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Comparison of polymerization contraction stresses between self- and light-curing composites
Y Kinomoto1, M Torii, F Takeshige
1Department of Conservative Dentistry, Osaka University Faculty of Dentistry, Japan. kinomoto@dent.osaka-u.ac.jp
Journal of Dentistry
|June 23, 1999
Summary
Polymerization velocity, not stress distribution, significantly impacts internal stress magnitude in dental composites. Light-curing composites generate higher stresses than self-curing ones due to faster polymerization.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Dental composite restorations are susceptible to internal stresses from polymerization shrinkage.
- Understanding these stresses is crucial for predicting restoration longevity and preventing failures.
Purpose of the Study:
- To investigate and compare the distribution and magnitude of internal stresses in self-curing versus light-curing composite restorations.
- To identify factors influencing stress generation during polymerization shrinkage.
Main Methods:
- Butt-joint box-shaped cavities were filled with self- or light-curing resin composites.
- Restorations were cross-sectioned and analyzed using polarizing microscopy.
- Photoelastic analysis was employed to evaluate principal stresses and cavity wall stresses.
Main Results:
- Similar stress distributions were observed in both self- and light-curing composites.
- Light-curing composite restorations exhibited twice the maximum stress at the cavity wall compared to self-curing ones.
- Stress magnitude was found to be independent of stress distribution patterns.
Conclusions:
- The velocity of polymerization is the primary factor influencing the magnitude of internal stresses in dental composite restorations.
- Differences in stress magnitude between self- and light-curing composites are attributed to polymerization speed, not stress distribution.
- Faster polymerization rates lead to higher internal stresses.