Assessment of light intensity of curing lights on different shades of composite

Objectives: There may be a link between greater loss of light intensity during the polymerisation of composite and its relation to shade being darker Aim: The aim of this study is to test the hypothesis that light intensity is lost for darker shades of a certain composite material as well as comparing intensity between a light emitting diode (LED) light curing unit and halogen curing unit. The objectives of this study are: 1. to determine whether there is loss in light intensity at the bottom of the restoration when using different shades of composites. 2: to determine whether the two lights namely LED and Halogen curing units has an effect on the curing intensity at the bottom of the restoration.
Methods: Initial light intensity readings for both LED and halogen curing lights were recorded using a radiometer (Curerite) to determine the light intensity at the top of the restoration. A matrix strip was placed over the radiometer and 2mm composite of various shades (A1, A2, A3, A3.5 and A4 (Ceram.X^® Universal) was placed into a Teflon ring and cured. The light intensity reading was recorded and compared to the light intensity of the initial readings.
Results: There was a marked reduction in the readings for both light curing units when the readings were compared. This reduction in light intensity was noted for all shades of composites and this was more so with the darker shades of composites. Overall, there was a light intensity reduction to 110Mw/cm² for LED and to 57Mw/cm² for halogen curing light when the means between the light intensity at the top and bottom of the restoration was measured.
Conclusions: It is imperative that manufacturer guidelines of 2mm as the maximum depth of cure be adhered to for maximum cure as there is definite loss of light energy through the material and more so through darker shades.