Abstract: PURPOSE: To compare the abrasion resistance and flexure strength of three bulk-fill resin composites with an universal nano-hybrid composite resins. METHODS: The specimens were prepared with three kinds of bulk fill composites (SDR , sonicfill, Tetric N-Ceram Bulk Fill) and an universal nano-hybrid composite resins(Herculite Precis). 10 mm in diameter × 2mm in height specimens were prepared for abrasion resistance, while 2 mm in width × 2 mm in depth×25 mm in length specimens were prepared for flexure strength. The specimens were mounted in a bal1-on-disc wear testing machine and abraded with the media artificial saliva(50 N loads, 10000 cycles).Flexural test was performed with an Universal Testing Machine at a cross-head speed of 1mm/min. One-way variance analysis was used to determine the statistical differences of volume loss and flexural strength among groups with SPSS 13.0 software package(P<0.05). RESULTS: The volume loss was as follows: SDR (1.2433±0.11) mm³<sonicfill (0.6331±0.09) mm³<Tetric N-Ceram Bulk Fill（0.3558±0.05） mm³ <Herculite Precis（0.3097±0.04） mm³. The flexural strength was as follows: sonicfill (136.2184±16.70) MPa<Herculite Precis(124.1468±19.96) MPa<Tetric N-Ceram Bulk Fill (119.2082±20.32) MPa< SDR(103.6246±7.13) MPa. There was no significant difference between Tetric N-Ceram Bulk Fill and Herculite Precis either in volume loss or flexural strength(P>0.05). CONCLUSIONS: With regard to wear resistance and flexural strength, Tetric N-Ceram Bulk Fill is recommended as an alternative for posterior restorations.

Key words: Bulk-Fill Composite Resin, Wear resistance, Flexural strength