title: Bond strength and micro-computed tomographic evaluation of pre-coated brackets.
abstract: OBJECTIVE
  The aim of the present study was to assess and compare the shear bond strength (SBS) of metal pre-coated orthodontic brackets bonded to fluorotic and non-fluorotic teeth treated with three different etching techniques. A second aim was to determine the volume of adhesive remaining on the tooth at debond using micro-computed tomography (μCT).
  
  
  METHODS
  Ninety extracted premolars were selected to include 45 fluorotic (test group) and 45 non-fluorotic (control group) teeth. Each group was divided into three subgroups of 15 each, which were treated as follows: 1) micro-etched; 2) acid-etched; and 3) both micro-etched and acid-etched. A bonding agent was applied to the prepared surfaces; pre-coated and light-cured brackets were attached to all teeth. An Instron universal testing machine was used to record the debonding force. Specimens were then scanned using a microCT to evaluate the amount of adhesive remaining on the teeth. The significance of the statistical tests was pre-determined at p < 0.05.
  
  
  RESULTS
  Two-way ANOVA showed that fluorosis of teeth had no influence on the SBS (p = 0.165) whereas the volume of adhesive remnants was significantly higher in the control group compared with the test group (p < 0.001).
  
  
  CONCLUSIONS
  Fluorosis had no influence on the SBS of brackets, whereas it had a negative influence on retaining adhesives onto the tooth surfaces.
authors.forename: Waleed
authors.initials: W
authors.lastname: Bakhadher
authors.forename: Nabeel
authors.initials: N
authors.lastname: Talic
authors.forename: Khalid
authors.initials: K
authors.lastname: Al Hezaimi
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000537:Aluminum Oxide / Q000737:chemistry; D001641:Bicuspid / Q000648:ultrastructure; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D055117:Curing Lights, Dental; D003722:Dental Alloys / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D045662:Dental Etching / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D009050:Fluorosis, Dental / Q000473:pathology*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation; D016910:Orthodontic Brackets; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D020099:Coated Materials, Biocompatible; D003722:Dental Alloys; D010756:Phosphoric Acids; D019279:Resin Cements; C477790:Transbond XT; C030242:phosphoric acid; D000537:Aluminum Oxide