Cephalometrics /certified fixed orthodontic courses by Indian dental academy

SEMINAR ON

CEPHALOMETRICS IN ORTHOGNATHIC
SURGERY

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


INTRODUCTION
AIM

& OBJECTIVES

HISTORY
RADIOGRAPHIC

CEPHALOMETRIC TECHNIQUE

CEPHALOMETRIC
TRACING
HARD
SOFT

LANDMARKS

TECHNIQUE AND IDENTIFICATION OF LANDMARKS

TISSUE ANALYSIS

TISSUE ANALYSIS

CEPHALOMETRIC
LIMITATIONS
RECENT

PREDICTION TRACING

OF CEPHALOMETRICS

ADVANCES

CONCLUSION
REFERENCES


ANCIENT

-

TIMES

Historically human form measurements.
1 - self portrayal in sculpture, drawing and
painting.
2 - relation of physique - health, temperament and
behavioral traits.


Paleolithic age some 35,000 years ago


The ancient Egyptians developed an intricate
quantitative system that defined the proportions of
the human body. It became the CANON.


THE CANONS

Unit –
length of
foot =
18 Horiz
lines

RENAISSANCE TO
2 0 TH C E N T U R Y

Leonardo da Vinci
(1451 – 1519)
Albrecht Durer
Petrus Camper
Spix
Welcker
Hellman
Korkhaus
Bjork


2 0 TH C E N T U R Y

Craniometry to Cephalometry
Van Loon
Paul Simon

Paccini
1922

1931

Carrera
Broadbent
Hofrath
Lucien de Coster


15"

5 feet

Film Plane

Source Plane

X-ray Source

Mid-saggital
Plane

X-ray Film in
Cassette

Patient in Head
Positioning Device


HARD TISSUE LANDMARKS

GLABELLA
NASION
SELLA
ORBITALE
PORION

ANTERIOR
NASAL SPINE

POINT A

BASION
PTERYGOMAXILLARE

GONION

POINT B
POSTERIOR NASAL
SPINE


POGONION

GNATHION
MENTON

SOFT TISSUE LANDMARKS

GLABELLA
NASION

PRONASALE
SUBNASALE
LABRALE SUPERIUS
STOMIUM SUPERIUS
STOMIUM INFERIUS

LABRALE INFERIUS

POGONION
MENTON
CERVICAL POINT








Radiograph with good resolution
Matte Acetate Tracing paper (non glossy side for the
tracing) – 0.003 inches thick & 8 x 10 inches thick
Sharp 3H fine drawing pencil
Protractor
Viewbox


PLACEMENT OF THREE ORIENTATION CROSSES


AVERAGING OF
BILATERAL IMAGES ON
TRACING USING A
BROKEN LINE


SEQUENCE OF STEPS INVOLVED IN CEPHALOMETRIC TRACING

1) Gross anatomic inspection
2) Identifying relevant landmarks
3) Initiate Tracing


A:sella: center of sella turcica
B:anterior cranial base

B

C:middle cranial base

A

C


A:Nasion ;
B:Orbitale;
C:Porion

A
C
B


A: ANS;
B: PNS;
C: “A” Point

B
A
C


Maxillary and mandibular dentition
Incisal Tip and Apex of maxillary
and mandibular incisor


Mandibular outline
“B” Point; Pogonion:
Gnathion; Menton;
Gonion


1st and 2nd Vertebrae

Posterior cranium


Soft tissue profile
Nasal Tip;
Subnasale;
Soft Tissue Pogonion


nasion
sella
porion


orbitale



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










SN PLANE
HP PLANE
PALATAL PLANE
OCCLUSAL PLANE
MANDIBULAR
PLANE
Constructed points like
Gnathion & Gonion


Length of cranial base is measured from Articulare
to nasion parallel to HP




Ar-Ptm
Ptm-N









Ar-PTM is measured
parallel to HP to determine
the horizontal distance
between the posterior
aspects of mandible and
maxilla.
Male – 37.1 +/- 2.8
Female – 32.8+/-1.9
Increase or decrease in
these values indicates
prognathism/retrognathism


MALE
FEMALE

52.8 +/- 4.1
50.9 +/- 3










In this analysis all measurements are made
parallel to HP
N-A-Pg(angle)
N-A (Linear)
N-B (Linear)
N-Pg (Linear)










