catechin-resin). Catechin-resin disks were incubated with the bacterial suspension at 37°C for 24 h. The bacterial counts (colony forming units) of the disk and the suspension were determined separately. Catechin release from catechin-resin was monitored. The catechin-containing composites were used to bond metal brackets to human premolars pretreated with self-etching primer. After the bonded samples were immersed in water at 37°C for 24 h, shear bond strength was measured.
The most significant antibacterial activity was observed in (-)-epigallocatechin gallate-resin disk and (-)-epigallocatechin gallate-resin-treated bacterial suspension when compared with the control. Catechin was released from catechin-resin during 6 week immersion in deionized water. (-)-Epicatechin gallate, (-)-epigallocatechin and (-)-epigallocatechin gallate showed a large amount of catechin release. Only significant differences was detected in bond strength between the control and (-)-epigallocatechin gallate. The addition of (-)-epigallocatechin gallate to 4-META/MMA-TBB resin confers an antibacterial effect while retaining sufficient bond strength.

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Low-level laser irradiation (LLLI) stimulates bone regeneration and may be useful for bone fracture and oral implant therapy. However, the molecular mechanism of LLLI in accelerating bone formation is not well known. In order to understand the mechanism of LLLI in accelerating bone formation, we attempted to identify gene expressions enhanced by LLLI by a subtractive gene cloning and DNA microarray analysis. Osteoblastic cell MC3T3-E1 was treated with 830 nm Ga-Al-As diode laser irradiation and total mRNA was recovered and used to construct a subtractive gene library of genes with transcription enhanced by LLLI. The DNA sequences of subtracted gene was subjected to a homology search using BLASTN program in the National Center for Biotechnology Information (NCBI). Genes with mRNA levels altered by LLLI were also analysed using Affymetrix GeneChip. The mRNA levels were confirmed by RT-PCR and real-time PCR. Subtracted gene clones MCL101 indicated high homology with GDP-dissociation inhibitor beta (GDPIB) genes. Affymetrix GeneChip^TM analysis was further analyzed and found that GDI alpha gene expression was also enhanced by LLLI. The increased mRNA level of GDIA and GDIB by LLLI was successfully confirmed by RT-PCR and real-time PCR. Since the up-regulation of GDIA is one of the mechanisms underlying the synergistic boneforming effect of parathyroid hormone and oestrogen. Moreover, GDIA and GDIB involve in the regulation of vesicle-mediated cellular transport and anti-apoptosis, the enhancement of GDIA and GDIB gene expressions by LLLI may be a part of mechanisms in the acceleration of bone formation by LLLI.

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Low-intensity pulsed ultrasound (LIPUS) is a biophysical intervention used to repair bone. LIPUS may reduce the healing time of bone defects covered with osteoconductive membranes. The purpose of this study was to identify the required characteristics of membranes used with LIPUS in guided bone-regeneration (GBR) procedures. Two bioabsorbable membranes (Bio-Mend^®, GC membrane), one non-bioabsorbable membrane (GORE-TEX^®), and one titanium membrane (FRIOS^® BoneShield) were evaluated with an oscilloscope in two settings: underwater and with an ultrasound gel. One side of the membrane was attached to the LIPUS transducer, and the other side was connected to the oscilloscope transducer. The commercial bioabsorbable and GORE-TEX ^® membranes transmitted only 7-16% of the 30- and 60-mW/cm² LIPUS waves with ultrasound gel or while underwater, whereas the titanium membrane transmitted 81-90% of these waves in both settings. Based on results of propagation analysis, we also examined the potency of LIPUS used with GBR in critical bone defects in vivo in a rat calvarium model. Two 5.0-mm defects were trephined in rat calvarium and covered with a GC membrane and FRIOS^® BoneShield, respectively. Rats were exposed to LIPUS 30 min/day for 3 weeks. In vivo, more active bone regeneration was observed in defects covered with titanium membranes than in those covered with GC membrane in the combined use of LIPUS with GBR. These results suggest that titanium membranes perform better than other commercial membranes in the combined use of LIPUS with GBR.

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The expression of inducible cAMP early repressor (ICER) has been demonstrated in cultured osteoblastic MC3T3-E1 cells, calvarial cultures and in vivo, mainly via the cAMP-PKA signaling pathway. To determine the molecular mechanism(s) for this action, a fragment of the CREM P2 promoter from -238 bp to +14 bp was linked to a luciferase reporter (CREMP2-Luc238). This region contains 2 clusters of cAMP-responsive element (CRE). The 5’ cluster contains CRE1 and CRE2 while the 3’ cluster contains CRE3 and CRE4 and the two clusters are separated by 12 bp. In order to study if any or all CREs are responsive to cAMP induction, osteoblastic MC3T3-E1 cells were stably transfected with constructs having serial deletions of each CRE or mutations in each cluster of the CREMP2-Luc construct. Agonists that stimulate the cAMP-PKA pathway induced CREMP2-Luc238 activity, and neither PKC nor Ca⁺⁺ pathways did. The deletion of CRE1 and CRE2 did not significantly abolish the cAMP inducibility of CREMP2-Luc238 activity. Electrophoretic mobility shift assay showed many DNA/protein complexes when probes from either CRE1-2 or CRE3-4 were incubated with FSK-treated nuclear extract from MC3T3-E1 cells. However, only a small portion of the complexes was competed by a consensus CRE oligonucleotide. Interestingly, a major DNA/protein complex seen in the binding of CRE3-4 was not competed by the consensus CRE oligonucleotide, but by a mutated CRE oligonucleotide suggesting that other transcription factor(s) may be involved in the binding of CRE3-4. The CRE binding DNA/protein complexes were supershifted mainly by antibodies against ICER and CREB, mildly by C/EBPβ suggesting these transcription factors may be involved in the FSK induction of the P2 promoter of the CREM gene.

