title: Effect of stepped vs. continuous light curing exposure on bond strengths to dentin.
abstract: OBJECTIVE
  To compare the 10-min and 24-hr shear bond strengths of three dentin bonding systems, polymerized with either a standard (Optilux 401) light for 60 s, or a stepped curing light (Elipar Highlight) that delivered a low light intensity for 10 s followed by high intensity for 50 s.
  
  
  METHODS
  Three bonding systems were used to bond two resin-based composites (RBC) to dentin at 34 degrees +/- 2C using the two curing lights. Single Bond (SB) and Prime & Bond 2.1 (P&B) were used with Z100 RBC, and EBS bonding system was used with Pertac II RBC. Ten specimens from each combination were debonded at 37 degrees +/- 1C 10 min after starting to light cure the bonding system. Ten other specimens were stored in water at 37 degrees +/- 1C for 24 hrs before debonding at 37 degrees +/- 1C (total 120 teeth).
  
  
  RESULTS
  The 10-min mean shear bond strengths were: Standard Cure; EBS 11.9 +/- 2.9 MPa, SB 14.6 +/- 2.2 MPa, P&B 14.7 +/- 4.2 MPa: Stepped Curing; EBS 7.4 +/- 2.1 MPa, SB 13.0 +/- 3.6 MPa, P&B 15.6 +/- 4.8 MPa. The 24-hr mean shear bond strengths were: Standard Cure; EBS 14.8 +/- 5.1 MPa, SB 25.1 +/- 3.3 MPa, P&B 25.2 +/- 8.8 MPa: Stepped Curing; EBS 15.1 +/- 4.6 MPa, SB 21.9 +/- 5.9 MPa, P&B 17.3 +/- 9.2 MPa. Three way ANOVA showed significant main effects for light, bonding system and time and no 2- or 3-way interaction effects at P = 0.01. The Least-Squares Means test with Sidak's adjustment for Multiple Comparisons showed that the bond strengths obtained using the standard light were significantly greater than the bond strengths obtained using the stepped curing light (P < 0.01). The 24-hr bond strengths were significantly greater (P < 0.01) than the 10-min bond strengths. The bond strengths obtained with EBS were significantly less than SB and P&B (P < 0.01), but there were no significant differences between SB and PB (P = 0.9752).
authors.affiliation: Department of Dental Clinical Sciences, Faculty of Dentistry, Dalhousie University, Halifax, Nova Scotia, Canada. rbprice@is.dal.ca
authors.forename: R B
authors.initials: RB
authors.lastname: Price
authors.forename: R A
authors.initials: RA
authors.lastname: Bannerman
authors.forename: A S
authors.initials: AS
authors.lastname: Rizkalla
authors.forename: G C
authors.initials: GC
authors.lastname: Hall
mesh_terms: D000268:Adhesiveness; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D016018:Least-Squares Analysis; D008027:Light; D008689:Methacrylates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry; D012822:Silicon Dioxide; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water; D015040:Zirconium
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C113072:EBS adhesive system; D008689:Methacrylates; C088836:Pertac-Bond; D010756:Phosphoric Acids; D011108:Polymers; D011109:Polymethacrylic Acids; C103500:Prime & Bond; D019279:Resin Cements; C083568:Z100 composite resin; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium