Surgical analysis1 /certified fixed orthodontic courses by Indian dental academy

SURGICAL ANALYSIS

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


SURGICAL ANALYSIS


BURSTONE & CO WORKERS – C.O.G.S
ANALYSIS.



SOFT TISSUE ANALYSIS FOR
ORTHOGNATHIC SURGERY – LEGAN &
BURSTONE.



QUADRILATERAL ANALYSIS – DI
PAOLO

INTRODUCTION
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Cephalometric analysis is the common language
for orthodontists & oral surgeon.
Used in – Diagnosis of skeletal and soft tissue
problems.
Establishing proper tooth jaw relations.
Determining the method & magnitude of
surgical correction.


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Successful treatment of the orthognatic surgical
patient is dependent on careful diagnosis.
Cephalometric analysis can be an aid in
diagnosis of skeletal and dental problems.


CEPHALOMETRICS FOR
ORTHOGNATHIC SURGERY


Developed at the university of Connecticut, based on system
developed at Indiana university by Charles J . Burstone.



Describes the horizontal & vertical position of facial bones by
use of constant coordinate system.

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Size of bones represented by direct linear measurements.

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Shape of bones – angular measurements.

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Sample – 16 females, 14 males.

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Following characteristics –
1 Chosen landmarks & measurements can be altered
by various surgical procedure.
2 Includes all of facial bones & cranial base.
3 Critical facial skeleton components are examined.
4 Standards are available for variations in age & sex
from 5 – 20 yrs.
5 Describes dental, skeletal & soft tissue variations.


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Landmarks used – Sella, Nasion.
Articulare, PTM.
Point A , B.
Pogonion,Menton,Gnathion,Gonion
ANS, PNS.
Planes –
Mandibular plane – From Me to Go.
Nasal floor – From PNS – ANS.


MEASUREMENTS
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CRANIAL BASE – Baseline for comparison of most
data in this analysis is HORIZONTAL PLANE.
Constructed plane , 7˚from SN line.
Most measurements are made either parallel or
perpendicular to horizontal plane.
Length of cranial base – Parallel to HP from Ar – N.
Should not be considered as absolute value, but a
skeletal baseline to be correlated to other
measurements.




Patient with large maxilla & mandible may have
a normal appearance because of large cranial
base.

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Ar – N is a stable anatomical plane; it can be
changed by cranial surgery that affects N, such
as Lefort II & III osteotomies.


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Ar – Ptm determines the
horizontal distance between
the posterior asoects of
mandible & maxilla.

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Greater the distance between
Ar- Ptm, more the mandible
will lie posterior to maxilla,
assuming all other facial
dimensions are normal.


HORIZONTAL SKELETAL
PROFILE


Angle of facial
convexity : formed by
line N – A and A-Pg.

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Gives an indication of
overall facial convexity,
but not a specific
diagnosis of which is at
fault – maxilla or
mandible.


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Positive angle – convex face.
Negative angle – concave face.
Clockwise angle is positive.
Counterclockwise is negative.
Next a perpendicular line from HP is dropped
through nasion.


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Inferior anatomic point
is horizontally measured
in relation to sup.
Structure ,
+ - anterior to line.
̶ : posterior to line.
Measure the horizontal
position of point A & B
is measured to this line.
( N-A, N-B).


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It describes the apical base of maxilla/mandible
in relation to N.
Surgeon has a quantitative assessment of A-P
position of jaws and degree of horizontal
dysplasia.
Measurement & related measurements are imp.
In planning of treatment of anterior horizontal
advancement / reduction or total
advancement / reduction.

N – Pg is measured in same
manner. Indicates the
prominence of chin.
Any unusual small or large
value must be compared with
N – B & B – Pg., to
determine if discrepancy is in
alveolar process, the chin or
mandible proper.
Helps to determine if there is a
horizontal genial
hyperplasia / hypoplasia.

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The measurements of horizontal skeletal profile
represent facial convexity, horizontal relation of
apical base A & B points, and chin as related to
N.

