IMPA
Pronunciation: IM-pah
Also written as: IMPA — Incisor–Mandibular Plane Angle
Incisor–Mandibular Plane Angle; a cephalometric measurement expressing the inclination of the long axis of the lower incisor relative to the mandibular plane.
Full Definition
The Incisor–Mandibular Plane Angle (IMPA) quantifies the axial inclination of the mandibular central incisor relative to the mandibular plane (usually drawn from gonion to menton). A normative value is approximately 90–95°, and deviations indicate incisor proclination (higher values) or retroclination (lower values). IMPA is commonly used alongside FMIA (Frankfort Mandibular Incisor Angle) and the interincisal angle when planning incisor torque control and treatment goals. Editors should expand the acronym on first use and note that some older texts use the alternative abbreviation IMPAng.
Usage
Usage note: Expand at first use. Use an en dash between 'Incisor' and 'Mandibular' in the full form. Do not confuse with FMIA, which references the Frankfort plane rather than the mandibular plane.
In Context
- "An IMPA of 108° indicated significant proclination of the lower incisors, which required extraction to correct." — Orthodontic diagnosis and treatment plan
- "The authors measured IMPA on pre- and post-treatment cephalograms to assess incisor decompensation outcomes." — Research article results section