Table 2 Landmarks, reference planes and measurements used in the study
From: Orthodontic incisor retraction caused changes in the soft tissue chin area: a retrospective study
Definition | |
|---|---|
Landmarks | |
N | Nasion: most anterior point of the frontonasal suture where the lines of the glabella profile meet those of the nasal bones |
S | Sella: Center of bony contour of sella turcica |
P | Porion: the midpoint of the upper contour of the metal ear rod of the cephalometer (machine porion) |
Or | Orbitale: the lowest point on the inferior margin of the orbit |
A | Most concave point between anterior nasalspine and superior prosthion |
U1 | The tip of the maxillary central incisors |
U1c | The most anterior point of clinical crown of maxillary central incisors |
L1 | The tip of the mandibular central incisors |
L1c | The most anterior point of clinical crown of mandibular central incisors |
B | Most concave point on mandibular symphysis |
Pog | Pogonion: the most anterior point on the osseous contour of the chin |
Me | Menton: the most inferior midline point on the mandibular symphesis |
LL | The most anterior point of the lower lip based on the reference plane |
Stmi | Uppermost point on vermilion border of lower lip |
B′ | The innermost point on the contour of the soft-tissue between the lower lip and the soft tissue chin |
Pog’ | Soft tissue pogonion: the most prominent point on the chin based on the reference plane |
Me’ | Soft tissue menton: the lowest point on the contour of the soft tissue chin |
Reference planes | |
FH | Frankfurt Horizontal plane formed by Portion and Orbitale |
MP | Mandibular plane through Me and the lower margin of mandibular angle |
VBL | A line passing through the B point and perpendicular to the FH plane serving as the vertical reference for the mandibular evaluations |
VNL | A line passing through the N point and perpendicular to the FH plane serving as the vertical reference for the maxillary evaluations |
Cephalometrics analysis index | |
ANB (°) | The ANB angle shows the difference between the maxilla and mandible |
SNA (°) | The SNA angle is used to establish the relationship of the maxilla to the cranial base |
SNB (°) | The SNB angle is used to establish the relationship of the mandible to the cranial base |
U1-L1 (°) | Upper and lower central incisors Angle: the intersection Angle of the long axis of the upper and lower central incisors, representing the relative protrusion of the upper and lower central incisors |
U1-NA (°) | The intersection Angle between the long axis of the upper central incisor and the NA line, representing the inclination of the upper central incisor |
L1-NB (°) | The intersection Angle between the long axis of the lower central incisor and NB line, representing the inclination of the lower central incisor |
SN-MP (°) | The Angle between the mandibular plane and the SN plane |
FMA (°) | The Angle between the Frankfurt Horizontal plane and the Mandibular plane |
Stmi-Me’ (mm) | Vertical distance between the landmarks of Stmi and Me’ |
Soft tissue area measurements | |
Area 1 (cm2) | The area of soft tissue chin from the border of B-B′ till the border of Me-Me’ |
Area 2 (cm2) | The area of lower lip till the border of B-B′ |
Soft tissue thickness measurements | |
L1c-LL (mm) | Distance between the landmarks of L1c and LL |
B-B′ (mm) | Distance between the landmarks of B and B′ |
Pog-Pog’ (mm) | Distance between the landmarks of Pog and Pog’ |