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After all the measurements are considered .the
surgeon has a quantitative skeletal cephalometric
facial description of horizontal anterior facial
discrepancy.

VERTICAL SKELETAL
MEASUREMENTS.


Divided into – Anterior & Posterior
components.

Anterior component – a) Middle third face
height (N-ANS).
b) Lower third face height (ANS-Gn).
Measured perpendicular to HP.

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Posterior component – a)
Posterior maxillary height is
length of a perpendicular line
from HP intersecting PNS.
b) Divergence of mandible
posteriorly is shown by MPHP angle.MP is formed by
Go-Gn.
It relates to posterior facial
divergence with respect to
anterior facial height.


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Vertical skeletal measurements of anterior &
posterior components of face will help in
diagnosis of anterior , posterior , or total vertical
maxillary hyperplasia or hypoplasia, and
clockwise or counterclockwise rotations of the
maxilla & mandible.


MAXILLA AND MANDIBLE
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Effective length of
maxilla is distance from
PNS-ANS.
This distance along with
measurements N- ANS,
N – PNS gives a
quantitative description
of maxilla in skull
complex.


MANDIBLE – 1) Ar-Go
quantitates the length of
mandibular ramus.
2) Go-Pg gives length of
mandibular body.
3) Ar-Go-Gn angle gives
relation between ramal plane
& mandibular plane.
4) B-Pg describes the
prominence of chin related to
mandibular denture base.
This can be related to N – Pg to
assess prominence of chin to
face.
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These measurements are helpful in diagnosis of
variations in ramus ht., that effect open
bite/deep bite problems,
increased /diminished mandibular body length,
acute or obtuse Go angle that also contribute to
skeletal open/closed bite.
Assessment of chin prominence.


DENTAL
MEASUREMENTS
First thing done is to relate the teeth to each other
through a common plane such as occlusal plane,or to a
plane in each jaw , MP or NF plane.
 Occlusal plane (OP) is drawn from buccal groove of
both permanent 1st molars through a point 1mm apical
of incisal edge of central incisors in respective arch.
 If anterior open bite is present 2 OPs must be drawn
and measured separately. Each OP is assessed as to its
steepness or flatness.
Vertical facial & dental heights should be considered to
determine which OP should be corrected.



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OP angle is angle between
OP and HP.

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INCREASED – Skeletal
open bite, lip incompetence,
increased facial height,
retrognathia or increased MP
angle.

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DECREASED – Deep bite,
decreased facial height, lip
redundancy.


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Measurement AB – OP
is done by dropping a
perpendicular line to OP
from points A & B, then
measuring distance
between two
intersections.
It gives relation of
maxillary & mandibular
apical base to OP.


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Angulation of maxillary
incisor to NF and
mandibular incisor to
MP is measured.
They determine the
procumbency or
recumbency of incisor &
are vital in assessing the
long term stability of the
dentition.


VERTICAL DENTAL
DYSPLASIA
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Divided into – a) Anterior b) Posterior

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Anterior – Anterior maxillary height is measured by
dropping a perpendicular from incisal edge to NF.
Anterior mandibular height – incisal edge to MP.
These 2 measurements determine how far incisors have
erupted in relation to NF and MP.

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POSTERIOR – a) From
maxillary 1st molar m-b cusp a
perpendicular line is drawn to
NF.
b) Similar line from
mandibular m-b cusp to MP.
All these values should be
related to ANS-Gn & MPHP to establish whether the
origin of maxillary &
mandibular discrepancies is
skeletal,dental or both.


Soft tissue analysis for
orthognathic surgery
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Treatment planning – Hard & Soft tissues.
Although hard tissue analysis show the nature of
existing skeletal discrepancy,it is incomplete in
providing information concerning facial form &
proportion of patient ,& in many instances may be
misleading.
Patients may appear more or less convex than indicated
by their hard tissue because of differences in thickness
of soft tissues.

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Lips – more protrusive / retrusive.
In planning surgery on patients with vertical
discrepancies, lip length is an important factor to
be considered.
Developed by Burstone in 1958.
Means & standard deviation derived from 40
orthodontically untreated white adults (20 men,
20 women).
Class I occlusion, Vertical facial proportions
within normal limits.

