An Evaluation of the Output from Budget Curing Lights

Objectives: Measure the power, irradiance, emission spectrum, and beam profiles from eight budget light-curing units(LCU) and one from 3M for 500 exposures each lasting 20s.
Methods: Radiant power was measured using a spectroradiometer attached to an integrating sphere(OceanOptics), see Table1. Every 10-20 exposures, (through 500 20s exposures,) measurements were recorded with 60⁺s rest between exposures. After 100 exposures, the LCUs were recharged. Irradiance distributions of the light beams were measured across the emitting surface of the lightguide using a laser beam profiler(Ophir^®Spiricon). Total radiant power output values were entered into Beamgage software, producing two and three-dimensional color-coded profile images of the irradiance distribution across the beam, Figure1. Mean radiant power, standard deviation and coefficient of variation were calculated to compare outputs.
Results: Several of the lights did not have serial numbers or shared the same number. Lights K and J were the same model. However, K was polywave and J was a single-peak blue LED. Emission spectra for all LCUs was within the manufacturers' range. The radiant power from lights B-G decreased as the number of exposures increased (greatest loss Lights H -146.6mW and I -138.0mW) while Lights A, L-Q were nearly unchanged. Lights K, H, and B showed the greatest variation in power output over 500 exposures(Coef. Var 0.346, 0.100, and 0.0694, respectively). The beam profiles from lights A and K were closest to an ideal shape. Lights B, C, F and G delivered narrow Gaussian shaped irradiance peaks of light. Light J although broad, was skewed.
Conclusions: None of the budget lights performed well in all categories. For most budget LCUs, the power output decreased with use. Lights A and Q delivered the most consistent power outputs (Coef. Var 0.010 and 0.014, respectively). A and K displayed a relatively flat beam profile, where the irradiance was evenly distributed across the light tip.