The aim was to evaluate the clinical performance of HEMA-containing and HEMA-free all-in-one self-etch adhesives with and without a surface sealing process with a nanohybrid composite in occlusal caries restorations. The hypothesis is that the HEMA-containing and HEMA-free all-in-one self-etch adhesive and the surface sealing process would significantly effect clinical performance of occlusal restorations.