The tungsten halogen curing light, also known as simply "halogen curing light" is the most frequent polymerization source used in dental offices. In order for the light to be produced, an electric current flows through a thin tungsten filament, which functions as a resistor. This resistor is then “heated to temperatures of about 3,000 Kelvin, it becomes incandescent and emits infrared and electromagnetic radiation in the form of visible light”. It provides a blue light between 400 and 500 nm, with an intensity of 400–600 mW cm−2. This type of curing light however has certain drawbacks, the first of which is the large amounts of heat that the filament generates. This requires that the curing light have a ventilating fan installed which results in a larger curing light. The fan generates a sound that may disturb some patients, and the wattage of the bulb is such (e.g. 80 W) these curing lights must be plugged into a power source; that is, they are not cordless. Furthermore, this light requires frequent monitoring and replacement of the actual curing light bulb because of the high temperatures that are reached. (For example, one model uses a bulb with an estimated life of 50 hours which would require annual replacement, assuming 12 minutes' use per day, 250 days per year.) Also, the time needed to fully cure the material is much more than the LED curing light.
