Table 2 Definitions of 3D skeletal and temporomandibular measurements used in the study
Measurements | Abb | Definition |
|---|---|---|
Reference planes, lines | ||
Horizontal plane | HP | A plane extending from right, left porion, and right orbital |
Mid-sagittal plane | MSP | A plane constructed by three-point N, BA, and IF |
Vertical plane | VP | A plane constructed of sella point and perpendicular to MSP and HP |
Mandibular plane | MP | A plane extending from right, left gonion and menton |
Nasion vertical line | Nv | A line extending from nasion perpendicular to the Frankfort horizontal plane |
Mandibular fossa horizontal plane | MFHL | A plane tangent to the mandibular fossa bony point and parallel to the horizontal plane |
TM line | TML | A line determined through the auditory meatus and anterior tubercle |
Mandibular fossa line | MFL | A line determined through two bony mandibular fossa MF |
Anteroposterior condylar line | ACP–PCP | A line extending from ACP to PCP |
Mediolateral condylar line | MCP-LCP | A line extending from MCP to LCD |
Skeletal measurements | ||
Anteroposterior position of the maxilla | SNA | The angle formed by the three-point landmarks S, N, and A |
Anteroposterior position of the mandible | SNB | The angle formed by the three-point landmarks S, N, and B |
Anteroposterior skeletal jaw relation | ANB | The angle formed by the three-point landmarks A, N, and B |
Pog-Nv distance | Pog-Nv | The linear distance measured between point Pog and Nv line, determining the anteroposterior position of the chin relative to the nasion vertical line |
A-Nv distance | A-Nv | The linear distance measured between point A and Nv line, measuring the anteroposterior position of the maxilla relative to the nasion vertical line |
Mandibular angle | SN-MP | The angle formed between the S–N line and mandibular plane Go-Me |
Facial height ratio | FHR | The ratio between the posterior facial height (S-Go) and the anterior facial height (N-Me) |
Mandibular fossa dimensions | ||
Mandibular fossa height (mm) | MFH | The perpendicular distance between bony MF and TM line |
Mandibular fossa width (mm) | MFW | The distance extending horizontally between AF and PF |
Inter-fossa distance (mm) | IFD | The distance extending horizontally between right and left MF bony points |
Articular eminence height | AEH | The perpendicular distance between AT and MFHL |
Mandibular fossa inclination | ||
Mediolateral (°) | MF-MLI | The angle constructed by MF line and VP |
Vertical (°) | MF-VI | The angle constructed by MF line and HP |
Anteroposterior (°) | MF-API | The angle constructed by MF line and MSP |
Mandibular fossa position | ||
Mediolateral (mm) | MF-MLP | The distance extending from the MF bony point to the MSP |
Vertical (mm) | MF-VP | The distance extending perpendicularly from the MF bony point to the HP |
Anteroposterior (mm) | MF-APP | The distance extending anteroposteriorly from the MF bony point to the VP |
Condylar inclination | ||
Mediolateral (°) | MCI | The angle between MCP-LCP and HP |
Vertical (°) | VCI | The angle between ACP-PCP and VP |
Anteroposterior (°) | APCI | The angle between MCP-LCP and MSP |
Condylar position | ||
Mediolateral (mm) | MLCP | The distance extending mediolaterally from MCP to the MSP |
Vertical (mm) | VCP | The distance extending vertically from SCP to the HP |
Anteroposterior (mm) | APCP | The distance between the ACP and VP |
AP condylar joint position (%) | APCJP | The anteroposterior condylar position within the joint according to the formula of Pullinger and Hollender |
Condylar dimension | ||
Condylar length (mm) | CL | The mediolateral condylar distance between LCP and MCP |
Condylar width (mm) | CW | The anteroposterior condylar distance between ACP and PCP |
Condylar height to TM line (mm) | CH | The distance which extends perpendicular from SCP to the TM line |
TMJ space | ||
Anterior joint space (mm) | AJS | Closest distance between AJSc and AJSf |
Superior joint space (mm) | SJS | Closest distance between SCP and MF |
Posterior joint space (mm) | PJS | Closest distance between PJSc and PJSf points |
Medial joint space (mm) | MJS | Closest distance between MJSf and MCP |
Volumetric total joint space (mm3) | VTJS | Total mandibular joint spaces (superior, anterior, and posterior) which are enclosed by the TM line |