Methods: Three types of unfilled resin matrices (TEGDMA-, UDMA- and BisGMA-based) were formulated and light cured. In addition, six different experimental dental composite resins with constant filler loading but varying in the type of monomer and the content of BisGMA were fabricated. Discs of each test material with 15.5 mm diameter and 1.0 mm thickness were prepared (N=3) and light cured. Total and diffuse transmittance values for each sample were measured using a UV/VIS spectrophotometer with the range of readings from 380 nm to 700 nm. Difference in colour was measured using the CIE Lab system.
Results: Statistical analysis by one-way ANOVA followed by Tukey's test showed that there was no statistically significant difference in transmittance values between the three unfilled resins. However, with the addition of filler, BisGMA-containing composite resins showed significantly higher transmittance values than the UDMA- and TEGDMA-based composite resins. Regression analysis revealed that there was a linear correlation between the percentage of BisGMA in the resin matrix and the total and diffuse translucency.
Conclusion: The amount of BisGMA used in the resin matrix has a significant effect on the translucency of silica-filler containing dental composite resins.