Cuspal flexure is inseparable from the shrinkage stress, adhesion, and curing of a restorative system. Shrinkage stresses are generated by shrinkage and development of elastic modulus during polymerization, but they will arise only if the composite has been bonded to the tooth structure. The main concern regarding a bulk fill technique is whether the composite cures fully; enough in the deeper portions to create a material that has acceptable physical and biocompatible properties. The aim of this study was thus to evaluate cuspal flexure of teeth restored with four different bulk fill composite resin restorative materials subjected to occlusal loading. Material and methods: The study was done in-vitro, using 40 extracted maxillary first premolars. Mesio-occluso-distal cavities were prepared. The cuspal flexure was measured before (unaltered teeth) and after restoring the teeth using a load of 150 N. Four different Bulk fill composite resins were used- Smart dentin replacement (Dentsply, Konstanz, Germany), Filtek bulk fill (3M ESPE, USA), Surefil (Dentsply Caulk, USA), Tetric N Ceram (Ivoclar Vivadent, Liechtenstein). Results: Teeth restored with Tetric N Ceram (Ivoclar Vivadent, Liechtenstein) showed lesser amount of cuspal deflection, but there was no statistically significant difference among the four groups. Conclusion: Surefil (Dentsply Caulk. USA) was the least effective than the rest. But no significant difference was observed amongst these even after application of sufficient load.