Landmarks


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Facial convexity – given
by angle G – Sn – Pg’.
Smaller value – Class III
profile.
Clockwise angle –
Positive.
Counterclockwise angle
– Negative.


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Maxilla & mandibular are
related to a line dropped
from glabella perpendicular
to HP.

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Maxillary – Distance to
subnasale from this line.
Gives amount of maxillary
excess or deficiency in A-P
dimension.
Anterior to line – Positive,
Posterior - negative

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This & other related A-P measurements are
important in planning treatment for anterior
maxillary advancement or reduction and for total
alveolar or lefort I maxillary horizontal
advancement or reduction.


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Mandible – distance
from perpendicular line
dropped from glabella to
Pg’.
Gives an indication of
mandibular prognathism
or retrognathism.


Lower face throat angle (Sn – Gn’ –C)
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Formed by intersection
of lines Sn-Gn’ & Gn’-C.
Critical in planning
treatment to correct A-P
dysplasias.
In case of obtuse angle,
clinicians should not use
procedure that reduce
prominence of chin.


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Class III patients with short ,heavy throats &
obtuse angle usually not have mandibular
setbacks.
Alternatives – maxillary advancement,
mandibular subapical procedure, mandibular
setback with advancement genioplasty,
compromise tooth position.


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Lower face vertical
height to depth ratio –
Sn – Gn’/C – Gn’.
Normally a little larger
than 1. if becomes more,
means patient has a short
neck.
Anterior projection of
chin should not be
reduced.


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Vertical – ratio of
distances G – Sn & Sn –
Me’ should be approx. 1.


Lip position
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Nasolabial angle – between
Cm-Sn-Ls.
Important measurement in
A-P maxillary dysplasias.
Acute angle allow us to
surgically retact maxilla or
maxillary incisors or both.
Obtuse angle – maxillary
advancementor proclination
of incisors.


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A-P lip position – line is
drawn from Sn-Pg’ &
amount of lip protrusion
or retrusion is measure as
perpendicular linear
distance from this line to
most prominent point of
both lips.


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Labiomental sulcus – from
depth of sulcus perpendicular
to Li-Pg’ line.
Sulcus of about 4mm
provides pleasing lower lip to
chin contour.
Uprighting lower
incisors,intruding maxillary
incisors,chelioplasty can help
in reducing a deep sulcus.


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Distance of upper lip to
maxillary incisor (Stm – 1) is
a key factor in determining
vertical position of maxilla.
Normal – 2mm of incisor
display.
Patients with vertical
maxillary excess tend to show
a large amount of upper
incisor with lips in repose.


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Vertical maxillary deficiency – No incisor display
with lips relaxed, edentulous look.
Orthodontically extruding maxillary teeth or
surgically positioning the maxilla inferiorly –
preferable treatment in patients with short face.
INTERLABIAL GAP – Approx. 3mm .
Patients with maxillary excess have large
interlabial gaps & lip incompetency.


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Raising maxilla – shortens facial height, allow
patient to close lips without muscle strain.

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Patient with maxillary deficiency – no interlabial
gap, have lip redundancy with a rolling out of
upper & lower lips.


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Lower third of face (Sn-Me’)
– divided into thirds.

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Length of upper lip (Snstm)is one third he total
distance of sn-Me’.

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Stm-Me’ is about two thirds.

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Sn-stm/stm-Me’ is 1:2

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When it becomes smaller
than half vertical reduction
genioplasty is considered.


QUADRILATERAL
ANALYSIS
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Formulated by Di Paolo in 1962.
It attempts to identify skeletal deviations, in size
and position, in both the horizontal and the
vertical dimensions, regardless of dentoalveolar
relationships. It provides an individualized
skeletal assessment of each patient.
Proportional analysis which is based on
theorems in Euclidean geometry.
Sample – 245 subjects, mean age-12.6 yrs.

