Effect of Light-curing Device on Mechanical Properties of Composites

Objectives: The purpose of this in vitro study was to evaluate the effect and performance of different light-curing units QTHs (Quartz Tungsten Halogen) and LEDs (Light Emitting Diode), on the degree of conversion and some mechanical properties of composites. Methods: Four resin composites; Point-4, Revolution-II (Kerr), Z-250, Filtek-Flow (3M-ESPE) were investigated. Table-1 shows the different polymerization modes used to light-cure five barshape specimens (25«2«2 mm) from each composite. The investigated properties were the dynamic modulus of elasticity, the three-point flexural strength and Vickers microhardness. Degrees of conversion were measured using Raman technology. Data were subjected to one-way analysis of variance (ANOVA) followed by a post-hoc Scheffe's test. Results: Anova test showed that the mode of polymerization affected the mechanical behaviour and the degree of conversion of resin composites. Conclusion: The polymerization of composites using LEDs units, according to manufacturers recommendation may not be sufficient in some cases. Increasing the polymerization duration may improve the mechanical properties to a level at least similar to the specimens polymerized with QTHs