Surgical orthodontics part 1

Contents:
Introduction
Historical aspect
Envelop of discrepancy
Esthetic and psychosocial considerations
and Psychological reactions to orthognathic
surgery
Recognition of deformity
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 Systemic evaluation of patient
 Cephalometric evaluation
 Prediction tracing
 Pre surgical orthodontics
 Mock surgery
 Surgical treatment
 Post surgical orthodontics & retention
 Conclusion

"Beauty lies in the eyes of beholder" .
Margaret Hungerford.
Physically attractive people are generally
thought to be more friendly, sensitive and
successful than others considering the face. As
a primary means of identification and a source
of non-verbal information, the psychological and
social implication of facial disfigurement should
not be underestimated.

In the popular ‘psychocybernetics’ Maxwel
Waltz wrote “ when you change a mans face
you almost invariably change his future,
change his physical image and nearly always
you change the mans personality, his
behavior and sometimes even his basic
talents and abilities ”

Before advent of surgical procedures to
correct deficiencies of maxilla the only way the
orthodontists could treat patients presenting
with vertical maxillary excess was by dental
camouflaging the skeletal problems.

David Sarver will deserve much of
the credit for bringing about the computer
simulations. Previously cephalometric
predictions of treatment outcome were
necessary, but nowadays, computer imaging
changed the very focus of orthodontic and
orthognathic treatment.

A) Origin of surgical procedures
B) Pre/post surgical orthodontics

Of the current surgical techniques for
repositioning the facial bones, many were
pioneered in Europe to treat trauma and
gunshot wounds during 1st and 2nd world war
and to lesser extent in United States.
The term orthognathic surgery was coined
by Hullihen in 1849.
(A) ORIGIN OF SURGICAL PROCEDURES:

Rene Le Fort in 1901 noted that the midface
consistently sustained fractures at sites of weakness .
Edward Angle in 1901 Commented on the patient who
had treatment of this type, described how the result
could have been improved .
Van Eiselberg and Pehr Gadd in 1906 , were the first
to conceive the idea of surgically correcting a retruded
mandible by means of a step shaped osteotomy in the
body of mandible.

In 1907 Blair introduced the first
ascending ramus technique in which he
sectioned the ramus horizontally above the
inferior alveolar nerve and vessels .
Limberg in 1928 modified Pehr Gadd's
step shaped sliding osteotomy operation by
inserting a pedunculated rib graft in
surgically created bony defect.

Wassmund in 1935 introduced a technique for
retruding the anterior maxillary alveolus and six
anterior teeth.
Kazanjian in 1936 modified Blair's basic
design by performing an oblique sliding
osteotomy.

Dingman performed an osteotomy in two
stages. First under local anesthesia and second
under general anesthesia and found that non-
union and parasthesia are common
complications
Caldwell in 1954 adapted his vertical
osteotomy technique for correction of
prognathism to the correction of
micrognathism.
Erich in 1958 believed that retrognathism is
best corrected by means of overlay prosthesis
on the lower anterior teeth.

Trauner and Obwegeser introduced sagittal
split osteotomy in 1959 and it marked the
beginning of new era in orthognathic surgery.
This technique used an intraoral approach,
which avoided the necessity of potentially
disfiguring skin incision.
Kole in 1959 introduced corticotomy as a
surgical adjunct to orthodontic therapy.
Although the foundations for present day
procedures were laid in Europe, the
development and refinement of orthognathic
surgery occurred in United States.

(B) PRE AND POST SURGICAL HISTORICAL
ASPECT:
William Bell in 1966 discussed different
methods of orthodontic surgical correction of
mandibular retrognathism.
Peter B. Mills in 1969 discussed the role of
orthodontists in surgical correction of dentofacial
deformities.

Bell, Thomas and Creekmore in 1973 stated
that the goal of surgical orthodontic treatment of
mandibular prognathism is to correct the
malocclusion of the teeth and restore facial
balance and harmony.
Epker and Fish in 1978 stated that pre-
surgical orthodontics should be directed towards
removing the existing dental compensations.

Dale B. Wade in1980 used modules for
intermaxillary fixation. It was developed to help
the orthodontists prepare his patient for surgery
and provide the surgeon with the stable fixation
need for proper healing.

Legan, Hill and Sinn in 1981 discussed role of
orthodontist in diagnosis and treatment
planning in dentofacial deformity cases. He
suggested that the pre-surgical orthodontic
treatment carried out for them included leveling
of mandibular occlusal plane, uprighting the
mandibular anterior teeth, correcting minor
rotations and angulation problems and
coordination of arches.

Joe Jacobs in 1983 stated the principles of
orthodontic mechanics in orthognathic surgery.
Flanary, Barnwell and Alexander in 1985
investigated the pre-surgical concerns and
motivations, preoperative preparation for
surgery and perception of post surgical outcome.

Fish and Epkar in 1987 discussed the
prevention of relapse after maxillary
advancement. Suggested that Post surgical
orthodontics include, prevention of relapse
during inter-maxillary fixation where surgical
occlusal splint with bilateral infra-orbital
suspension wires were attached.

The limits of correcting a malocclusion
vary both by the tooth movement that would be
needed and by the patient's age as quoted by
William R. proffit.

There are 3 possibilities of treatment;
Tooth movement by orthodontic treatment.
Tooth movement by orthodontic treatment
combined with growth modifications.
By orthognathic surgery.

