highly significantp < 0.0000001
Introduction of ACP filler into resins resulted in modest, though highly significant (two-sample independent t -test), reduction of DVC in all systems: 9.7% in the Bis-GMA group ( p < 0.0000001), 7.1% in the EBPADMA group ( p < 0.000003), and 5.4% in the UDMA group ( p < 0.00007).