COMPARISON BETWEEN HALOGEN LIGHT AND LED CURING UNITS: THE DEGREE OF CONVERSION OF ONE NANOFILLED RESIN COMPOSITE

Resumo

This study evaluated the effectiveness of LED curing units (Radii, Ledition, and Optilight LD Max) and one halogen-based curing unit (Optilux 501) regarding the immediate degree of conversion (DC) of one nanofilled resin composite (RC - FiltekTM Z350- A2) using Fourier Transformed Infrared analysis (FTIR). A 2-mm thick resin composite layer was applied to the horizontal diamond ATR element in the optical bench of a FTIR spectrometer. FTIR spectrum was collected from specimen in the uncured state. The specimens were exposed to curing light for 20 s according to the manufacturer’s instructions and another FTIR spectrum was collected from the cured resin composite layer immediately after light-exposure. DC values were calculated by standard methods using changes in the ratios of aliphatic-to-aromatic C=C absorption peaks in the uncured and cured states obtained from the infrared spectra. The DC data were submitted to 1-way ANOVA followed by post-hoc Tukey’s test at a pre-set alpha of 5%. Specimens light-activated by Ledition and Radii showed the highest immediate DC values, while Optilight LD Max promoted the lowest DC values among all groups. Specimens light-activated by Optilux 501 showed lower DC values than those specimens light-activated by Ledition and Radii and higher DC values than those light-activated by Optilight LD Max. The monomer conversion of the nanofilled RC is rather product-dependent than related to the type of curing unit.