Applies Treatment Liners, Acid Etch, and Bonding Materials
Protect, then bond
This domain covers materials placed before or during restoration: liners, etchants, and bonding agents. The exam tests purpose, sequence, and handling.
Liners and bases
A liner is a thin coating placed on dentin to protect the pulp and reduce sensitivity, commonly calcium hydroxide. A base is thicker and provides thermal insulation and mechanical support under a restoration. Know that liners are thin and placed only where needed, while bases fill undercuts. In the absence of pulpal involvement, liners are protective, not endodontic treatment.
Acid etch and bonding
Etching with phosphoric acid creates microporosity in enamel for micromechanical retention. Know the sequence: isolate, clean, etch, rinse thoroughly, dry appropriately (enamel often dried, dentin kept moist per the bonding system), apply bonding agent, thin it, and light cure. Contamination with saliva or blood after etching ruins the bond and requires re-etching.
Traps
Sequence questions dominate. A common distractor places bonding before etching or omits rinsing. Another trap is over-drying dentin with a system that requires moisture. Also watch for confusing a liner with a base, and for implying that liners are placed in every restoration.
Rule of thumb
Etch, rinse, control moisture, bond, cure. If contamination occurs after etching, the answer is to re-etch, not to proceed.