Beam Profiles of Four Curing Lights Through Resin Composite

Objectives: It is assumed that the light beam from dental curing lights (LCU) disperses evenly when passing through resin composite. This study examined the effect of LCU optics and beam profile on the dispersion of light through resin composite.

Methods: Standard beam profiles from four different LCUs: (a) single peak LED, (b) PAC, and (c and d) two polywave LEDs were measured at zero millimeter distance using a Spiricon Beam Profiler (Logan, UT). The polywave LCU beam profiles were measured through band pass filters to distinguish the beam profiles produced from the different LED chips. Four resin composite screens were made 1 and 2 mm thick using an A2B shade of Filtek Supreme Ultra Flow (3M-ESPE, St. Paul, MN) and an opaque white shade of Variolink resin (Ivoclar-Vivadent, Amhurst, NY). The beam profiles from the LCUs at zero millimeter distance were compared to the beam profiles through these four different screens. Curing light optics were evaluated as a function of distance using a MARC-RC (BlueLight, Halifax, NS) and the beam profiles were evaluated both visually and using their Top Hat Factors (THF).

Results: Both LCU optics and beam profile had an effect on the dispersion of light through the cured resin composite screens. The composite screens did not evenly disperse the light. A light with poor optics  and poor beam uniformity (a) produced the most non-uniform beam profile through the resin composite screens. A combination of good optics and uniform beam profile (b) produced the most uniform beam profiles through the resin composite screens.

Conclusions: The beam profile reaching the top surface of the resin is important because the light is not evenly dispersed as it passes through the resin. Curing lights should have good optics and uniform beam profiles.