title: Comparison of wire loop and shear blade as the 2 most common methods for testing orthodontic shear bond strength.
abstract: BACKGROUND
  The purpose of this study was to compare 2 common methods of measuring orthodontic shear bond strength.
  
  
  METHODS
  Brackets were bonded to 40 bovine incisors, and the teeth were mounted in a jig. The teeth were paired for symmetry, and the pairs were divided into 2 groups for debonding. In group 1, the shear force was applied with a rectangular wire under the tie wings. In group 2, a shearing blade applied force to the junction between the bracket base and the adhesive.
  
  
  RESULTS
  Debonding with the shear blade produced higher (24.86 +/- 7.44 MPa) and more dispersed (coefficient of variation = 29.91%) bond strengths compared with the wire loop (17.12 +/- 3.16 MPa, coefficient of variation = 18.44%). Adhesive remnant index (ARI) scores showed a tendency for cohesive failure in the enamel in the shear-blade group (ARI = 5) compared with adhesive failure (ARI = 3) in the wire group.
  
  
  CONCLUSIONS
  There is a need to standardize bond strength tests. The results of this study favor the wire-loop method, which might have more similarity to clinical loads. The regression formula might make comparison of previous studies easier.
authors.affiliation: Department of Orthodontics, Kerman School of Dentistry, Kerman, Iran. mojzad@sina.tums.ac.ir
authors.forename: Faramarz
authors.initials: F
authors.lastname: Mojtahedzadeh
authors.forename: Mohammad Sadegh Ahmad
authors.initials: MS
authors.lastname: Akhoundi
authors.forename: Hassan
authors.initials: H
authors.lastname: Noroozi
mesh_terms: D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D003799:Dental Stress Analysis / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D019544:Equipment Failure Analysis; D016910:Orthodontic Brackets; D012044:Regression Analysis; D019279:Resin Cements; D033081:Shear Strength
chemical_list: D019279:Resin Cements; C477790:Transbond XT