lateral cephalometric analysis in orthodontic

Prepared by:- Bilal A.M.Prepared by:- Bilal A.M.
Faculty of dentistry-Mansoura university -Faculty of dentistry-Mansoura university -

Tracing roentgenograms
Instruments required for tracing:
(1) Paper:
Trace a lene or acetate paper (0.003)" thickness, one side
glossy and one side matted, has good transparency
even when seven or eight tracings are super-imposed.
Other transparent waterproof paper maybe used.
(2) T. square:
Makes parallel and projected lines easier to trace.
(3) Pencils:
Hard and soft pencils indifferent colours.
A hard pencil (NO. 10) is used for accuracy, that is true for
well defined lines as: The contour of the profile and the
lower border of the mandible.

A soft pencil (NO. 3) is used for the rest of the
stractures as seen on the film, which have a certain
thickness, close to 1mm. as: supra or bital roof, the
palate, the contour of the teeth (un less perfect
superimposition)., the clivus.
As it becomes more accurate and decreases the
amount of individual errors.
(4 H) pencil should be used if the tracing is to be made
on paper.
(2 B) pencil be used if the tracing is made directly on
the film.
Coloured pencils: will help when doing an analysis,
many lines cross in nearly the same area.

It is of good routine to use one colour for the midsagittal
structures and an other for bilateral ones. This help to
keep in mind that the flat surface of the film represents
depth and volume.
(4) viewing box:
Should be large enough to accommodate the lateral and
posterior – anterior films simultaneously.
It is advisable to trace an inch grid with thin lines on the
transparent surface with India ink. This helps orient the
films.

The light should be cold, two or three intensities
of light controlled by switch is important
because the films or their different areas do not
have the same darkness. To see the soft –
tissue of the profile, hide bony structure and
use the most intense light.
If one area is not clearly differentiated, look
through a black paper cone only at this area.

A photo – retouching table or a box constructed
with two (10 – watt) fluorescent bulbs and a milk
glass cover the size of (8 x 10) inch film can be
used.
It should be possible to vary the amount of light.
(5) A transparent millimeter rules 12 mm long.
(6) Two triangles (one small and plain, one
large).
(7) A small protractor, long arm dividers, and an
artgum eraser. And paper clipsor scotch tape.

Tracing technique:
•1- Distinguishing marks should be put on the right and left sides
of the roentgenogram.
•2- Place the roentgenogram on the tracing table, place tracing
paper on top of the film, attach the left hand margins of the paper
to the corresponding side of the film with scotch – tape or paper
clips to permit folding the tracing paper back to check direct by on
structural details use a hard fine pencil line.
•

•3- Profile tracing:
Should be started from
the outer out line of
the roentgenogram
and continued to the
inner parts:
Trace the soft tissue
profile while hiding the
rest with a black
paper.

Then, trace the bony profile:
A- The lower border of the mandible, posterior
border of the ramus, draw the posterior border of
the brain case.
B- Locate the foramen magnum.
C- Trace the odontoid process of the axis, go up
ward and trace the clivus up to sella turcica (part
of and trace the clivus is hidden by the ear rods),
forward and upward, trace the roof of the orbit up
to the supra orbital ridge. Here, come down word
tracing the laTeral and lower borders of the orbit.

D- Come back to sella turcica and trace the
planum, and anteriorly the cribriform plate,
continued more anteriorly and upward by
the inner plate of the frontal bone.
E- In the midface, trace the palate (floor of
nose and roof of mouth), posterior by the
pterygo maxillary fissure, just below and
behind the palate, trace the soft – palate,
the pharyngeal wall, and the root of
toungue.
F- Trace the teeth, mainly the first permanent
molars, the canines, and the most prominent
incisors

Tracing in details:
1- The soft tissue profile:
Only on the lateral films, it does not offer any difficulty if the
film is not burned out, if the viewing box has in tense light,
and if the bony structures are hidden by a black paper.
Possible deformations:
At the level of nasion, some cephalostats use a rest against
that area and the out line of the soft tissues is pressed in.
At the level of the lips and chin, the outline is different
(changing the position of the landmarks).
When the lips and mental muscles are at rest or in
contraction. This difference, may have a diagnostic value
concerning the vertical shortness of the lips, compared to the
bony anterior lower face.

At the level of nasion, some cephalostats use a rest
against that area and the out line of the soft tissues is
pressed in. At the level of the lips and chin, the outline
is different (changing the position of the landmarks).
When the lips and mental muscles are at rest or in
contraction.
This difference, may
have a diagnostic value
concerning the vertical
shortness of the lips,
compared to the bony
anterior lower face.

2- The bony structures: From above to down:
(1)The frontal bone:
The external plate goes down ward with a convexity at
the level of the supra orbital ridge, to nasion. The
internal plate continues, the cribriform plate upward
between the external and internal plate. The frontal
sinus can be located with varying size. At the level of the
frontal sinus, the supra orbitale can be located.

2-The nasal bone:
Starts from nasion and goes down ward and forward,
it is continued down ward and backward to form the
lateral wall of the nasal cavity, it meets the floor of
the nose at naso spinale.

3-The maxilla:
The anterior contour of the palate and the a lveolar
bone.Extend on the profile between the anterior nasal
spine to curve back ward in a concavity at the deepest
point of which lies point A. (subspinale).
It continues anteriorly down ward, up to the junction with
the incisor at prosthion.
.

4-The incisors:
The most prominent one should be traced, the upper
central incisors does not offer difficulty, but in the
lower, the four incisors are super imposed and the
apices are very difficulty to differentiate

5- The chin:
Start at infra dentale, curves posteriorly to point B (supra
– mentale), goes down ward and forward to pognoion,
curves back ward to gnathion and menton, and it
continued to form the internal plate of the symphysis
back to the incisors lingually.

6- the mandible:
posterior to the symphysis, the lower border extends to
the gonion, at the level of the bicuspids, it has a convex
shape, and is concave at the level of the insertion of the
masseter (antegonial notch) it curves to reach gonion.

7- The ramus:
Upward and backward up to the neck of the condyle
which is more backwardly inclined. The posterior
border can be followed up to the point (articulare)
where it is shadowed by the basisphenoid.

8- The head of the condyle:
Unless an open mouth film is token it can not
be accurately located, as it being masked
generally by the ear rods of the apparatus
used.
9- The coronoid process:
Can be located but not with enough accuracy
to be used for land marks.
10- The alveolar process:
Is difficult to locate accurately, may be
guessed.

3- Upper face:
It is the area between the cranial base and the
palate. Antero – posteriorly we find:
(1)The orbit:
The roof has been defined as double lines go down
ward from the supra orbital ridge to lower most
point orbitale.

The midlines between the two
shadows should be defined oblique
line crosses the orbital cavity.
It represents the greater wings of
sephenoid in the frontal film.

(2) Maxillo – zygomatico – temperal sulcus:
It is a vertical line which can be straight or like situated
just posterior to the lateral contour of the orbit, but
extending farther below.

It goes from the cribri from plate, down to the floor of the
nose at the level of the upper first molar, and curves
upward toward orbitale.
The lower most point at the curvature is the key-ridge
being bilateral, the midline between the two shadows
should be taken.

(3) The pterygo maxillary fissure Ptm:
It forms a boucle just above and posterior to the posterior
nasal spine and the soft palate.
Its anterior contour represents the tuberosity of the maxille.
Its posterior contour represents the ptergoid bone which is
difficult to trace.
Being bilateral, the midline between the two shadow should
be taken.

4- Midlface:
It is represented by the hard palate which is
enclosed between the floor of the nose and the
roof of the palate.
It extends from anterior nasal spine to posterior
nasal spine (This land mark may be masked by
the last molar).

At the level of Ptm it makes a U-turn and
comes anteriorly to the upper central
incisor from the alveolar process of the
incisor area.

5- Cranial base:
Cranial base is the demakration that the brain makes with
the face and the neck.
Traditionally, it is divided into anterior, middle, and
posterior fossae.

A- Anterior cranial fossa:
Extends from the frontal bone to the lesser wing of
sphenoid. It represented bilaterally by the roof of the
orbits, and in the median plane by the cribriform plate
of ethmoid and the planum sphenoidale.

B- Middle cranial base:
Extends from lesser wing of sphenoid to the
petrous bone.
petrous bone

C- Posterior cranial fossa:
Extends bilaterally from the occipital bone
posteriorly and the petrous bone anteriorly.
In the median plane it comprises the occipital
bone, the foramen magnum, the clivus up to
sella.
As can be seen, the three fossae overlap
antero-posteriorly.

6- cranial base lines:
1- Posterior arm (The clivus):
It extends between the foramen magnum and sella
turcica on the mid sagittal plane.
On the lateral film, it can be located at both
extermeties but it is masked in its midsection by the
ear rods.
It is composed of the occipital and the sphenoid
bones.
The sulture or synchondrosis between them is difficult
to locate.
At the lower end it starts at basion situated just above
the tip of the odontoid process of the axis, goes
obliquely upward, crosses the instru-mental porion and
continues up to the posterior clinoid of sella turcica.

2- The hinge (sella – turcica):
Saddle shaped , pituitary fossa, situated on the mid
sagittal area at the centre of corpus sphenoidale.
On the lateral film, its curved contour extends from
anterior to posterior clinoids.

In the body around sella, there is a sphenoidal sinus of
varying size.
In roentgenographic cephalometry, because its
accurate delineation, points have been defined all
around its contour and at its center.

3-Anterior arm:
Divided in two lines, the roof of the orbit above
and the planum with the cribriform plate below:
A- Roof of the orbit:
Bilateral, there fore, often two master shadows
on the lateral film festooned by small crests on
its superior surface. The midline and the
general direction should be taken and can be
represented by a continuous line starting at
anterior clinoid, crossing the supra orbital ridge.

B- Planum:
Is separated from the orbital roof and anterior
clinoid just anterior to sella. It is flat and horizontal.
It joins the cribriform plate at the level of the lesser
wing.
C- Cribriform plate:
It represented by doted lines, it continues forward
and curves slightly upward to join the internal plate
of the frontal bone.
D-Crista galli:
Sometimes visible on the lateral, but dimly at the
junction between ethmoid and frontal inner plate.

7- The teeth:
The accuracy in drawing the teeth depends on
their symmetry and the good orientation of the
head.
The key teeth to trace are first permanent
molars, the canines, and the central incisors.
1.Molars:
Are generally well defined, on the occlusal
surface no attempt should be made to draw
each cusp, it may be the source of too many
errors. Instead on approximate line
demarcating the occlusal surface of upper and
lower first permanent molars is enough.

