Preparation of an experimental dental composite with different Bis-GMA/UDMA proportions.

Three types of matrix with constant amount of TEGDMA (30 wt.%), and Bis-EMA (10 wt.%) and variable values of Bis-GMA (10, 5, or 0 wt.%) and UDMA (50, 55, or 60 wt.%) were prepared. Composites were filled with 45 wt.% of silanized silica. Both matrices and composites were tested for flexural strength (FS), diametral tensile strength (DTS), hardness (HV) and polymerization shrinkage stress. There were no significant differences for the DTS test. All materials meet the FS requirements for type 2 dental composites. A significant decrease in HV was observed for matrix non-containing Bis-GMA. The highest value of shrinkage stress had material without Bis-GMA and it amounted 16,6 ± 1.0 MPa (filled) or 13.6 ± 0.8 MPa (unfilled). It was also shown that increasing the amount of UDMA while simultaneously reducing Bis-GMA in the studied materials increases polymerization shrinkage stress, which could be unfavorable for dental materials. [ABSTRACT FROM AUTHOR]