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Periodontitis is a common disease worldwide and is a cause of tooth loss. For these reasons, many investigators have examined periodontitis not only by in vivo studies but also in vitro studies. For in vivo studies, it is very important which animal is used and how to make experimental periodontitis easily and efficiently in animals. Although the process of periodontitis in monkeys and dogs is similar to that in humans, rats and mice are much more useful animals for experiments because of ease of handling and low cost. For the induction of periodontitis, bacterial inoculation and wire ligature methods were examined previously; however, these methods had temporal and technical problems. Therefore, a simple, easy and reliable experimental model for periodontitis using rats and/or mice is required. In this study, the authors attempted to establish a novel experimental model for periodontitis in the rat lower jaw using carrageenin-immersed silk ligature wire, and examined the change of alveolar bone morphology by micro-computerized tomography. As a result, carrageen-inimmersed silk ligature wire induced inflammation of the periodontium with severe alveolar bone loss in all experimental rats. In addition, the degree of absorption of the alveolar bone depended on the dosage times of carrageenin treatment. These findings suggested that this experimental model of periodontitis using carrageenin in rats may be a useful experimental model for periodontal research.

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Extracellular nucleic acids were found in the culture filtrate of Lactobacillus DM8909 at exponential growth phase. The study focused on the source, characteristics, nucleotide sequence and biological functions of extracellular nucleic acids in Lactobacillus DM8909.
Nucleic acids in the culture filtrate were proven to be RNA by agarose gel electrophoresis which closely paralleled bacterial growth. Different experimental procedures (according to viral infection course) to assay the potential antiviral activity of RNA were used. Cell survival and viral inhibition were determined by antiviral assay and confirmed by immunofluorescence. Results showed the “excess” extracellular RNA which could inhibit viral infection to the host cells in vitro.
The “excess” extracellular RNA may be excreted from Lactobacillus DM8909. The possible mechanisms of antiviral activity include: 1) interfering virus attachment or entry into the cells, perhaps by steric hindrance; 2) conducting as a signaling molecule in the cross-talk between probiotics and host; 3) inducing the immunocytes to produce IFN-α to modulate virus infection.
This is the first study demonstrating the excretion of RNA in gastrointestinal commensal bacteria. Extracellular RNA may function as a new signaling molecule in the cross-talk between host and commensal bacteria.

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Interleukin (IL)-17 plays an important role in many autoimmune and inflammatory diseases. We recently demonstrated the various direct and indirect effects of IL-17A on osteoclastogenesis. However, the effect of IL-17A on bone matrix formation by osteoblasts is unclear. Therefore, we examined the effect of IL-17A on IL-17 receptor (IL-17R), extracellular matrix protein (ECMP), and cyclooxygenase (COX) expression; prostaglandin (PG) E₂ production; alkaline phosphatase (ALPase) activity; and mineralized nodule formation in osteoblastic ROS17/2.8 cells. We also examined the indirect effect of PGE₂ on IL-17-induced ECMP expression using NS398, a specific inhibitor of COX-2 activity. Cells were cultured with 0 (control), 1, 10, or 100 ng/mL IL-17A in the presence or absence of 50 ng/mL neutralizing anti-IL-17A antibodies or 1 μM NS398. IL-17RA, IL-17RC, type I collagen, bone sialoprotein (BSP), osteocalcin, osteopontin, COX-1, and COX-2 expression was examined by real-time PCR and Western blotting. PGE₂ production was examined by ELISA. The expression of IL-17RA, type I collagen, BSP, osteocalcin, osteopontin, and COX-2, and PGE₂ production were increased significantly in the presence of IL-17A, whereas the expression of IL-17RC and COX-1, cell proliferation, ALPase activity, and mineralized nodule formation were unaffected. Anti-IL-17 antibodies blocked IL-17Ainduced ECMP expression. NS398 blocked IL-17A-induced PGE₂ production, but it did not affect IL-17A-induced ECMP expression. These results suggest that IL-17A stimulates ECMP expression via IL-17RC and/or IL-17A-induced IL-17RA in osteoblasts; however, mineralized nodule formation by the cells was unaffected by the addition of IL-17A. Furthermore, our results indicate that the stimulatory effect of IL-17A on ECMP expression is independent of the indirect effect of IL-17A-induced PGE₂.

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The lateral pterygoid muscle has unique anatomical, physiological and functional properties. Since it is attached to the temporomandibular joint (TMJ) disc, its pathologies are closely related to TMJ disorders, which affect many people worldwide. Muscle structures and units are characterized by their morphological appearance, nerve distribution and function. In the present study, we examined the intramuscular innervation pattern of the lateral pterygoid muscle using modified sihler’s method. Two types of innervation pattern were evident. In type I, representing the majority of the samples, a total of three branches arising from the main trunk of the mandibular nerve and the buccal nerve innervated the inferior head of the muscle, while branches from the buccal nerve innervated the superior head. In type II, divisions of the lateral pterygoid nerve branched from the buccal nerve located between the heads of the lateral pterygoid muscle and innervated each head separately. Interestingly, muscle bundles with a stronger tendineous structure showed much more innervation than other parts of the muscle. Future studies including quantitative analysis of the nerve distribution to the muscle bundles are warranted.

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