2- Canines:
Not always easy to locate. One method may be to
start from the molars and eliminate progressively,
the bicuspids, then start from the incisors and go in
opposite ways eliminating the laterals. This may be
used for both lateral and postero-anterior
cephalogram.
3- Incisors:
The upper offer little difficulty. On the lateral the
apex may sometimes be masked or not very sharp.
The lower central incisor offers more difficulty as the
four lower incisors are aligned nearly at the same
level and have approximately the same size.

Any measurement involving the axis of the
lower incisor should be allowed a large
margin of tracing errors.
Besides these key teeth, the others (except
the lower and upper lateral incisors) do not
offer much difficulty.
Postero – anterior tracings should show the
following:
1- The contour of the cranium.
2- The mastoid.
3- The lateral out lines of the ramus.
4- The lower border of the mandible.
5- The coronoid process.

6- The orbital lines.
7- The lesser wings of the sphenoids.
8- The crista galli.
9- The nasal septum.
10-The lateral walls of the nose.

Location of the porion:
The porion is not distinguishable on the roentgeno-
gram. It actually is approximately 3mm. above the ear
rod. The external auditory meatus used in
cephalometrics for head fixation is not as a rule on
the same bilateral plane and the integuments do not
always rest on the ear posts.

Since the tissues of the outer ear canal are sensitive
to pressure, insertion of the ear rods in the same
position is uncertain.

Determination of the right and left sides:
•In all cephalomertic roentgenograms the centeral
ray goes through the ear rod or porion, the maxillary
left first molar is closer to the ear rod than the
maxillary first right molar.
•The maxillary canine left is closer than the
maxillary right canine.
•The left jugal buttress is closer than the right.
•The lower border of the body of the mandible on
the left side is superior to the corresponding borders
on the right side.
•The posterior border of the ascending ramus on the
left side is distal to that of the right.

•The left side of the mandible is superior to the right,
and the line denoting the inferior border must cross
over the corresponding line of the right side in the
region of the angle and become the posterior or distal
outline.
•The candyle is frequently obsecured by the ear rod
image and the petrous portion of the temporal bone.
The tracing may have to be terminated 6 or 8 mm.
below the condyle.
•In most films, only the crowns of the molar teeth can
be seen easily because of left and right side super
imposition.

•In the incisor region, the full crown usually
can be seen a long with the labial root out line.
The lingual root outline from cinulum to apex is
usually obscured and must be drawn from a
knowledge of tooth morphology or from a
template.
•In the mandible, as in the maxilla, incisor
teeth and molar teeth should be traced by
tracing the teeth in rest position, the occlusal
surface and incisal margins can be reproduced
accurately.

•To obtain correct condylar morphology by
using a template: two profile
cephalograms are taken the one with the
teeth in full occlusion is used to measure
angles and lines. The second
cephalogram is used to obtain condylar
outline. This is taken with the mandible
wide open, and the condyles down ward
and forward.

Errors in tracing:
•Some degree of error is inherent in tracing film, some
errors are duo to the character of the film traced, and
to the person doing the tracing.
•Personal errors are recognized as a feature of all
tracings, the experienced tracer will avoid errors duo
to in experience.
•Tracing should be limited to those parts necessary
for required information.
•It is advised that the tracer, having at hand a set of x
ray films and a skull. It is only by comparing, at each
step, on to the other, that clear visualization will
emergy and anatomical accuracy be achieved.

•The denser the structure, the whiter the
reproduction on the film. Actually only the teeth
offer a well delimited and compact delineation.
•The reproduction of bony structures depends
on their orientation as well as their density.
•This is one of the reasons why the image is
clearer on the lateral than opstero-anterior film.
•On the lateral film all structures besides
median sagittal plane are bilateral and if
symmetrical they double (for the same
structure).

•Practically, even if the face is perfectly oriented and if
the bilateral structures are symmetrical, they are not
necessarily super imposed because the x-rays are not
parallel but divergent. There fore, if double image is
seen on the film, it does not necessarily mean
asymmetry.
However, without the frontal film, it is not possible to
decide between asymmetry and malposition. Unless
just one structure is asymmetrical. There fore, when
double image is present (lower border of the
mandible), check if all bilateral structures are double
(e.g the roof of the orbit), if not it is a local asymmetry.

•While asymmetry between the two sides of
the mandible should be bisected severe
asymmetry should be traced as found.
•The temperomandibular articulation and the
condyle can not be seen on the profile
roentgenogram when the teeth are in occlusion
and must be traced from a film taken with the
mouth wide open. This is used as a template.
It will be good to strat with a lateral view, then
try to find the corresponding structures on the
frontal film. Some of them are clearer on the
postero – anterior film than on the lateral and
vice versa.

•Some can not be located accurately on either
(T.M.J) unless an open mouth is taken.
•Generally, for height and depth proportions
use the lateral films and for breadth and
symmetry use the frontal film.
•The frontal film in more difficulty to interpret
because the structures at different depth are
super-imposed. (e.g) at the level of the odonoid
process of the axis.
•The next step is to clear this confusion of lines
and shadows, to make a selective
interpretation by tracing neatly the most
significant structures.

Lateral land marks
1- Nasion (N):
•The midlle point on the fronto-
nasal suture, intersected by the
median sagittal plane.
•The junction of the frontal and
nasal bones.
•The soft – tissue nasion (N):
The most concave or retruded
point in the tissue overlying the
area of the fronto-nasal suture.
•The point of maximum
convesity between nose and
fore head.
Cephalometric land marks

2- Sella Turcica (s):
•Sella trucica is the pituitary fossa of the sphenoid
bone. Sella (s) is the centre of the sella turcica.
3- Se:
The mid point of the entrance
of the sella.

4- Subnasale (sn):
The point at which the nasal septum between
the nostrils merges with the upper cutaneous
lip in the mid sagittal plane.

5- Sub spinale (point A):
•The deepest midline point in the curved bony outline
contour of the alveolar process of the maxilla.
•At the deepest point between the anterior nasal
spine and the prosthion.
•The anterior limit of the maxillary basal arch.

6- Prosthion (Pr):
The lowest, most anterior interdental point on the
alveolar mucosa in the median plane between the
maxillary central incisors.

7- Incisor superius (I.S):
The most forward incisal point of the most prominent
maxillary central incisor.
8- Apicale ┴ (Ap _) :
The root apex of the most prominent maxillary
central incision.

9- Incisor inferius (I.I):
The most forward incisal point of the most prominent
mandibular central incisor.
10- Apicale T (Ap T):
The root apex of the most prominent mandibular central
incision.

11- Infra dentale (I.d):
The highest, most anterior, interdental point
on the alveolar mucosa in the median plane
between the mandibular central incisors.

12- Supra mentale (point B):
The deepest point on the contour
of the mandibular alveolar process
betweeninfradentale and pogonion.

13- Pogonion (Pog):
Most anterior point of the bony chin.

14- Gnathion (Gn):
•According to martin and saller (1956): it is the
lowest point in the median plane of the mandible,
where the anterior curve in the outline of the chin
merges into the body of the mandible.
•It is a point on the bony border palpated from
below which lies posterior to the tegumental
border of the chin.
•

•In cephalomertic, it is the mid point between the
most anterior and inferior points on the bony chin.
•Measured at the intersection of the mandibular
base line and nasion-pogonion line (facial plane).
(Mandibular plane and facial plane).

15- Gonion (Go):
•The lowest, posterior and most outward point on
the angle of the mandible.
•This is obtained in cephalometrics by: bisecting
the angle formed by tangents to the lower and
posterior borders of the mandible.

•When the angles of both sides of the mandible
appear on the profile roentgenogram, the point
midway between the right and left sides is used.
The midpoint in the curve of the mandible between the
ramus and the lower border.

16- Menton (Me):
•The lowest point on the chin,
•from which the face height is
• measured.

17- Articulare (Ar):
•The point was introduced Bjork (1974)
•The point of intersection of the external dorsal
contour of the mandibular condyle and the temporal
bone.
•The mid point is used when the profile roent –
gengram show double
projections of the rami.
•The ventral surface of
the basilar part of the
occipital bone intersects
the posterior border of
the ascending ramus
and the outer margin
of the cranial base.

18- Condylion (cd):
•Most superior point on the
• head of the condyle.

19- Orbitale (or):
•The lowest point on the inferior bony margin of the
orbit. In cephalometric roentenogram the orbitale
located on the
lower margin
of the orbit
directly below
the pupil when
the patient looks
straight a head.

20-Anterior nasal spine (ANS):
The median, sharp, bony process of
the maxilla at the lower margin
of the anterior nasal opening.

21- Posterior nasal spine (PNS):
•Process formed by the united projecting ends of
the posterior borders of the palatal processes of
the palatal bones.

22- Anterior point for the occlusal plane (APocc):
•A constructed point, the midpoint of the incisor
over bite in occlusion.
23- Posterior point for the occlusal plane (ppocc):-
the most distal point of contact between the most
posterior Molars an occlusion

24- Basion (Ba):
•The most forward and lowest point on the
anterior margin of the foramen magnum.
•Bjork and palling prvide a more specific roent –
genographic definition:
The perpendicular projection of the anterior border of
the foramen magnum. On a target through the lower
margin of the condylar head.

Other cephalometric land marks:
Pterygo maxillary fissure (Ptm):
An oval shaped radiolucency resulting from the
fissure between the anterior margin of the pterygoid
process of the sphenoid bone and the profile out line
of the posterior surface of the maxilla.
Appears as iverted tear-drops, its
anterior margin represents
the posterior margin of the
tuberosity of the maxilla.

Porion (P):
The mid point on the upper edge of the external
auditory meatus.
As a cephalometric landmark it is located in the
middle of the metal rods of the cephalometer.

Key ridge (KR):
The lowest point of the zygomatico – maxillary ridge.
Acanthion (Ac):
Tip of the anterior nasal spine.
Clinoidale (Cl):
Most superior point on the contour of the anterior
clinoid.

Clinoidale (Cl):
Most superior point on the contour of the
anterior clinoid.
Bolton point (BP).
Spheno occipital synchon-drosis (So).
Registration point (R).
Bolton point (Bp):
The highest point on the profile
roentgenogram at the notches on the posterior
and of the occipital condyles on the occipital
bone.

Broad bent registration point (R):
Mid point on a perpendicular from the centre of
sella to the Bolton – nasion line.
Spheno – occipital synchondrosis (so):
The cartilaginous union of the anterior end of the
basilar portion of the occipital bone and the
posterior surface of the body of the sphenoid
bone.
Tragion (T):
The notch just above the tragus of the ear. It lies
1-2 mm below the spina helicis which can be
palpated.

