title: Dissolution effect and cytotoxicity of diamond-like carbon coatings on orthodontic archwires.
abstract: Nickel-titanium (NiTi) has been used for implants in orthodontics due to the unique properties such as shape memory effect and superelasticity. However, NiTi alloys are eroded in the oral cavity because they are immersed by saliva with enzymolysis. Their reactions lead corrosion and nickel release into the body. The higher concentrations of Ni release may generate harmful reactions. Ni release causes allergenic, toxic and carcinogenic reactions. It is well known that diamond-like carbon (DLC) films have excellent properties, such as extreme hardness, low friction coefficients, high wear resistance. In addition, DLC film has many other superior properties as a protective coating for biomedical applications such as biocompatibility and chemical inertness. Therefore, DLC film has received enormous attention as a biocompatible coating. In this study, DLC film coated NiTi orthodontic archwires to protect Ni release into the oral cavity. Each wire was immersed in physiological saline at the temperature 37 degrees C for 6 months. The release concentration of Ni ions was detected using microwave induced plasma mass spectrometry (MIP-MS) with the resolution of ppb level. The toxic effect of Ni release was studied the cell growth using squamous carcinoma cells. These cells were seeded in 24 well culture plates and materials were immersed in each well directly. The concentration of Ni ions in the solutions had been reduced one-sixth by DLC films when compared with non-coated wire. This study indicated that DLC films have the protective effect of the diffusion and the non-cytotoxicity in corrosive environment.
authors.affiliation: Department of Electronic and Computer Engineering, Tokyo Denki University, Hatoyama, Saitama 350-0394, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Ohgoe
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Ozeki
authors.forename: Kenji
authors.initials: K
authors.lastname: Hirakuri
authors.forename: Hideki
authors.initials: H
authors.lastname: Aoki
mesh_terms: D002244:Carbon / Q000009:adverse effects / Q000737:chemistry*; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D020099:Coated Materials, Biocompatible / Q000009:adverse effects / Q000138:chemical synthesis* / Q000737:chemistry; D003343:Corrosion; D018130:Diamond / Q000009:adverse effects / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D019563:Mechanics; D008954:Models, Biological; D009062:Mouth Neoplasms / Q000473:pathology; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires / Q000009:adverse effects; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014099:Toothbrushing / Q000009:adverse effects; D014407:Tumor Cells, Cultured
chemical_list: D020099:Coated Materials, Biocompatible; C040654:titanium nickelide; D002244:Carbon; D018130:Diamond; D009532:Nickel; D014025:Titanium