Postoperative tooth sensitivity following composite resin restoration is most commonly caused by:

Post-operative sensitivity after composite restoration is most commonly caused by over-drying (desiccation) of the dentin surface with compressed air before applying the adhesive. This collapses the collagen network in the etched dentin, preventing proper resin infiltration, and causes outward fluid movement in the dentinal tubules through osmotic effects, triggering pain. The dentin should be kept moist ('moist bonding') before applying primer. Other causes include polymerization shrinkage stress and incomplete sealing of the adhesive layer. Occlusal contacts can also cause sensitivity if the restoration is high.