Alveolar point (Al.P):
The lowest point of the a lveolar process at the
midline between the maxillary central incisors.
Occipital condyle (O.C):
The condyle on the occipital bone near the
foramen magnum.
Opisthion (O.P):
The posterior midsagittal point on the posterior
margin of the foramen magnum.
Opithcranion (OPC):
The posterior midsagittal point of the greatest
cranial length from glabella.

Sphenoidale (SPH):
Point of the greatest convexity between the
anterior contour of the sella turcica and planum
sphenoidale.
Bregma (Br):
The anterior end of the sagittal suture where it
meets the coronary suture.
Cheilion (ch):
The lateral terminus of the oral slit i.e. (The outer
corner of the mouth).
Dorsum sella (D.S):
The square shaped bone which forms the
posterior boundary of the sella turcica.

Endo basion (E.b):
The perpendicular projection of the anterior border of
the foramen magnum on a tangent through the lower
margin of the condylar head at the foramen magnum.
Ethmoid triad (Eth.Tr):
A point located on the planum sphenoid, the ethmoid
line, midway between the greater wings of the
sephenoidale bone.
Ethmoidale (Eth):
The lowest point on the cribri form plate of the ethmoid
bone in relation to the sella – rasion line.
The deepest sagittal point on the cribriform plate of the
ethmoid bone in the anterior cranial fossa.

Tuber culum sellae (T.S):
Anterior boundary of the sella turcica.
Zygoin (Z):
The most lateral projection of the zygomaticarch.
Rhinion (RH):
The most anterior intersection of the nasalbones, which
forms the tip of the bony nose.
Pterygo – maxillare (Ptm):
The point where the pterygoid process of the sphenoid
bone and the pterygoid process of the maxilla begin to
form the pterygo maxillary fissure. The anterior wall
represents the retromolar tuberosity of the maxilla and
the posterior wall is the anterior curve of the pterygoid
process of the sphenoid.
The lowest point of the opening is used in cepha-
lometric roentgenogram.

Euryon (Eu):
The most lateral point on the side of the head.
Fronto temporale (Ft):
The most anterior point of the termporal line near
the root of the zygomatic process of the frontal
bone.
Inion (n):
The most elevated point on the external occipital
protuberance, at the crossing of the midline with a
tangent to the superior nuchal line.
Lambda (La):
Intersection of the sagittal and the lambdaidal
sutures on the cranial vault.

Mandibular notch (M.N):
The concavity between the coronoid and
condyloid process of the mandible.
Ophryon (Oph.):
Mid sagittal point just above the galbella
intersecting on arc from the fronto temporalis
across the frontal bone.
Vertex (v):
The highest point of the head, in the
midsagittal plane, when the head is help
erectly or in the frank fort horizontal position.
Postero-anterior cephalometric landmarks:

Poster-antrior cephalomeric landmarks
Glabella (Gl):
The most anterior point of the frontal bone in
the midsagittal plane of the bony prominence
joining the supra orbital ridges.
Trichion (Tr):
The mid point of the hair line at the top of the
fore head.
Nasion (N) Tragion (T)
Orbitale (O)
Prosthion (Pr) Infradentale (I.D)
Gonion (Go) Gnathion (Gn)

Soft tissue points: (Burstone 1959)

Soft tissue points: (Burstone 1959)
Glabella (G):
Determined by a tangent to the forehead from
a line passing through subnasale.

Soft tissue nasion (N`):
The most cocave or retruded point in the
tissue overlying the area of the frontonasal
sutures, the intersection of the SN line with
the soft – tissue anterior to rasion.

Nasal crown (Nc):
A point a long the bridge of the nose halfway
between soft-tissue nasion and pro nasale.
Pronasale (Pn):
The most prominent or anterior point of the
nose.

Subnasale (sn):
The point where the maxillary lip and nasal
septum form a definite angle.
If the depression is a gentle curve, subnasale is
interpreted as the most concave point in this
area as measured by a line angle 45 degrees
from nasal floor.

Soft – tissue sub spinale (A`) (ss):
The point of greatest concavity in the midline
of the upper lip between subnasale and
labrale.

Labiale superius (Ls):
The most prominent point on the upper lip as
measured from a perpendicular to nasal floor.

Stomion (sto):
The junction in the midline of the upper and
lower lips.

Labiale inferius (Li):
The most prominent point on the lower lip as
determined by a perpendicular from nasal
floor.

Soft – tissue supra mentale – point B`
(Sm):
The point of the greatest concavity in the
midline of the lower lip between the soft –
tissue chin and labiale inferius.

Soft – tissue pogonion (Pog`):
The most prominent or anterior point on the
soft – tissue chin in the mid sagittal plane.

Soft – tissue gnathion (Gn`):
The mid point between the most anterior and
inferior points of the soft – tissue chin in the
mid sugittal plane.

Superior labial sulcus:
The deepest point on the upper lip as determined by
a line drawn from subnasale inclined so that it forms
a tangent with labiale superius.

Inferior labial sulcus:
The most concave point on the lower lip as
determined by a line tangent to the menton
and labrale inferius.
Menton (Me`):
The most anterior and inferior point on chin.
Determined by a line tangent to the lower lip
and the chin.

Cephalometric lines and planes:

1- The commenly used horizontal lines and planes:
•S – N line:
The cranial line between the centre of sella turcica (s)
and the anterior point of the fronto nasal suture (nasion).
This represents the
anterior cranial base.

•Bolton plane:
(Broad bent – Bolton line): BP- N:
The line connects nasion to the upper most point
on the posterior end of the occipital condyles on the
occipital bone. (Bolton point).

•Frankfort horizontal plane (FH):
Plane intersecting right and left porion and left
orbitale. It is drawn on the profile roentgenogram from
the superior margin of the acaustic meatus to orbitale.

•Palatal plane:
Line connecting the anterior nasal spine (ANS) and the
posterior ansal spine (PNS).

•Occlusal plane: (OCC)
The occlusal plane of the teeth, a line drawn between
points representing one half of the incisor overbite and
one half of the cusp height of the last occluding molars.

•Mandibular plane:
Several mandibular planes are used, depending on the
analysis:
The most common ones are:
A.A tangent to the lower
border of the mandible.
B. A line between gonion
(Go) and ganthion (Gn)
steiner.
C. A line between gonion
(Go) and Menton (M)
tweed.

•Alternative lines and planes:
• A.B Plane:
Line between A point (sub spinale) and B- point (supra
mentale) it represents the anterior points of the basal
arches of the jaws to one
another and to the facial line.

•Facial plane:
A line from the anterior point of the frontonasal
suture (N) to the most anterior point of the mandible
(Pog).

•Ramus line:
A line tangent to the posterior border of the
mandibular ramus either from:
A- A point posterior to the mandibular condyle.
B- A point immediately
below the condyle.
C- Articulare.

•Orbital plane (O.P):
Perpendicular to Frankfort horizontal plane from
orbitale.

•S – BP plane:
Line connecting sella with the Bolton
point. This line indicates the posterior
portion of the cranial base.
•Anonymous line:
Gla bella to opisthion.
•B Jork's line:
Nasion to articulare (the point on the profile
roentgenogram where the posterior border
of the condyle intersects the contour of the
temporal bone.

•Blumenbach's plane:
The plane drawn through the points on
the skull, without the mandible, which
touch a flat horizontal surface.
•Broad bent's line:
Nasion to sella trucia mid point on the
profile roentgenogram.

•Broca's line:
Prosthion to lowest point on the occipital
condyle when the skull is resting on a
horizontal surface.
•Camper's line:
Line from the tip of the anterior nasal spine
(acathion) to the external auditory meatus.

•Camper's plane:
Line from tip of the anterior nasal spine
(acathion) to the centre of the bony external
auditory meatus in the right and left sides.
•Camper's triangle:
Camper's line and a line tangent to the facial
profile.
•Cranial base length:
Nasion to botton point.

•Cranial length:
Galbella to opisthocranion.
•De caster's line:
The plano-ethmodial line from the anterior
contour of sella turcica to the roof of the cribri
from plate and the internal plate of the frontal
bone.

•His's line:
Extends from acanthion to opisthion and divides the
face into an upper and a lower dental part.
•Hamy's line:
Galbella to lambda.
•Montagus line:
Nasion to porion.
•His's line:

•Huxley's line:
Nasion to basion.
•Krogman's Nassion parallel:
Sella – nason to Frankfort horizontal.
•Martins line:
Nasion to the most elevated point on the
external occipital protuberance (inion).

•Margolis line:
Nasion to top of spheno occipital
synchondrosis.
•Montagus line:
Nasion to porion.
•P-O plane:
Porion – orbiotale, the Frankfort plane.

•Pterygo maxillary fissure (PTM):
The fissure formed by the retromolar
tuberosity of the maxilla and the anterior
curve of the pterygoid process of the
sphenoid.
•Pycraft's line:
Nasion to centre of bony external meatus of
the ear.

•Rickets esthetic line:
Tangent to the tip of the nose and the most
anterior point on the chin.
•Salzmann's basal arch:
The basal arch is the area in the jaws which
begins at the most constricted point in the
body of the maxilla and of the mandible
when seen on the profile roentgenogram.

It includes Down's a point (subspinale) and B
point (supra mentale), Axel lunds trom's apical
base (which is a line around the apices of the
fully formed permanent teeth). And extends
around the jaws at the most constricted portions
of the alveolar processes.

These are the areas to which tweed referred
as (basal bone).
•Schmidt's plane:
Ophryon to inion.
•Schwalbe's line:
Galbella to ionion.
•Spheno ethmoidal junction (S-E):
Read as a distance on the S-N line by
dropping a perpendicular.

•Super orbital line:
A line from the anterior clinoid process a
long the roof of the orbits, bounded
anteriorly by the frontal bone and posteriorly
by the sphenoid bone.
•Von Baer's line:
Follows the antero posterior axis of the
zygomatic arch, tangent to its upper most
convexity.

•Von thering's line:
Orbitale to the centre of the bony external
meatus (Frankfort horizontal).
•Cranial base references planes:
•1-The Bolton line (Bolton point – nasion).
2- The sella – rasion line.
3- The spheno occipital synchondrosis.
4- The Frankfort horizontal, because of its
close relation to the cranial base may also
be used.

•Mandibular references planes:
•1- A line tangent to the lower border of
the mandible especially when the
antegonial notch is extremely pronounce
when the mandibular border shows a
decided downward curvature it makes
thisplane highly variable.
2- A line joining gonion and gnathion.
3- A line joining gonion and menton
(both points show variability during
growth).

