Effects of whisker-to-silica ratio on the reinforcement of dental resin composites with silica-fused whiskers

Resin composites need to be strengthened to improve their performance in la rge stress-bearing restorations. This study aimed to reinforce composites w ith whiskers and to investigate the effects of the whisker:silica ratio. It was hypothesized that changing the whisker-silica ratio would affect the w hisker-matrix bonding and the filler's distribution, and hence alter the co mposite properties. Silica particles and whiskers were mixed at various whi sker:silica mass ratios, thermally fused, and combined with a dental resin at filler mass fractions of 0-65%. Whisker:silica ratio and filler level ha d significant effects on composite properties. At 60% filler level, the sil ica composite (whisker:silica = 0:1) had a flexural strength (mean = SD; n = 6) of 104 +/- 21 MPa; that at a whisker:silica ratio of 1:0 was 74 +/- 36 MPa. However that of the silica-fused whisker composite (whisker:silica = 5:1) was 210 +/- 14 MPa, compared with 109 +/- 23 MPa and 114 +/- 18 MPa of two prosthetic controls. Mixing silica with whiskers minimized whisker ent anglement, improved filler distribution in the matrix, and facilitated whis ker silanization and bonding to the matrix, thus resulting in substantially stronger composites.