 The first envelope shows the amount of change
that could be produced by orthodontic tooth
movement alone.
 Second envelope of discrepancy indicates the
changes in the teeth movement that can be
achieved orthodontically along with growth
modification.
 Third envelope shows, the changes that can be
achieved by orthognathic surgery.

RETRACTION
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MAXILLA

PROCLINATION
RETRACTION
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MANDIBLE

Esthetic and Psychosocial
considerations

 The negative effect of psychic & social well
being from dentofacial disfigurement is well
documented, and it is clear that this is why
most patients seek orthodontic treatment.
 Those who look differently are treated
differently and this becomes a social handicap.
 Although most individuals who are evaluated
for orthognathic surgery desire an
improvement in function as well as esthetics,
several studies has shown that 75%-80% seek
esthetic improvement.

.Data from psychological testing of patients
in the University of North Carolina
Dentofacial programme, through which
orthognathic surgery patients were evaluated
and managed, showed a high prevalence of
psychological distress (15%-37%) .

 Orthodontic treatment primarily affects the
prominence of the teeth and the contours of
the lip. The changes in the position of the
chin and nose are likely to have a greater
impact on the patients aesthetics than
changes limited to the lips, and the effect of
orthognathic surgeries on the lower face
extends the aesthetic impact of treatment
considerably.

• If aesthetic improvement is a major goal
of treatment ,it makes sense that changes in
the nose , and perhaps and other changes
in the facial soft tissue contours that would
be produced by facial plastic surgery should
be considered in treatment planning.

• A more contemporary approach is
to decide how the patient soft
tissues should look , and then work
backward to determine what would
have to be done to the underlying
hard tissues to produce the desired
soft tissue outcome.

Psychological reactions to
orthognathic surgery:
 On “objective” evaluation , most observers
would conclude that both orthodontic
treatment alone and orthognathic surgery
usually improve patient appearance , but the
important consideration is whether patients
agree?

 About 90% of patients who undergo
orthognathic surgery report satisfaction with
the outcome and over 80% say that ,
knowing the outcome and what the
experience was like, they would recommend
such treatment to others and would undergo
it again. This does not mean that there are
no negative psychological effects from this
type of surgical treatment.

First , a few patients have great
difficulty in adapting to significant
changes in their facial appearance .This
is more likely to be a problem in older
individuals. If you are 19 yrs your facial
appearance has been changing steadily
for all your life, and another change is
not a great surprise.

 If you are 49 yrs and suddenly see a different
face when you look in the mirror, the effect may
be unsettling. Psychological support and
counseling , therefore, are particularly important
for older patients, and major aesthetic changes in
older adults may not be desirable. The older
group may need orthognathic surgery to achieve
their goal ,but for them , often treatment should
be planned to limit facial change ,not maximize it.

 Second , whatever the age of the patient ,
period of psychological adjustment
following facial surgery must be expected
.In part, this is related to the use of steroids
at surgery to minimize post-surgical
swelling and oedema.Steroid withdrawal
even after short term use ,causes mood
swings and a drop in most indicators of
psychological well being. The adjustment
period lasts longer than can be explained
by steroid effects.

• A surgeon learns to put up with
complaining patients for the first week
or two post-surgical .By the time
orthodontic treatment resumes at 3-6
weeks post surgery, the patients are
usually – but not always –on the positive
side of the psychological scale.
Sometime the orthodontist also has to
wait for a patient to make peace with the
surgical experience.

 With current technology ,it is possible now
to show patients computer simulations of the
aesthetic impact of surgical treatment. The
psychological impact of doing this has been a
matter of considerable concern.
 Current research shows that there is little
or no danger of producing unrealistic
aesthetic expectations ,and on balance, it is
better to share simulations with the patients .

According to V. Mani (1995) the deformities
are classified as;
1.Maxillary prognathism - Skeletal
- Dentoalveolar
2.Maxillary retrognathism - Skeletal
- Dentoalveolar

3. Maxillary vertical deformity -Excess
-Deficient
4. Maxillary transverse deformity -Broad
-Narrow
5. Mandibular prognathism - Skeletal
- Dentoalveolar
6. Mandibular retrognathism - Skeletal
- Dentoalveolar

7. Chin
Excessive - Vertical
- Horizontal
Recessive - Horizontal
- Vertical
8. Deep bite deformity

9. Open bite deformity or Apartognathia
10. Asymmetry

Maxillary deformity:
Epkar and Fish (1994) quoted that the
deformities of maxilla are of several types. The
deformities are either in the basal bone or in
dentoalveolar segment. The most common
deformity encountered can be horizontal,
vertical or combined. The deformity can be
associated with deep bite or open bite.

Schendel S.A. quoted that in vertical excess,
1) the exposure of the upper anterior teeth is
more than 3 mm
2) in response the upper lip may be short or
normal
3) the length of lower third of face is more than
the middle third of face.
Open bite can also occur as a result
of deformity in anterior or posterior region.

Mandibular deformity:
Mandibular deformity can be present
anywhere from the condyle to chin. Ankylosis of
TMJ jeopardize the mandibular growth.
Unilateral ankylosis causes hemi facial deformity
with the midline shifted to the affected side.
Mandibular prognathism is mainly due to
horizontal excess of the body of the mandible as
quoted by Opdebeeck H and Bell W.H.