•Middle face references planes:
•1- The palatal plane (joining ANS and
PNS).
•2- The occlusal plane which bisects the
maxillary first molar cusps and incisor
overbite.
3- One of the mandibular planes also may
be used, especially in relation to mandibular
denture changes.

Cephalometric angles:
•Angle of convexity (Downs):
Angle between (nasion – subspinale – pogonion) (N-
point A- pog).
This angle is read in
positive or negative
degrees from zero. If the
line pogonion-point A is
extended (see dotted line
in Fig.) and located
anterior to the N-A line,
the angle is read as
positive.

A positive angle suggests
prominence of the maxillary
denture base relative to the
mandible. A negative angle
of convexity is associated
with prognathic profile. The
range extends from a
minimal of -8.5 degrees to
a maximal of+ 10 degrees,
with a mean reading of 0
degree.

•Facial angle (Downs):
Frankfort plane intersection
of nasion – pogonion line
(inner lower angle).
Facial angle establishes
antero posterior relation of
the mandible to the upper
face, at the Frankfort
horizontal. (FH-N-POG).

•FMIA (Tweed):
Angle between Frankfort plane and the
mandibular incisor plane.
This measures the procumbency of the
mandibular incisor to Frankfort planer.
•I.A:
Internal angle of the mandibule.
•MIA:
Mandibular incisor angle. This is used to
measure the procumbency of mandibular incisor
to the mandibular plane.

•N-S-Gn:
Angle between SN line with the line
connects N with the chin point (Gn).
It is used in locating the anterior end of Go-
Gn line.

•N-S-MP:
Projection of line SN with a tangent to the lower
border of the mandible (MP).

•N-ANS-PNS:
Angle from nasion (N) to
the anterior nasal spine
(ANS) to posterior nasal
spine (PNS).

•S-N-A angle:
Angle between points sella – nasion – subspinale
(point A).
It represents antero
posterior relationship
of the maxillary basal
arch to the anterior
cranial base. This
shows the degree of
maxillary prognathism.

•S.N.B angle:
Angle between points
sella rasion – supra
metnale (point B).
It shows the anterior
limit of the mandibular
basal arch in relation
to the anterior cranial
base.

•SNA – SNB Angle:
The angle formed by
subspintale (point A)
rasion supramentale
(point B).
It indicates the antero
posterior relationship
of maxillary and
mandibulary and
mandibular basal
arches to the anterior
cranial base.

•S-N-I:
Angle between SN line and the line connects N to
tip of _ (tip of the maxillary central incisor).
This is used to
determine the position
of the maxillary
incisor to the anterior
cranial base.

•B.P – SN (Broad bent):
Formed by the lines s (sella) – N (Nasion) and s
(sella) – B.P (Bolton point).
By connecting the points B.P and N, the Bolton
plane (B.P – N) is obtained.
And the angles
S-B.P-N and S-N-B.
P may be ascertained.

•Y-axis angle:
It is read at the angle toward the profile of the face
below the Frankfort horizontal.
It is indicator of the down ward and forward
mandibular
growth.

•N-S-MI (maxillary first molar):
Angle between SN line with S-MI line.
(line froms to the notch between the mesial
and the distal cusps of the maxillary first
permanent molar).

Dawn's analysis
•The control materials studied was derived from 20
living individuals ranging in age from 12 to 17 years
and equally divied as to sex.
•Both the skeletal criteria and the denture criteria
will be discussed.

Skeletal criteria :-
Facial angle :- ( 1948 )
This angle is an expression of the degree of
recession or protrusion
of the chine. It is
determined by
drawing a line
from nasion to
pogonion, this plane
called the facial plane.

•The inferior inside angle of its intersection
with the Frankfort horizontal is designated as
the facial angle.
•The mean value : 87.8O
± 3O
.
•The range was from 82O
( recessive chin ) to 95O
( protrusive chine ).
•Mansoura measurements :
•Male : 86.4O
± 5O
.
•female : 85.7O
± 5O
.
•Mean : 86.1O
± 5O
.

•If angle smaller than normal this indicates : A
skeletal class II malocclusion, with a retrognathic
mandible.
•If facial angle larger than normal this indicates :
A skeletal class III malocclusion, with a
prognathic mandible.
•Age changes:-
This angle increases with age, as mandibular
growth concides with general growth.

•Angle of convexity :
( Na – point A – pog ).
•This is a measure of the protrusion of the maxillary
oart of the face in relation
• to the total profile.
•The angle is formed by
• two lines, one form
•nasion and the other
•from pognoion, both
• meeting at point A.

•The mean value of the angle is 0O
( the angle of
convexity would concide with the facial plane ) and
becomes 180O
.
•Normally, points N, A, pog fall on a straight line.
•If point A fell posterior
• to the facial plane,
•the formed angle was
• read in a minus degree
• ( - ) .

•If point A anterior, the angle was read in a plus
degree ( + ).
•The rang was + 10O
( convex ) to – 8.5O
( concave ).
•Male : 4.3O
± 4O
.
•female : 4.6O
± 2O
.
•Mean : 4.4O
± 3O
.

•This angle reveals the convexity or concavity of the
skeletal profile.
•If angle larger than normal this indicates : A
skeletal class II malocclusion and a convex skeletal
profile ( + ).
If angle smaller than normal this indicates : A
skeletal class III malocclusion and a concave
skeletal profile ( - ).
Age changes :-
The skeletal profile becames more concave with
age because the mandibular growth usually surpass
growth of the maxilla.

•A-B plane to facial plane angle : ( Down's ) :-
•The angle formed by the intersection of the A-B
plane with the facial plane
( Na – Pog ).
•It is a measure of the
• anteroposterior position
• of the maxillary
•denture base and the
•mandibular denture base
• to the facial plane.

•Average value : ( - 4.6O
± 3O
) range ( 0 to – 9O
) .
•In normal class I skeletal relationship, where point A
is anterior to point B ( or anterior to facial plane ) the
angle is expressed as a ( - )
number.Large negative value
means protrusion of the
maxilla and retrusion of
the mandible ( class II
relationship ).

•If point A is posterior to the facial plane, the angle
is expressed as a ( + ) number.
•Zero and positive measurements indicates class III
skeletal malocclusion.
•The location of A-B plane in relation the facial
plane is a measure of the relation of the anterior
limits of the maxillary and mandibular denture
bases to each other and to the profile.
•It helps the operator in gaining correct incisal
relationships and satisfactory axial inclinations of
the incisors and helps to check ANB angle.

•Mandibular plane angle :-
( MP to FH )
•This is a measure of the relationship between the
Frankfort horizontal plane and a tangent to the lower
border of the mandible.
•The mean value : 21.9O
with a range from 28O
to 17O
.
•Male : 23O
± 6O
.
•female : 26O
± 5O
.
•Mean : 24O
± 5O
.

•If the angle is larger than normal ( as in skeletal
class II division I ) it indicates a vertical growth of
the mandible.
•If the angle is larger than normal ( as in skeletal
class II division 1 ) it indicates a vertical growth of
the mandible.
•If the angle is smaller than normal ( as in class II
division 2 ) growth of the mandible will be horizontal
in nature.

Y-( Growth) Axis
The y-axis is measured as the acute angle formed by
the intersection of a line from the sella turcica to
gnathion with the Frankfort horizontal plane . This
angle is larger in Class II facial patterns than in Class
III tendencies.

The y-axis indicates the degree of the downward,
rearward, or forward position of the chin in relation
to the upper face.
A decrease of the y-axis in serial radiographs may
be interpreted as a greater horizontal than vertical
growth pattern.

An increase in the y-axis is suggestive of vertical
growth exceeding horizontal (or forward) growth of the
mandible.
The range extends from a minimal of 53 degrees to a
maximal of 66 degrees with a mean reading of 59.4
degrees.

( In the appraisal of severe malocclusions, where
the incisors in extreme positions of supra or infra
occlusion, molars and premolars are used instead
of incisors ).
•The angular relation between the Occlusal plane
and the Frankfort plane ranged from 1.5O
to 14O
with a mean value of 9.3O
.
•The class II cases have a steep Occlusal plane,
the class III cases have Occlusal plane tends to
became more horizontal.

•Denture criteria :-
•Occlusal plane angle :-
( OP to FH )
•Cant of the Occlusal plane :
In order to make
angular readings, the Occlusal plane was
represented as a
straight line. by
bisecting the first
molar cups height line.

When the anterior part of the plane is lower than the
posterior, the angle would be positive. Larger
positive angles are found in Class II facial patterns.
Long rami tend to decrease this angle.
The minimal angular
measurement is +1.5
degrees; the maximal,
+14 degrees; and the
mean, +9.3 degrees.

•Inter incisal angle :-
( T to ⊥ )
•This angle relates the angular position of the long axis of
the upper and lower central incisors to each other.
•It is a measure of the
•degree of procumbency
•of the incisor teeth.
•The mean value :
•135.7O
with a range
•from 130O
to 150.5O
.

•Male : 122.8O
± 12O
.
•female : 122O
± 8.6O
.
•Mean : 122O
± 1.8O
.

•If angle smaller than normal this indicates :-
•Class I bimaxillary protrusion in which fullness of
the lips are seen, and both the teeth and alveolar
bones are too far forward from the denture bases.
In BlacK races, this biprotrusion is normal.
•Class II division I malocclusion.

If angle larger than normal this indicates :-
Class II division 2 malocclusion which associated with
deep anterior over bite because there is no ( incisal
stop ) to prevent supra eruption of the incisors.

Therefore, in cases of deep anterior over bite, not
only is it important to correct the vertical problem, but
it is also important to treat the incisors to a proper
inter incisal angle to prevent its relaps.
In biretrusion cases, the incisors are up right, in those
patient dished in faces are seen.

•Lower incisor to Occlusal plane :-( T to OP )
•This angle indicates the inclination of the lower
central incisor in relation to the Occlusal plane.
•The angle measured is the inferior inside angle
( the complement of the angle formed by the inter
section of the long axis of T with the Occlusal
plane.

Mean value : 14.5O
with a range from 3.5O
to 20O
.
This angle is larger than normal in class II division
1 and smaller than normal in class III
malocclusion.

•Lower incisor to mandibular plane :- ( T to MP )
•This angle reveals the inclination of the loser central
incisor in relation to the mandibular plane.
The mean value : 91.4O
or 90O
, the difference in the
mean is duo to the slightly different methods of
locating the mandibular plane. ( 90O
± 5O
).

•All previous studies have located the mandibular
plane tangent to the lower border of the
mandibular at gonion and the lowest anterior
point which usually is found beneath the
premolars.

