Which retention feature should NOT be used when restoring an endodontically treated tooth?

Correct answer: B. Dentine pins

• A. Bonded composite in the access cavity is the standard conservative restoration where enough tooth structure remains.
• B. CORRECT. DENTINE PINS are contraindicated in the endodontically treated tooth. The remaining dentine is already reduced by access and instrumentation, and pin placement introduces stress concentrations and microcracks in that weakened structure — a well-documented cause of vertical root fracture. Pin channels also risk perforating into the periodontal ligament.
• C. A Nayyar (coronal-radicular) amalgam core uses the pulp chamber and the coronal 2 to 4 mm of the canals for retention. It is a well-established technique in molars with a substantial chamber.
• D. A post and core is appropriate where insufficient coronal structure remains to retain a core. The post retains the core; it does not reinforce the root.

Note: The principle behind all of this: a post does NOT strengthen a root — it weakens it, because the space must be prepared by removing dentine. What actually protects the endodontically treated tooth is a FERRULE of 1.5 to 2 mm of sound circumferential dentine above the margin, plus cuspal coverage on posterior teeth. Conserve tooth structure; do not add retention features that consume it.