Comparison of halogen, plasma and LED curing units

Area of Science:

• Dental materials science
• Photopolymerization technology

Background:

• Dental light-curing units are essential for polymerizing dental composites.
• Conventional tungsten-halogen units have limitations in efficiency and spectral output.
• Emerging technologies like plasma arc and LED curing units offer potential improvements.

Purpose of the Study:

• To evaluate and compare the performance of plasma arc and blue light emitting diode (LED) light-curing units against conventional tungsten-halogen units.
• To assess light intensity, spectral distribution, surface temperature rise, and depth of cure for each unit type.

Main Methods:

• Light intensity and depth of cure measured per ISO standards.
• Spectral distribution analyzed using a spectro-radiometer.
• Temperature increase monitored with a thermocouple on bovine enamel surfaces.

Main Results:

• Plasma arc units exhibited higher light intensities (400-515 nm) and some emitted UV-A light.
• Plasma arc and LED units required longer irradiation times (6-9s and 40-60s, respectively) for equivalent composite cure depth compared to halogen (20s).
• Temperature increases ranged from <10°C (LED) to 15-60°C (plasma arc), with halogen units around 15°C.

Conclusions:

• Plasma arc and LED light-curing units demonstrate distinct characteristics compared to tungsten-halogen units.
• Clinicians must consider the extended irradiation times needed for plasma arc and LED units.
• Potential risks associated with plasma arc units include significant thermal rise and UV-A emission.