The thermal and mechanical properties of poly( methyl methacrylate) prepared at different curing times were studied using DSC, TGA, tensile, and three-point bending test methods. The molecular weights of the polymer samples were determined from the viscosity measurements. The curing time applied for two different commercial materials, manufactured for dental use, ranged from 15 to 180 min. The samples cured for 15 and 20 min were soluble in chloroform completely, but the others were partially soluble. The insoluble fraction increased with curing time but the molecular weight of the soluble fraction remained constant. DSC thermograms showed further curing of the samples cured for 15 and 20 min. After curing for 180 min and/or annealing at room temperature for about 13 months, the samples were completely crosslinked. The characteristic values obtained from the tensile and the three-point bending tests were similar for samples cured at different times. (C) 1998 John Wiley & Sons, Inc.