Chin deformity :
The chin can be either recessive or
excessive, vertically or horizontally The
measurements are as follows,
1) Facial axis
2) Facial depth angle

SURGICAL DECISION
1. Maxillary setback:
Indicated in maxillary protrusion cases.
The features associated are;
 Convex face
 SNA angle increased
 Distance from point A to facial plane (N-Pog)

 Horizontal dimension of maxilla 
Epkar and Fish (1994)

 Angulation of upper incisor 
 Gummy smile
 Nose-lip angulation 
 Maxillary depth angle 
 Max length : Mand length (ratio )

2. Superior repositioning of maxilla
Indicated in cases where vertical dimension
of lower third of face is increased along with
increased exposure of anterior teeth and inter
labial distance. The features associated are;
 Distance from subnasale to menton 
 Chin prominence 
 Alar bases widened
 Facial convexity 

3. Subapical osteotomy of the anterior
mandible
Indicated in cases where
 Anterior cross bite with no lip chin deformity
 Lower lip pronounced
 Closure of open bite
 In bimaxillary protrusion
 In combination with mandibular advancement

4. Maxillary advancement
 Concave face due to maxillary deficiency
 May be associated with class-III
malocclusion
 Accentuated nose lip angulation

5. Mandibular setback
  Chin prominance
 Over exposure of lower lip
 Lack of lip chin definition

  Lower third height
  Mandibular plane angle
  Facial axis angle/depth angle
 Distance from point A to facial
plane (N-Pog) 
 Class-III malocclusion with or
without crossbite

Mandibular set back done at the level of
ramus is called – Sagittal split osteotomy
At the level of premolar or body of the
mandible – Subsigmoid vertical osteotomy

6. Mandibular advancement
  Facial axis angle
  Facial depth angle
 Length of mandible is less in relation to
maxilla
  Vertical dimension of lower third of face

7. Genioplasty
Indicated in cases where the deformity is in the
chin. chin can be repositioned in all three
dimensions. soft tissue movement is 60%-70% with
bony movement.

(A) General patient evaluation
(B) Social psychologic evaluation
(C) Esthetic facial evaluation
(D) Cephalometric evaluation
(E) Panoramic or full mouth periapical
evaluation
(F) Occlusal evaluation
(G) Masticatory and TMJ evaluation

Epkar and Fish Quoted that certain
examinations are necessary to evaluate the
individual with dentofacial deformities and to
plan treatment. These are;
(A) General patient evaluation:
1) Medical history
-cardiopulmonary, endocrine,
hematologic, neurologic and allergic
problems.
2) Dental evaluation
a. Dental history
b. Dental health

(B) Social psycologic evaluation :
Unrealistic patient expectations regarding the
result of treatment
The patient must be made aware of and accept
the fact that even with the most skillful therapy
they will probably never look exactly like they did
before.
Post surgical psychology (swelling)

(C) Esthetic facial evaluation
The esthetic facial evaluation is done directly
on patient, with the patient standing or seated
comfortably. The patient maintains head
posture with the Frankfort horizontal and
interpupillary lines parallel to the floor.
1. Front face analysis
2. Profile analysis

1. FRONT FACE ANALYSIS:
General facial characteristics:
David Sarver (1998) quoted that symmetry,
balance and morphology are important in
production of good front face esthetics.
A) Symmetry : No face is perfectly
symmetrical. The absence of obvious
asymmetry is necessary for good esthetics.

B) Balance : The total face height is defined by the
distance from points trichion (Tr) to gnathion (Gn) and
divided into facial thirds by points glabella (G) and
Gnathion(Gn) . The upper, middle and lower facial
thirds may be defined as the distance from trichion to
glabella, glabella to Subnasal and Sub nasal to
gnathion respectively. In normal attractive person the
ratio of these thirds is 0.30, 0.35 and 0.35 respectively.

0.30
0.35
0.35

C) Morphology :
The morphology of any face is determined
by the distance between the points fronto-
temporale (Ft) - the slight elevation of the linear
temporalis on either side of forehead.
The width of middle third of face is defined
by the distance between the points zygion (Zy)
- the most lateral point of zygomatic arch.
The distance between gonion (Go)
bilaterally determines the width of the lower
third of face.

UPPER THIRD FACE:
Hairline to eyebrows (Tr-G)
 It is affected by the hairline
and hair style.
 Morphology : It is
quantified by calculating
the ratio of bitemporal
width'(Ft-Ft) to the height
of the upper third face (Tr-
G) the ratio in an attractive
individual is 2:20.
2:20

MIDDLE THIRD FACE:
Morphology is quantified
by calculating the ratio
of bi-zygomatic width
(Zy-Zy) to the height of
the middle third face (G-
Sn). The ratio in
attractive individual is
2:20.
2:20

Eyes and orbits :
Examination begins with
measurement of intercanthal
and interpupillary distances.
Vertical symmetry of inner
and outer canthi is recorded.
EARS : The ears are
observed for symmetry level
and projection.

NOSE: When deformity
exists, then glabella,
dorsum tip and alar
bases are noted.
CHEEK: includes
sequential assessment
of the malar eminence,
infraorbital rims and
paranasal areas for
symmetry.

LOWER THIRD FACE
(Subnasal to menton)
Morphology is
quantified by
calculating the ratio of
bigonial width (Go-Go)
to the height of the
lower facial third(Sn-
Gn). Normal ratio
is1:30.
1:30

LIPS: Lips are important in overall
esthetics of face. At rest, the symmetry of
lips relative to the face and dentition is
noted.
TEETH : Symmetry is single most
important factor in producing an esthetic
smile. It includes the symmetry of both lip
movement and tooth exposure.

