Curing lights, which are frequently used in all dental offices, harden direct restorative materials such as composite resins, cements and other adhesives used to fill cavities or root canals. Restorative materials contain photoinitiators that react to the particular wavelength emitted by the curing light, hardening to become a fixture in the patient’s mouth. Since the release of LED lights in 2001, the technology quickly emerged as the most popular form of curing light used by dental offices, replacing a significant portion of the market for halogen and plasma arc lights, the latter of which is far less common in Europe than the United States. LED lights emit a more concentrated beam of light and therefore, are the most efficient curing light. The dental LED curing lights use LEDs that produce a narrow spectrum of blue light in the 400 to 500 nm range. Most of today’s composites use camphorquinone as the photoinitiator. This chemical, often referred to as CPQ, requires a specific wavelength of light to trigger it into starting polymerization of the composite resin. Because LEDs can be fine-tuned to produce just a specific wavelength or range of wavelengths, these curing devices now produce light where every photon that is produced can be used in the curing process. This translates to better and more efficient curing. Many non-LED curing devices, such as fast halogen lights, produce lots of photons that are wasted because they are outside the range used by CPQ. LED lights are lightweight, portable and effective. The heat generated from LED curing lights is negligible. The portability of it comes from the low consumption of power. The LED can now use rechargeable batteries, making it much more comfortable and easier to use.