Post-Retained Crown — ORE Part 1 MCQ
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Correct answer: E — 4–5 mm
Explanation lettering: D = shown as A · E = shown as D · A = shown as E
The recommended minimum gutta-percha apical seal after post space preparation is 3–5 mm, with 4–5 mm (option A) representing best practice. Evidence consistently shows that the best apical seal is achieved with the maximum safe length of remaining gutta-percha; 3 mm (option C) is the bare minimum but carries increased periapical radiolucency risk. Options B (1–2 mm) provide inadequate seal, option D (7–8 mm) leaves insufficient post space, and option E removes all apical seal, violating endodontic principles. The 4–5 mm range optimally balances post retention, coronal access, and apical seal preservation in anterior teeth.
Reference: Post preparation techniques and their effect on the apical seal (PubMed PMID: 2090807, 1990); Evaluation of Students' Proficiency in Removing Gutta-Percha Prior to Fiber Post Placement (PMC 11056200, 2024). https://pubmed.ncbi.nlm.nih.gov/2090807/