Effect of composite type, light intensity, configuration factor and laser polymerization on polymerization...

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Polymerization contraction force is a critical factor in dental restorations, potentially leading to marginal gaps and secondary caries.
• Understanding the variables influencing this force is essential for optimizing composite resin performance and longevity.

Purpose of the Study:

• To investigate the impact of composite type, light intensity, configuration factor (C-factor), and polymerization method (conventional light vs. laser) on polymerization contraction force.
• To quantify the relationship between these parameters and the resulting forces generated during composite curing.

Main Methods:

• Dental composites (chemical-cure, microfill, hybrid) were subjected to polymerization using a conventional visible light unit and two types of lasers.
• Contraction forces were measured using a universal testing machine with varying light intensities and configuration factors.
• Statistical analysis (One Way ANOVA, Duncan's Multiple Range Test) was performed to determine significant differences.

Main Results:

• Hybrid composites generated significantly higher contraction forces than microfill and chemical-cure composites.
• Increased light intensity led to a higher maximum polymerization contraction force.
• Higher configuration factors (C=1) resulted in greater forces compared to lower factors (C=5).
• Laser polymerization yielded statistically lower contraction forces than conventional visible light curing.

Conclusions:

• Composite type, light intensity, and configuration factor significantly influence polymerization contraction force.
• Hybrid composites and higher light intensities should be used cautiously due to increased contraction forces.
• Laser polymerization may offer an advantage in reducing polymerization stress compared to conventional methods.