CHIN : Often the chin may be more tapered or square.
Chin is evaluated for symmetry, vertical relations and
morphology and its relationship to the mandibular
angles and inferior border of mandible.
Sub Mental and Neck Area: This is examined by
having the examiners and patients head at the same
level looking directly into one another's eyes and
check for any asymmetry.

2. PROFILE ANALYSIS:
It is carried out in upper middle and lower
third of face.
A) Upper third face:
The projection of supra-orbital rims is
evaluated as they relate to globe. They project
5-10 mm beyond the most anterior projection
of globe. Distinction is made between frontal
bossing and supra-orbital hypoplasia.
The glabellar angle is evaluated. This angle
is formed by the intersection of the lines
glabella - nasion and nasion - pronasale.
Normal angle is 132  5 deg .This angle is
judged as excessive, normal or deficient.

132°  5°...

B) Middle third face:
Eyes: The lateral orbital rim normally lies 8 to
12 mm behind the most anterior projection of
the globe while infra-orbital rim is normally 0
to 2 mm anterior to globe.
NOSE: The nasal bridge projects 5-8 mm
anteriorly to the globes. The nasal dorsum is
described as normal, convex and concave in
appearance. Differentiation is made between
the dorsal hump and down turned nasal tip.
Nasolabial angle is assessed. Normal 90°-
110°.

C) Lower third of face:
Lips: The protrusion or retrusion of
the upper lip is described as it
relates to subnasal perpendicular
an imaginary line through subnasal
and perpendicular to Frankfort
horizontal. The most prominent
portion of the vermilion of the
upper lip should lie not more than
2 mm ahead or behind the
subnasale perpendicular.
Normally upper lip projects slightly
(2 mm) anterior to the lower lip.

CHIN PROJECTION:
It relates to the nose and subnasal
perpendicular in the middle third face and lips in
the lower third face. It should lie 2 - 6 mm
behind an imaginary subnasale perpendicular
line assuming normal nasal and maxillary
prominence.
Submental and neck area: It is subdivided into;
>Mandibular angle
>Neck chin angle (110°)
>Neck chin length.(50mm)

(D) Cephalometric evaluation
1. Soft tissue
2. Skeletal
3. Dental
(E) Panoramic or full mouth periapical
evaluation
(F) Occlusal evaluation
1. Functional – done to determine the
compatibility between CO & CR. Failure to
appreciate in this may result in errors in the
treatment planning and surgery.

2. Static – it is done in 3 parts.
a) Intra arch relations where midline of the arch
relative to the skeleton & soft tissue of face is
noted. Arch form, symmetry, anomalies of
Occlusal plane and curve of spee noted.Crowding
is also measured.
b) Inter arch relations exist in 3 planes of space.
Anteroposteriorly Angles classification is observed
for both canine & molar & incisor overjet is also
measured.
Vertically overbite is noted.
Transversly co-ordination of upper & lower
midline & buccal or lingual crossbite are
evaluated.

c) Tooth mass relation is
critical.Such discrepancies must
be taken into consideration to
achieve good occlusion with
normal overjet, overbite
relations.Use of Boltons analysis
is recommended.

(G)Masticatory and TMJ evaluation
 Masticatory muscles
 Mandibular movements
 TMJ symptoms
 TMJ signs

Cephalometry is an excellent tool for
quantifying, classifying and communicating
patient data.
It is useful as a treatment-planning tool
through the construction of prediction tracings
to study profile changes and to allow the
planning of extractions and orthodontic
mechanics to meet the treatment objectives.

The shape of the face depends mostly on
the basic skeletal architecture. Thus skeletal
analysis is mandatory for identifying and
classifying any deformity. Innumerable analysis
has been proposed to study the skeletal
relations. Among them some are;
Burstone's analysis ( COGS for both hard and
soft tissue)
Dipaolo's (Quadrilateral analysis)
Grummon’s analysis

Successful treatment of the orthognathic
surgical patient is dependent on careful diagnosis.
Cephalometric analysis can be an aid in the diagnosis
of skeletal and dental problems and a tool for
simulating surgery and orthodontics by the use of
acetate overlays. Cephalometric analysis also allows
the clinician to evaluate changes after surgery.
The first step in the diagnosis of the
orthognathic surgical patient is to determine the
nature of the dental and skeletal defects.

Patients who require orthognathic surgery usually
have facial bones as well as tooth positions that must be
modified by a combined orthodontic and surgical
treatment. For this reason, a specialized cephalometric
appraisal system, called Cephalometrics for
Orthognathic Surgery (COGS), was developed at the
University of Connecticut. This appraisal is based on a
system of cephalometric analysis that was developed at
Indiana University, with the addition of clinically
significant new measurements.

The COGS system describes the horizontal and
vertical position of facial bones by use of a constant
coordinate system; the sizes of bones are represented
by linear dimensions and their shapes, by angular
measurements.
The standards are based on a sample obtained
from the Child Research Council of university of
Colorado School of Medicine. Although the sample of
16 females and 14 males is small, the mean
measurement values closely correspond with those of
other northern European populations.
This longitudinal sample was selected to
ensure consistent standards by age and rate of
growth.

