title: Influence of time and adhesive system on the extrusion shear strength between feldspathic porcelain and bovine dentin.
abstract: OBJECTIVE
  The behavior of dual-cure cements over time remains unclear. This study evaluated the extrusion shear strength of the bond between feldsphatic porcelain and bovine dentin at different time intervals, using three adhesive systems based on dual-cure cements and one based on a self-cure cement.
  
  
  METHODS
  The adhesive systems evaluated included: C&B/One-Step, Enforce/Prime&Bond NT Dual-Cure, RelyX ARC/Single Bond and Variolink II/Syntac SC. Discs of bovine root dentin, 2.5 mm thick, had the root canal prepared with a standardized taper. Porcelain truncated cones etched with 4% hydrofluoric acid and silanized were bonded into the perforations. The extrusion shear test was performed after 15 min, 4 h, 12 h, 24 h, and 7 days. Data were analyzed using the Weibull distribution. The failure mode was accessed by stereomicroscope and SEM.
  
  
  RESULTS
  Statistical differences were found between 15 min and 7 days for Variolink II/Syntac SC and RelyX ARC/Single Bond, and between 15 min and 24 h for Enforce/Prime&Bond NT Dual-Cure. For C&B/One-Step, difference was found between 15 min and 4 h. Between 24 h and 7 days, only the system RelyX ARC/Single Bond showed a significant increase in the characteristic strength. SEM analysis revealed that the failure involved the hybrid layer/dentin or the hybrid layer/adhesive interfaces, regardless of the time interval and adhesive system.
  
  
  CONCLUSIONS
  High characteristic strengths were observed after 15 min when dual-cure cements were used. In general, the values found at 24 h or 7 days were higher than at 15 min. However, there was always a considerable probability of bonding failure at low stress levels for all the systems tested.
authors.affiliation: Department of Dental Materials, University of São Paulo, School of Dentistry, São Paulo, Brazil. rrbraga@siso.fo.usp.br
authors.forename: R R
authors.initials: RR
authors.lastname: Braga
authors.forename: R Y
authors.initials: RY
authors.lastname: Ballester
authors.forename: M
authors.initials: M
authors.lastname: Daronch
mesh_terms: D000134:Acid Etching, Dental; D000268:Adhesiveness; D000538:Aluminum Silicates / Q000737:chemistry*; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001896:Boron Compounds / Q000737:chemistry; D002417:Cattle; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006858:Hydrofluoric Acid / Q000008:administration & dosage; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011109:Polymethacrylic Acids / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000538:Aluminum Silicates; D001896:Boron Compounds; C095997:DCR cement; D003738:Dental Cements; D017220:Dentin-Bonding Agents; C103503:EnForce-Sure Cure; D008689:Methacrylates; D008768:Methylmethacrylates; D011109:Polymethacrylic Acids; D017680:Potassium Compounds; C103500:Prime & Bond; C097531:Rely a Bond system; D019279:Resin Cements; D012821:Silanes; C078484:Syntac dentine adhesive; C115612:single bond; D003776:Dental Porcelain; C016447:feldspar; C103502:Variolink; D017438:Bisphenol A-Glycidyl Methacrylate; C049495:Super-bond; D006858:Hydrofluoric Acid