title: Influence of calcium hydroxide dressing and acid etching on the push-out bond strengths of three luting resins to root canal dentin.
abstract: OBJECTIVE
  This study aims to investigate the effects of calcium hydroxide (Ca(OH)2) dressing in root canals and the effects of subsequent acid etching on the adhesion of luting resins to root canals.
  
  
  METHODS
  Root specimens were prepared from extracted human permanent molars. Specimen canals were (1) filled with etch-and-rinse (Nexus® third generation (NX3)) and two self-adhesive (RelyX Unicem, Maxcem Elite) luting resins, respectively; (2) dressed with Ca(OH)2 before Ca(OH)2 removal and luting resin filling; (3) dressed with Ca(OH)2 before Ca(OH)2 removal and post-cementation; or (4) treated as described in item (2) except that the canals were further etched with phosphoric acid before luting resin filling. Push-out bond strengths were measured and analyzed using one-way analysis of variance, and Fisher's multiple comparison tests provided a follow-up comparison among these four canal treatments. Attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to analyze the specimen surfaces.
  
  
  RESULTS
  Ca(OH)2 dressing adversely affected the bond strengths to canal dentin of the three luting resins tested. Acid etching did not increase the bond strengths. Infrared analysis revealed that Ca(OH)2 dressing caused no structural changes on the dentin surface. XPS and SEM analyses revealed Ca(OH)2 remnants as the ultimate chemical cause leading to the decrease in bond strength.
  
  
  CONCLUSIONS
  The bond strength of luting resin to dentin was affected by Ca(OH)2 dressing. Acid etching treatment could not increase the bond strength.
  
  
  CONCLUSIONS
  Adhesion of the fiber post to the root canal wall may be compromised after Ca(OH)2 dressing. An effective method for complete removal of Ca(OH)2 dressing or increase of bond strength for luting resin needs to be developed.
authors.affiliation: Graduate Institute of Oral Biology, School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Bor-Shiunn
authors.initials: BS
authors.lastname: Lee
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Lin
authors.forename: Sing-Fu
authors.initials: SF
authors.lastname: Chen
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Chen
authors.forename: Che-Chen
authors.initials: CC
authors.lastname: Chang
mesh_terms: D000134:Acid Etching, Dental; D001458:Bandages; D002126:Calcium Hydroxide / Q000008:administration & dosage*; D003738:Dental Cements; D003786:Dental Pulp Cavity / Q000378:metabolism*; D003804:Dentin / Q000378:metabolism*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003738:Dental Cements; D002126:Calcium Hydroxide