title: Effectiveness of silica-lasing method on the bond strength of composite resin repair to Ni-Cr alloy.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effectiveness of silica-lasing method for improving the composite resin repair of metal ceramic restorations.
  
  
  METHODS
  Sixty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 μm aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1-airborne-particle abrasion alone (AA); group 2-Nd:YAG laser irradiation (LA); group 3-silica coating (Si-CO); group 4-silica-lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si-LA); group 5-silica-lasing plus etching with HF acid (Si-LA-HF); group 6-CoJet sand lased (CJ-LA). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The shear bond strength values were analyzed using ANOVA and Tukey's tests (α = 0.05). The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X-ray spectroscopy.
  
  
  RESULTS
  Si-CO showed significantly higher shear bond strength in comparison to other groups (p < 0.001). The shear bond strength values of the LA group were significantly higher than those of the AA group (p < 0.05). No significant difference was found among lased groups (LA, Si-LA, Si-LA-HF, CJ-LA; p > 0.05). The failure mode was 100% adhesive for AA, Si-LA, Si-LA-HF, and CJ-LA. LA and Si-CO groups showed 37.5% and 87.5% cohesive failure, respectively.
  
  
  CONCLUSIONS
  Silica coating of Ni-Cr alloy resulted in higher shear bond strength than those of other surface treatments.
authors.affiliation: Department of Prosthodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Azam S
authors.initials: AS
authors.lastname: Madani
authors.forename: Pedram Ansari
authors.initials: PA
authors.lastname: Astaneh
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Nakhaei
authors.forename: Hossein G
authors.initials: HG
authors.lastname: Bagheri
authors.forename: Horieh
authors.initials: H
authors.lastname: Moosavi
authors.forename: Samin
authors.initials: S
authors.lastname: Alavi
authors.forename: Niloufar Tayarani
authors.initials: NT
authors.lastname: Najjaran
mesh_terms: D000268:Adhesiveness; D002858:Chromium Alloys / Q000737:chemistry* / Q000528:radiation effects*; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects*; D003776:Dental Porcelain / Q000737:chemistry / Q000528:radiation effects; D017269:Dental Prosthesis Repair / Q000379:methods*; D006858:Hydrofluoric Acid; D053844:Lasers, Solid-State; D008422:Materials Testing; D016876:Metal Ceramic Alloys; D008669:Metallurgy / Q000379:methods; D008855:Microscopy, Electron, Scanning; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry* / Q000528:radiation effects*; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D002858:Chromium Alloys; D003188:Composite Resins; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D012822:Silicon Dioxide; D006858:Hydrofluoric Acid
keywords: Base metal alloy; laser; metal-ceramic repair; shear bond strength; silica coating