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Effectiveness of composite cure with pulse activation and soft-start polymerization
1Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Republic of Singapore.
Operative Dentistry
|February 2, 2002
Summary
Pulse activation and soft-start polymerization may reduce composite cure effectiveness at the bottom surfaces. Standard light curing showed superior results compared to some pulse and soft-start modes, particularly for bottom surface hardness and conversion. Further research is needed to optimize these techniques.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Effective polymerization of dental composites is crucial for restoration longevity and performance.
- Novel light-curing modes, including pulse activation and soft-start polymerization, are developed to improve cure depth and reduce stress.
- Understanding the impact of these advanced modes on composite cure effectiveness is essential for clinical application.
Purpose of the Study:
- To evaluate and compare the effectiveness of composite cure using different light-curing modes, specifically pulse activation and soft-start polymerization.
- To determine the influence of these modes on both the top and bottom surface hardness and the degree of conversion of dental composites.
- To identify optimal light-curing strategies for achieving adequate polymerization throughout the composite restoration.
Main Methods:
- Six distinct light-curing modes were tested: Control, Pulse Delay I, Pulse Delay II, Soft-start, Pulse Cure I, and Pulse Cure II, utilizing a specialized light-cure unit.
- Composite (Z100) specimens (2 mm thick) were subjected to these modes, and cure effectiveness was assessed via Knoop microhardness testing on top and bottom surfaces.
- Fourier Transform Infrared (FTIR) spectroscopy was employed to analyze the degree of conversion on the bottom surfaces, with data analyzed using ANOVA/Scheffe's test.
Main Results:
- No significant differences in top surface hardness were observed across most modes, except for Pulse Delay I and Pulse Delay II.
- The control group exhibited significantly greater bottom surface hardness compared to Pulse Delay II, Soft-start, and Pulse Cure II modes.
- FTIR analysis corroborated hardness findings, showing a significantly higher absorbance ratio (indicating greater conversion) for the control group versus Pulse Delay II and Pulse Cure II.
Conclusions:
- Certain pulse activation and soft-start polymerization regimens may compromise the cure effectiveness at the bottom surfaces of dental composites.
- Traditional continuous light curing (Control) demonstrated superior performance in achieving adequate polymerization at depth compared to some advanced modes.
- Clinical protocols employing specific pulse and soft-start settings require careful consideration to ensure complete composite material conversion and long-term restoration success.