Cephalometrics for orthognathic surgery
(COGS)
•Charles J Burstone
•Randal B. James
•Legan
•G. A. Murphy
•Louis A. Norton

Cephalometric Analysis
Sella (S) : the center of the pituitary fossa.
Nasion (N) : the most anterior point of the nasofrontal
suture in the midsagittal plane
Articulare (Ar) : the intersection of basisphenoid and
the posterior border of the condyle mandibularis.
Pterygomaxillary fissure (PTM) : the most posterior
point on the anterior contour of the maxillary
tuberosity

Subspinale (A) : the deepest point in the midsagittal
plane between the anterior nasal spine and prosthion,
usually around the level of and anterior to the apex of
the maxillary central incisors.
Pogonion (Pg) : the most anterior point in the
midsagittal plane of the contour of the chin
Supramentale (B) : the deepest point in the midsagittal
plane between infradentale and Pg, usually anterior to
and slightly below the apices of the mandibular incisors.
Anterior nasal spine (ANS) : the most anterior point of
the nasal floor; the tip of the premaxilla in the
midsagittal plane.

Menton (Me) : the lowest point of the contour of the
mandibular symphysis
Gnathion (Gn) : the midpoint between Pg and Me,
located by bisecting the facial line N-Pg and the
mandibular plane (lower border).
Posterior nasal spine (PNS) : the most posterior point
on the contour of the palate.
Mandibular plane (MP) : a plane constructed from Me to
the angle of the mandible (Go).
Nasal floor (NF) : a plane constructed from PNS to ANS.
Gonion (Go) : located by bisecting the posterior ramal
plane and the mandibular plane angle.

The baseline for comparison of most of the data
in this analysis is a constructed plane called the
horizontal plane (HP), which is a surrogate Frankfort
plane, constructed by drawing a line 7° from the line S
to N. Most measurements will be made from projections
either parallel to HP or perpendicular to HP.

CRANIAL BASE
First, it is necessary to establish the length
of the cranial base, which is a measurement
parallel to HP from Ar to N. This measurement
should not be considered an absolute value but a
skeletal baseline to be correlated to other
measurements, such as maxillary and
mandibular length, to obtain a diagnosis of
proportional dysplasia.

Ar-pterygomaxillary fissure (Ar-PTM) is
measured parallel to HP to determine the
horizontal distance between the posterior aspects
of the mandible and maxilla. The greater the
distance between Ar-PTM, the more the mandible
will lie posterior to the maxilla, assuming that all
other facial dimensions are normal. Therefore, one
causal factor for prognathism or retrognathism
can be evaluated by this measurement of the
cranial base.

HORIZONTAL SKELETAL PROFILE
A few simple measurements should be made on
the skeletal profile to assess the amount of
disharmony. We call this the horizontal skeletal profile
analysis because all the measurements are made
parallel to HP. This is very practical because most
surgical corrections. primarily made in the
anteroposterior direction.
The first measurement quantitatively describes
the degree of skeletal convexity in the patient. The
angle of skeletal facial convexity is measured by the
angle formed by the line N-A and a line A to Pg. The N-
A-Pg (angle) gives an indication of the overall facial
convexity, but not a specific diagnosis of which is at
fault -the maxilla or mandible

A perpendicular line from HP is dropped through N
and the inferior anatomic point is horizontally measured in
relation to the superior structures
The horizontal position of A is measured to this
perpendicular line (N-A). This measurement describes the
apical base of the maxilla in relation to N and enables the
clinician to determine if the anterior part of the maxilla is
protrusive or retrusive.
The measurement and related measurements are
important in the planning of treatment of anterior maxillary
horizontal advancement or reduction, and of total maxillary
horizontal advancement or reduction.
Point B and Pog [ pogonion ] are measured in the same way.

VERTICAL SKELETAL AND DENTAL
A vertical skeletal discrepancy may
reflect an anterior, posterior, or complex
dysplasia of the face. Therefore, the vertical
skeletal cephalometric measurements are
divided into anterior and posterior
components.

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MAXILLA AND MANDIBLE
The total effective length of the maxilla is the
distance from PNSANS that is projected on a line parallel
to the HP. The ANS-PNS distance, with the previous
measurements N-ANS and PNS-N, give a quantitative
description of the maxilla in the skull complex.
Four measurements relate to the mandible
Ar to Go
Go-Pg
Go angle [represents the relationship between the ramal
plane and MP]
B-Pg [Distance from B point to a line perpendicular to
MP through Pg.]

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DENTAL
In the assessment of dental anomalies
cephalometrically, one must attempt to relate the
teeth to each other through a common plane,
such as the occlusal plane (OP) or to a plane in
each jaw, the MP, or the NF plane.
Various angles measured are,
Occlussal plane angle
1-NF angle
Lower incisor-MP angle
AB-OP

.
.
..

Discussion:
A cephalometric appraisal is only one step in
diagnosis and planning of treatment. It gives the clinician
insight into the quantitative nature of the skeletal-dental
dysplasia.
If surgery is planned to produce cephalometric
changes that makes the face approach the normative
standards, usually a more typical and desirable face is
produced. It is a mistake, however, to treat to a standard
that avoids other considerations.
The soft tissues can and do mask the underlying
bone and teeth; therefore one must compensate for this
variations.

ADVANTAGES:
A cephalometric analysis for patients who needs
orthognathic surgery
It is based on the landmarks that can be altered by
various surgical procedures.
These rectilinear measurements examine critical
facial components that can be readily transferred to
acetate overlays and study casts for detailed
planning of treatment and post surgical evaluation.

SOFT TISSUE CEPHALOMETRIC ANALYSIS FOR
ORTHOGNATHIC SURGERY:
Treatment planning for patients who require
orthognathic surgery should include both a hard tissue
and soft tissue cephalometric analysis.
The hard tissue will show the nature of the
existing skeletal discrepancy, it is incomplete in
providing the information concerning the facial form and
proportions of patient. The soft tissue covering the teeth
and bone is highly variable in its thickness and this
variation may be greater.

