Relative efficiency of radiation sources for photopolymerization

The aim of this study was to evaluate the characteristics of new-generation light-emitting diode (LED) units in comparison with the conventional tungsten-halogen, plasma arc, and first-generation LED units reported in our previous study. The irradiance of light from new-generation LED units, the temperature rise of the bovine enamel surface, and the depth of cure of composites exposed to each unit were investigated. The irradiances in the range 400–515 nm emitted from the new-generation LED units were greater than those from the first-generation LED units. The temperature increase was 15–25°C for new-generation LED units compared with a typical value of 5°C for the first-generation LED units at 10 s of irradiation. The relationship between the depth of cure and the logarithm of total exposure energy suggested that LED units can cure light-cured composite resins more efficiently than tungsten-halogen or plasma arc units.