A periapical radiograph shows radiolucency BELOW the composite restoration in the crown, extending to the root canal orifice area. What is the MOST likely explanation?

Correct answer: C. Inadequate sealing of the root canal orifice

• A. Inadequate core compression could create voids within the composite body but would appear as radiolucencies WITHIN the restoration, not between it and the root.
• B. Excessive bonding material would appear as a radiopaque layer (resin cements are variably radiopaque), not a radiolucency.
• C. Correct. Radiolucency beneath a post-endodontic composite restoration at the level of the root canal orifice most likely indicates inadequate sealing of the canal orifice (coronal leakage). This allows bacteria to re-contaminate the root canal system, causing periapical pathology.
• D. Internal root resorption would appear as a radiolucent expansion within the root canal walls, not beneath the crown restoration.