Polymerization and polymerization shrinkage stress: fast cure versus conventional cure

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Clinical Dentistry

Background:

• Dental light-curing units have evolved from conventional halogen lights to advanced LED technologies.
• Manufacturers offer diverse curing strategies, from slow initial cures to rapid-cure approaches.
• Conventional curing requires specific light intensity (≥400 mW/cm²) and duration (≥40s) for adequate composite polymerization.

Purpose of the Study:

• To review and compare the effects of fast-cure versus conventional light-curing approaches on dental composites.
• To analyze the impact on polymerization, polymerization shrinkage, and associated stresses.
• To discuss other contributing factors to polymerization shrinkage stress.

Main Methods:

• Literature review and comparative analysis of existing studies on dental composite curing techniques.
• Examination of polymerization kinetics and shrinkage data under different light-curing protocols.
• Discussion of clinical implications and influencing factors on polymerization shrinkage stress.

Main Results:

• Fast-cure protocols (e.g., 5-10 seconds at >2000 mW/cm²) are proposed but may overlook negative consequences.
• Conventional methods emphasize sufficient light intensity and exposure time for optimal cure.
• Alternative strategies involve initial slower cure followed by higher intensity to balance flow and degree of cure.

Conclusions:

• The potential adverse effects of rapid polymerization and shrinkage stress in fast-cure methods require careful consideration.
• Understanding the interplay between curing time, light intensity, and material properties is crucial for clinical success.
• Further research is needed to optimize light-curing protocols, balancing speed with material integrity and minimizing stress.