Which type of curing light produces the narrowest spectrum of light without filtration?

The choice of Light Emitting Diode (LED) as the correct answer is based on its ability to emit a narrow spectrum of light without the need for filtration. LEDs specifically designed for dental curing applications produce light predominantly in the blue region of the spectrum, which aligns well with the photoinitiators commonly used in dental resins. This specificity allows for efficient curing with minimal waste of energy, as the light is directed primarily at the wavelengths that activate the materials.

In comparison, Quartz-Tungsten Halogen (QTH) lights produce a broader spectrum, which includes wavelengths outside the ideal curing range, requiring filtration to narrow it down. Plasma Arc Curing (PAC) lights can also emit a wide range of wavelengths, although they operate at a higher intensity. Low-Level Light Therapy (LLLT) utilizes low-intensity light, primarily in the red spectrum, which is not typically used for curing dental materials.

The focused light output of LEDs contributes to their growing popularity in dental practices, particularly because they reduce the potential for damage to surrounding tissues while improving curing times and efficiency.