A patient reports sensitivity following a deep composite restoration. Which technique error is the most likely cause?

Correct answer: A. Over-drying (desiccating) the etched dentin before applying the adhesive

• A. CORRECT. After phosphoric acid etching, dentin is left with an exposed collagen scaffold suspended in water. Air-drying it collapses that scaffold, the adhesive resin cannot infiltrate it, and the result is an incomplete hybrid layer with open tubules beneath. Fluid movement through those tubules produces the classic hydrodynamic postoperative sensitivity.
• B. Over-curing is not a recognized cause of sensitivity; inadequate curing is a far more likely problem.
• C. Too little adhesive causes marginal breakdown over time rather than immediate postoperative sensitivity.
• D. Under-etched enamel gives a weaker bond and marginal staining, but is not the principal driver of dentinal sensitivity.

Note: Wet bonding: after rinsing the etchant, blot with a cotton pellet or use gentle air from a distance to leave the dentin visibly moist and glistening, never chalky-white and dry. Self-etch adhesives largely sidestep this problem because they do not create a demineralized zone deeper than they infiltrate.