CEPHALOMETRIC ANALYSIS DENT 657. ANALYSIS UTILIZING THE CEPHALOMETRIC TRACING 1) Describe the...

CEPHALOMETRIC ANALYSIS

DENT 657

ANALYSIS UTILIZING THE CEPHALOMETRIC TRACING

1) Describe the subject’s dento-facial morphology

2) Quantitative description of morphological deviations

3) Make diagnostic and treatment planing decisions

2) Evaluate change over time - treatment induced and growth process

Morphological Description

Skeletal - horizontal and vertical Dental - horizontal and vertical Comparing individual subject’s tracing

to the “ideal” Reference sampleCross-sectional

Longitudinal - growth studies eg. Bolton-Brush, Ann Arbor and Burlington

Cephalometric Analyses

Down’s Steiner’s Tweed’s McNamara’s OSU

Cephalometric Evaluation

Identification of anatomic landmarks Landmarks: stable reference structures

and maxillary and mandibular skeletal and dental

Graphically relating the dento-facial elements to these reference structures

Angular and or linear measurements

METHODS OF CEPHALOMETRIC ANALYSIS

Two basic approaches Metric approach - use of selected linear

and angular measures Graphic approach - “overlay” of

individual’s tracing on a reference template and visual inspection of degree of variation

Metric Method - Use of selected linear and angular measures

Graphic Method - Use of a Composite Template

GOALS OF CEPHALOMETRIC ANLYSIS

Evaluating relationships, both horizontal and vertical of 5 major functional components of the face:

the cranial base; the maxilla; the mandible, the maxillary and mandibular dento-

alveolus

REFERENCE LINES

Frankfort’s Horizontal (porion to orbitale)

Sella - Nasion line True horizontal plane True vertical plane

sella nasion

porion orbitale

Reference Lines

SKELETAL HORIZONTAL - MAXILLA

SNA 82 ± 2 deg

NA TO FH 90 ± 3 deg

SNA 82 ± 2 deg

NA TO FH 90 ± 3 deg

s n

a

F H

SKELETAL HORIZONTAL - MANDIBLE

s n

bP g

F H

SNB 80 ± 2 deg

N-PG TO FH

88 ± 6 deg

SNB 80 ± 2 deg

N-PG TO FH

88 ± 6 deg

SKELETAL HORIZONTAL - MAXILLA TO MANDIBLE

N

A

B

ANB 2 ± 2 degANB 2 ± 2 deg

SKELETAL VERTICAL

F H

S

G NM E

G O

FH TO GOGN 22 ± 5 deg

Y AXIS 59 ± 6 deg

LFH 55% OF TFH

FH TO GOGN 22 ± 5 deg

Y AXIS 59 ± 6 deg

LFH 55% OF TFH

DENTAL - UPPER TO LOWER INCISOR

INTERINCISAL 130 ± 5 deg

INTERINCISAL 130 ± 5 deg

DENTAL - MAXILLARY INCISOR

F H

N

A

U1 TO FH 110 ± 5 deg

U1 TO NA 22deg

U1 TO NA 4mm

U1 TO FH 110 ± 5 deg

U1 TO NA 22deg

U1 TO NA 4mm

DENTAL - MANDIBULAR ANTERIOR

GO

GN

B

N

L1 TO NB 25deg

L1 TO NB 4mm

L1 TO GOGN 91 ± 6deg

L1 TO NB 25deg

L1 TO NB 4mm

L1 TO GOGN 91 ± 6deg

SOFT TISSUE

NASOLABIAL ANGLE 102 ± 8 deg

L.LIP TO E PLANE -2 ±2mm

NASOLABIAL ANGLE 102 ± 8 deg

L.LIP TO E PLANE -2 ±2mm

Limitations of the Metric Method

Stable reference structures are only relatively stable

Validity of landmarks Error in landmark identification

Graphic Method

Template Changes between 2 time points

Superimposition Method - on the cranial base

Maxillary and mandibular superimposition

Limitations of Cephalometric Analysis

Individual variability Ethnic variability Gender variability