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Published on: July 21, 2014
Shrinkage evaluation of composite polymerized with LED units using laser interferometry.
Alena Knezevic1, Kristina Sariri, Ivica Sovic
1Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Zagreb, Croatia. ma505ak@yahoo.com
Quintessence International (Berlin, Germany : 1985)
|April 9, 2010
Summary
Lower initial light intensity in LED curing units reduces composite resin polymerization shrinkage. Using a soft-start mode minimizes negative consequences like temperature rise, improving material performance.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Composite resin materials undergo polymerization shrinkage, a process that can lead to adverse clinical outcomes.
- The degree of shrinkage varies depending on the specific composite material and the light-curing parameters employed.
Purpose of the Study:
- To evaluate and compare the linear polymerization shrinkage of five different composite resins.
- To assess the impact of two LED curing units and their distinct polymerization modes on shrinkage percentages.
Main Methods:
- Five composite resins (two fine-particle hybrid, one nanohybrid) were polymerized using two LED curing units (Bluephase C5 and Bluephase C8) with specified modes (high-power, soft-start).
- Linear polymerization shrinkage was measured in real-time using laser interferometry for each second of the polymerization cycle.
- Statistical analysis was performed using ANOVA and Tukey's post hoc test to determine significant differences.
Main Results:
- The high-power mode of the Bluephase C8 unit resulted in the highest shrinkage values (up to 0.69%).
- The soft-start mode of the Bluephase C8 LED and the Bluephase C5 unit yielded the lowest shrinkage (as low as 0.35%).
- Artemis A2 exhibited the greatest overall dimensional change across all tested light-curing sources.
Conclusions:
- Employing polymerization programs with lower initial light intensity, such as the soft-start mode, can effectively mitigate polymerization shrinkage.
- Prolonging the pregel phase through controlled light intensity helps diminish negative consequences associated with polymerization shrinkage and temperature increase.
