Mandibular Plane Angle
Also written as: MPA — Mandibular Plane Angle
A cephalometric measurement of the steepness of the lower jaw's inferior border relative to a cranial base reference plane, reflecting vertical facial growth pattern.
Full Definition
The mandibular plane angle is defined as the angle formed between the mandibular plane (typically constructed through Gonion and Menton, or Gonion and Gnathion) and a reference such as the Frankfort horizontal or the sella-nasion plane. A high mandibular plane angle indicates a steep, hyperdivergent facial pattern associated with anterior open bite tendencies, whereas a low angle reflects a hypodivergent or deep-bite facial type. Editors will encounter this measurement frequently in growth and treatment-outcome studies and must ensure that the reference planes used to construct the angle are clearly defined in methods sections. Variation in landmark definitions across studies can affect reported norms. The measurement is often abbreviated MPA or IMPA (when specifically describing incisor axial inclination) — these must not be conflated.
Usage
Usage note: Specify the reference plane used (e.g., Frankfort horizontal vs. SN plane) when the abbreviation MPA is introduced, as norms differ by reference.
In Context
- "The patient's high mandibular plane angle of 38° was a key factor in selecting vertical-control mechanics." — Orthodontic treatment plan
- "Subjects were classified as hyperdivergent (MPA > 35°), normodivergent (25–35°), or hypodivergent (MPA < 25°)." — Research classification criteria