Thirty patients with similar dental caries on both sides of the jaws were selected. After cavity preparation, each tooth was randomized to one of the following restoration methods. Teeth in the control group were restored using etch-and-rinse adhesive and universal microhybrid composite resin. Restoration in the control group was similar except that 2% chlorhexidine solution was applied on the etched dentin for 60 seconds. Chlorhexidine significantly decreased immediate postoperative sensitivity of posterior teeth by composite resin.