The effect of the elastic modulus of low-viscosity resins on the microleakage of Class V resin composite restorations under occlusal loading

This study aimed to evaluate the effectiveness of various intermediate layers on the microleakage of Class V restorations under an occlusal load. Wedge-shaped cavities were prepared on the buccal surface of 72 extracted premolars, which were then treated with an adhesive system (One Up Bond F Plus), divided into three groups, and restored with: 1) Estelite Sigma resin composite, 2) a resin composite with Low Flow flowable composite, or 3) a resin composite with High Flow flowable composite. The specimens were subjected to a nano-indentation test to evaluate the elastic modulus of successive layers at the resin-dentine interface and were subjected to a microleakage test under either unloaded or loaded conditions. The elastic moduli were significantly different among substrates (p