A patient presents with a mobile post-core-crown restoration. What is the most appropriate FIRST step in management?

Before any treatment decision a periapical radiograph is needed to determine the cause of mobility (fractured root, failed post, lost ferrule, or periodontal/periapical bone loss), which dictates whether the tooth is restorable.Other options: Extraction, re-cementation, or implant referral are premature without knowing the cause; re-cementing over an undiagnosed root fracture would fail.Key exam takeaway: Diagnose before you treat: radiograph first to rule out root fracture and assess restorability.