Radiographic findings show that the post in tooth #9 is displaced and the tooth is mobile; tooth #8 also has an existing post (limited additional information provided). What is the most appropriate treatment?

Correct answer: B. Redo the post and crown on both #8 and #9

• A. Observation of a mobile tooth with a displaced post allows infection and is not appropriate management.
• B. CORRECT — When the post in #9 is displaced and the tooth is mobile, the failing post-and-core restoration must be redone. Because #8 shares the anterior segment and also has a post, replacing only #9 while leaving a compromised #8 risks recurrent failure; both should be re-treated as one restorative plan.
• C. Extraction is premature if endodontic and restorative retreatment can save the teeth.
• D. Root canal treatment alone doesn't address the displaced post; crown lengthening is only indicated if ferrule is inadequate — not the primary treatment here.