Light-emitting diode (LED) polymerisation of dental composites: flexural properties and polymerisation potential

The clinical performance of light polymerised dental composites is greatly influenced by the quality of the light-curing unit (LCU) used. Commonly use d halogen LCUs have some specific drawbacks such as decreasing of the light output with time. This may result in low degree of monomer conversion of t he composites with negative clinical implications. Previous studies have sh own that blue-light-emitting diode (LED) LCUs have the potential to polymer ise dental composites without having the drawbacks of halogen LCUs. Despite the relatively low irradiance of current LED LCUs, their efficiency is clo se to that of conventional halogen LCUs with more than twice the irradiance . This phenomenon has not been explained fully yet. Hence, more tests of th e LED LCU's effectiveness and of the mechanical properties of oral biomater ials processed with LED LCUs need to be carried out. This study investigate s the flexural properties of three different composites with three differen t shades, which were polymerised with either a commercial halogen LCU or an LED LCU, respectively. In most cases no significant differences in flexura l strength and modulus between composites polymerised with a halogen LCU or an LED LCU, respectively, were found. A simple model for the curing effect iveness based on the convolution absorption spectrum of the camphorquinone photoinitiator present in composites and the emission spectra of the LCUs i s presented. (C) 2000 Elsevier Science Ltd. All rights reserved.