In planning surgery on patients with vertical
discrepancies, lip length is an important factor. Sometime
lips may be short,allowing the patient to close with great
difficulty. Amount of incisor exposure will be more during
speaking. Therefore, the diagnosis of vertical
discrepancies will be depend upon both soft and hard
tissues factor.
Therefore, Charles J. Burstone in 1980 developed a
soft tissue cephalometric analysis for orthognathic
surgery.

Cephalometric landmarks:
Soft tissue landmarks used are;
Glabella (G) : The most
prominent point in the
midsagittal plane of the forehead.
Columella point (Cm) : The most
anterior point on the columella of
nose.
Subnasale (Sn) : The point at
which the nasal septum merges
with the upper cutaneous lip in
the midsagittal plane.
Labrale superiors (Ls) : A point
indicating the mucocutaneous
border of upper lip.

Stomion superius (Stms) :
Lower most point on the
vermilion of the upper lip.
Labrale inferius (stmi) : The
upper most point on the
vermilion of the lower lip.
Labrale inferius (Li) : A point
indicating the
mucocutaneous border of
lower lip.
Mentolabial sulcus (Si) : The
point of greatest concavity in
the midline between the
lower lip and chin.
Soft tissue pogonion (Pg) :
The most anterior point on
soft tissue chin

Soft tissue gnathion (Gn) : The
constructed midpoint between
soft tissue pogonion and soft
tissue menton.
Soft tissue menton (me) : Lowest
point on the soft tissue chin,
found by dropping a
perpendicular from horizontal
plane through menton.
Cervical point (C) : Innermost
point between the submental
area and neck located at the
intersection of lines drawn
tangent to neck and submental
areas.
Horizontal reference plane (HP) :
Constructed by drawing a line
through nasion 7° up from sella
- nasion line.

SOFT TISSUE ANALYSIS
Facial form
To describe the soft tissue
profile of patient, angle of facial
convexity, or facial contour
angle, G - Sn - Pg is evaluated.
G -Sn - Pg : 12° 4°
A line perpendicular to
horizontal plane (HP) is dropped
from glabella and the
relationship of the maxilla and
mandible is related to it to
determine if the problem is
maxillary or mandibular.

G-Sn
G-Pg
.
. .

G-Sn (Hp): The distance from subnasal (Sn) to
vertical line parallel to the horizontal plane is
measured which describes the amount of
maxillary protrusion or retrusion in
anteroposterior dimension.
Negative number is maxillary retrusion,
large positive number,is maxillary
procumbency.
G - Sn (HP): 0  3 mm

G-Pg (HP) : The position of pogonion is
measured parallel to HP from the
Perpendicular line dropped from glabella. This
measurement gives an indication of
mandibular prognathism or retrognathism.
G - Pg : 0  4 mm

Vertical height ratio 
G - Sn / Sn - Me (HP):
In vertical
dimension, anterior facial
proportionality is assessed
by taking the ratio of
middle third facial height
to lower third facial height
measured perpendicular
to HP. The ratio less than
1 to 1 connote a
disproportionality large
lower third of face .
Normal: 1 mm
G-Sn
Sn-Me

Lower face - throat
angle (Sn - Gn - C):
It is formed by
intersection of the lines
Sn - Gn and Gn - C.
An obtuse lower face
neck angle warns the
clinician not to use
procedures that reduce
the prominence of
chin.
Sn-Gn-C

Nasolabial angle (Cm - Sn - Ls) : 4  2mm
It is important in assessing antero-posterior
maxillary dysplasia. An acute nasolabial angle
will often allow us to surgically retract the
maxilla or retract the maxillary incisors.
Obtuse nasolabial angle suggests a degree
of maxillary hypoplasia.
Cm - Sn - Ls: 102°  8°

Upper lip protrusion Ls to (Sn - Pg) : 3  1 mm
Lower lip protrusion Li to (Sn - Pg) : 2  1 mm
It is evaluated by drawing a line from subnasal to
soft tissue pogonion and amount of lip protrusion or
retrusion is measured by perpendicular linear distance
from this line to the most prominent point of both lips.
Labio-mental sulcus Si to (Li – Pg) 4  2 mm
It is measured from the depth of the sulcus
perpendicular to Li- Pg line. Sulcus of about 4 mm is
average in pleasing lower lip to chin contour.

..
.
. Sn
Pg

Vertical lip chin ratio Sn-Stms / Stms-Me: 0.5 mm
Lower third of face (Sn - Me) is divided into length of
upper Sn - Stms. It should be approximately 1/ 3rd the
total and distance Stms - Me is about 2/3rd.
Sn - Stms/Stms - Me should be 1: 2 ratio and if it
becomes smaller than one half- vertical reduction
genioplasty is considered.
Distance of upper lip to the maxillary incisor (Stms - 1)
is key factor in determining the vertical position of
maxilla. Patient with vertical maxillary excess tend to
show a large amount of upper incisors with the lip in
response.

Interlabial gap - 3 mm:
Vertical distance between the upper lip
and lower lip with then lip in rest position is
normally 3mm. In vertical maxillary excess
tend to have large Interlabial gap, lip In
competency results.

Dipaolo R.J’s quadrilateral analysis
Various parameters used in this analysis are
1.Maxillary Bony Arch Length
• measured from ANS to PNS along the
palatal plane.
• The anterior point is the foot of the
perpendicular from point A to palatal plane.
• The posterior point is the foot of the
perpendicular from most inferior position of
Ptm to palatal plane.

