A tooth has dark cervical caries and an existing intact MOD amalgam. If you replace it with a composite, the chief concern at the deep cervical margin is:

Correct answer: A. Inadequate isolation/moisture control

• A. Correct. A deep, subgingival/cervical margin is hard to keep dry; composite bonding fails without proper isolation, risking microleakage and recurrent caries.
• B. Composite radiopacity is adequate; it is not the cervical-margin concern.
• C. Wear resistance is unrelated to the cervical bonding problem.
• D. Galvanic corrosion involves dissimilar metals, not composite restoration.