title: The effect of casein phosphopeptide amorphous calcium phosphate on the in vitro shear bond strength of orthodontic brackets.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on the shear bond strength (SBS) of brackets bonded to non-demineralized teeth with either phosphoric acid etching or self-etching primer.
  
  
  METHODS
  Sixty human premolars were randomly assigned to 1 of 4 treatment groups (n = 15 each): phosphoric acid etching (group 1); self-etching primer (group 2); CPP-ACP for 2 weeks + phosphoric acid etching (group 3), and CPP-ACP for 2 weeks + self-etching primer (group 4). After bonding of the maxillary premolar metal brackets, specimens were subjected to shear forces in a testing machine. Scanning electron microscopy was used to observe etching patterns on the enamel surfaces of all teeth. A 2-way analysis of variance was used to test for effects of CPP-ACP and etching system on SBS.
  
  
  RESULTS
  Significantly higher mean SBSs were observed in groups subjected to phosphoric acid etching (i.e., groups 1 and 3; p < 0.05). On the other hand, SBSs did not appear to be influenced by CPP-ACP (i.e., groups 3 and 4; p > 0.05). We observed a uniform and clear etched pattern on the enamel surface of the phosphoric acid etching groups.
  
  
  CONCLUSIONS
  CPP-ACP does not significantly affect the SBS of orthodontic brackets bonded to non-demineralized teeth, regardless of which adhesive method is used to bond the brackets.
authors.affiliation: Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Sun-Youn
authors.initials: SY
authors.lastname: Park
authors.forename: Jung-Yul
authors.initials: JY
authors.lastname: Cha
authors.forename: Kyoung-Nam
authors.initials: KN
authors.lastname: Kim
authors.forename: Chung-Ju
authors.initials: CJ
authors.lastname: Hwang
keywords: Bracket; CPP-ACP; Self-etching primer; Shear bond strength