Objective: To test the hypothesis that different nickel-titanium (NiTi) archwires may have dissimilar corrosion resistance in a fluoride-containing oral environment. Materials and Methods: Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance (R p ), of four different commercial NiTi archwires in artificial saliva (pH 6.5) with various NaF concentrations (0%, 0.01%, 0.1%, 0.25%, and 0.5%). Two-way analysis of variance was used to analyze R p with the factors of archwire manufacturer and NaF concentration. Surface characterizations of archwires were analyzed using scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. Results: Both archwire manufacturer and NaF concentration had a significant influence on R p of NiTi archwires. Different surface topography was present on the test NiTi archwires that contained the similar surface chemical structure (TiO 2 and trace NiO). The surface topography did not correspond to the difference in corrosion resistance of the NiTi archwires. Increasing the NaF concentration in artificial saliva resulted in a decrease in R p , or corrosion resistance, of all test NiTi archwires. The NiTi archwires severely corroded and showed similar corrosion resistance in 0.5% NaF-containing environment. Conclusions: Different NiTi archwires had dissimilar corrosion resistance in acidic fluoridecontaining artificial saliva, which did not correspond to the variation in the surface topography of the archwires. The presence of fluoride in artificial saliva was detrimental to the corrosion resistance of the test NiTi archwires, especially at a 0

Curcumin is a common food ingredient derived from the plant Curcuma longa and is a potent drug against tumorigenesis. Both insulin-like growth factor binding protein-5 (IGFBP-5) and CCAAT/enhancer-binding protein a (C/EBPa) are suppressors of head and neck carcinogenesis. We identified curcumin as an inducer of IGFBP-5 expression in multiple types of oral keratinocytes; furthermore, curcumin induces IGFBP-5 promoter activity in SAS oral cancer cells. Promoter deletion mapping identified a region (nt 271 to nt 259 relative to the transcription start site) as containing a C/EBPa-binding element that is indispensable for curcuminmediated IGFBP-5 upregulation. Chromatin immunoprecipitation assays revealed that in vivo binding of C/EBPa to this region was remarkably increased in the presence of curcumin. Curcumin increased nuclear C/EBPa expression and IGFBP-5 expression through p38 activation and this was abrogated by SB203580 treatment. Furthermore, MKK6 expression activated p38 and C/EBPa, increasing IGFBP-5 promoter activity and expression. Finally, curcumin-induced IGFBP-5 expression is associated with the suppression of xenograft tumorigenesis in mice due to oral cancer cells. We conclude that curcumin activates p38, which, in turn, activates the C/EBPa transactivator by interacting with binding elements in the IGFBP-5 promoter. The consequential upregulation of C/EBPa and IGFBP-5 by curcumin is crucial to the suppression of oral carcinogenesis.Insulin-like growth factors (IGFs) that bind IGF receptors (IGFRs) with high affinity play important roles in regulating cell phenotypes, including proliferation, differentiation, migration and apoptosis. Diferuloylmethane (Curcumin), found in significant amounts in the Indian spice turmeric, is a polyphenol derived from the plant Curcuma longa and is a common food ingredient across the world. 8,9 Accumulated evidence has indicated that this polyphenol can be used to both prevent and treat cancer. 10,11 Curcumin exhibits cancer chemopreventive effects in a range of animal models of chemical carcinogenesis, including those resulting in head and neck squamous cell carcinoma (HNSCC) and OSCC. 12,13 This compound also has anti-oxidative effects, anti-inflammatory effects, anti-

Hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films were prepared in the present study using a radio-frequency plasma magnetron sputtering system at various CH4/Ar gas ratios. The a-C:H/Cu films were characterized by scanning electron microscopy, atomic force microscopy, Raman spectroscopy, transmission electron microscopy, nano-indentation and a contact angle goniometer. The antibacterial properties and cell cytotoxicity of a-C:H/Cu films were evaluated as per JIS Z2801:2010 and ISO 10993-5 specifications, respectively. The analytical results revealed that the production of a-C:H/Cu films varied with the CH4/Ar ratio, and the phase transformation (amorphous-like → nano-polycrystalline structure) was induced by Cu doping/ion bombardment and radical reactions. Moreover, it was found that the microhardness of the a-C:H/Cu films decreased with increasing Ar fraction in the gas ratio. The a-C:H/Cu films exhibited a high hydrophobic surface feature. The film which contained 77.3  ±  4.4 at.% Cu did not influence cell adhesion and proliferation behaviors. Antibacterial tests also demonstrated that a-C:H/Cu films possessed excellent antibacterial properties. Therefore, a-C:H/Cu films could be developed as promising antibacterial coatings for biomedical applications.

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