Monomer conversion at different dental composite depths using six light-curing methods

This study used infrared spectroscopy to compare the degree of conversion (DC) of Z250 resin composite at different depths, using a variety of light-curing sources. Photo-activation was performed with: plasma arc (PAC) light, a blue light emitting diode (LED) and four different exposure scenarios using quartz-tungsten-halogen (QTH) light. Cured composite cylinders were transversally cut into 300 μm-thick slices corresponding to surface, 1-5 mm depths. Each disc was finely pulverized, incorporated into KBr pellets, and analyzed by FTIR. Results demonstrated that for the surface and depths of 1 and 2 mm, conversion values did not differ significantly between lights or exposure treatments. At 3 and 4 mm depths, the LED source showed significantly higher DC than did the PAC light. All QTH methods were not significantly different to either LED or PAC. At 5 mm, there was no significant difference in DC between methods, except that PAC was not able to cure the composite.