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Measuring the residual stress in dental composites using a ring slitting method
Jeong Won Park1, Jack L Ferracane
1Department of Conservative Dentistry, School of Dentistry, Kyungpook National University, 101, Dongin-dong 2-ga, Joong-gu, 700-422 Daegu, South Korea. pjw@knu.ac.kr
Summary
The ring slitting method effectively measures residual stress in dental composites. Early slitting and delayed measurement yield the highest residual stress values, impacting composite performance.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Dental Materials
Background:
- Residual stress (RS) in dental composites can influence their mechanical properties and longevity.
- Accurate measurement of RS is crucial for understanding material behavior after polymerization.
Purpose of the Study:
- To employ the ring slitting method for quantifying residual stress in dental composites.
- To investigate the impact of slitting time and measurement interval on polymerization-induced residual stress.
Main Methods:
- Dental composite rings were fabricated and polymerized using a standard curing unit.
- Rings were slit at either 1 hour (Early-group) or 24 hours (Delayed-group) post-polymerization.
- Circumferential residual stress was calculated by measuring changes in inter-point distance using an image analyzer system.
Main Results:
- Residual stress varied among the tested composites (Z100, Herculite, Heliomolar), with Z100 generally exhibiting the highest values.
- The highest residual stress was observed in the Early-group (1-hour slitting) with measurements taken at 24 hours post-slitting.
- Degree of conversion was assessed using FTIR, showing no significant difference between early and delayed time points.
Conclusions:
- The ring slitting method provides a viable approach for measuring residual stress in dental composites.
- Both the timing of the ring slitting and the subsequent measurement interval significantly affect the calculated residual stress values.