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Polymerization shrinkage of visible-light-cured composites
1Department of Restorative Dentistry, National University of Singapore, 5 Lower Kent Ridge Rd, Singapore 119074 Republic of Singapore.
Operative Dentistry
|February 24, 2001
Summary
Polyacid-modified composite resins exhibit less long-term shrinkage than conventional composites. Hydration causes initial expansion after polymerization shrinkage in both dental materials.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Dental composite resins are widely used restorative materials.
- Understanding polymerization shrinkage and dimensional stability is crucial for clinical longevity.
- Polyacid-modified composites offer potential advantages over conventional resins.
Purpose of the Study:
- To investigate the long-term dimensional changes of conventional and polyacid-modified composite resins.
- To evaluate the impact of hydration on polymerization shrinkage and subsequent dimensional stability.
- To compare the shrinkage behavior of the two composite types over a one-month period.
Main Methods:
- Linear polymerization shrinkage was measured using a strain-monitoring device.
- Composites were tested in a free-state condition.
- Specimens were stored in water (37°C) or air (26°C) for one month.
Main Results:
- Both composite types exhibited dimensional shrinkage during polymerization, continuing post-curing.
- Maximum shrinkage occurred within one hour of storage in water for both materials.
- A slow water uptake and subsequent expansion were observed between one day and one month.
- Polyacid-modified composites demonstrated significantly less overall polymerization shrinkage after one month in water compared to conventional composites.
Conclusions:
- Polymerization shrinkage is an inherent characteristic of both conventional and polyacid-modified composite resins.
- Hydration plays a significant role in the long-term dimensional stability of these dental materials.
- Polyacid-modified composite resins show improved dimensional stability with reduced long-term polymerization shrinkage under hydration, suggesting potential for enhanced clinical performance.