title: Bond angle effects on microtensile bonds: laboratory and FEA comparison.
abstract: OBJECTIVE
  To test the hypothesis that there is a reduction in bond strength when a microtensile load is applied to adhesive junctions prepared at 10, 20 and 30 degrees to the usual perpendicular interface. To evaluate the effect of bond angle and adhesive layer thickness on stress levels within the adhesive joint utilizing FEA.
  
  
  METHODS
  Twenty-four non-carious third molars were selected, occlusal enamel removed and polished perpendicular to the long axis of the tooth. The Clearfil SE Bond and Single Bond were applied on the dentin. A 4 mm resin restoration, Z 100, was built up. The teeth were sectioned at 10 degrees, 20 degrees and 30 degrees to the bonding interface (n = 3). The control (n = 3) group had all cuts parallel to the tooth longitudinal axis (0 degrees bond angle). The bond values were calculated in MPa and Two-Way ANOVA and Tukey test applied. FEA was performed (1 mm/side square specimens) to obtain the maximum principal stress (MPS) in the microtensile-model for each bond angle and for varying adhesive thickness from 20 microm to 200 microm for each group.
  
  
  RESULTS
  The bond strength results diminish as the angle on the interface increased (P<0.05) for Clearfil SE Bond between 0 (control) and 30 degrees, and for Single Bond between 0 (control) and 10, 20, and 30 degrees. The hypothesis can be fully accepted for Single Bond and partially accepted for Clearfil SE Bond. For the FEA, there was a trend toward decreasing MPS as the bond angle increased, while the MPS for each angled group increased with adhesive layer thickness.
  
  
  CONCLUSIONS
  The MPS results for angled interfaces, exhibited the same trend as the lab values. FEA results indicated an MPS increase with increased adhesive thickness.
authors.affiliation: Department of Biomaterials and Biomimetics, Department of Prosthodontics, New York University, College of Dentistry, 345 East 24th Street, Room 804, New York City, NY 10010, USA.
authors.forename: Nelson R F A
authors.initials: NR
authors.lastname: Silva
authors.forename: Christine S
authors.initials: CS
authors.lastname: Calamia
authors.forename: Masly
authors.initials: M
authors.lastname: Harsono
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Carvalho
authors.forename: Luiz F
authors.initials: LF
authors.lastname: Pegoraro
authors.forename: Carlos A O
authors.initials: CA
authors.lastname: Fernandes
authors.forename: Antonio C B
authors.initials: AC
authors.lastname: Vieira
authors.forename: Van P
authors.initials: VP
authors.lastname: Thompson
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003198:Computer Simulation; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D019246:Tooth Preparation / Q000379:methods*; D015040:Zirconium / Q000737:chemistry
chemical_list: C438313:Clearfil SE Bond; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C083568:Z100 composite resin; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium