title: The effects of various surface treatments on the shear bond strengths of stainless steel brackets to artificially-aged composite restorations.
abstract: OBJECTIVE
  To compare the shear bond strengths (SBS) of stainless steel brackets bonded to artificially-aged composite restorations after different surface treatments.
  
  
  METHODS
  Forty-five premolar teeth were restored with a nano-hybrid composite (Tetric EvoCeram), stored in deionised water for one week and randomly divided into three equal groups: Group I, he restorations were exposed to 5 per cent hydrofluoric acid for 60 seconds; Group II, the restorations were abraded with a micro-etcher (50 Iim alumina particles); Group III, the restorations were roughened with a coarse diamond bur. Similar premolar brackets were bonded to each restoration using the same resin adhesive and the specimens were then cycled in deionised water between 5 degrees C and 55 degrees C (500 cycles). The shear bond strengths were determined with a universal testing machine at a crosshead speed of 1 mm/min. The teeth and brackets were examined under a stereomicroscope and the adhesive remnants on the teeth scored with the adhesive remnant index (ARI).
  
  
  RESULTS
  Specimens treated with the diamond bur had a significantly higher SBS (Mean: 18.45 +/- 3.82 MPa) than the group treated with hydrofluoric acid (Mean: 12.85 +/- 5.20 MPa). The mean SBS difference between the air-abrasion (Mean: 15.36 +/- 4.92 MPa) and hydrofluoric acid groups was not significant. High ARI scores occurred following abrasion with a diamond bur (100 per cent) and micro-etcher (80 per cent). In approximately two thirds of the teeth no adhesive was left on the restoration after surface treatment with hydofluoric acid.
  
  
  CONCLUSIONS
  Surface treatment with a diamond bur resulted in a high bond strength between stainless steel brackets and artificially-aged composite restorations and was considered to be a safe and effective method of surface treatment. Most of the adhesive remained on the tooth following surface treatment with either the micro-etcher or the diamond bur.
authors.affiliation: Department of Orthodontics and Dental Research Center, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ladan
authors.initials: L
authors.lastname: Eslamian
authors.forename: Ali
authors.initials: A
authors.lastname: Borzabadi-Farahani
authors.forename: Nasim
authors.initials: N
authors.lastname: Mousavi
authors.forename: Amir
authors.initials: A
authors.lastname: Ghasemi
mesh_terms: D020906:Air Abrasion, Dental; D001641:Bicuspid; D003188:Composite Resins; D003722:Dental Alloys; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D006801:Humans; D006858:Hydrofluoric Acid; D008422:Materials Testing; D053761:Nanocomposites; D016910:Orthodontic Brackets; D019279:Resin Cements; D033081:Shear Strength; D013193:Stainless Steel; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D019279:Resin Cements; C501891:Tetric EvoCeram; D013193:Stainless Steel; D006858:Hydrofluoric Acid