A-P Spread
Also written as: A-P — Anteroposterior
The anterior-to-posterior distance between the most anterior and the most distal implant in a full-arch reconstruction, used to calculate the maximum cantilever length of the prosthesis.
Full Definition
Anteroposterior (A-P) spread is the linear distance, measured in the sagittal plane, from the centre of the most anterior implant to a line connecting the distal aspects of the two most posterior implants in a full-arch or multi-unit implant case. It is a key biomechanical parameter: a larger A-P spread permits a longer cantilever extension without risk of prosthetic fracture or implant overload. The recommended maximum cantilever is generally 1 to 1.5 times the A-P spread. Editors should ensure A-P is hyphenated, capitalised appropriately, and that the accompanying cantilever calculation, when cited, is expressed in millimetres.
Usage
Usage note: Hyphenate as 'A-P spread'. Distinguish from 'inter-implant distance', which is measured between adjacent implants, not across the full arch.
In Context
- "By tilting the posterior implants, the surgeon increased the A-P spread from 18 mm to 26 mm, allowing a 20 mm cantilever." — Treatment planning notes
- "The A-P spread is a critical determinant of permissible cantilever length and must be documented in the prosthetic planning record." — Prosthodontics textbook chapter