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Published on: July 21, 2014
Shrinkage stress of three composites under different polymerization methods
Cesar Henrique Zanchi1, Rodrigo Varella de Carvalho, Sinval Adalberto Rodrigues Junior
1Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas.
Brazilian Oral Research
|August 1, 2006
Summary
LED polymerization significantly reduced shrinkage stress in dental composites compared to conventional halogen methods. The presence of co-initiators further lowered stress, indicating a promising approach for minimizing polymerization-induced strain.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Polymerization shrinkage stress is a critical factor in dental restorations, potentially leading to marginal gaps and secondary caries.
- Different polymerization methods, including conventional halogen and light-emitting diode (LED) techniques, influence the development of this stress.
- Understanding the interplay between composite composition and curing protocols is essential for optimizing clinical performance.
Purpose of the Study:
- To evaluate and compare the shrinkage stress generated by three dental composites under distinct polymerization conditions.
- To investigate the effect of conventional halogen polymerization, soft-start halogen polymerization, and LED polymerization on shrinkage stress.
- To analyze the influence of composite formulation, specifically the presence of co-initiators, on stress development.
Main Methods:
- Three dental composites (Filtek Z-100, Filtek Z-250, Solitaire 2) were tested.
- Polymerization was performed using conventional halogen (G1), soft-start halogen (G2), and LED (G3) methods with specified light intensities and durations.
- Shrinkage stress was measured over time (10-120 seconds) using a universal testing machine with a custom mold setup.
Main Results:
- A consistent, significant linear increase in shrinkage stress was observed over time for most tested conditions.
- LED polymerization (G3) generally resulted in lower shrinkage stress compared to conventional halogen polymerization (G1).
- Composites with additional co-initiators exhibited reduced stress when polymerized with LED light (G3).
Conclusions:
- LED polymerization effectively reduces the initial shrinkage stress of dental composites compared to conventional halogen methods.
- The formulation of the composite, particularly the inclusion of co-initiators, plays a significant role in modulating polymerization stress when using LED light.
- The choice of polymerization method and composite material significantly impacts the resulting shrinkage stress patterns.
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