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Polymerization contraction stress in light-cured compomer restorative materials
H Y Chen1, J Manhart, K-H Kunzelmann
1Department of Restorative Dentistry, Dental School of the Ludwig--Maximilians-University, Goethe Street 70, Munich 80336, Germany. hchen@dent.med.uni-muenchen.de
Summary
Compomers generally exhibit polymerization contraction stress similar to hybrid composites. Dyract showed significantly lower shrinkage stress, suggesting superior bond maintenance with tooth structure compared to other tested materials.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Polymerization contraction stress is a critical factor in the bond failure of adhesive dental restorations.
- Understanding the magnitude and kinetics of this stress is essential for developing durable dental materials.
Purpose of the Study:
- To determine the polymerization contraction stress and its kinetics for seven commercial compomers.
- To compare these properties with those of two hybrid composites.
Main Methods:
- Seven compomers and two hybrid composites were light-cured for 40 seconds (800 mW/cm²).
- Contraction force was measured for 300 seconds using a Stress-Strain-Analyzer at room temperature.
- Maximum contraction stress, gradient, and relative force rate were statistically analyzed using ANOVA and Tukey's test.
Main Results:
- Compoglass F and F2000 Rasant exhibited the highest contraction stress, while Dyract showed the lowest.
- No significant differences in maximum stress were found between Glasiosite, Hytac, and Tetric Ceram.
- No significant differences in maximum stress were found between Compoglass F and Prodigy.
Conclusions:
- Compomer contraction stress and kinetics are generally comparable to hybrid composites under dry conditions.
- High contraction stress and rapid force development can lead to bond failure with tooth structure.
- Dyract's low shrinkage stress indicates potential for superior bond maintenance with cavity walls.