abo analysis
TRANSCRIPT
ABO Analysis
American Board of Orthodontics
Dr. Rajiv Yadav.M.S.D. Ortho.
What is ABO Analysis?
Standard cephalometric analysis proposed by the American Board of Orthodontics (ABO)
Compilation of other analyses:DownsSteiners McNamaraWits AppraisalTweedsRickets
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Cranial Base
Ba
S N
130º
Cranial Base
Ba–S-N 130º
Skeletal landmarks:
Basion, Sela, Nasion
Effects:
-less than 130o short-face
-more than 130o long-face
If angle changes, there’s an effect on the temporal bone
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Types of measurements
A. Maxilla to Cranial Base
Maxilla to Cranial Base
SNA 82 º
Point A
S N
82º Skeletal landmarks:
Sela, Nasion, Point A
From Steiners analysis
Determines location of Maxilla in relation to Cranial Base
Increase angle prognathic
Decrease angle retrognathic
FH
N
90º
Point A
B. Maxilla to Cranial Base
Maxilla to Cranial Base
N-A-FH 90 º
Skeletal landmarks:
Nasion, Point A, Frontal Horizontal plane
From McNamara analysis
If increase forward growth of maxilla or prognathic.
If decrease backward growth of maxilla or retrognathic.
C. Maxilla to Cranial Base
Maxilla to Cranial Base
A-Nas Vert. (mm)
-2mm
FHNas Vert.
Point A-2mm
Skeletal landmarks:
Point A, Nasion Verticale
From McNamara analysis
Draw a perpendicular line from the frontal horizontal plane
If increases prognathic maxilla
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Types of measurements
A. Mandible to Cranial Base
Point B
S N
80º
Mandible to Cranial
Base
SNB 80 º
Skeletal landmarks:
Sela, Nasion, Basion
From Steiners analysis
Determines location of Mandible in relation to Cranial Base
Increase angle prognathic mandible
Decrease angle retrognathic mandible
B. Mandible to Cranial Base
FH
N
88º
Pog
Mandible to Cranial
Base
NPog-FH 88 º
Skeletal landmarks:
Nasion Pogonion, Frontal Horizontal plane
From Downs analysis
Increase angle prognathic mandible
Decrease angle retrognathic mandible
C. Mandible to Cranial Base
Mandible to Cranial
Base
Pog-N Vert. (mm)
-6mm
FH
Nas Vert.
Pog
-6mm
Skeletal landmarks:
Pogonion, Nasion Vertical
From ABO analysis
Nasion vertical line is perpendicular to Frankfurt Horizontal line
From Nasion Vertical to Pogonion, measure the distance:
-Increase mm retrognathic
-Decrease mm prognathic
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Types of measure-ments
A. Maxillo-Mandibular Relationship
Point B
Point A
N
2º
Maxillo-Mandibular
Relationship
ANB 2 º
Skeletal landmarks:
Point A, Nasion, Point B
From Steiners analysis
Relates to the maxillary denture base to mandibular denture base
Increase angle Class II
Decrease angle Class III
B. Maxillo-Mandibular Relationship
Maxillo-Mandibular
Relationship
A-NPog 1mm
Pog
N
Point A
1mm
Skeletal landmarks:
Point A, Nasion Pogonion
Measure the distance from Point A to Nasion Pogonion line
Effect:
-more than 1 mm prognathic maxilla
-less than 1 mm retrognathic maxilla
C. Maxillo-Mandibular Relationship
Maxillo-Mandibular
Relationship
Wits 2mmAO
BO
2mmOcclusal
An occlusal line from posterior teeth in occlusion to incisal tip
Perpendicular line from Point A to occlusal plane, and perpendicular line from Point B to occlusal plane. Measure distance between BO to AO.
Increase mm prognathic denture base
Decrease mm retrognathic denture
base.
