title: [Effects on the shear bond strength of orthodontic brackets with different concentration of fluorided etching fluid].
abstract: OBJECTIVE
  This study was to find out the most suitable concentration of added NaF to enough bonding strength of brackets.
  
  
  METHODS
  Sixty-four teeth were randomly divided into A, B, C and the control group. NaF of four different concentrations (1.23%, 2%, 3% and 0%) was added into 35% phosphoric acid. The four group teeth were etched with four kinds of fluoride etching fluid respectively and were bonded with brackets. Four specimens in each group were selected by turns after 1, 4, 12 and 24 weeks of bonding. The shear bond strength of the teeth were tested, and the adhesive residual index (ARI) of bonding interface were recorded.
  
  
  RESULTS
  The shear bond strength at four test time in each group was no significant (P > 0.05). There was statistical difference of the shear bond strength between four groups (P < 0.05), and group C was lower than the other groups. The ARI was no statistical difference between four groups.
  
  
  CONCLUSIONS
  The effects of etching and bonding had no significant changes when the concentration of added NaF was no more than 2%. The shear bond strength decreased while the concentration of NaF was higher than 3%.
authors.affiliation: Dept. of Orthodontics, Stomatological Hospital of China Medical University, Shenyang 110002, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Ma
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yu-hua
authors.initials: YH
authors.lastname: Hong
mesh_terms: D000134:Acid Etching, Dental; D001840:Dental Bonding; D006801:Humans; D016910:Orthodontic Brackets; D010756:Phosphoric Acids; D019279:Resin Cements; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D010756:Phosphoric Acids; D019279:Resin Cements; C030242:phosphoric acid