What is the effect of composite light cure with high intensity for 1 second?

From the Guidelines

Composite light cure with high intensity for 1 second is not recommended due to potential inadequate polymerization and reduced restoration longevity. The provided evidence does not directly address the effect of composite light cure with high intensity for 1 second, but it discusses the importance of proper light curing in dental restorations 1. Most composite materials require 10-20 seconds of light curing at high intensity (1000-1500 mW/cm²) to achieve adequate polymerization. While some manufacturers market "1-second cure" lights with extremely high intensities (3000+ mW/cm²), these typically don't allow sufficient time for optimal cross-linking of polymer chains, potentially resulting in inferior mechanical properties, increased shrinkage stress, and reduced restoration longevity.

• Key factors to consider in light curing include:
  • Intensity: 1000-1500 mW/cm²
  • Curing time: 10-20 seconds per 2mm increment
  • Type of composite material: bulk-fill composites can be placed in 4-5mm increments with 10-20 second cure times
• Inadequate curing can lead to increased wear, discoloration, secondary caries, and restoration failure, which can negatively impact patient outcomes, including morbidity, mortality, and quality of life 1.
• It is essential to follow manufacturer's recommended curing times and use a high-quality LED curing light to ensure proper polymerization and optimal restoration longevity.

From the Research

Effect of Composite Light Cure with High Intensity for 1 Second

• The effect of composite light cure with high intensity for 1 second is not directly addressed in the provided studies, as they investigate different curing times and intensities.
• However, a study by 2 found that 3200 mW/cm(2) ×3 s light irradiation did not initiate light curing of the specimens, suggesting that a longer curing time may be necessary for effective polymerization.
• Another study by 3 found that shortness light-curing may result in similar properties for new bulk-fill RBCs, but it does not specifically investigate a curing time of 1 second.
• A study by 4 recommends routine exposure times of 60 seconds using light-source intensities of at least 400 mW/cm2, and suggests that incremental layer thickness should not exceed 2 mm.
• It is worth noting that the effectiveness of cure and shrinkage can be material-dependent, as shown in a study by 5, which found that the effect of the curing method on the effectiveness of cure and shrinkage was material-dependent.

Material-Dependent Effects

• The study by 5 found that polymerization of IT and TC with Spectrum for 40 seconds resulted in significantly more effective cure than polymerization with Astralis for 10 seconds.
• The same study found that polymerization of ZO with Spectrum for 40 seconds resulted in significantly more shrinkage than polymerization with Astralis for 10 seconds.
• The study by 6 found that the effectiveness of cure at the bottom surfaces of composites may be increased by soft-start and turbo polymerization regimens.

Curing Time and Intensity

• The study by 2 found that 3200 mW/cm(2) light intensity should be used for irradiation at least for 6 s, which could initiate light curing of flowable composite core to sufficient polymerization.
• The study by 4 found that sources with intensity values less than 233 mW/cm2 should not be used because of their poor cure characteristics.
• The study by 3 suggests that new bulk-fill RBCs can be light-cured with a short exposure time and high intensity, providing a time-saving benefit in clinical practice.