Effects of monomer composition and original filler content on filler loading in the resulting centrifuged composites.

This study examined the effects of monomer composition, original filler content, and application of centrifugal force on the resulting filler loading of composites. Either Bis-MPEPP or UDMA was mixed with TEGDMA at a molar ratio of 1 : 1. Silane-treated silica (14-20 wt%) was added to each mixture. After the mixtures were centrifuged and light-polymerized, rate of increase was determined as the filler increment of 2.0-mm-high, disk-shaped sections of specimen when compared against the uncentrifuged filler content. Both the original filler loading and monomer composition influenced the filler content of the centrifuged composites. Fillers in Bis-MPEPP-based composites exhibited a higher rate of condensation after application of centrifugal force than did UDMA-based composites. The results were suggestive of underlying relationships among the composition, component stability, and post-polymerization properties of flowable composites.