This measurement
indicates the degree of
skeletal convexity
Male – 3.9 +/- 6.4o
Female – 2.6 +/- 5.1o
+ ve angle indicates
convex face
-ve angle indicates
concave face










Here apical base of maxilla is
related to N.
Used to determine if anterior
part of maxilla is
protrusive/retrusive.
Male – 0.0 +/- 3.7
Female - -2 +/- 3.7
+ve indicates prognathism
-ve indicates retrognathism







Here apical base of
mandible is related to
N.
Male : -5.3 +/- 6.7
Female : -6.9 +/- 4.3
This quantitates the
AP position of
mandible and degree of
mandibular horizontal
dysplasia







This indicates
prominence of chin
Male - -4.3 +/- 8.5
Female - -6.5 +/- 5.1











In this analysis all measurements are made
perpendicular to HP.
Reflects the anterior, posterior or complex dysplasia
of face.
N-ANS(Linear)
ANS-GN(Linear)
PNS-N(Linear)
MP-HP(Angle)







It signifies the
middle third facial
height.
Male – 54.7 +/3.2
Female – 50 +/- 2.4








It signifies the
lower third facial
height.
Male – 68.6 +/3.8
Female – 61.3 +/3.3







It signifies the
posterior maxillary
height
Male – 53.9 +/1.7
Female – 50.6 +/2.2









It signifies the posterior
divergence of mandible
shown by MP angle.
The angle relates the
posterior facial divergence
with respect to anterior
facial height
Male - 23o +/- 5.9o
Female – 24.2o +/- 5o



Measurements for this analysis
UI perpendicular to NF
LI perpendicular to MP
U6 perpendicular to NF
L6 perpendicular to MP











It denotes the anterior
maxillary dental height.
Aids to evaluate the total
vertical dimensions of
premaxilla from approximate
piriform aperture
perpendicular to tip of
maxillary incisor crown.
Signifance: indicates how far
the incisor have erupted in
relation to nasal floor.
Male - 30.5 +/- 2.1
Female – 27.5 +/- 1.7









This measures the anterior
mandibular dental height.
Determines the total
dmensions of anterior
mandible from MP
perpendicular to tip of
mandibular incisor crown.
Signifance: denotes how
far the incisor have
erupted in relation to MP
Male - 45 +/- 2.1
Female – 40.8 +/- 1.8






This measures the
posterior maxillary
dental height.
Male - 26.2 +/- 2
Female – 23 +/- 1.3







Measures the posterior
mandibular dental
height
Male - 35.8 +/- 2.6
Female – 32.1 +/- 1.9




This is analysed by following measures
PNS – ANS
AR – GO
GO - PG
AR-GO-GN
B - PG






Denotes the total
effective length of
maxilla.
Male - 57.7 +/- 2.5
Female – 52.6 +/3.5






Quantitates the length
of mandibular ramus
Male - 52 +/- 4.2
Female – 46.8 +/- 2.5






Aids in establishing the length of mandibular body
Male – 83.7 +/- 4.6
Female – 74.3 +/- 5.8







This measurements denotes prominence of chin related
to mandibular denture base
Male - 8.9 +/- 1.7
Female – 7.2 +/- 1.9







This angle denotes relationship between ramal plane and
MP.
Aids in diagnosis of skeletal open/closed bite problems.
Male – 119.1o +/- 6.5o Female – 122o +/- 6.9o


Measurements for this analysis

OP – HP (Angle)

A – B(Linear)

U6 – NF(Angle)

L1 – MP(Angle)











OP denotes its
steepness/flatness
Increased angle: assess
skeletal open bite, lip
incompetence,increased
facial height,
retrognathia.
Decreased angle: assess
deep bite, decreased facial
height, lip redundancy.
Male - 6.2o+/- 5.1o
Female – 7.1o+/-2.5o









This linear measurements
represents the relationship
of maxillary and
mandibular apical base to
OP
Male - -1.1 +/- 2
Female - -0.4 +/- 2.5
Significance: if A-B
distance is large with
point B projected
posteriorly to point A
denotes class II occlusion
and vice versa









Represents angulations of
maxillary central incisors to
NF
Male - 111o +/- 4.7o
Female – 112o +/- 5.3o
Signifance: aids to
determine the
procumbency/recumbency of
incisor
Vital in assessing long term
stability of dentitionwww.indiandentalacademy.com







Denotes angulation of
mandibular incisors to MP
Male - 95.9o+/- 5.2o
Female – 95.9o+/-5.7o
Significance: determines the
procumbency/recumbency of
lower incisor.