. .

2.Mandibular Bony Arch Length
• linear measurement along
mandibular plane (Go-Gn).
• The anterior point is the foot of the
perpendicular from point B to Go-Gn.
• The posterior point is the foot of the
perpendicular from point J to Go-Gn.

.
.

3. Point J
• located at the deepest point of the
curvature formed at the junction of anterior
portion of ramus and corpus of mandible .
• it’s posterior limit of denture base .
• this point is located by bisecting the angle
formed by a line drawn tangent to the
anterior border of the ramus and the
superior aspect of corpus of mandible.

4. Anterior Lower Facial Height or ALFH
• vertical linear measurement from anterior
limit of maxillary corpus to anterior limit of
mandibular corpus.

5. Posterior Lower Facial Height or PLFH
• Vertical linear measurement from posterior
limit of maxillary corpus to posterior limit of
mandibular corpus.

6. Anterior Upper Facial Height or AUFH
• vertical linear measurement from anterior
limit of maxillary corpus projected on palatal
plane from nasion.

7. Angle of Facial Convexity
• measurement of the skeletal profile formed by
intersection of ALFH with AUFH and relates the
quadrilateral to the upper face.
• 1650-1780.
.

8.Sagittal Angle
• intersection of horizontal planes of the
quadrilateral i.e.., the max bony arch length
and mand bony arch length .
• 23010
.

9.Sagittal Ratio:
• A mathematical expression that identifies
and locates the angular , vertical and saggital
relation of max corpus to mand corpus.

Skeletal measurements

3 types of faces

 Type 1 is the average downward and
forward growth pattern. There is a good
lower face pattern in good relationship
with the upper face. In this type, all
malocclusions are dento-alveolar in
origin (including an imbalance in size of
teeth to arch, forward position of upper
teeth, forward position of lower teeth to
upper teeth).

 Type 2 is the pattern in which the dominant direction
of growth is horizontal accompanied by little vertical
growth resulting in reduction of lower face height. Deep
bite in this type is always due to undesirable growth
pattern. Type 2 subdivisions are:
 A. Upper and lower bony arches are comparable in size.
 B. Upper bony arch is larger in size than lower bony
arch.
 C. Lower bony arch is larger in size than upper bony
arch.
All of the subdivisions may be accompanied by
malocclusions of dento-alveolar origin.

 Type 3 is the pattern in which the dominant direction of
growth is vertical accompanied by little horizontal growth,
resulting in increase in lower face height. Posterior alveolar
compensation may result in an acceptable anterior overbite.
A deep curve of Spee is such a compensation and is
desirable in Type 3. It would be undesirable in Type 2 since
it would deepen the bite. In Type 3 open bite is always due to
undesirable growth pattern. Type 3 subdivisions are:
 A. Upper and lower bony arches are comparable in size.
 B. Upper bony arch is larger in size than lower bony arch.
 C. Lower bony arch is larger in size than upper bony arch.
 All subdivisions may be accompanied by malocclusions of
dento-alveolar origin.

Dental measurements
1. Upper incisor position
• determined by drawing a line parallel to
ALFH through point A.
• perpendicular from this line to the
anterior most point on the max incisor is
measured in mm.
• 5 1 mms.

5 1 mms

2. Lower incisor position
ALFH through point B.
anterior most point on the mand incisor
is measured in mm.
• 0  2 mms.

0  2 mms

3. Pogonion line
ALFH through pogonion.
anterior most point on the mand incisor
is measured in mm.
• 2 mm anterior or posterior to the
pogonion line.

ORTHODONTIC SURGICAL
CEPHALOMETRIC PREDICTION TRACING
(Epkar and Fish, 1994):
One of the most important planning tools
in surgical cases is the cephalometric
prediction tracing. Once the problem is
recognized and the type of surgery provisionally
decided, prediction tracing is done accordingly.

Types of prediction tracings ;
1) Orthodontic surgical
2) Surgical
Orthodontic surgical tracing is used for overall
treatment planning and illustrates the effect of both
orthodontic tooth movements and surgical skeletal
changes.
surgical tracing is done as a part of two patient
concept.

The orthodontic surgical tracing is done for the
following reasons :
To assess accurately the profile esthetic results of the
proposed surgery and orthodontics.
Determine desirability of adjunctive surgical
procedures such as genioplasty.
To help determine the sequencing of surgery and
orthodontics.
To help decide if extractions are necessary.
To determine which teeth to extract if extraction
treatment is required.
To determine the anchorage requirements.

Esthetics directly depends on the soft tissue
morphology and harmony. So, it is important to know
the soft tissue changes associated with the surgical
procedure.
Certain points to be kept in mind during prediction
tracing are;
With the antero-posterior movement of the incisors,
60-70% change is seen in lips. With the vertical
movement of incisors, associated with soft tissue
changes are minimal but lip rotation is almost equal to
the rotation of mandible.
In mandibular advancement, lip movement is 60-70%,
but the soft tissue chin movement is almost as equal to
the base movement.

In maxillary advancement, the nose tip
is slightly elevated, but the change is usually
temporary. In maxillary retro positioning, the
movement of the base of the upper lip is only
20% of that of point A. The lower lip rotates
along with the mandibular rotation.
In surgery of chin, the soft tissue reacts
about 60-70% to forward advancement.

