title: Effect of re-etching oxalate-occluded dentin and enamel on bonding effectiveness of etch-and-rinse adhesives.
abstract: OBJECTIVE
  To determine whether or not re-etching of oxalate-treated dentin and enamel increases microshear bond strength (µSBS) and improves hybridization.
  
  
  METHODS
  Two single-bottle etch-and-rinse adhesives, SingleBond (3M/ESPE) and OptiBond S (Kerr), were bonded to deep occlusal dentin and enamel after perfusion under 20 mmHg simulated intrapulpal pressure. For each adhesive tested, the experimental groups were: G1: bonding according to manufacturer's instructions (control); G2: application of oxalate desensitizer (D/Sense Crystal, Centrix) to acid-etched substrate followed by 60 s water rinsing prior to bonding; G3: same as G2, but with a further 15-s re-etching with 35% phosphoric acid before bonding. The microshear bond strength (µSBS) to dentin and enamel was tested (n = 15); a scanning electron microscopic (SEM) analysis of surface topography (n = 2), interface (n = 2), and failure mode was also performed. The data were statistically analyzed using ANOVA and Tukey's tests at p ≤ 0.05.
  
  
  RESULTS
  In enamel, both adhesives showed no significant difference in μSBS among groups. In dentin, the highest statistically μSBS for both adhesives was recorded for G1, followed by G2, with the lowest values revealed remnants of calcium oxalate crystals that were removed only from enamel surfaces after re-etching. SEM images of the interface revealed inadequate dentin hybridization in G2 and G3 compared to G1.
  
  
  CONCLUSIONS
  Re-etching after oxalate treatment compromises bonding of single-bottle etch-and-rinse adhesives to dentin and provides no added benefits to enamel bonding.
authors.affiliation: Department of Restorative Dentistry, Faculty of Oral and Dental Medicine, Cairo University, Egypt. maiyousri@hotmail.com
authors.forename: Mai Mahmoud
authors.initials: MM
authors.lastname: Yousry
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000268:Adhesiveness; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry; D003782:Dental Pulp / Q000502:physiology; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure*; D057133:Dentin Desensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010070:Oxalates / Q000737:chemistry / Q000494:pharmacology*; D010756:Phosphoric Acids / Q000737:chemistry; D011312:Pressure; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C554641:Adper single bond 2; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D057133:Dentin Desensitizing Agents; D017220:Dentin-Bonding Agents; C474035:Filtek Supreme; C092987:Optibond; D010070:Oxalates; D010756:Phosphoric Acids; D019279:Resin Cements; D014867:Water; C030242:phosphoric acid