TY - JOUR
T1 - A comparative evaluation of polymerization stress data obtained with four different mechanical testing systems
AU - Gonçalves, Flávia
AU - Boaro, Leticia C.
AU - Ferracane, Jack L.
AU - Braga, Roberto R.
N1 - Funding Information:
The authors thank ESSTECH for kindly donating the monomers, and CAPES ( PDEE 3283-08-9 ) for funding this project.
PY - 2012/6
Y1 - 2012/6
N2 - Objectives: The null hypothesis was that mechanical testing systems used to determine polymerization stress (σ pol) would rank a series of composites similarly. Methods: Two series of composites were tested in the following systems: universal testing machine (UTM) using glass rods as bonding substrate, UTM/acrylic rods, "low compliance device", and single cantilever device ("Bioman"). One series had five experimental composites containing BisGMA:TEGDMA in equimolar concentrations and 60, 65, 70, 75 or 80 wt% of filler. The other series had five commercial composites: Filtek Z250 (3M ESPE), Filtek A110 (3M ESPE), Tetric Ceram (Ivoclar), Heliomolar (Ivoclar) and Point 4 (Kerr). Specimen geometry, dimensions and curing conditions were similar in all systems. σ pol was monitored for 10 min. Volumetric shrinkage (VS) was measured in a mercury dilatometer and elastic modulus (E) was determined by three-point bending. Shrinkage rate was used as a measure of reaction kinetics. ANOVA/Tukey test was performed for each variable, separately for each series. Results: For the experimental composites, σ pol decreased with filler content in all systems, following the variation in VS. For commercial materials, σ pol did not vary in the UTM/acrylic system and showed very few similarities in rankings in the others tests system. Also, no clear relationships were observed between σ pol and VS or E. Significance: The testing systems showed a good agreement for the experimental composites, but very few similarities for the commercial composites. Therefore, comparison of polymerization stress results from different devices must be done carefully.
AB - Objectives: The null hypothesis was that mechanical testing systems used to determine polymerization stress (σ pol) would rank a series of composites similarly. Methods: Two series of composites were tested in the following systems: universal testing machine (UTM) using glass rods as bonding substrate, UTM/acrylic rods, "low compliance device", and single cantilever device ("Bioman"). One series had five experimental composites containing BisGMA:TEGDMA in equimolar concentrations and 60, 65, 70, 75 or 80 wt% of filler. The other series had five commercial composites: Filtek Z250 (3M ESPE), Filtek A110 (3M ESPE), Tetric Ceram (Ivoclar), Heliomolar (Ivoclar) and Point 4 (Kerr). Specimen geometry, dimensions and curing conditions were similar in all systems. σ pol was monitored for 10 min. Volumetric shrinkage (VS) was measured in a mercury dilatometer and elastic modulus (E) was determined by three-point bending. Shrinkage rate was used as a measure of reaction kinetics. ANOVA/Tukey test was performed for each variable, separately for each series. Results: For the experimental composites, σ pol decreased with filler content in all systems, following the variation in VS. For commercial materials, σ pol did not vary in the UTM/acrylic system and showed very few similarities in rankings in the others tests system. Also, no clear relationships were observed between σ pol and VS or E. Significance: The testing systems showed a good agreement for the experimental composites, but very few similarities for the commercial composites. Therefore, comparison of polymerization stress results from different devices must be done carefully.
KW - Elastic modulus
KW - Polymerization stress
KW - Resin composites
KW - Volumetric shrinkage
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U2 - 10.1016/j.dental.2012.03.004
DO - 10.1016/j.dental.2012.03.004
M3 - Article
C2 - 22456007
AN - SCOPUS:84860749266
SN - 0109-5641
VL - 28
SP - 680
EP - 686
JO - Dental Materials
JF - Dental Materials
IS - 6
ER -