RESUMO
PURPOSE: To compare the thermal conductivity of two different composite materials, with five light-cure units, in a series of different material thicknesses and light source distances. METHODS: Two commonly used resin composite restorative materials and three light emitting diodes (LED), one halogen, and one plasma arc lights were selected. The thermal conductivity of the composite materials with different light curing units (LCU) was measured and compared. A K-type thermocouple and digital thermometer were used to assess the thermal conductivity. Materials depths of 1 mm, 2 mm and 4 mm and curing distances of 0 mm, 3 mm and 6 mm were compared. Four-way ANOVA was used to analyze the Ln transformation of the maximal temperature and a Tukey test for multiple comparisons. RESULTS: Significant differences in temperature rise were observed between the two restorative materials. The thermal emission of the LED lights was higher than the other LCU's measured. An inverse ratio was found between material thickness and the measured thermal conductivity and the distance of the light tip from the restorative material.