Ceph and model mock surgery for orthodontic surgery planning

For Orthodontic Surgical Planning.
“Ceph” &
Model Mock
Surgery
Nov 25/11/03www.indiandentalacademy.com

INTRODUCTION:
“Ceph” and model mock surgery is
done, by using cephalometric tracings
and dental casts or by the help
computers, to simulate the effects of
the orthodontic and surgical treatment.
Cephalometric prediction allows two
dimensional evaluation of both dental
and skeletal movements, whereas cast
predictions shows detailed three
dimensional dental relationships that
indirectly reflect underlying skeletal
changes. www.indiandentalacademy.com

Orthognathic surgery
Minor procedures Major procedures
www.indiandentalacademy.com

Minor procedures
Exposure of impacted teeth.
Transplantation of teeth.
Removal of third molars.
These usually does not require “ceph” and
model surgery.

Major procedures
Mandibular Advancements.
Maxillary Superior
Repositioning.
Combined maxillary and
mandibular surgeries.

So, what’s
ur opinion?
ORAL SURGEON
ORTHODONTIST
C’MON,
LET’S MOCK
IT !!!!

1. Manual acetate tracing "cut and paste"
techniques as described by Cohen,
McNeill et al., and Henderson.
2. Manipulation of patient photographs to
illustrate treatment goals.
3. Computerized diagnostic and planning
software that produces a soft tissue
profile "line drawing"; as a result of
manipulation of digitized structures of
lateral cephalometric radiographs.
There are five general methods of
visualizing, planning, and predicting surgical
orthodontic outcomes(AJO1997 Dec):

4. Computerized diagnostic and
planning software that integrates
video images with the patient's lateral
cephalogram to aid in planning and
predicting surgical orthodontic
procedures (Videocephalometrics).
5. Three-dimensional computer
technology for planning and
predicting orthognathic surgery.
Moss et al. expanded on the early
methods of three-dimensional
planning by including laser scanning
to model the soft tissue response to
hard tissue movements.www.indiandentalacademy.com

Prediction cephalometric tracing:
The most important aim of the prediction
tracing is to asses the esthetic profile
result after the surgery.
NOTE: Whatever the prediction method,
producing the predicted soft tissue outline
is more of an art form than a scientific
exercise.

Prediction cephalometric tracing:
Tracing
overlay
method
Template
method
Computer
methods
Photographic
method
1
2
3
4

Tracing overlay method
 The tracing overlay approach is the
simplest way to simulate the effects of the
mandibular surgery.
 The final prediction tracing is
produced without any intermediate
tracings.
 This method is limited to surgery
that does not affect the vertical position of
the maxilla(i.e., the mandible does not
rotate around the condylar axis.)

Steps in tracing overlay method:
Original tracing
Tracing of the structures
that will not be changed
by mandibular surgerywww.indiandentalacademy.com

Slide Overlay tracing so that the mandibular
teeth can be seen through it in the desired
post-surgical position and trace the lower
teeth and the jaw.www.indiandentalacademy.com

Measurements are made to find, how far
the lower incisor has moved forward by
superimposing the overlay back to the
cranial base.( lower lip will move forwards
by 2/3 rd’s
and is marked. )www.indiandentalacademy.com

Superimpose again on the mandible.
Draw the soft tissue chin and the
complete the soft tissue profile.www.indiandentalacademy.com

Super impose again on the cranial base
and complete the soft tissue profile
with the help of table.www.indiandentalacademy.com

Template method
The use of templates for intermediate
tracings between the original and the
final tracing is mandatory when the
maxilla will be repositioned vertically,
repositioning of the chin and in cases
where major teeth movements has to
be carried-out.
 Templates can be used for any type
of prediction surgery.
Disadvantage: Time consuming.

Special considerations:
1. Color coding of templates.
2. Use of different colors for the structures
to be repositioned.
3. When mandibular template is prepared,
the approximate center of the condyle
on the original tracing should be
marked, and this mark is transferred to
the template. The mandibular template
can be rotated around this point.www.indiandentalacademy.com

Template method
Template for maxillary teeth.www.indiandentalacademy.com

Two mandibular templates are prepared
–one without extraction second one with
the extraction(crowding resolved.)www.indiandentalacademy.com

Ready templates.

