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Shrinkage of Dental Composite in Simulated Cavity Measured with Digital Image Correlation
Published on: July 21, 2014
Impact of curing protocol on conversion and shrinkage stress
H Lu1, J W Stansbury, C N Bowman
1Department of Chemical & Biological Engineering, Engineering Center, University of Colorado at Boulder, 80309-0424, USA.
Journal of Dental Research
|August 20, 2005
Summary
Soft-start photocuring reduces shrinkage stress in dental composites by slightly decreasing final conversion. This method offers a way to lower stress without significantly compromising material properties.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Dental composite curing generates significant shrinkage stress, potentially leading to restoration failures.
- Soft-start photocuring protocols aim to mitigate this stress while maintaining adequate polymerization.
- The relationship between shrinkage stress, conversion, and curing methods requires further investigation.
Purpose of the Study:
- To evaluate the impact of soft-start and pulse photocuring protocols on shrinkage stress and polymerization conversion.
- To test the hypothesis that soft-start photocuring reduces stress and conversion.
- To elucidate the primary mechanism behind stress reduction in alternative curing protocols.
Main Methods:
- An experimental dental composite was subjected to three photocuring protocols: soft-start, pulse, and standard.
- A novel setup enabled simultaneous measurement of shrinkage stress, monomer conversion, and temperature.
- Data analysis focused on the correlation between stress development and conversion.
Main Results:
- Shrinkage stress increased significantly with conversion, particularly in the vitrified state.
- Both soft-start and pulse curing protocols resulted in lower final conversion and reduced shrinkage stress compared to standard curing.
- A modest decrease in final conversion was identified as the main factor for reduced shrinkage stress.
Conclusions:
- Soft-start and pulse photocuring protocols effectively reduce shrinkage stress in dental composites.
- The primary mechanism for this stress reduction is a slight decrease in the final degree of conversion.
- These findings support the use of alternative photocuring strategies to improve dental restoration longevity.
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