The aim of the present work is the study of some physicochemical properties of two current commercial dental self-curing two component composites, i.e., of Concise (TM) (3M (TM), Dental Products, St. Paul, USA), and Alfacomp (VOCO GmbH, Germany). Based on their filler type Concise is characterized as conventional or macrofilled composite and Alfacomp as hybrid. The resin matrix of Concise is a copolymer of 2-bis[4-2-hydroxy-3-(methacryloxy)-propyl]phenyl propane (Bis-GMA)/triethyleneglycol dimethacrylate, while that of Alfacomp a homopolymer of Bis-GMA. The composites were prepared in accordance with the manufacturers' instructions by mixing equal amounts of the two components at room temperature. The degree of conversion of double bonds of resin matrix during curing was determined in thin film of composites using FTIR transmission spectroscopy. The degree of conversion of Concise and Aflacomp was found to be correspondingly (73.63 +/- 4.33)% and (47.75 +/- 1.80)% after a day-polymerization. Sorption, solubility, and volumetric change were determined after storage of composites in water or ethanol/water solution 75 vol % at 37 degrees C (a good food/oral simulating fluid) for 30 days. These properties for both composites were higher in ethanol/water solution than in water. Also these properties for Concise were lower than those for Alfacomp in both liquids. Thermal stability of composites was studied by thermogravimetric analysis which performed in air atmosphere from 50 to 800 degrees C. This analysis of composites showed the degradation of their resin matrix in three steps. The organic resin content of Concise was found to be 18.0% w/w and that of Alfacomp 20.1% w/w. Concise showed generally better properties than Alfacomp. This behavior must due to the differences in the chemical structure of the organic resin matrix and the type of inorganic filler. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012