title: The impact of surface preparation on shear bond strength of metallic orthodontic brackets bonded with a resin-modified glass ionomer cement.
abstract: OBJECTIVE
  The aim of this study was to assess the effects of four enamel preparation techniques on shear bond strength (SBS) of brackets bonded with a resin-modified glass ionomer cement (RMGIC). Adhesive Remnant Index (ARI) and enamel surface roughness (Ra) were also investigated after cement removal.
  
  
  METHODS
  One hundred and forty-four human premolars were divided into four groups (n = 36 in each group) as follows: Group 1, 37% phosphoric acid (i.e. conventional); Group 2, sandblasting; Group 3, sodium hypochlorite and 37% phosphoric acid; and Group 4, sodium hypochlorite and sandblasting. Twenty-four hours after bonding, the brackets were debonded with an Instron machine using a crosshead speed of 1·0 mm/min; the ARI was evaluated by an image analyser system; the Ra was measured by profilometry; and the morphology of the tooth enamel surface was observed by scanning electron microscope evaluation. Data were submitted to ANOVA and the Kruskal-Wallis test (α = 0·05).
  
  
  RESULTS
  Mean SBS values for Groups 1-4 were 13·86, 9·08, 17 and 9·63 MPa, respectively. Mean ARI for Groups 1-4 were 11·16, 2·06, 20·66 and 3·73%. The SBS and ARI showed statistically significant differences between the four groups (P<0·001). The Ra (μm) showed no significant differences between groups.
  
  
  CONCLUSIONS
  Bracket bonding using RMGIC showed adequate adhesion for clinical use, and the type of enamel preparation had a significant influence.
authors.affiliation: Orthodontic Unit, School of Dental Science, Universiti Sains Malaysia, Kelantan, Malaysia.
authors.forename: Ayman A S
authors.initials: AA
authors.lastname: Elnafar
authors.affiliation: Orthodontic Unit, School of Dental Science, Universiti Sains Malaysia, Kelantan, Malaysia.
authors.forename: Mohammad K
authors.initials: MK
authors.lastname: Alam
authors.affiliation: Orthodontic Unit, School of Dental Science, Universiti Sains Malaysia, Kelantan, Malaysia.
authors.forename: Rozita
authors.initials: R
authors.lastname: Hasan
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000268:Adhesiveness; D000537:Aluminum Oxide / Q000737:chemistry; D001641:Bicuspid / Q000648:ultrastructure; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D045662:Dental Etching / Q000379:methods*; D003799:Dental Stress Analysis / Q000295:instrumentation; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D012973:Sodium Hypochlorite / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D005899:Glass Ionomer Cements; D010756:Phosphoric Acids; D019279:Resin Cements; D014867:Water; C084541:Fuji glass-ionomer lining cement; D012973:Sodium Hypochlorite; C030242:phosphoric acid; D000537:Aluminum Oxide
keywords: Adhesive Remnant Index (ARI); RMGIC; orthodontic brackets; shear bond strength (SBS); surface roughness