•As the latter point is not in the midline and
appositional growth occure in this area, the
lowest point of the mandible in the mid sagittal
plane (menton) is used as the anterior tangant
point ,by down’s .(Go-Me).

As the relationship of the lower incisors to
the mandibular plane is a right angle (90)
so the labial tip of the incisors is described
as plus the number degrees in excess of
90.
Mansoura measurements:-
Male: 101.6 ±8
Female: 97.7 ±7
Mean 100.1 ± 7.8

Upper incisors to Apo line :-
(The protrusion of the maxillary)
incisors is measured as the
distance between the incisal
edge of the maxillary central
incisor to the line from point
A-pogonion. This distance is
positive if the incisal edge is
ahead of the point A-pogonion
line and indicates the amount
of maxillary dental protrusion.

The reading is negative if the incisal edge lies behind
the point A-pogonion line and
suggests a retruded position
of maxillary incisors.
The minimal reading is —1.0
mm; the maximal, +5 mm;
and the mean, +2.7 mm.

Tweed's analysis :-
•In order to study the human dentition, Tweed
selected one hundred patients of both sexes and
various age groups with normal, healthy occlusions
of the permanent dentition which are esthetically
pleasing.

Tweed's triangle :-
•It is formed by the Frankfort horizontal
plane, mandibular plane and a line drawn
through the long axis of the most protrusive
lower incisor.

•The Frankfort mandibular incisor angle ( FMIA ) : is
formed by the Frankfort plane and the line drawn
through the long axis of the mandibular incisor.
•Tweed's belief that the ideal relationship of the
lower to the Frankfort plane should give an angle of
65O
.

•Any reading below 65O
indicates a procumbency of the lower
incisors to basal bone.
•Any reading above 65O
indicates a lingual axial relationship
of the mandibular incisors to basal bone.
•The mandibular incisor plane angle ( IMPA ) : is formed by
mandibular plane and line drawn through the long axis of the
loser incisor.
According to Tweed this angle should measure 90O
± 5O
,
depending on the Frankfort mandibular angle.

•With a short ramus and an obtuse gonialongle the
IMPA may read below 90O
.
•While in squared jaw individuals, the angle may
read above 90O
.
•Tweed's triangle :- ( The requirements )
harmonious face with normal occlusion requires :-
•ANB angle : not exceeds 4.5O
.
•FMIA : 65O
.
•IMPA : 90O
( 5O
.
•FMA : 20O
– 30O
.

•By using the Tweed's triangle, Tweed assessed the linear
arch length. To determine if extraction of teeth is needed or
not during treatment of the malocclusion.
•Eacth tooth anterior to the first molar is measured with a
caliper. This called the required space.
•The linear measurement of the arch from the mesial surface
of the first molar of one side to the missal surface of the first
molar of the other side is called the available space.

The incisal reduction ( IR ) :-
•A line drawn from the apex of the most
procumbent lower incisor to a point 65O
on the
Frankfort plane is Known as the incisal Reduction
( IR ).This designates the true position of the basal
bone.

•When the line falls lingual to the mandibular incisor,
the reading is a minus and indicates the lower teeth
are in procumbent relationship to the basal bone.

•Conversely, when the IR line lies labial to the lower
incisors, the reading is a plus and indicates : the
mandibular incisors are in a lingual axial relationship
to basal bone.
•The IR number must be multiplied by 2 because
the mandible is eliptical in shape. and must be
considered geometrically.

•The mass tooth discrepancy : is determined from
the figures which represents the available space,
Required space, and the incisal reduction.
•Any minus reading indicates the need for
extraction. The prognosis for the facial balance and
harmony is depend on the FMA.
•Any reading 35O
is considered favorable, while any
reading above 35O
presents a poor profile with an
unfavorable prognosis.

Tweed's objectives :-
•The best balance and harmony of facial
lines ( facial esthetics ).
•Stability of the denture after treatment
( permanency of result ).
•Healthy mouth tissues ( longevity of
dentition ).
•An efficient chewing mechanism.

Tweed's formula for treatment :-
•Non. Extraction – FMIA 65O
or greater with sufficient
arch length.
•Border line – FMIA 62O
to 65O
and sufficient arch
length.
•Extraction –FMIA 62O
or less.
•The lower incisor should be oriented to give a
pleasing face and this determines whether or not
extraction is to be made.

•Harmony of Tweed's clinical findings :
( balanced and harmony ) :-
•FMA : from 16O
to 28O
progonosis from excellent to
good.
•FMA : from 28O
to 32O
progonosis from good to fair.
•FMA : from 32O
to 35O
progonosis from fair to
favorable.
•FMA : from 35O
to anything upward progonosis gets
lees favorable.
FMA : of 45O
and above progonosis is nill.

•Determining the tooth mass discrepancy :-
( All measurements are made in the mandible ) :-
•1- Available space :-
The linear measurement from the mesial of the
first molar on one side to the mesial of the first
molar on the opposite side is measured with a
brass wire.

The wire is easy contoured so that it runs
along the buccal cusps of the premolars and
the incisal edges of the anterior teeth as far
labially as the most protrusive incisor.
This wire is laid along a millimeter ruler
and the measurement is recorded.

•2 - The IR or incisal reduction :-
This is determined cephalometrically by dropping
a line from the FH at a 65O
angle to the apex of the
lower central incisor. It is done to establish the true
position of the basal bone as it is related to the linear
measurement of the available space.

•If the line falls lingual to the lower incisor, or if FMIA
less than 65O
, the IR must be a minus reading.
•If the IR line lies labial to the lower incisor, or if
FMIA greater than 65O
, IR must be plus.
•IR measurement must be multiplied by 2 duo to the
elliptical shape of the mandible. ( either + or - ).
3- Correcting the available space :-
The IR measurement is either add or subtracted
from the previous available space obtained with the
brass wire. This will correct any labial or lingual
deviation of the lower incisors from the true basal
bone.

•4- The required space :-
The sum total of the mesio-distal widths of each
tooth mesial to the first molars.
This will include the four premolars, two cuspids,
two laterals and two centrals.
It can be done with the aid of caliper using the
patient's models to measure the erupted permanent
teeth and intra oral xrays can be used to measure the
un erupted permanent teeth.

•5- If the required space is lees than the corrected
available space :-
The tooth mass discrepancy is recorded as a plus
figure.
•When the required space is greater than the
corrected available space: the tooth mass
discrepancy is recorded as a minus figure.
A minus tooth mass discrepancy indicates a lack of
the clinical linear measurement.

•Tweed analysis :- N.B :
•A cephalometric evaluation can not be considered
complete without including the soft-tissue facial
contours, and racial differences.
•A patient's profile may affect the decision to need
to extract or not.
•When one has a well developed nose or chine, the
extraction may be contra indicated, because he was
wind up with a dished in appearance if teeth would
be extracted.
•Person that is fleshy and round faced may look well
with a bimaxillary protrusion.

Ricketts analysis
•Ricketts established live minimum
cephalometric measurements :-
•1-Facial angle :-
As established by Down's
the superior border of the
extranal auditory canal is
used in constructing the FH.

The mean is 85.4O
± 3.7O
.
One degree represents 1.5 mm of difference in
position of the chine. Relative to the nasion point.
•Facial angle 80O
are retrognathic.
•Facial angle 85O
are orthognathic
•Facial angle 90O
are prognathic

•2- X – Y axis :- ( Facial axis )
•A line from sella to gnathion.
•X – y axis is an indicator of the facial height.
•This is measured where the x – y axis crosses the
nasion – basion line.

•A differenc of one degree represents a lmost 2 mm
of height relative to depth.
•The average angle is 93O
or plus 3O
.
•The rang of variation is from – 12O
to 29O
with a
standard deviation of 3O
.

•This suggests that x-y measurement less than zero
tend towards greater length in facial from as opposed to
depth.
•The x-y axis is considerd plus if it is more than 90O
and
minus if it is less than 90O
those with less than 90O
are
retrognathic.

•3- Maxillary incisors to A.point – pogonion line :-
•The A point – pogonion line is an indicator of denture
position in relation to the facial line.
•This is 5.7 mm with arrange
• from -8 mm to 15 mm.
•One standard deviation is
• the equivalent of 3 mm.

•4-Mandibular incisors to A. point – pogonion line :-
•The average mandibular
• incisor tip is located
•approximately 0.5mm
•arterior to the A. pog line
• one standard deviation is
• 2.7 mm.
•The rang of variation is
•between + 10 mm and –
10 mm.
•The mandibular incisors
•inclines on an average 20.5O
•to the line A- pog.

•One standard deviation of inclination is 6.4O
.
•The range of angulations is from -11O
to + 53O
the
range of standard deviation is 15O
to 27O
.
•Mansoura measurements :-
•Male : 4.35 ± 3 mm.
•Female : 4.06 ± 2 mm.
•Total : 4.24 ± 3 mm.

Facial contour :-
•This is A. point related to the facial line.
•It is used to determine the relationship of the
maxilla to the mandible as seen in the bony profile.
•At the usual distance
from nasion to A.point 1
degree of difference from
the line N.A to the facial
line equals about 1 mm
on an arc from A. point to
the facial line.

•There fore direct measurement from A.point to the facial
line is used to measure variation of the profile a straight line.
•A reading of 10 mm distance from A.point to the facial line
is about 20O
of convexity as
measured by Downs, or about
half that of the angular value
in millimeters.
•There is an average of 4.1 mm
• and a standard deviation of 2.8
•mm.

•Faces with a convexity or concavity of not more
than 2 mm are regarded as being orthognathic.
•Those with up to 5 or 6 mm convexity or concavity
are classified as moderately
• convex or concave.
•At, 10 mm or over, the faces
• are severely convex or
• concave.

•Facial esthetic line ( E-
line ) :-
•The facial esthetic line
extends from the tip of the
nose to the end of the chin.
•These measurements
indicate the antero-posterior
position of the lips with
reference to the line between
the most anterior point of the
soft-tissue chine ( pogonion )
and the most anterior point
of the nose ( pro nasale ) .

•The lower lip is on an
average 0.3 forward to this
line with a standard of 3
mm.
•The upper lip is on an
average 1 mm posterior to
the lower lip when related to
the facial esthetic line.
•The mean is – 7 mm.
At age of 11 to 14 years
there is an average
practically no variation of
the lower lip to the facial
esthetic line. In adults the
difference is -4 mm.

