A comparison of polymerization by light-emitting diode and halogen-based light-curing units

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Light-emitting diode (LED) technology offers advantages for light polymerization of resin-based composites.
• However, the efficacy of LED light-curing units (LCUs) compared to traditional halogen-based LCUs requires thorough investigation.

Purpose of the Study:

• To evaluate the adequacy of cure of commercially available LED light-curing units (LCUs) for resin-based composites.
• To compare the performance of LED LCUs against halogen-based LCUs in polymerizing hybrid and microfilled composites.

Main Methods:

• Two halogen-based and two LED LCUs were used to polymerize hybrid and microfilled resin-based composite specimens.
• Knoop hardness testing was performed on the top and bottom surfaces of polymerized specimens.
• Bottom:top hardness ratios were calculated to determine the percentage of cure, with 120 total observations.

Main Results:

• Both composite type and curing light significantly affected the hardness measurements (P < .0001).
• Hybrid composites exhibited significantly higher hardness than microfilled composites.
• Halogen-based LCUs produced significantly harder composite surfaces compared to LED LCUs.

Conclusions:

• Current commercially available LED LCUs may not provide an adequate cure for resin-based composites when compared to halogen-based LCUs.
• Improvements in LED light output are necessary to match the polymerization efficacy of halogen-based LCUs.
• Inadequate polymerization can lead to restoration failures and adverse pulpal reactions.