Methods: To obtain the specimens, a circular matrix of stainless steel was used. Composite materials (Tetric Nceram, Filtek Silorane and Kalore GC) were put into the mold and pressed under 500 gr siker. The specimens were cured by either Bluephase LED for 20 s, or Coltolux halogen for 40 s. Degree of conversion was measured using FT-IR spectroscopy. Vickers microhardness of top and bottom surfaces was also evaluated. To compare the degree of conversion and microhardness between composites, Kruskall-Wallis test and pairwise comparison were used. Mann-Whitney U test was used for comparison of efficacy between the two light curing units.
Results: The degree of conversion or microhardness between bottom and top surfaces of all test groups were significant (P<0.05). The degree of conversion or microhardness for all the specimens polymerized by LED was significantly higher than that of halogen (P<0.05). Filtek Silorane exhibited a better degree of polymerization compared with that of other composites polymerized either by QTH or LED light (P<0.05).
Conclusions: Silorane-based composite showed a better degree of polymerization than that of other methacrylate-based composites. The degree of conversion and Vickers microhardness were affected by the type of resin composite material, light curing units, and curing depths.