title: Effect of chlorhexidine incorporation into dental adhesive resin on durability of resin-dentin bond.
abstract: OBJECTIVE
  This study evaluated the effect of chlorhexidine (CHX) incorporation into experimental dentin adhesives with different hydrophilicities on the microtensile bond strength (µTBS) to dentin.
  
  
  METHODS
  Flat, deep dentin surfaces were prepared from 60 extracted human third molars. Three ethanol-solvated (50 wt% ethanol/50 wt% comonomers) experimental adhesives with varying degrees of hydrophilicity were prepared for the CHX-free groups. For the CHX-containing groups, chlorhexidine diacetate was further added to the ethanol-solvated adhesives to form a concentration of 2.0 wt% CHX. Dentin surfaces were etched with 37% phosphoric acid for 15 s, rinsed and blot dried before bonding. The adhesives were generously applied to dentin with a microbrush for 15 s. A second application of fresh adhesive was made and light cured for 20 s (600 mW/cm2) after solvent evaporation. Composite buildups were made using Filtek Z250 (3M ESPE). The bonded teeth were sectioned into 0.9 mm x 0.9 mm beams and stressed to failure at a crosshead speed of 1 mm/min. Testing was performed 24 h after specimen preparation and 12 months after storage in artificial saliva. The µTBS data were analyzed using three-way ANOVA and Tukey's multiple comparison tests. Fractographic analysis was performed by SEM.
  
  
  RESULTS
  Significant differences were observed for the three factors "adhesive hydrophilicity" (p < 0.001), "CHX incorporation" (p = 0.001), and "storage time" (p < 0.001). Interaction among these three factors was also significant (p < 0.001). Incorporation of CHX had no effect on the immediate bond strength of the three experimental adhesives (p > 0.05). After storage in artificial saliva, significant reduction in bond strength was observed in all adhesive groups, except for CHX-containing adhesive I (p < 0.001). The µTBS of the CHX-containing experimental adhesive III was significantly higher than the corresponding CHX-free adhesive (p < 0.001) after aging.
  
  
  CONCLUSIONS
  When incorporated into hydrophilic dental adhesives, chlorhexidine can partially reduce the degradation of the resin-dentin bonds.
authors.affiliation: Faculty of Dentistry, University of Hong Kong, Hong Kong SAR, China. ckyyiu@hkucc.hku.hk
authors.forename: Cynthia K
authors.initials: CK
authors.lastname: Yiu
authors.forename: Noriko
authors.initials: N
authors.lastname: Hiraishi
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Nigel M
authors.initials: NM
authors.lastname: King
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002710:Chlorhexidine / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry; D003799:Dental Stress Analysis; D003804:Dentin / Q000648:ultrastructure*; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D012464:Saliva, Artificial / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C444701:Filtek Z250; D008689:Methacrylates; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; D019279:Resin Cements; D012464:Saliva, Artificial; D012997:Solvents; C020946:triethylene glycol dimethacrylate; D000431:Ethanol; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; C030242:phosphoric acid; D002710:Chlorhexidine