Ring-opening monomers with a reduced shrinkage stress “silorane" are being used as matrix resins for recently introduced dental composites. Thisstudy aimed to analyzethe mechanical behavior(Flexural StrengthFS, Abrasion Resistance AR) of the silorane-based composite (Filtek P90) in comparison to two methacrylate-based composites (Tetric- Evo Ceram & packable hybridTetric Ceram HB).