Place the upper anterior template in the
desired position approximately 2mm below the

Check for the better fit of the mandibular teeth by
placing either of mandibular templates. It is clear
that the prominence of the upper anterior teeth will
be a function of how much the mandibular incisors
are retracted and how far up the maxilla is moved.www.indiandentalacademy.com

Position the upper posterior template.

Complete the prediction tracing on the
fresh tracing paper.

Is an attempt to improve communication
with patients. This was proposed,as a
method of illustrating to the patient, the
soft-tissue results of the suggested plan.
Photographic method:

METHOD
The photographs are physically
sectioned;the cut-outs represents the
parts that will be moved in the planned
osteotomies and are arranged to simulate
surgical movements
Advantages: It gives the patient better
visualization of the profile changes than a
acetate tracing does.www.indiandentalacademy.com

Disadvantages:
1.Does not permit change to soft
tissue contours that occurs with
treatment.
2.Unavoidable gaps in photo have an
unnatural appearance.
3.An experienced clinician with
artistic skill are essential with this
methodology.www.indiandentalacademy.com

Computer method:
The first step in using a computer
program for Cephalometric
prediction is to enter the digital
model of the patients tracing in to
computer memory.

Rocky mountain data systems has
developed the the computerized
“visual norm” based on the size,
age, sex and race. (JCO 1977)
Using this data and Brodbents
template method, surgical VTO can
be constructed.

The final red surgical VTO is prepared showing
the skeletal, dental, and soft tissue changes.www.indiandentalacademy.com

Soft tissue changes from the surgical- orthodontic treatment.

Model surgery simulates
actual surgery, in the dental
arch models of the patient. It
gives the three dimensional
understanding of the post
operative relationship of the
jaws.
Model surgery

Major aims of the model surgery:
1.To get the definite idea about the
extent of bone / arch advancement or
reduction required in the surgery.
2.To get a post-operative relationship of
the jaws, dentition and occlusion.
3.To decide about the post-surgical
orthodontic treatment.
4.As a vehicle for fabrication of splints
for stabilization after surgery.www.indiandentalacademy.com

ARMAMENTARIUM:
1) A fret saw and fine blades (size M2) or a
10cm (4 inch) fine fiber or metal cutting
disc mounted on a lathe.
2) Hand-piece and motor.
3) A steel fissure bur.
4) A plaster bur or an Ash acrylic cutter
pear.
5) Surgical scalpel blades, NO.10 or 20.
6) Plaster knife, Spatula, 15 cm(6 inch)
rubber bowl. www.indiandentalacademy.com

7) Bunsen burner, spirit lamp,or soldering
iron.
8) Wax knife and carver.
9) Soft ribbon wax, hard modeling and
sticky wax.
10) 15cm (6inch)flexible ruler.
11) Spring dividers(15cm /6 inch)
12) Plane line hinge articulator, and face
bow. www.indiandentalacademy.com

Diagnostic set-up
A diagnostic set up is employed
to be sure that it will be possible
to get the teeth to fit together if a
given orthodontic treatment plan
is employed.

Method:
Individually remove the tooth from
the dental cast and reset the
tooth in soft wax so that their
alignment and interdigitation can
be observed.

Diagnostic pre-orthodontic set-up showing the
proposed extractions and tooth movements.www.indiandentalacademy.com

Paper set- up:
Is an alternative method to diagnostic
set up, where the occlusograms are
digitized which provides the two
dimensional representation of the
planned post treatment dental arch
form and alignment with the help of
soft-wares.

Methods of model surgery:
Simple method.
Anatomically oriented model
surgery.

Simple method:
Simple method is only satisfactory to basic surgical changes.
1. Sulcus impressions of the upper and
lower arches are obtained.(midline
marking can be done before making the
impressions)
2. The impressions are cast in stone.
Models are trimmed and two duplicate
sets prepared.
3. The master set is dated, labeled and
stored as preoperative reference study
models. www.indiandentalacademy.com

4. If movements of the whole arch are
anticipated, the upper and lower
models are first occluded in the
planned postoperative position and
carefully marked using a pencil.
The amount of movement between
the pre-operative and post-operative
position is then measured and noted
on the models. This may be done with
the hand held trimmed study model
or,with plaster-less articulator.

