Table 1 Definition of anatomical landmarks, skeletal reference planes and measurements used in the study
Identification | Abbreviation | Definition |
|---|---|---|
Anatomical Landmark | ||
 Nasion | N | Anterior and superior frontonasal suture |
 Basion | Ba | The foramen magnum’s inferior-anterior margin in the skull base midline |
 Orbital | Or | The orbit lowest midpoint at its inferior border |
 Anterior Nasal Spine | ANS | The maxillary anterior nasal spine most anterior point |
 Gonion | Go | The intersection of the bisecting angle point between the mandibular plane and the mandibular ramus plane at the mandibular angle |
 Menton | Me | The lowest bony point of the chin at the MD symphysis |
 Condylion | Co | Most superior point of the condyle |
 Mid-Gonion | MGo | The midpoint between left and right Gonion |
Reference Planes | ||
 Facial midsagittal plane | FMSP | The plane constructed by (N), (BA), and (ANS) passing through (N) as the coordinate origin |
 Orbital-Facial midsagittal plane | Or-FMSP | A plane passing through right orbital, left orbital and perpendicular to FMSP |
 Horizontal plane | HP | A plane parallel to Or-FMSP passing through (N) as the coordinate origin |
 Coronal plane | CP | The plane perpendicular to both (FMSP) and (HP) passing through (N) as the coordinate origin |
 Mandibular Plane | MP | The plane constructed by left and right (Go) and (Me) |
 Mid-mandibular plane | MMP | The plane passing through the (MGo) and (Me) and perpendicular to the mandibular plane |
Three Dimensional Measurements | ||
3D, TMJ joint spaces | ||
 Anterior Joint Space | AJS | The shortest distance from the fossa to the sagittal anterior tangent point (AC) of the condyle |
 Posterior Joint space | PJS | The shortest distance from the fossa to the sagittal posterior tangent point (PC) of the condyle |
 Superior Joint Space | SJS | The shortest vertical distance from the mid-point of the total width on the condyle surface to the opposing fossa wall |
 Medial Joint Space | MJS | The shortest vertical distance from the junction of the medial first and second sextants of the condyle to the opposing fossa wall |
 Lateral Joint Space | LJS | The shortest vertical distance from the junction of the lateral first and second sextants of the condyle to the opposing fossa wall |
3D Condyle position | ||
 Condylion-X axis | Co-x | The distance from Condylion (Co) to midsagittal plane |
 Condylion-Y axis | Co-y | The distance from Condylion (Co) to horizontal plane |
 Condylion-Z axis | Co-z | The distance from Condylion (Co) to the coronal plane |
3D Mandible | ||
 Chin deviation (mm) | CD | The horizontal distance from Me point to FMSP |
 Mandibular rotation (°) | FMSP-MMP | The intersection angle between FMSP and MMP (Z-axis) |
 Mandibular canting (°) | HP-MMP | The angle between HP and MMP (Y axis) |
 Mandibular divergent (°) | MP-HP | The intersection angle formed by MP and HP intersecting at Gn (X-axis) |