title: Bonding metals to poly(methyl methacrylate) using aryldiazonium salts.
abstract: OBJECTIVE
  Many dental devices, such as partial dentures, combine acrylic and metallic parts that are bonded together. These devices often present catastrophic mechanical failures due to weak bonding between their acrylic and metallic components. The bonding between alloys and polymers (e.g. poly(methyl methacrylate), PMMA) usually is just a mechanical interlock, since they do not chemically bond spontaneously. The aim of this study was to develop a new method to make a strong chemical bond between alloys and polymers for dental prostheses based on diazonium chemistry.
  
  
  METHODS
  The method was based on two steps. In the first step (primer), aryldiazonium salts were grafted onto the metallic surfaces. The second step (adhesive) was optimized to achieve covalent binding between the grafted layer and PMMA. The chemical composition of the treated surfaces was analyzed with X-ray photoelectron spectroscopy (XPS), and the tensile or shear bonding strength between metals and poly(methyl methacrylate) was measured.
  
  
  RESULTS
  XPS and contact angle measurements confirmed the presence of a polymer coating on the treated metallic surfaces. Mechanical tests showed a significant increase in bond strength between PMMA and treated titanium or stainless steel wire by 5.2 and 2.5 folds, respectively, compared to the untreated control group (p<0.05).
  
  
  CONCLUSIONS
  Diazonium chemistry is an effective technique for achieving a strong chemical bond between alloys and PMMA, which can help improve the mechanical properties of dental devices.
authors.affiliation: Faculty of Dentistry, McGill University, Montreal, QC, Canada; College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Omar
authors.initials: O
authors.lastname: Alageel
authors.affiliation: Faculty of Dentistry, McGill University, Montreal, QC, Canada.
authors.forename: Mohamed-Nur
authors.initials: MN
authors.lastname: Abdallah
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC, Canada.
authors.forename: Zhong Yuan
authors.initials: ZY
authors.lastname: Luo
authors.affiliation: Faculty of Dentistry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Del-Rio-Highsmith
authors.affiliation: Department of Mining and Materials Engineering, McGill University, Montreal, QC, Canada. Electronic address: marta.cerruti@mcgill.ca.
authors.forename: Marta
authors.initials: M
authors.lastname: Cerruti
authors.affiliation: Faculty of Dentistry, McGill University, Montreal, QC, Canada. Electronic address: faleh.tamimimarino@mcgill.ca.
authors.forename: Faleh
authors.initials: F
authors.lastname: Tamimi
mesh_terms: D000268:Adhesiveness; D001585:Benzoyl Peroxide / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry; D003979:Diazonium Compounds / Q000737:chemistry*; D008422:Materials Testing; D056951:Photoelectron Spectroscopy; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D003722:Dental Alloys; D003764:Dental Materials; D003979:Diazonium Compounds; D019904:Polymethyl Methacrylate; D001585:Benzoyl Peroxide
keywords: Bonding diazonium; Dental prosthesis; Poly(methyl methacrylate); Stainless steel; Titanium