•Male : upper lip : -2.23 ± 1.96 mm.
Lower lip : -0.12 ± 2.7 mm.
•Female: upper lip : -5.2 ± 2.1 mm.
Lower lip : -1.44 ± 2.8 mm.
•Total : upper lip : -3.4 ± 2.45 mm.
Lower lip : -0.62 ± 2.75 mm.

•This reference line
describes facial esthetics
and lip position.
•Dentures that are forward
( class I bimaxillary
protrusion and, class II
division 1 malocclusion )
produce a convex profile
with the lips ahead of the
E-line.
•Straight or concave
profiles ( class II division 2,
and class III ) are
associated with returned
lips.

•Larger noses or large chin
buttons or combination of the
two cases produce
erroneous measurements of
the lips to the E- lone.
•In such cases, a rhino
plasty or genioplasty may be
necessary in order to arrive
at a pleasing profile.

Sassouni's analysis
•In order to study the stracture of the skull for the
purpose of growth analysis and treatment, Sassouni
constructed planes, arcs and axes on the lateral
cephalogram.

•From these planes he determines the centre, and
then he uses the reference 0, after analysis of these
planes, the problem becaomes obvious to you. This
analysis is individual in nature and is not proportional
but translates the anomaly in millimeter.
.

•Steps of the analysis :-
•1- Construction of the planes.
•2- Locate the centre O.
•3- Construction of the arcs.
•4- Construction of the axes.
•5- Evaluation of the profile.

A- Construction of the planes.
1- Anterior cranial base planer or Basal plane
( OS ) :-
Two parts, first draw a tangent from the anterior
clinoid to the superior part of the roof of the orbit which
called the : cranial base plane and second draw a
plane parallet to the first one and tangent to the
inferior border of the sella turcica and called : the
supra orbital plane.

•2- Palatal plane ( ON ) :-
It is perpendicular to the midsagittal plane, going through
the anterior nasal spine ( ANS ) and the posterior nasal spine
( PNS ) and extended posteriorly as you can.
•3- Occlusal plane ( OP ) :-
Similar to Downs. ( Midpoint of incisor over bite through
the incisal edges of the upper and the lower central incisors,
and cusp height through the mesial cusps of the permanent
upper and lower first molars.
In open bite ignare the incisors and use the posterior teeth
only.
In deep over bite ( deep curve of spee ) take the occlusal
surfaces of the molars and premolars do not use the incisors.

• In deep over bite ( deep curve of spee ) take the
occlusal surfaces of the molars and premolars do not
use the incisors.
•4- Mandibular plane ( OG ) :-
Of Down's, from ME-tangent to the lower border of
the mandibular body.
•5- Ramus plane ( RX ) :-
The plane runs tangent to the posterior border of
the ascending ramus.

B- Locate the centre O.
To locate the centre O make sure when you put the
tracing paper on the film that you are taking the
lesser amount of soft tissue profile and extend the
planes posteriorly as you can.
Also look at the posterior area, if you have any
doubt to find this area, locate the two extreme
planes i.e take the most divergent two planes and
draw a vertical lines, the lines will decrease in
length and the increase gradually.

O is the centre or the midpoint of the shortest vertical
line beyond which the planes will diverage.
O will located up in cases of :
(1)Skeletal open bite.
(2)Deep bite.
Ignore any bizarre plane, in this case take the
other three planes.

C- Construction of the arcs.
a - For the antero-posterior
dimension :-
1- Anterior arc.
2- Basal arc.
3 - Mid facial arc.
4 - Posterior arc.

1- Anterior arc.
The anterior arc is the arc of a circle, between the
anterior cranial base plane and the mandibular
plane, with O as centre and O-ANS as radius.
Use the centre O, as the one end of the compass,
and open it until the N and draw an arc that pog and
ANS posterior to this arc draw another arc because
N may be too forward.
If you find pog and ANS too forward to this arc
draw another arc with ANS as radius i.e spinal arc.

•2- Basal arc :-
Using the centre O to point A as a radius and
draw another arc but if ANS is closer to the anterior
arc than the pog, take the ANS as a radius from the
centre O.
•3- Mid facial arc :-
Using the centre O to temporali, draw an arc
down to the occlusal plane.
Temporali (Te ) is the intersection of the shadows
of the ethmoid and anterior wall of the infratemporal
fossa.

4- Posterior arc :-
Between the anterior cranial base plane and
the mandibular plane, of a circle with its centre
at O and OSA
as ( SA
is the most posterior point
on the rear margin of sella turcica ) posterior arc
from O to the centre of the contour of sella as a
radius.

b -Arcs for the vertical dimensions :-
•1- From as a centre to supra orbitale ( eye brow ) as
a radius make a small arc and then rotate the
compass downward and draw another arc down.
In adult patient draw a second small arc 10 mm
below the first one, both are below the chin.
•2- Posteriorly from PNS as a centre and the point of
inter section of the parallel to plane (1) and posterior
arc draw (2) arcs up and down.

•In deep bite : you will find parallel planes and
centre O will shift away from the profile.
•In open bite : steeper planes and centre O is very
close to the profile.
•In class II skeletal cases, centre O is lower.
•In class III cases, it is higher relative to foramen
magnum.

•Evaluation of the profile :-
•1- From the anterior arc :-
Evaluate the labial surface the maxillary incisors
pogonion and ANS.
•A- In well balanced face all these points are on the
anterior arc.
If you find ANS and pogonion are anterior to this arc
by equal amount this situation considers normal.
•B- If you find ANS and pog equal distance too
forward or too backward this is normal.

•C- ANS on the arc and pogonion is not on the arc
:
•1- ANS on the arc and pog anterior to the arc this
means chin protusion.
•2- ANS on the arc and pogonion posterior to the
arc this means mandibular retrusion.
•D- Combination if pog is on the arc, ANS could
be anterior or posterior.

•2- From the basal arc :-
Normally from A will pass through point B or
approximating this area.
•3- From mid facial arc :-
Evaluate the maxillary first molar, the mesial
contour of the first molar should be tangent to this
arc.
In the mixed dentition the first mnolar will be 2
mm distal to the arc because of the lee way space.

•4- Posterior arc :-
Normally it passes through the gonion
and indicates either the chin is protrusive or
retrusive.
In well balanced face the corpus size is
equal to the cranial size i.e from the anterior
are the posterior arc.

•The vertical balance :-
The outer upper and lower facial height
should be equal in adult male, the lower face
height is larger 6-7 mm than the upper.
The distance from N to the inter section of
the anterior arc with the first plane should be
added to the lower face height from menton.

In posterior vertical height the upper
posterior and lower posterior heights should
be equal i.e the upper posterior and lower
posterior parts of the arc should be equal.
•Limitation :-
With this analysis you have to dissociate
between the soft-tissue and the skeletal
reading in class II skeletal with open bite on
the other hand it correlates well with class III.

•Axes :-
•M, M', M Axis of –
6
•m, m' Axis of –
6
•I, I', I Axis of ⊥
•I, I' Axis of T

•The Sassouni norm :-
In a well-proportioned face the four planes :-
•1- that tangent to the sella and parallel with anterior
cranial base, (2) the palatal plane, (3) the occlusal
plane, and (4) the mandibular plane, meet at O.
•2- while an arc from O to the anterior nasal spine
( ANS ) as a radius, will pass also through the
pogonion, the incisal edge of the maxillary central
incisor, the nasion, and the frontoethmoid junction.

•3- If a circle has centre O, an arc that passes
through the posterior wall of the sella turcica will
pass also through the gonion.
•A dysplasia in any one part of the face is reflected in
the face as a whole.
•4- The relation of the four planes to the commen
point, O, permits the classification of four facial types
:-
Type1: anterior cranial base plane does not pass
through O.
TypeII: palatal plane does not pass through O.
Type III: Occlusal plane does not pass through O.
Type IIII: Mandibu for base plane does not pass
through O.

•The axial relation of the maxillary and
mandibular teeth to the maxillary and
mandibular teeth to the palatal plane and
mandibular plane such that:
•Angle M = angle I + 10.
•Angle M = angle I + 5.
•The angle formed by the ramal plane with
the occlusal plane ® is equal to the angle
formed by the inc lination of the mandibular
centralincisor and the occlusal plane (I)
(angle R = angle I).

•Since the norm concept can not be
accepted as absolute for the individual,
Sassouni advocales measure ment of
proportionality in the individual as a base
for growth study, diagnosis, and
treatment planning.
•N.B: discrepancy within 1 – 2 mm by
archival analysis considers normal.

•Steiner's analysis (1953)
•1- SNA angle:
•Used by riedel in 1950 and
•then Steiner in 1953.
•It provides in formation
• of the anteroposterior
•position of the apical
•base of the maxilla
•either protruded or
• retruded to the anterior
• cranial base.
•Mean value is 81 sd 3.

•If it greater than 80, it
indicates protrusion of
the maxilla (skeletal
class II mal occlusion).
•If lt less than 80, it
indicates retrusion of the
maxilla (skeletal class III
malocclusion).
•This is describing the
position nothing
regarding the size.

•This angle influenced
by antero postemrior
position and also
bertical position of
nasion.
•If nasion is more
forward, higher, lower
or backward, this will
influence the value of
the angle.

Age change:
•This angle imdergpesminor age changes, there is
proportional growth between the maxilla and
anterior cranial base, it has to stay constant.
•Mansoura measurements:
Male: 82.15 + 2.8 female: 80.69 + 2.5.
Mean: 81.6 + 2.8.

2- SNB angle:
•It provide information of
the antero posterior
position of the apical base
of the mandible either
protruded or retruded to
anterior cranial base.
The mean value is 78 with
sd ± 3

•If the angle is smaller
than normal (class II)
malocclusion that is
caused by a
retrognathic mandible).
•If the angle is greater
than normal (class III
malocclusion duo to a
prognathic mandible).
•It is influenced by
antero posterior and
vertical position of the
nasion.

Age changes:
•This angle increase with
age, because the mand ible
grows more than the
maxilla, and the growth is in
horizontal direction.
Male: 79.69 + 2.4.
female: 77.8 + 3.29.
Mean: 78.9 + 3..

3- ANB angle :-
•It is the difference
between SNA and SNB
agles.
•It indicates the antero-
posterior position of the
maxillary apical base
relative to the mandibular
apical base.
•The mean value is 6 + 3.

If the value is larger than
the mean, this means that
maxillary protrusion or
mandibular retrusion, but it
will not tell you where the
maxilla is forward and
where the mandible is back
ward. (class II skeletal
malooclusion).

•If the value is smaller than
the mean, this means that
maxillary retrusion or
mandibular protrusion
(class III skeletal
malocclusion). But it does
not tell you which one is
wrong.
Mansoura measurements:
Male:205 + 1.8.
female: 2.88 + 1.09.
Mean: 2.46 + 1.53.

