A comparative evaluation of polymerization stress data obtained with four different mechanical testing systems

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• 作者：Flá ; via Gonç ; alves^a ; ^{flaviapec@ig.com.br} ; ^{fgoncalves@usp.br} ; Leticia C. Boaro^a ; Jack L. Ferracane^b ; Roberto R. Braga^a
• 关键词：Resin composites ; Polymerization stress ; Volumetric shrinkage ; Elastic modulus
• 刊名：Dental Materials
• 出版年：2012
• 期刊代码：29_01095641
• 类别：ms
• 出版时间：June, 2012
• 卷：28
• 期：6
• 页码：680-686
• 文件大小：414 K

摘要

Objectives

The null hypothesis was that mechanical testing systems used to determine polymerization stress (蟽_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, 鈥渓ow compliance device鈥? and single cantilever device (鈥淏ioman鈥?. 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. 蟽_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, 蟽_pol decreased with filler content in all systems, following the variation in VS. For commercial materials, 蟽_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 蟽_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.