Currently, there are three methods of prediction
tracing.
A) It involves repositioning acetate tracing. of the various
bony and skeletal segments over the original tracing to
duplicate the movement of potential treatment
procedures. The post treatment soft tissue outline is
established by considering the ratio of soft tissue to hard
tissue change.

B) In Second technique appropriate landmarks from the
cephalometric tracing are digitized and entered into a
computer using commercial programs clinician can
simulate surgical movements on screen and rapidly
compare several possible options using computer is no
more accurate than doing prediction by hand.
C) The third method involves overlying the digitized
image of the lateral cephalometric tracing on to a video
image of patient. The surgical predictions produced
from the digitized cephalometric tracing can be
integrated with the video image so that the prediction
includes not only a line drawing but also a
corresponding facial image.

The available surgical prediction programs
include
o Dentofacial planner plus
o Quick Ceph and
o Prescription Planner / Portrait, OTP, TOMAC, Dr. Ceph
etc

Mandibular advancement:
First the bony and soft tissue landmarks are
traced. Frankfort horizontal plane is drawn and
then a line is passed from nasion through point A
and extending inferiorly. Point A is frequently in its
normal relation (900 maxillary depth).
Begin the prediction by tracing the distal
portion of the mandible, the soft tissue chin, and
the occlusal plane on clean acetate paper. A lightly
dotted line is used for soft tissue chin and the
corresponding part of mandible. It makes easier to
add genioplasty whenever required.

In deep bite cases, occlusal plane is made
between functional plane and molar incisor
occlusal planes. The choice must be made
carefully as it affects the esthetics the amount
and direction of advancement and the
necessary orthodontic treatment.
Functional occlusal plane
Wolford L.M., Chemello B.D. and Hilliard F.
(1994) quoted that deep bite is frequently
associated with excessive curve of spee in lower
arch and a reverse curve of spee in the upper
arch

Molar incisor occlusal plane:
The patient with deep bite has two divergent
molar incisor occlusal planes. One from maxillary
incisor to maxillary molar and another from
mandibular molars to mandibular incisors.
If mandible has to be advanced along these
divergent planes, then rotate clockwise the distal of
mandible, so that both planes get coincide. The teeth
are advanced more than pogonion and lower face height
is increased by the amount of excessive overbite.

After tracing the fixed structures, draw A -
Pog line and the facial axis on the prediction.
This line is used to place the teeth in their ideal
position.
Ideal position of lower incisor determined
by Rickets, is with the incisal edge 1 mm ahead
of the A - Pog line and the long axis at 22° to A -
Pog line.

The single most common problem
encountered in doing a cephalometric
Prediction tracing for mandibular
advancement is the inability to produce the
desired lower incisor tooth movements
because the total arch length discrepancy is
greater than the width of two premolars.

Then start soft tissue profile
prediction by superimposing the prediction
on the tracing. As the position of upper
incisor was changed the upper lip vermilion
will change in the same direction but about
half as much. Draw appropriate lip in the
new appropriate position and connect it to
subnasale by a smooth curve .

Lower lip frequently not only supported by
lower incisor but is also everted by the upper
incisors. Generally lower lip thickness is equal from
point B superiorly and usually the same thickness
in upper lip. Then lay the prediction on tracing,
touch upper lip, incisal edge of upper incisor and
labial surface of lower incisor on the prediction and
then trace the vermilion portion of the lip.
Finally, connect the lip to the soft tissue chin
with a smooth curve to produce completed
prediction tracing

SUPERIOR REPOSITIONING OF THE MAXILLA AND
ADVANCEMENT GENIOPLASTY:
Routine tracing of pretreatment cephalogram with
skeletal, dental and soft tissue landmarks done.
Then to start with prediction - fresh tracing of the
patients cephalogram without analysis line made.
Construct subnasal perpendicular this tracing to allow
assessment of changes in chin and lip position. For soft
tissue chin and mandible use dotted lines, as it is easier
to add genioplasty.

Note : Accurate tracing of condyle is important
as it serves as center of rotation for mandible,
Functional occlusal plane ( molar-premolar) is
used.
Then the prediction is rotated
counterclockwise around the condyle keeping
the condyle in fossa, until the functional
occlusal plane is 1-3mm below the upper lip
on tracing .Where to place the occlusal plane
is based on the amount of upper tooth
exposed before treatment.

Then hold the prediction and draw the fixed
structures,observe the anteroposterior position of
chin. The soft tissue chin optimally lies 2 - 6 mm
behind the subnasale perpendicular on tracing.
If chin is deficient at this time augmentation
genioplasty is done. There the bone to soft tissue
ratio is 1 : 0.7.

For augmentation genioplasty, draw a
horizontal line parallel to FH plane on
symphysis. Then superimpose the tracing on
prediction. Slide the prediction until the bony
chin of the tracing projects anteriorly. Then
hold the prediction and draw the new chin
position, relative to both subnasale
perpendicular and the forehead and nose. Then
draw A - Pog line and it should be coincident
with this line. Place the teeth in their ideal
position. Superimpose the Prediction on tracing
and soft tissue can be compared.

TWO JAW SURGERY (MAXILLARY SUPERIOR
REPOSITIONING AND MANDIBULAR
ADVANCEMENT)

CONCLUSION
Orthognathic surgery is probably the
most challenging and gratifying field in the
whole of maxillofacial surgery. It is still in
an infant stage and lots of innovations are
possible .In the near future, one can get a
face one aspires for.

Surgical orthodontics part 1

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Surgical orthodontics part 1