Factors affecting the values of SNA, SNB and
ANB.Angles:
(a) Size of the anterior crania base if it is
large or small this will change the
angulation.
(b) Position of nasion, higher or lower.
(c) Maxilla and mandible in relation to
position are bar word or back word or rotated
in a slight

The method of Richard reidal:
(1)Because the points S and N are both
located in hard, nonyielding tissue, are
directly and easily visible in a profile x-
ray picture, and particularly because
they one located in the midsagittal plane
and there for are displaced to a
minimum degree by movement of the
head, the SN line was chosen as a
reference line for all of the assessment
measurements.

4- SND angle:
(1)Point d: the middle of the symphysis. It is
used to represent the anterior aspect of the
mandible in a sagittal plane.
(2)Point D can be
established on the
mandible to serve as
equivalent purpose.

(3) The cross section of
the body of the mandible is
only considered.
(1)Alveolar process is
ignored because it is
influenced by the positions
of the teeth and is
changeable. Either visually
or with instrument,
establish a poing at the
centre of the mass of this
cross section. It is called
point D, like point sin in the
cranium.

It is well surrounded by sturdy
done, it is protected from
outside influences and is well
isolated from the area where
movement of the teeth and
normal grow the changes
occur. The SND angle is used
to esprss and evaluate the
antero posterior location of the
anterior portion of the
mandible in relation to the
head as whole.
SND will record the changes
more accurately than when
using the angles SNB or SNB
og.

Point D can also be used to
determine chnges, in the
position of the mandibular
teeth within the mandible. To
do so, erect a line through D
perpendicular to the line Go –
Gn. To a position even with
the incisal edge of the lower
incisor (d- line).
Generally D – line will pass
through the lower central
incisor but the varied
relationship of this totth to this
D- line will be a surprise.

D point is sued as a reference
point, and is transferred to
subsequent tracings by coping it
directly from the first.
Copy the line go – gn and the
point D from the first to the
subsequent tracing.
The line go – gn and poing D will
serve the same purposes for the
moving mandible, as does the
line SN and the poing N for the
rest of the skull. When the
mandible moves, line go-gn and
point D move with it.

Denture criteria:
Upper incisor to NA:
(linear).
•The upper incisor
should lie on the line
NA in such a way that
the most mesially
placed point on its
crown is 4 mm in front
of the line NA.
This measurement
indicates the interpose.

•Rior position of the
incisal edge ot he upper
central incisor, with
reference to the NA line.
•The clinician can decide
whether the incisor has
to be protruded or
retruded by tipping
mechanics, bodily
movement, or by a
combination of the two
procedures.

•This angle indicates the
inclination of the upper
central incisor.
•The axial inclination of to
NA line is 22.
•It is preferred to use NA
line instead of facial plane
because NA is
established by two fixed
points plane because NA
is established by two fixed
pints one of them on the
maxilla and in juxta
position to the tooth in
question.
Upper incisor to NA:

•It is preferred to use NA line
instead of facial plane
because NA is established by
two fixed points plane
because NA is established by
two fixed pints one of them on
the maxilla and in juxta
position to the tooth in
question. In contrast the facial
plane is depedent on a
changeable moving part.
•The chin point pogonion).
•A larger than normal angel,
is seen in class II division I
mal occlusion.

•Clinically, this angle is important in torgue control
when retracting or advancing upper incisors.
Mansoura measurements:
(1)to NA (linear): male: 5.81 mm + 3.77 mm.
female: 5.31 mm + 0.59 mm.
mean: 5.26 mm + 2.95 mm.
(1)to NA (angle(: male: 24.69 + 7.72.
femal: 24.88 + 2.84.
mean: 24.78 + 6.21.

Lower incisor to NB: (angle):
•This angle reveals the
•inclination of the lower
• central incisor.
•The axial inclination of
•the I to the NB line is 25.
•This angle is larger than
• normal in a class II
•division I malocclusion.
•This angle is smaller than
• normal in skeletal class III
malocclusion.
•Male: 29.45 + 6.35.
Mean: 29.62 + 6.1.

Lower incisor to NB
(linear):
•This measurement gives an
idivation of the antero-
posterior linear measurement
of the lower central incisor
with refrence to the NB line.
•The most mesial point on the
crown of the t is 4 mm in front
of the line NB.

•This measurement is larger
than normal, (protrusive or in
positive direction) in
malocclusions associated with
a convex profile. (class I
bimaxillary protrusion and class
II division 1).
•And larger in a negative
direction (retrusive) in mal
occlusions associated with a
straight or concave profile
(class II division 2 or class III).
•Male: 7.35 + 2.69 mm.
•Female: 6.91 + 1.44 mm.
•Mean: 6.90 + 2.25 mm.

Pogonion to NB (linear):
•The degree of prominence
of the chin should contribute
to a determination of the
placement of the lower.
There fore, the method of
holdaway is followed
and the distance is
measured from pogonion
(pog) the line NB.

•This distance will vary so wide
by among individuals that an
average or norm measurement
of it would have little diagnostic
value. Because the chin point
varies according to type in off
individuals so the difference
between the two
measurements T to NB and
pog to NB will vary widely
among normal individuals.
•Holdaways liked this distances
to be equal.

•He beleives that the overlying
soft tissues one of average
thickness and arrangement,
acceptable results can be
obtained when these
measurements vary within a
range of 2 mm. he regards a
3mm variance is being tolerated.
•The ratio between these two
measurements can be greatly
influenced by orthodontic
therapy and it can be brought
within acceptable limits.

•This measurement indicates
the amount of bony chin
buttons present in the
symphysis of the mandible.
•Clinically, this measurement
dictates the anterior
positioning of the lower
incisor during treatment.
•An in sufficient bony chin
contributes to a convex
skeletal profile, thereby
necessitating retraction of the
lower incisor to improve the
esthetics.

•A good chin enhances the profile and allows a
more labial placement of the lower incisor to
prevent a dished in appearance to the lower soft –
tissue profile.
•Average value is pog 4 mm in front NB line.
•Male 7.35 + 2.65 mm.
•Female: 6.81 + 2 mm.
•Mean: 7.14 + 2.4 mm.
•(t – NB / pong – nb)

Inter incisal angle:
This angle was illustrated in the downs analysis.
This angle used as a
supplementary method
of appraisal of the angulations
of these teeth (T to ┴ )
to each other and to the face.
This measurement indicates
the total variation from
normal of these teeth to
each other.
Average value is 131.

Occlusal plane angle (occl – SN):
The angle of the occlusal plane to SN (principle of
downs) except that this analysis uses the SN line
instead of the Frankfort horizontal plane. used by
downs.

A cephalometric survey of a case of malocclusion
would be incomplete without the appraisal of the
location of the teeth in occlusion to the face and to
the skull.

SN to mandibular plane agnle (go. Gn To
SN)"
The angle go-gn to SN is very useful in:
(1)Measures the degree of warpage or malformation
of the mandible it self or the surfaces with Which it
articulates.

(2) As an indication of the growth history. The line
Go-Gn has been taken to represent the body of the
mandible ( Riesel ). A line which more nearly
represents the mass of the body of the mandible
rather than its lower border is preferred. ( Mean
value is 32O
)

•Upper incisor to SN :-
•This angle reveals the inclination of the central
incisor, as related to the cranial base line ( SN ).

•Mean value is ( 104O
) .
•A larger than normal
angle indicates class II
division 1 and class III
malocclusion.
•A smaller than normal
angle indicates class II
division 2 malocclusion.
•Clinically this angle is
important torque control
when retracting or
advancing upper incisors.

•Modification of Tweed- Holdaway and
Steiner :-
Dr. Tweed selected 100 people of both sexes and
different age groups whom he considered to have
excellent facial profiles and who did not need any
orthodontic regulation.
Their occlusions were considered to be normal
and healthy in every respect.

He then proceded to make a comprehensive
cephalometric analysis of these patients using the
statistical data as the normal objective to be
attained in evaluating a malocclusion.
In this manner he advised his 90O
( ± ) 5 formula.
It is his contention that the lower incisor must be
upright on basal bone. This theory has been criticized in
many quarters because it is a cut and dry method in
dealing with numerous complex situations which are not
accounted for.

Dr. Holdaway, who feels that Dr. Tweed's
estimate has some merit, none the less claims that
the relationship of the mandible to the maxilla can
not be ignored when making any sort of evaluation
as to the proper axial inclination of the anterior teeth.
•1- To prove this point, he took Dr. Tweed's data of
the same 100 patients and found that the ANB
varied from minus 1O
to plus 5O
.

•2- He then put the patients into specific groupings
and found that the median normal for ANB was
( 2O
) Further study showed that long axis of the
upper central to the NA line formed an angle of
( 22O
) with the incisal edge 4 mm. distant from the
NA line along the occlusal plane.
3- Like wise, he found that the long axis of the lower
incisor to the NB line formed an angle of ( 25O
) with
the incisal edge 4 mm. from the NB line along the
occlusal plane.

•4- These findings challenged D. Tweed's formula.
•There is no doubt that the angle ANB definitely
influences the axial inclination of the upper and
lower anteriors.
5- The fact is, as the ANB increases, the axial
inclination of the maxillary incisors decreases, while
the axial inclination of the mandibular incisors
increases.

•6- Proportionately, as the procumbency of the
uppers diminishes, the incisal edge of the
maxillary incisors lies closer to the NA line.
•7- In the lower arch, as the procumbency of the
incisors increases, the distance from the incisal
edge to the NB line increases.
8- If the ANB reading falls beyond minus 1O
to plus
5O
, it can be certain that an aesthetic or stable
result can hardly be expected.

Dr. Steiner, has formulated what he refers to as
( the ideal acceptable Arrangements ) Rather than
be committed to a statistical median normal, it is his
contention that man must have several normal
arrangements which may be considered
aesthetically acceptable and stable.
In other words, all people do not fall into a rigid
pattern, as Dr. Tweed contends, nor do people
necessarily have to conform to any sort of a median
norm since the normal range varies to such a great
degree.
All this reasoning was brought forth from the data
accumulated from Tweed's 100 cases.

