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Updated: May 23, 2026
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A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli
Published on: December 11, 2014
A comparative evaluation of polymerization stress data obtained with four different mechanical testing systems.
Flávia Gonçalves1, Leticia C Boaro, Jack L Ferracane
1Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, Brazil.
Summary
Mechanical testing systems ranked experimental composites similarly, but showed few similarities for commercial composites. Careful comparison of polymerization stress results from different devices is necessary.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Mechanical Engineering
Background:
- Polymerization stress (σ(pol)) is a critical factor in dental composite performance.
- Accurate measurement of σ(pol) is essential for material development and clinical success.
- Various mechanical testing systems exist, but their inter-system agreement for σ(pol) is not well-established.
Purpose of the Study:
- To evaluate the agreement between different mechanical testing systems in ranking polymerization stress.
- To determine if mechanical testing systems rank experimental and commercial composites similarly.
- To investigate the relationship between polymerization stress, volumetric shrinkage, and elastic modulus.
Main Methods:
- Two series of composites (experimental and commercial) were tested using four mechanical testing systems: universal testing machine (UTM) with glass rods, UTM with acrylic rods, a low compliance device, and a single cantilever device (Bioman).
- Polymerization stress (σ(pol)) was monitored for 10 minutes.
- Volumetric shrinkage (VS) and elastic modulus (E) were measured using a mercury dilatometer and three-point bending, respectively.
- Reaction kinetics were assessed using shrinkage rate, and data were analyzed using ANOVA/Tukey tests.
Main Results:
- For experimental composites, σ(pol) decreased with increasing filler content across all testing systems, correlating with volumetric shrinkage (VS).
- For commercial composites, σ(pol) rankings showed minimal agreement between the testing systems, with no variation observed in the UTM/acrylic system.
- No consistent relationships were found between σ(pol) and VS or elastic modulus (E) for commercial composites.
Conclusions:
- Mechanical testing systems demonstrate good agreement for ranking polymerization stress in experimental composites.
- Significant discrepancies exist in the ranking of polymerization stress for commercial composites across different testing systems.
- Direct comparison of polymerization stress data obtained from dissimilar testing devices requires careful consideration due to inter-system variability.
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