Finite element analysis and bond strength of a glass post to intraradicular dentin: comparison between microtensile and push-out tests.
OBJECTIVE
This study tested the hypothesis that the stress distribution and bond strength of glass posts to intraradicular dentin is influenced by the mechanical testing methodology.


METHODS
Thirty single rooted endodontically treated teeth were prepared for luting of tapered fiber-glass posts (Reforpost, Angelus, Londrina, PR, Brazil) with a conventional adhesive system and resin luting cement (Adper Scotchbond Multi-purpose, Rely X ARC, 3M ESPE, St. Paul, MN, USA). The teeth were randomly divided (n=10 per group) into micro-push-out (Mpo), hourglass- (Mh) and rectangular stick-shaped (Ms) microtensile testing groups before sectioning each root into five 1-mm-thick specimens. During specimen preparation for microTBS testing 46/50 stick and 4/50 hourglass specimens prematurely failed; therefore, the Ms group could not be included in the mechanical testing. The remaining specimens were tested at 0.5 mm/min until bond failure. Stress distribution within each specimen type for the three mechanical test methods was analyzed by finite element analysis (FEA). Qualitative analyses were carried out through Von Mises, XY and Sy criterion.


RESULTS
Mpo and Mh had a mean microTBS of 11.89+/-6.55 and 14.98+/-12.72 MPa, respectively, which was not significantly different (p=0.1311). The push-out test demonstrated a more homogenous stress distribution by FEA and less variability in mechanical testing.


CONCLUSIONS
Therefore, the recommended testing method for determining the bond strength of glass posts to intraradicular dentin is by Mpo.
Soares
Carlos J
CJ
Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil. carlosjsoares@umuarama.ufu.br
Santana
Fernanda R
FR
Castro
Carolina G
CG
Santos-Filho
Paulo C F
PC
Soares
Paulo V
PV
Qian
Fang
F
Armstrong
Steven R
SR
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004548:Elasticity; D020342:Finite Element Analysis; D005898:Glass / Q000737:chemistry*; D006801:Humans; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013718:Tensile Strength; D019553:Tooth, Nonvital / Q000473:pathology
D003764:Dental Materials; D017220:Dentin-Bonding Agents; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C009753:fiberglass; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate