In this article, three kinds of surface-modified methods were used to treat beta-Si3N4 whiskers before being incorporated into Bis-GMA/TEGDMA dental resin matrix in order to improve the whiskers' reinforcing effect. The experimental results showed that composites with directly heat-treated and then silanized beta-Si3N4 whiskers had the best reinforcing effect. They had flexural strength of 160 +/- 7.0 MPa (mean +/- SD; n = 6), compressive strength of 371 +/- 1.4 MPa (mean +/- SD; n = 5) and HRA of 48.4 +/- 0.5(mean +/- SD; n = 5), respectively. In addition, water sorption and solubility test demonstrated that the composites were reliable to use as the dental restoration materials. Therefore, the directly heat-treated and then silanized beta-Si3N4 whiskers (better than beta-Si3N4 whiskers mixed with SiO2 nanoparticles or SiO2 sols) were most suitable fillers to reinforce dental resin composites. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 41-46, 2013