The minimum acceptable height for an abutment preparation is that which allows the tooth structure to interfere with the arch of rotation. This is critical because adequate height ensures proper retention and resistance form, preventing dislodgement of the prosthesis under functional forces. Height alone (e.g., 2 mm, 4 mm, or 6 mm) cannot be the sole criterion since the geometric relationship and engagement with the path of insertion determine stability. Ensuring the tooth structure crosses the arch of rotation creates a mechanical advantage by maximizing resistance to lateral forces and torsion, which is essential for long-term success.

Reference: Principles of Prosthodontics, Anil M. Lal, 3rd Edition.