What is the recommended taper per wall (axial wall convergence angle) for a full-coverage crown preparation to achieve optimal retention and resistance form?

The recommended taper (convergence angle) per wall for crown preparation is 2-5 degrees (sometimes expressed as 6 degrees per wall in some textbooks), with a total occlusal convergence (TOC) of approximately 10-22 degrees. A smaller taper (closer to 0 degrees) maximizes retention and resistance but risks creating undercuts. The 2-5 degree per-wall taper provides adequate draft for crown seating while maintaining frictional retention. Clinically, preparations often have greater taper (10-15 degrees per wall) due to operator technique, but this reduces retention. A taper greater than 25 degrees total significantly reduces retention. Short preparations with inadequate taper require additional features (grooves, boxes) for resistance form.