title: Effect of desensitizer application on shear bond strength of composite resin to bleached enamel.
abstract: OBJECTIVE
  Tooth sensitivity is common after vital tooth bleaching. The aim of this study is to evaluate the effect of a desensitizing agent on shear bond strength of composite resin to bleached enamel; and determine whether a delay of one or two weeks in bonding procedure is sufficient subsequent to bleaching/desensitizer regimen.
  
  
  METHODS
  Buccal enamel surfaces of ninety-six human sound molars were prepared and divided into eight groups. The surfaces of specimens in Group 1 as negative control group were bonded by composite resin using the single bond adhesive. Specimens in Groups 2-4 were bleached with an at-home bleaching agent (Daywhite ACP). Relief ACP desensitizing gel alone was applied in Group 5. In Groups 6-8, specimens were bleached same as in Group 2 and relief ACP desensitizing gel was applied same as in Group 5 subsequent to each bleaching session. Composite cylinders were bonded after 24 h, 7 days and 14 days in Groups 2-4, respectively, and also in Groups 6-8, respectively. The shear bond strengths of the cylinders were tested and data was analyzed using two-way ANOVA and Tukey test (α = 0.05).
  
  
  RESULTS
  The results showed that bleaching and bleaching/desensitizer regimens significantly reduced the bond strength of composite resin to enamel. However, desensitizer alone did not reduce bond strength. No statistically significant differences were found between bleaching and bleaching/desensitizer regarding bond strength.
  
  
  CONCLUSIONS
  Bleaching or bleaching/desensitizer treatment significantly decreases bond strength of composite resin to enamel. In both regimens, adhesive bonding is recommended after two weeks.
authors.affiliation: Dental Materials Research Center and Department of Operative Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Khoroushi
authors.forename: Ali
authors.initials: A
authors.lastname: Ghazalgoo
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D057133:Dentin Desensitizing Agents / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D008422:Materials Testing; D010756:Phosphoric Acids / Q000737:chemistry; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D057133:Dentin Desensitizing Agents; D010756:Phosphoric Acids; D058205:Tooth Bleaching Agents; C083568:Z100 composite resin; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D006861:Hydrogen Peroxide; D015040:Zirconium; C030242:phosphoric acid