Abstract
Aims: To determine the correlation between intensity (I) of light–emitting diode (LED) and tungsten–halogen light sources, and depth of cure of a resin composite at different distances. Materials and Methods: LED curing light (Ultra Lite 200E plus) and tungsten halogen light (Astralis 5 Vivadent) were evaluated. Intensity was measured at distances of 0, 2, 4, 6, 8, and 10mm between the light tip and detector. A blackened aluminum plate, 0.5mm thick, with a 4mm–diameter aperture was placed over the detector. The use of this aperture limited the amount of light reaching the detector to a uniform area for both curing lights and also corres-ponded to the area of the mould for the depth of cure studies. Both light tips were centered on this aperture to reduce any influence of varying I across the light tip. Depth of cure (DOC) of light–curing universal micro hybrid composite shade A2 was also measured. A metallic mould was used to measure the depth of cure at distances of 0, 2, 4, 6, 8, and 10mm between light tip and mould. The degree of divergence of the light of both light curing units was also determined by tracing the illuminated area at a 10mm distance for each of the curing lights. Results: For both lights, intensity decreased as distance increased. While, both I and DOC decrease with increasing distance, the relationship between these factors and distance may not be similar for both lights and may depend on the characteristics of individual lights. Conclu-sions: Both I and DOC decreased with increasing distances. DOC usually decreases with de-creasing I, the rate of decline varies between various light brands.
