title: Effects of self-curing activator and curing protocol on the bond strength of composite core buildups.
abstract: OBJECTIVE
  To determine the effect of the polymerization mode of simplified bonding systems and the corresponding core buildup resin composite on the bond strength to dentin.
  
  
  METHODS
  Composite core buildups were bonded to flat prepared dentin surfaces of 320 human molars using a two-step etch-and-rinse (Excite, ER) and a two-step self-etching (AdheSE, SE) bonding system. Bonding systems were used both with and without their respective self-curing activators (Excite DSC, ER+SC; AdheSE DC, SE+SC). Six curing protocols for the dual-curing composite (MultiCore Flow) were examined: self-curing for 5 min (a); irradiation with light from each aspect for 10 s (b), 20 s (c), and 40 s (d); and irradiation with light from the occlusal aspect only for 60 s (e) and 120 s (f). Shear bond strengths were measured immediately after curing. Additional measurements were performed after water storage of the specimens for 24 h at 37°C. These specimens had been cured according the curing protocols given in the manufacturer's instructions (groups a and d). Failure modes were analyzed using scanning electron microscopy.
  
  
  RESULTS
  Immediate bond strengths were significantly different among the bonding systems (p < 0.001): SE > ER > ER+SC > SE+SC. Immediate bond strengths of ER and SE were significantly lower when the composite was self-cured (p < 0.05). The use of SC activators reduced the bond strength and promoted adhesive failures to dentin. A severe incompatibility problem was observed between the composite and SE+SC.
  
  
  CONCLUSIONS
  Dentin bonding of dual-curing composite core buildups in combination with simplified bonding systems is still unsatisfactory, even when SC activators are employed. For adequate bonding to dentin, polymerization of the dual-curing composite should always be light initiated.
authors: Department of Operative Dentistry and Periodontology, University of Ulm, Germany. andreas.rathke@uniklinik-ulm.de
authors: Andreas
authors: A
authors: Rathke
authors: Ulrike
authors: U
authors: Balz
authors: Rainer
authors: R
authors: Muche
authors: Bernd
authors: B
authors: Haller
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D058105:Polymerization; D011176:Post and Core Technique; D019279:Resin Cements / Q000737:chemistry; D055116:Self-Curing of Dental Resins; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; C489662:AdheSE cement; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C420130:Excite cement; D008689:Methacrylates; C509715:MultiCore Flow; D019279:Resin Cements; D014867:Water