title: Degradation of the mechanical properties of orthodontic NiTi alloys in the oral environment: an in vitro study.
abstract: Appropriate characterization studies are needed to demonstrate the mechanical and biological effects of interaction between archwires and the oral environment. The aim of this study was to investigate, in vitro, the impact of this acidic and fluoridated environment on the electrochemical behavior and the mechanical properties of orthodontic alloys in nickel titanium and in stainless steel (controls) for the following parameters: Young's modulus (E), elastic limit (σe) and the maximum tensile load (σm). Six samples of each archwire alloy were used to assess these parameters. An Instron universal test apparatus (model - 88512) was used for the traction tests on the wires after immersion in solutions at different concentrations of fluoride and at various pH levels. Observations were made using an electron scanning microscope (ESM) to evaluate the surface and an ICP (inductively coupled plasma) mass spectroscopy analysis was made to quantify the substances released into the immersion solution. For the NiTi archwires, immersion in the fluoridated and acidic medium showed a statistically significant reduction of the Young's modulus (E), the elastic limit (σe) and the maximum tensile load (σm). Similarly, a higher level of released nickel proportionate to the increase in the fluoride concentration and acidity was observed in the immersion solutions. ESM observations revealed the status of the surface of the different alloys and the presence of corrosive pitting.
authors.affiliation: Équipe de biotechnologie et matériaux du milieu buccal, faculté de médecine dentaire de Rabat, université Mohammed V, Souissi, Morocco. Electronic address: wiam.rerhrhaye@um5s.net.ma.
authors.forename: Wiam
authors.initials: W
authors.lastname: Rerhrhaye
authors.affiliation: Équipe de biotechnologie et matériaux du milieu buccal, faculté de médecine dentaire de Rabat, université Mohammed V, Souissi, Morocco.
authors.forename: Loubna
authors.initials: L
authors.lastname: Bahije
authors.affiliation: Institute of nanomaterials and nanotechnology, MAScIR, Rabat, Morocco.
authors.forename: Khalil
authors.initials: K
authors.lastname: El Mabrouk
authors.affiliation: Équipe de biotechnologie et matériaux du milieu buccal, faculté de médecine dentaire de Rabat, université Mohammed V, Souissi, Morocco.
authors.forename: Fatima
authors.initials: F
authors.lastname: Zaoui
authors.affiliation: Équipe de biotechnologie et matériaux du milieu buccal, faculté de médecine dentaire de Rabat, université Mohammed V, Souissi, Morocco.
authors.forename: Nadia
authors.initials: N
authors.lastname: Marzouk
mesh_terms: D000143:Acids; D001696:Biomechanical Phenomena; D002327:Cariostatic Agents / Q000737:chemistry; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D004548:Elasticity; D055664:Electrochemical Techniques; D005459:Fluorides / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009055:Mouth / Q000502:physiology*; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D013054:Spectrophotometry, Atomic; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014143:Traction
chemical_list: D000143:Acids; D002327:Cariostatic Agents; D003722:Dental Alloys; C023988:beta titanium; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium; D005459:Fluorides
keywords: Acid; Degradation; Fluoride; Mechanical properties; Nickel titanium