Which action will most likely cause collapse of collagen fibrils during dentin bonding?

Correct answer: A. Excess drying of the dentin

• A. Correct. After acid etching removes smear layer and demineralizes dentin, the exposed collagen network is supported by water. Excess drying collapses the hydrophilic collagen fibrils, preventing resin tag penetration and drastically reducing bond strength.
• B. Incorrect. Excess preparation removes tooth structure but does not specifically collapse collagen fibrils.
• C. Incorrect. Excess etching can over-demineralize, but fibril collapse is specifically caused by drying.
• D. Incorrect. Excess bonding agent may cause bubbles or incomplete polymerization, not collagen collapse.