VARIOUS SOFT TISSUE CEPHALOMETRIC ANALYSES
HAVE BEEN PUT FORTH…….

Steiner
Ricketts
McNamara
Merrifield’s Z angle
Holdaway
Burstone – COGS
Arnett, Bergman et al - STCA

HORIZONTAL
PLANE

COLUMELLA

CERVICAL
POINT


GNATHION

This analysis describes overall horizontal soft tissue profile.
The following analysis is used:

Facial convexity angle(G-Sn-Pg)

Maxillary prognathism(G-Sn)

Mandibular prognathism(G-Pg)

Vertical height ratio(G-Sn/Sn-Me)

Lower face throat angle(Sn-Gn-C)

Lower vertical height depth ratio(Sn-Gn/C-Gn)

FACIAL CONVEXITY ANGLE



MEAN VALUE : 12 ⁰ +/- 4



POSITIVE VALUE –
CONVEX PROFILE



NEGATIVE VALUE CONCAVE PROFILE

G – Sn - Pog

ANTERO - POSTERIOR
MAXILLARY (Mean value 6+/-3) AND
MANDIBULAR (Mean value 0+/-4) MEASUREMENTS
,

(G-Sn To Sn-Me)
Mean value 1:1
Inference: Ratio <1
denotes
disproportionality and
there is large lower 3rd
face height and viceversa

LOWER FACE THROAT
ANGLE (Sn-Gn –C)
MEAN VALUE – 100 DEGREES
DECREASE IN VALUE INDICATES
PROMINENT CHIN

LOWER FACIAL HEIGHT TO
DEPTH RATIO

Mean value 1.2:1
Inference
Ratio>1 indicates short neck


The following analysis is used









Nasolabial angle(Cm-Sn-Ls)
Upper lip protrution(Ls to Sn-Pg)
Lower lip position(Li to Sn-PG)
Mento labial sulcus(Si to Li-Pg)
Vertical lip chin ratio(Sn-Stms/Stmi-Me)
Maxillary incisor exposure(Stm-U1)
Interlabial gap(Stms-Stmi)

NASOLABIAL ANGLE
(Cm – Sn – Ls)

Mean Value - 102o +/- 8o

Obtuse angle indicates
maxillary hypoplasia and
vice-versa

UPPER AND LOWER LIP PROTRUSIO

Sn
Ls

Li

Pog

Mean Values
Ls – Sn Pog

3 ± 1mm

Li – Sn Pog

2 ± 1mm

LIP POSITION AND FORM

MENTO LABIAL SULCUS

Li

Mean Value - 4 ± 2mm

Sm
Pog


VERTICAL LIP : CHIN RATIO
(Sn-Stms /Stmi-Me)
Mean Value - 1:2
INTER LABIAL GAP

Mean Value - 2 ± 2 mm
MAXILLARY INCISOR EXPOSURE

Mean Value- 2 mm

By Epker and Fish (1980 JCO)
adopted in part from the mechanics developed by Ricketts for
cephalometric analysis, growth prediction and visual treatment

objective construction as presented by Bench, Gugino, and Hilgers.

Newer advances and techniques

Digital cephalometry
Softwares
- Dolphin
- Vistadent
- OPAL



Burstone CJ, Legan HL: Cephalometrics for orthognathic surgery, J Oral
Surg 1978;36:269-277



Text book of Radiographic Cephalometry by Alexander Jacobson.



Textbook of Essentials of orthognathic surgery by Johan P Reyneke



Text book of Orthodontic Cephalomerty by Athanasios E Athanasiou



A colour atlas and manual of Three Dimentional cephalometry by GRJ
Swennen



Textbook of Orthognathic surgery by Raymond Fonseca


Thank you
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Cephalometrics /certified fixed orthodontic courses by Indian dental academy

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