QUADRILATERAL ANALYSIS OF LOWER
FACE
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Maxillary bony arch length measured, horizontally
between two points projected
onto the palatal plane.
anterior limit - projecting a
perpendicular from Pt A
upward to the palatal plane
(ANS-PNS),
posterior limit - projecting a
perpendicular from the most
inferior portion of the PTM
downward to the palatal
plane.


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Mandibular bony arch length
horizontally between two
points projected onto the
mandibular plane (GoGn).
anterior limit - determined
by projecting a perpendicular
from Pt B downward to the
mandibular plane (Go Gn),
posterior limit - determined
by projecting a perpendicular
from point J downward to
the mandibular plane (Go
Gn).


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Point J - deepest point of the
curvature formed at the junction of
the anterior portion of the ramus
and the corpus of the mandible.
A line is drawn from articulare
tangent to the most posterior point
on the ramus.
A parallel line is then drawn
through the innermost point on the
curvature of the anterior aspect of
the ramus.
At a point where the remaining
alveolar crest contacts the last
molar, a line is drawn parallel to
the gonion-gnathion plane. The
angle formed is then bisected, and
point J is located where this line
crosses the inner curvature of the
mandible.


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Anterior lower facial
height (ALFH) is
measured, as vertical
linear measurement
from the projection of
point A onto the palatal
plane to the projection of
point B onto the goniongnathion plane


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Posterior lower facial
height (PLFH) is
measured, from the
projection of PTM onto
the palatal plane to the
projection of point J
onto the goniongnathion plane


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These four measurements –
maxillary bony base length,
mandibular bony base
length,
anterior lower facial height,
and posterior lower facial
height form the basis for the
quadrilateral analysis of the
lower face.


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The quadrilateral analysis indicates that in a
balanced facial pattern a 1:1 ratio exists between
the maxillary bony base length (Max.Lth.) and
the mandibular bony base length (Mand.Lth.);
Average of the anterior lower facial height
(ALFH) and posterior lower facial height
(PLFH) equals these bony base lengths.
Max.Lth. = Man Lth = ALFH + PLFH
2

Dental Analysis
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Maxillary incisor position:
determined by drawing a line
through point A parallel to
the anterior lower facial
height (ALFH).

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A perpendicular from this
line to the most anterior
point on the maxillary incisor
should result in a
measurement of 5 mm ± 1
mm.


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Mandibular incisor
position - drawing the
line through point B
parallel to anterior lower
facial height (ALFH).

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The perpendicular
distance to the most
anterior point of the
lower incisor is 2 mm ±
1 mm.


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Pogonion line - drawing a
line tangent to pogonion,
parallel to anterior lower
facial height (ALFH).

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The most anterior point of
the mandibular incisor
should be ± 2 mm to this
line.

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This measurement will
indicate if the chin is
excessive or deficient in size


Sagittal Ratio


Important in assessing the relative anteroposterior position of
the maxillary and mandibular bony bases.



Skeletal malformations of the jaws may be either in the bony
bases or located posteriorly. Therefore, pinpointing the area of
the deformity will have a significant impact on whether or not
certain surgical procedures are indicated.
For example, if we are to perform a surgical correction of a
mandibular prognathism, it would be necessary to determine
whether we should reduce the bony base lengths (body
ostectomy or sagittal split setback) or whether we should
perform mandibular surgery posterior to the bony base area
(vertical osteotomy, etc.).

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The lines used to measure
the bony base lengths in are
extended posteriorly to point
x, which is the sagittal angle
When the anterior and
posterior lower face heights
are parallel and the maxillary
and mandibular bony bases
are equal, a proportional
relation exists with sides A,
B, C, and D of the similar
isosceles triangles.
The ratio of A to B and C to
D is called the sagittal ratio.




Any forward or retroposition of the bony base
will cause unequal lengths of the posterior legs
(lines A and C).

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In balanced skeletal patterns the sagittal ratio in
adolescents is 1.0:1.50 ± 0.05;

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in adults it is 1.0:1.45 ± 0.05



sagittal angle is 23° ± 1°.

Angle of facial convexity
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Measurement of the skeletal profile.



