Retention Form Definition — NDEB AFK MCQ
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Correct answer: D — Along the path of withdrawal (path of insertion)
Retention form comprises the features of a cavity preparation that prevent displacement of the restoration along the path of insertion/withdrawal. For amalgam, retention is mechanical (undercuts, dovetails, convergent walls, retention locks, slots, pins). For composite, retention is primarily through adhesive bonding (micromechanical and chemical adhesion). For cast restorations (crowns, inlays), retention depends on near-parallel walls (controlled taper), adequate preparation height, and cement adhesion. Resistance form (distinct concept) prevents displacement by oblique forces.
Reference: Heymann – Sturdevant's Art and Science of Operative Dentistry, 7th ed., 2019