title: In-vitro orthodontic bond strength testing: a systematic review and meta-analysis.
abstract: BACKGROUND
  The aims of this study were to systematically review the available literature regarding in-vitro orthodontic shear bond strength testing and to analyze the influence of test conditions on bond strength.
  
  
  METHODS
  Our data sources were Embase and Medline. Relevant studies were selected based on predefined criteria. Study test conditions that might influence in-vitro bond strength were independently assessed by 2 observers. Studies reporting a minimum number of test conditions were included for meta-analysis by using a multilevel model with 3 levels, with author as the highest level, study as the second level, and specimens in the study as the lowest level. The primary outcome measure was bond strength.
  
  
  RESULTS
  We identified 121 relevant studies, of which 24 were included in the meta-analysis. Methodologic drawbacks of the excluded studies were generally related to inadequate reporting of test conditions and specimen storage. The meta-analysis demonstrated that 3 experimental conditions significantly affect in-vitro bond strength testing. Although water storage decreased bond strength on average by 10.7 MPa, each second of photopolymerization time and each millimeter per minute of greater crosshead speed increased bond strength by 0.077 and 1.3 MPa, respectively.
  
  
  CONCLUSIONS
  Many studies on in-vitro orthodontic bond strength fail to report test conditions that could significantly affect their outcomes.
authors.affiliation: Department of Orthodontics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. k.j.finnema@dmo.umcg.nl
authors.forename: Katrina J
authors.initials: KJ
authors.lastname: Finnema
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Post
authors.forename: Yijin
authors.initials: Y
authors.lastname: Ren
authors.forename: Pieter U
authors.initials: PU
authors.lastname: Dijkstra
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry* / Q000528:radiation effects; D006801:Humans; D008422:Materials Testing; D009967:Orthodontic Appliances; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D033081:Shear Strength; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003738:Dental Cements; D011108:Polymers; D014867:Water