This angle is formed by the intersection of anterior lower facial
height with anterior upper facial height and relates the
quadrilateral to the upper face.(165 - 178˚)

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It shows possible areas of skeletal discrepancies, such as posture
of the lower facial complex, cranial base deflections, and bony
base discrepancies.

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The degree of facial convexity will vary, depending upon the
skeletal type and the position of the quadrilateral pattern as it
relates to the upper face.


Facial Types


Type 1. This face has a normodivergent pattern
showing a favorable vertical growth .

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In the majority of Type 1 cases, the maxillary and
mandibular basal arch lengths are equal and the average
vertical height is equal to the arch length. This balance
indicates a harmonious skeletal development of the
lower face.

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Malocclusions in this group are dentoalveolar in origin.
Tooth size— arch length discrepancies or anterior or
posterior position of the teeth on their respective
denture bases account for the majority of problems.

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Type 2. This face is hypodivergent, predominantly horizontal
growth pattern .
There is a reduction in lower face height with an undesirable
growth pattern, resulting in a skeletal deep-bite. In these patients
the average vertical height is deficient when compared to the
denture base lengths.
3 possibilities: (A) Maxillary and mandibular denture base lengths
are comparable in size,
(B) maxillary base length is larger than the mandibular base
length, and
(C) mandibular base length is larger than the maxillary base
length.
The significance is that anteroposterior skeletal malrelationships
can exist in skeletal deep-bite patterns.


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Type 3. This face is hyperdivergent, predominantly vertical
growth pattern .
There is an increase in lower face height with an undesirable
growth pattern, resulting in a skeletal open-bite.
In these patients the average vertical height is excessive when
compared to the denture base lengths.
Posterior alveolar compensation may prevent a dental open-bite
in some cases .
These cases usually present with a deep curve of Spee and a lack
of posterior alveolar development. Leveling mechanics in these
patients will cause the underlying skeletal open-bite to be
manifested dentally.


3 possibilities:
(A) Maxillary and mandibular denture base lengths are
comparable in size,
(B) maxillary base length is larger than the mandibular
base length, and
(C) mandibular base length is larger than the maxillary
base length.
The significance is that anteroposterior skeletal
malrelationship can exist in skeletal open patterns.

SUMMARY




Because of the increase in the scope of surgical
orthodontics, visual interpretation of cephalometric
films has become obsolete.
Surgical orthodontics requires reliable diagnostic
methods that can differentially assess the location and
degree of the skeletal dysplasias. The surgical analysis
not only attempts to satisfy these objectives but also
gives the clinician an individualized skeletal assessment.




Proper incisal positioning prior to surgical
intervention is essential if we are to achieve
optimum denture base relationships. An
undesirable position of the upper and/or lower
incisor teeth will cause the surgeon to be misled
during surgery, resulting in a less than desirable
facial harmony.


REFERENCES
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1 Burstone CJ, James RB, Legan H: Cephalometrics for
orthognathic surgery.J Oral Surg 1979 (36);269-77.
2 Legan H, Burstone CJ: Soft tissue cephalometric
analysis for orthognathic surgery.J Oral Surg 1980
(38);744-751.
3 Burstone CJ: Integumental Profile. AJO 1958 (44); 125.
4 Di Paolo RJ, Philip C, Maganzini A: The quadrilateral
analysis: An individualized skeletal assessment. AJO
1983 (83),1;19-32.


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5 Albert Chinappi, Di Paolo RJ: A quadrilateral analysis
of lower face skeletal patterns. AJO 1970 (58),4;341350.
6 Di Paolo RJ, Philip C, Maganzini A: The quadrilateral
analysis: A differential diagnosis for surgical
orthodontics. AJO 1984 (86) 6;470-482.
7 Athanasios E Athanasiou: Orthodontic
Cephalometry. 1st edtn,1995.Mosby-Wolfe.Pg- 247,
253,267,268.
8 Di Paolo RJ, Markowitz JL:Cephalometric diagnosis
using quadrilateral analysis. JCO 1970 (4); 30-35.


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