title: Effects of cyclic loading on the bond strength of metal orthodontic brackets bonded to a porcelain surface using different conditioning protocols.
abstract: OBJECTIVE
  To evaluate cyclic and static shear bond strengths (SSBSs) of metal orthodontic brackets bonded to a porcelain surface using different conditioning protocols.
  
  
  METHODS
  A total of 100 feldspathic porcelain disks were fabricated. The specimens were divided into four equal groups. Porcelain surfaces were conditioned with different protocols. In group 1, hydrofluoric acid and Embrace First-Coat primer were used. In group 2, hydrofluoric acid and silane were utilized. In groups 3 and 4, sandblasting with aluminum oxide powder was done instead of etching. Metal brackets were bonded to the porcelain surfaces using Transbond XT adhesive. SSBS testing was carried out in 10 specimens, while cyclic shear bond strength (CSBS) testing was done in 15 specimens from each group. The data were subjected to analysis of variance, least significant difference post hoc, and Student's t-tests.
  
  
  RESULTS
  Embrace First-Coat and silane exhibited a comparable SSBS. The sandblasting process significantly increased SSBS. No significant difference was found in bond SSBS utilizing either hydrofluoric acid and Embrace First-Coat or sandblasting and silane. With regard to CSBS, the use of sandblasting and Embrace First-Coat revealed the highest significant CSBS value, followed by sandblasting and silane. Etching with hydrofluoric acid prior to application of either primer exhibited the least CSBS values; however, no significant difference was found between them. The SSBS was significantly higher than CSBS.
  
  
  CONCLUSIONS
  Embrace First-Coat could be used successfully as an alternative to silane. Sandblasting provides higher bond strength than did hydrofluoric acid. Cyclic loading significantly decreased bond strength.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Mansoura University, Egypt. dryasserlotfy@yahoo.com
authors.forename: Yasser L
authors.initials: YL
authors.lastname: Abdelnaby
mesh_terms: D020906:Air Abrasion, Dental; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods*; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D023381:Endpoint Determination; D008670:Metals; D016910:Orthodontic Brackets; D019279:Resin Cements; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D008670:Metals; D019279:Resin Cements; C477790:Transbond XT; D003776:Dental Porcelain