•The lower line: symbolizes the long axis of
the lower central as it relates to the NB line
in mm. and degrees.
At an ANB of 2O
, the readings are 4 mm and
25O
.
•As the ANB increases, the figures
representing the upper central decrease
while the figures representing the lower
central increase.
•The reverse is true when the ANB goes
below 2O
.
•

•A patient with an FMA between 15O
to 35O
and an
ANB of -1O
to +5O
may be considered one that falls
within a normal range.
With an ANB above 9O
or below -3O
, the prognosis
is poor.
Should such patient have a 40O
FMA or above, the
prognosis is hopeless.
•When ANB increases, by 1O
, ⊥ to NA decreases
by 1 ( millimetric or angular ) and T to NB increases
by 0.25 mm and 1O
.
•When ANB decreases, by 1O
, ⊥ to NA increases by 1
( millimetric or angular ) and T to NB increases by
0.25 mm and 1O
.

•Michigan analysis.
•SNA. ( Steiner 1953 )
•SNB. ( Steiner 1953 )
•ANB. ( Steiner 1953 )
•Facial angle : ( Down's
1948 )
•It is determined by drawing a
line from nasion to pogonion,
this plane is called the facial
plane. The inferior inside
angle of its intersection with
the FH is the facial angle.

•Downs used FH as a reference plane because it
gives him the natural position of the head in
determining this angle.
•There is one factor which affect this angle which
is the morphology of the symphysis :-
•(1) Long and narrow, in this condition there is no
difference between B point and pogonion.

2- Button like chin, and in assessing SNB in a
case you may find its value indicates a class II but
facial angle tells you it is class III duo to the button
like symphysis.
3- Short and broad chin.
•Age changes :-
If you have a child syears old and shows some
tendency toward larger Facial angle, it will
becomes larger and, the larger. So if you have a
class II at syears, the profile of this patient is
improving because of the growth of the mandible.
This angle tests the SNB. And gives some
verification.

•Angle of convexity ( Down's ) :-
•A-B to facial plane angle ( Down's ) .
•A-B to occlusal plane : ( Bushra 1974 )
•It measures the relative position of point A
and B to occlusal plane.
•If B point is forward the inferior posterior
angle formed by A-B line and occlusal plane
is increased than 90O
which is the mean.
•If point B more backward, the angle is
decreased.

•Male : 0.96 ( ± ) 2.25 mm.
•Female : 0.94 3 ( ± ) 3.22 mm.
•Mean : 0.24 ( ± ) 2.75 mm.
There are two types the occlusal plane :-
•(1) Functional occlusal plane :-
Which is formed by bisecting cusp heights of molars and
bicuspids, but not the incisors. Because in open bite and
deep over bite cases the anatomical occlusal plane is
distorted.
(2) Anatomical occlusal plane :-
Formed by bisecting the incisor overbite and cusp
height of the molars.

•Wits appraisal ( Jacobson
1975 ) :-
The wits appraisal of jaw
disharmony is a measure of
the extend to which the jaws
are related to each other
antero posteriorly .
•It entails drawing
perpendiculars on a lateral
tracing from points A and B
on the maxilla and mandible
respectively onto the
occlusal plane which is the
functional occlusal plane.

•The points of contact on the
occlusal plane are labeled Ao and
Bo.
•The normal value : for
Female, is 0 i.e Ao and Bo
concided ( ± ) 2.
: for male, -1 to -2 point b forward.
If Bo is anterior to Ao, the value will
be negative.
If Bo is posterior to Ao, the value
will be positive.
Wits eliminates the problem of
SN either too forward or too
backward so it assess points A
and B.

•SN. To Mandibular plane :- ( Steiner )
It is formed by intersection of the SN line with the
mandibular plane.
•There are two basic mandibular plane :-
•(1) From menton to just behind the antegonial notch
tangent to the lower border of the mandible.
• ( Down's and Tweed ).

•From Go-Gn ( Steiner ) :-
•The angle formed by SN and mandibular
plane provides information in vertical and
antero posterior dimensions. i.e the lower half
of the face and position of the chine.
•In flat mandibular plane angle ( smaller
angle ) :-
oPNS could be normal or tipped up
ward.
oThe gonial angle is acute.
oThe condyle is lower in position.

•In higher or steep mandibular plane
angle ( larger angle ) :-
oRamus is short, corpus is short i.e
oral size of the mandible is short.
oThe gonial angle is obtuse.
oThe condyle is very high relative to
the sella turcica.

•Clinically :-
•(1) Patients with higher or steep mandibular
plane angle : have – Large lower face height
– Retrusive chin.
•Steep mandibular plane is usually
associated with class II open bite.
•Higher steep mandibular plane is not related
to the prognosis of the case because you
many find a case nice looking and has only
steep mandibular plane.

2- Patients with flat mandibular plane angle : have
– The posterior facial height is smaller than the
anterior lower face height or equal to it – forward
position of the chine.
•There is a negative correlation between the facial
angle and mandibular plane.
If the facial angle is large, the mandibular plane
will be flat.
If it is small, the plane will be steep.
Mansoura measurements :-
Male : 29O
( ± ) 6.07O
.
Female : 33.75O
( ± ) 4.3O
.
Mean : 30.81O
( ± ) 5.84O
.

•SN to palatal plane angle
•It gives information regarding position of ANS, PNS
or rotation of the plate. PNS may be tipped up or
down relative to ANS. i.e in clockwise or counter
clock wise direction.

•If you have smaller angle : this means that
there is no displacement of PNS down ward in
counter clock wise direction.
•This will decrease the anterior lower face
height.

•If the angle is greater than 8O
: this means
that the ANS tipped down ward and this is
associated with large anterior facial height.
•In normal subjects palatal plane will pass
through the odontoid process and basion this
gives a very good clue regarding the
displacement of PNS.
•Male : 9.19O
( ± ) 3.4O
.
•Female : 11.25O
( ± ) 5.12O
.
•Mean : 9.98O
( ± ) 4.15O
.

•Palatal plane to Mandibular plane :-
( used in 1936 by Schwarz and picked up by
Sassouni ).
•It can figures if there is something wrong regarding
SN or palatal plane.
•Large angle indicates :
Steep mandibular plane. or PNS tipped down ward
or both.

•It is usually associated with large anterior
facial height, and small posterior facial height.
•Large angle suggest open bite or class II.
•Male : 20.27O
( ± ) 6.37O
.
•Female : 22.88O
( ± ) 5.4O
.
•Mean : 21.26O
( ± ) 6.03O
.

•Cranial base angle :-
( used by Pjork 1947 and Ricketts )
•It is formed by 2 lines SN and SBa.
•It denotes the of glenoid
fossa and TMj and some
information regarding
malocclusion.

You are measuring the angle in midsagittal plane but
the glenoid fossa is bilaterally positioned so it may
implied for the synchronized growth in the midsagittal
and lateral directions.
In obtuse angle cases :
The mandible is carried
backward which reflects
chin backward.

•In acute angle cases : TMJ will be forward
and the mandible is carried forward creating
class III or protrusive mandible.
•Even if the mandible has normal shape and
size it may has different position if cranial
base angle is large or small.
•Male : 147.12O
( ± ) 9.6O
.
•Female : 148.5O
( ± ) 6.2O
.
•Mean : 147.6O
( ± ) 8.5O
.

•Frankfort horizontal to mandible Plane
angle :-
( Tweed 1946 and Down ).
•It is very similar in information gained by SN
to mandibular plane.

•Facial axis ( Ricketts ) :-
•It is constructed of Na – Ba and gnathion –
foramen – rotundum.
•It is an expression of growth in the horizontal and
vertical direction of the
• face.
•Large values will have
• more or less skeletal
• problems.

•If the chin is too forward, you will have large value,
if it is too posterior, you will have small value.
It is very similar to Down's Y axis.
•It gives information regarding the downward and
forward growth direction during development.
•If you have equal horizontal growth to vertical
growth, the angle will be 90O
.
If the vertical growth exceeds the horizontal growth,
the angle is decreased.

If the angle is larger, this denotes that
the growth is in horizontal direction.
•Try to relate facial axis with the facial
angle, facial axis alone gives the
position of the chine only.

•Posterior facial height to anterior
facial height :-
•The mean value is 65 % ( it is the percentage
of S- Go to Na-Me ).
•Smaller values, are associated with skeletal
open bite, this denotes that anterior facial
height is large and posterior facial height is
smaller.
•You can use SN palatal plane or Mand. plane
to palatal plane because the latter angle give
the same things.

•Lower anterior face height to total pace height :-
•The mean value of ( ANS - Me to Na - Me ) is 54.6 % .
•Larger values tends to reflects skeletal open bite.
You have to correlate with the bizygomatic width to see
either it matches or exceptible wide face with large
lower facial height and the face looks good so this is
compatible.

Aging reduced lower facial height and
persons with low anterior facial height aged
early.
•At 6 years in males and females th upper
face height and lower anterior face height are
equal in length.
•At 12 years, in females the 2 dimensions are
equal, but in males the lower anterior face
height is 3 mm longer than the upper anterior
one.
•In adult age, lower anterior face height in
female is 3 mm longer than the upper one
and in males 7.10 mm longer than the upper.

•T to Mandibular plane ( IMPA ) :- ( Tweed )
•It relates the axial inclination of the most labial
incisor to the mandibular plane.
•It depends on the morphology of the mandible and
the mandibular plane.
•If the mandibular plane is small or flat, the angle will
be small.
If the mandibular plane is steep, the angle will be
large.

•In class III the lower incisors are lingually
inclined and the mandibular plane is small and
mandibular plane is flat, and IMPA smaller
than 90O
, this is very important in performing
surgery for the mandible, the cause of the
lingual inclination of the incisors in class III is
the pressure of the lower lip because in this
case there is no toughie pressure on these
teeth.
•Male : 101.65O
( ± ) 8.1O
.
•Female : 97.75O
( ± ) 7.2O
.
Mean : 100.17O
( ± ) 7.8O
.

•T to FH ( FMIA ) :- ( Tweed )
•It express lower incisor to bony profile, the
average is 65O
.
•If IMPA is large, FMIA will be smaller and
vise versa.
IMPA, FMIA and MPA form the Tweed
triangle.
•Lower incisors upright with age, IMPA will
decrease, FMIA will increase.

•So when we see crowding the reason may
be either duo to improper angulation by
orthodontic treatment or duo to late growth
changes.
•Male : 55.15O
( ± ) 5.8O
.
•Female : 55.3O
( ± ) 5.75O
.
•Mean : 55.21O
( ± ) 5.66O
.

•T to ⊥ ( Down's )
•T to NA ( Steiner )
•It relates the ⊥ to denture base either angular
or linear.
•T to NB ( Steiner ) :-
•This angle checks the procumbency of T relative
to the denture base.
•The average is 25O
and 4 mm.
•The distance in mm will decrease with age duo to
righting of the incisors from 6 – 12 years of age.
The angle will increase from 6 – 12 years duo to
labial eruption of permanent incisors.

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