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Types of measurements
A. Vertical Height
MPA
SN
32º
Vertical Height
SN-MPA
32 º
32 º
Extend mandibular plane and sela nasion line to get an angle of 32o
From Steiners analysis
Effect:
-increase vertical height skeletal open bite
-decrease vertical height skeletal deep bite
B. Vertical Height
FH
25º
MPA
Vertical Height
FMA 25º
Extend mandibular plane and frankfurt horizontal line to get an angle of 25o
From Downs analysis
Effect:
-increase vertical height skeletal open bite
-decrease vertical height skeletal deep bite
C. Vertical Height
ANS
Me
N
45%
55%
Vertical Height
N-ANS (%)
45%
ANS-Me (%)
55%
Normally, lower region of face comprises 55% because mandible grows downward and forward which suggests its bigger proportion
If not normal, then unproportion face
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Types of measurements
A. Maxillary & Mandibular Incisor Position
U1
SN
104º
Max. & Mand. Incisor
Position
U1-SN 104 º
Landmarks:
-sela nasion tip of incisal and apex of root bisects the line to get the angle
To determine the position of incisors
Effect:
-if angle increases protrusion of upper incisors
-if angle decreases retrusion of upper incisors
B. Maxillary & Mandibular Incisor Position
Max. & Mand. Incisor
Position
U1-NA (mm)
4mm
U1Point A
N
4mm
Utilizes nacion and point A
From the NA line measure the distance the labial surface of upper central incisors or U1
From Steiner analysis
Effect:
-increase distance upper incisors protruded
-decrease distance upper incisors retruded
C. Maxillary & Mandibular Incisor Position
U1
Point A
N
22º
Max. & Mand. Incisor
Position
U1-NA 22 º
From Steiners analysis
Utilizes the nasion point A line and bisecting line of upper one.
Effect:
-increase angle labioversion or protrusion of U1
-decrease angle linguoversion or retrusive U1
D. Maxillary & Mandibular Incisor Position
IMPA
90º
Max. & Mand. Incisor
Position
IMPA 90 º
From Tweeds analysis
This relates to the mandibular plane to lower incisors.
The value 90o for lower incisors makes it stable because it is located on the basal bone (most compact part of the bone)
Effect ;
-angle increases protrusion
-angle decreases retrusion
E. Maxillary & Mandibular Incisor Position
Max. & Mand. Incisor
Position
L1-NB (mm)
4mm
L1
Point B
N
4mm
From Steiners analysis
Utilizes the nasion point B line
Measure the distance from NB line to the labial surface of the lower incisors.
Effect:
-distance increases protruded incisors
-distance decreases retrusive incisors
F. Maxillary & Mandibular Incisor Position
Point B
25º
N
L1
Max. & Mand. Incisor
Position
L1-NB 25 º
From Steiners analysis
Utilizes the NB line and bisecting line of lower incisors or L1
Effect:
-angle increases labioversion of the lower incisors
-angle decreases linguoversion of the lower incisors
G. Maxillary & Mandibular Incisor Position
Max. & Mand. Incisor
Position
L1-APog
2mm
L1
Point A
Pog
2mm
Utilizes the point A Pogonion line and measure the distance
from APog line to the labial surface of lower incisors
Effect:
-distance increases protrusion
-distance decreases retrusive
H. Maxillary & Mandibular Incisor Position
130º
U1
L1
Max. & Mand. Incisor
Position
U1-L1 130 º
From Downs and Steiners analysis
This utilizes the bisecting line of the upper incisors or U1 and bisecting line of lower incisors or L1 to get the interincisal angle
Effect:
-if angle increases there is uprighting of upper and lower incisors
-if angle decreses protrusion
Area of Study
Cranial Base- Maxilla to Cranial Base- Mandible to Cranial Base
Maxillo-Mandibular relationshipVertical heightMaxillary and Mandibular incisor
positionSoft tissue
Soft Tissue
Soft Tissue E-line-Lower lip
-2mm
Tip of nose
Tip of chin
-2mm
Analysis for soft tissue
Draw a line from tip of the nose to the tip of the chin, and then measure the distance between the E-line (or aesthetic line) and the lower lip
Effect:
-if increases protrusion of the lips
-if decreases retrusion of the lips
Summary