The marked models may also be
mounted with plaster on a metal
hinge articulator in the planned
postoperative position.
This mounted set of models is also
used for designing or making the
means of fixation.

5. If segmental movements are
involved, a set of models is sectioned
at the osteotomy sites. Care should
be taken when sawing not to damage
teeth other than those which are going
to be extracted at the time of
surgery.
The sectioned segments are then
sited in the desired position and
fixed with soft red ribbon wax which
will allow the manipulation in to the
planned position.www.indiandentalacademy.com

 Cuspal interferences can be
marked on the cast which can be
later ground intra-orally.
 Establish a proper over-jet and
overbite in the anterior region.
 A degree of over-correction may
be necessary to compensate for
the relapse, especially with
mandibular forward movements.www.indiandentalacademy.com

6. Once the desired position is
achieved the ribbon wax is
replaced with hard modelling or
sticky wax to secure the
mobilized segments in their new
place.

Anatomically oriented model surgery.
In complex cases, especially where
multiple bimaxillary movements are
required, it is essential to use a more
refined technique such as the following
variant of a popular “North American
method”

In this technique, in addition to
the impressions and sqash bite,
a face-bow recording is taken.
1. The working models are
anatomically trimmed and articulated
on the semi adjustable articulator
using the face-bow recording and
then the standard squash bite.
Technique:

2. Horizontal and vertical reference
lines are drawn on the mounting
plaster to register the post-operative
position of each maxillary and
mandibular segments before surgery.
Two sets of parallel horizontal lines
A/A and B/B are drawn on the upper
and lower models. These are easily
done by rotating the detached model
with the felt pen.

The B lines should be just clear of the
apices of the teeth, and not less than
15mm from the A lines. The actual
distance between the A and B lines is
then recorded on the plaster. These
lines will be used to plan the vertical
movements.

3. Three vertical lines VC, VB, VM are
drawn from upper base line (A) to the
lower baseline (A) on each buccal
segment. These lines pass through the
buccal surfaces of the upper cuspid,
bicuspid and the distal cusp of the last
upper molar tooth., and they are extended
to their occluding partners.
These will help to indicate the
anteroposterior movements achieved by
the model surgery.
Upper and lower midlines are also drawn.www.indiandentalacademy.com

Marked models with the
recorded distances.www.indiandentalacademy.com

4. The vertical distances from the
buccal cusp tips of the three reference
teeth to their A base lines are
recorded to help calculate any vertical
movements.
Transverse changes are recorded by
the inter-canine and inter-molar
distances measured across the palate
and recorded by taking reference
points on the canine tips and the
mesiobuccal cusp of the first molars.www.indiandentalacademy.com

Cuspal reference points are used for
transverse changes.www.indiandentalacademy.com

5. When all the reference lines have
been drawn and the
measurements completed, the
osteotomy lines are drawn between
A and B lines to correspond with the
bone cuts.
The plaster mounting assembly is
then sectioned at the osteotomy
sites with a saw or large abrasive
disc and the whole arch or segments
are repositioned in the planned post-
operative position.www.indiandentalacademy.com

Interrupted line is the
proposed osteotomy site.www.indiandentalacademy.com

6. After making the horizontal cut,
rotate the dental midline on the
model to match the facial midline
on the mounting plaster.
This will rotate the model VB and
VM on the deviated side forwards
and the contra-lateral side VB and
VM lines backwards.
Carefully mark their new positions.
Additional forward movements
are then measured from these new
vertical references.www.indiandentalacademy.com

This will be important at the
operation, when a significant
rotation will increase the actual
movement on the deviated side
and may eliminate any obvious
movement on the contra-lateral
side.

Maxilla is reassembled with the wax after
the osteotomy cuts. Mandible closes in to
the intermediate occusal relationship.
Intermediate wafer is made at this stage.

