title: A new fixation method for stick-shaped specimens in microtensile tests: laboratory tests and FEA.
abstract: OBJECTIVE
  To introduce a new fixation method for stick-shaped specimens for use in microtensile tests and to evaluate the effect of this new method on microtensile bond strength, failure modes, and stress distribution.
  
  
  METHODS
  Flat mid-coronal dentin surfaces were prepared on 12 caries-free human third molars and randomly divided into two groups for testing with two dental adhesives (Adper Single Bond 2 [SB2] and Clearfil SE Bond [SEB]). Following adhesive application and composite buildups, the bonded teeth were sectioned into beams. Sticks from each tooth were then equally divided into two subgroups for microtensile bond testing according to the utilized gripping devices (a flat Ciucchi's jig and the experimental setup). Failure modes were examined with a field-emission scanning electron microscope (FESEM). Three-dimensional models of each gripping device and specimen were developed, and stress distributions were analyzed by finite element analysis (FEA). Statistical significance was set at α = 0.05 RESULTS: Compared to those fixed using a flat Ciucchi's jig, sticks fixed with the experimental setup yielded lower bond strength values (p = 0.021 for SB2 and p = 0.007 for SEB) and more mixed failure patterns (p = 0.036 for both SB2 and SEB). In addition, the experimental setup guaranteed a uniaxial tensile force that was perpendicular to the bonding interface and produced a more uniform stress distribution at the bonding interface.
  
  
  CONCLUSIONS
  An experimental setup for fixing microtensile sticks was proposed that was designed to provide a uniform stress distribution at the adhesive interface. FEA and failure mode analysis confirmed such uniform distribution, thus supporting the validity of the bond strength results obtained with this new fixture design.
authors.forename: Shuai
authors.initials: S
authors.lastname: Lu
authors.forename: San-Jun
authors.initials: SJ
authors.lastname: Zhao
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Gao
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qi
authors.initials: Q
authors.lastname: Dou
authors.forename: Ji-hua
authors.initials: JH
authors.lastname: Chen
mesh_terms: D000268:Adhesiveness; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D003799:Dental Stress Analysis / Q000295:instrumentation* / Q000379:methods; D003804:Dentin / Q000648:ultrastructure*; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing / Q000379:methods; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C554641:Adper single bond 2; C438313:Clearfil SE Bond; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; C444701:Filtek Z250; D019279:Resin Cements; D014867:Water