Recently, light emitting diode (LED) curing lights have been introduced. Objective: Spectral emission profiles of LEDs and a quartz-tungsten-halogen (QTH) curing light were measured and normalized with respect to absorption needs of the photoinitiator, camphorquinone (CQ). Methods: Irradiance of LED lights (CoolBlu, Apolloe, and Lux-O-Max) and a QTH unit (Optilux 501) was obtained using a laboratory-grade spectral radiometer between 350-500 nm. The visible absorption spectrum of CQ was determined, and a normalization routine was developed providing a scaling factor at every wavelength by dividing maximal CQ absorption by value at each wavelength. Irradiance values were multiplied at each wavelength by the scaling factor to yield "normalized power." Effectiveness=(power/normalized power)^* 100%. Statistics: n=5 trials per light, 1-WAY ANOVA, Tukey-Kramer post hoc. Significance: p < 0.05. Results: Within a column, similar letters connect statistically equivalent values:

Light unit	Peak l (nm)	Power (mW)	Normalized power (mW)	Effectiveness (%)
Apolloe	465.0 ± 0.0a	120.2 ± 1.5c	102.3 ± 1.4c	85.1 ± 0.1c
CoolBlu	464.8 ± 0.4a	69.7 ± 0.7b	85.4 ± 0.3b	85.4 ± 0.3c
Lux-O-Max	468.8 ± 1.1b	52.0 ± 0.4a	42.2 ± 0.5a	81.5 ± 0.3b
Optilux 501	478.0 ± 0.0c	408.6 ± 9.0d	277.4 ± 6.0d	67.9 ± 0.0a

Conclusion: LED lights had peak l values 10 nm lower than the QTH. All LED lights produced lower power than QTH, even after normalization. At least 80% power emitted by LED lights matches needs of CQ, while less than 70% of QTH power matches (effectiveness value).

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