Lower segmental set-down of 3mm is
carried out with the forward slide of 5mm to
correct the interarch occlusal relationship.www.indiandentalacademy.com

Anterior view: models showing the upper
midline split to widen the intercanine
width and the lower anterior set-down.www.indiandentalacademy.com

Computer methods
Advantages:
1. Software programs often include automatic
adjustments in the soft-tissue profile, this
can speed up the prediction process and
make it more consistent.
2. Having digital model in the computer, it is
easy to produce several slightly different
cephalometric predictions, so the impact of
minor changes can be examined in more
detail.
3. Helpful in integrating the information from
the dental cast with the cephalometric
information. www.indiandentalacademy.com

Disadvantages:
1.Cost of the necessary software and
hardware.
2.Limitations of the existing programs.

Recent advances:
Over the past few years attempts have
been made to image the skull in three
dimensions.
Computerized tomography(CT) and
laser imaging have not only allowed
the three dimensional imaging of the
skull but also the development of
techniques to simulate surgery and
predict post-operative facial features
before surgery.www.indiandentalacademy.com

Three dimensional image of the
skull is produced by octree
encoding which means the image is
built up from cubes derived from the
scan.
Once the image is digitized it can be
easily manipulated to mock the
surgery using the soft-wares.

3D CT image

Sub apical osteotomy cuts are marked
on the screen with the trackerball.www.indiandentalacademy.com

Maxillary set-down 3mm, mandibular
upward 5mm www.indiandentalacademy.com

Pre-op (CT)www.indiandentalacademy.com

Post-op (CT, mock)www.indiandentalacademy.com

P
r
e
-
O
p
P
o
s
t
-
O
p

Post- Op photos and radiographs

VIDEOCEPHALOMETRY.
Video imaging technology is a method in
which orthodontist gathers facial
frontal,profile,and dental images and
modify them to project potential esthetic
treatment goals (David .M .Sarver).
Definition:

Video cephalometric
prediction methodology is
virtually identical to the
cephalometric tracing
method.
Hence the difficulties
encountered is similar to the
tracing method.(except the
improved visualization and
recognition of facial profile
changes.) www.indiandentalacademy.com

Video cephalometry technique helps
in quantifying treatment plans. In
other words, co-ordination of
calibrated profile images with facial
profile images permits precise
measurement of bony and dental
movements, and through the
application of algorithmic prediction
ratio’s images are produced that
express the expected surgical and/or
orthodontic outcome.

Digitization:
Direct
Indirect

Direct
Radiograph is placed on the
digitizing tablet, and the
anatomy and anatomical
landmarks are digitized using
a potentiometer such as
“electronic pen” or “cross
hair cursor”

Indirect
ö A video camera or a scanner
captures an image of the
cephalometric radiograph.
ö Digital radiography can also be
used.
Captured image can be then displayed
on the computer monitor and can be
indirectly digitized via mouse or an
“onscreen” electronic pen.www.indiandentalacademy.com

Method:
Video imaging techniqueVideo imaging technique
1.counseling phase 2.treatment planning phase

Involves the use of facial or dental
image modification without any
quantitative aspect to the process.
It is simply a graphic way of
communicating ,concepts that are
difficult to present verbally.
1.counseling phase

Pre treatment profile modification sessions
may be performed with the patient before full
records are taken.
In the counseling phase profile image is
gathered and displayed on the computer screen,
& profile changes expected with surgery are
illustrated through the use of cut & paste tools

An initial profile image was captured and
displayed on computer screen for graphic
illustration of the facial changes that should be
anticipated with orthodontic decompensation
and surgical mandibular advancement.
The use of cut & paste art functions in the
software programme allows us to copy
outlined segments of the image to RAM for
short term storage and graphic movement.

The counseling phase is performed
without videocephalometric
integration,but simulation of the soft
tissue reaction to the planned hard-
tissue movements (orthodontic and
orthognathic) can be performed.

First the initial image is captured and
displayed on the computer screen with
selected ceph analysis overlaid on the
profile image.
Application of the ceph analysis to the
profile demonstrates the dental
compensation and mandibular deficiency
present in this patient.
procedureprocedure

Image obtained with video camera , stored & then displayed
for digitization and analysiswww.indiandentalacademy.com

Simulation of orthodontic
decompensation of maxillary incisors
through torque and advancement of
upper incisors is then performed using
the cut and paste function.
Profile changes expected with maxillary
advancement in preparation for surgery
are illustrated by advancing the upper lip
on the profile image.

