ABO Analysis

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



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



positionSoft tissue

Area of Study



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


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


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



positionSoft tissue

Area of Study



positionSoft tissue


A. Mandible to Cranial Base

Point B

S N

80º

Mandible to Cranial

Base

SNB 80 º

Skeletal landmarks:

Sela, Nasion, Basion


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



positionSoft tissue

Area of Study



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


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



positionSoft tissue

Area of Study



positionSoft tissue


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


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



positionSoft tissue

Area of Study



positionSoft tissue


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


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


Position

U1-NA 22 º


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


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


Position

L1-NB (mm)

4mm

L1

Point B

N

4mm


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


Position

L1-NB 25 º


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


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


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



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

Documents

ABO Analysis