In the computer simulation, a box is placed
encompassing the upper lip and copied to
RAM.The box is then moved forward by the
mouse.The new position reflects soft tissue
reaction to decompensation.

The next step is to simulate
mandibular advancement. A new
copy box is placed on the mandible
and copied to RAM.
This outlined portion is then moved
anteriorly to simulate mandibular
advancement

Click& drag

The mandible is moved forward ,the
amount estimated by the clinician to
correct the class II
This image simulates orthodontic
decompensation and correction of
mandibular deficiency & class II
malocclusion

The next logical procedure is advancement
genioplasty to improve chin projection.This
is simulated by outlining another template
on the chin,copying the section of the chin
to RAM and then moving the chin
anteriorly to an esthetically desired
position.

Click & drag
Simulation of genioplastywww.indiandentalacademy.com

The final profile created by image
modification effectively communicates the
anticipated effect of orthodontic
decompensation ,surgical mandibular
advancement,and advancement
genioplasty

Final Profile.

Pre & post counseling photosPre & post counseling photos

In this short preliminary visit the patient has
received graphic communication regarding the
potential facial changes that will occur during
ortho treatment & the anticipated outcome of the
proposed treatment plan.
After this phase of counseling, patients may
then decide whether they value the esthetic
changes & are reassured enough by the image
modification to pursue more comprehensive
treatment planning

The treatment planning phase of video imaging
involves the integration of the facial profile
image with the ceph and calibrating it to profile
video so as to relate the underlying hard-tissue
to overlying soft-tissue. It allows quantification
of hard & soft tissue movements and to apply
algorithmic response ratios between the two, to
project the soft-tissue reaction to hard tissue
movement.
2.treatment planning phase

In the adult patient the computer projection
can be quite accurate.In the adult, major
inaccuracy is the actual treatment itself.
In the adolescent the unpredictability of the
growth dynamics greatly diminishes the
predictive value of video cephalometric
projection.

procedureprocedure
The same patient example will be used to
explain the treatment planning phase.After the
profile image is captured, calibration
procedures are performed when the “ceph” is
matched to video image.
The computer can then perform algorithmic
calculations so that the movements on the
video screen are translated into real life terms.

A profile treatment planning template is
created by integration of the cephalogram,
calibrated to the facial profile, and displayed
on the computer monitor.
Profile projections(hard tissue movement
with appropriate soft tissue response)are
drawn from the computer data base & applied
in algorithmic fashion when the dental or
osseous segments are moved.

A profile planning template is created by integration of
ceph,calibrated to the facial profile and displayed.www.indiandentalacademy.com

Simulation of orthodontic decompensation
is created by up righting and advancing the
upper incisor template.
The computer not only allows overlay &
visualization of the pretreatment tracing &
projected dental movement but also
measures these anticipated and planned
movements, which are reflected in a table
on the left, which is shown in the figure.

Anticipated and planned movements,
which are reflected in a table

Simulation of orthodontic decompensation is created by up
righting and advancing the upper incisor template.www.indiandentalacademy.com

The soft tissue outline of the upper lip is
automatically adjusted through the algorithmic
response calculations.

The video portion of the software is adjusted to
the prediction outline, simulating a soft-tissue
response to the incisor movement.

Simulation of mandibular advancement
is accomplished by clicking and
dragging the mandibular template
forward.
The quantitation table supplies the
amount of advancement required to
achieve ideal over jet and over bite.

Simulation of mandibular advancement is accomplished by
clicking and dragging the mandibular template forward.www.indiandentalacademy.com

See the
soft-tissue
response

The profile is judged to be still
moderately convex, so an advancement
genioplasty is simulated by advancing
the template of the chin.
The figure illustrates the cephalometric
outline prediction of a 4 mm anterior
movement of chin.

Advancement
genioplasty

This image is auto treated.This movement can be
greatly influenced by patient direction and desire
because there are few functional demands on this
movement

The final prediction image now reflects a
treatment plan that has corrected the
malocclusion and arrived at an
esthetically pleasing profile to both
patient and clinician.

ceph tracing
blinked off
Final projected profile outcome with
ceph tracing blinked off

VCDACTUAL

The skeletal and soft tissue
response to surgery is different for the
type of surgical procedure and
osteosynthesis used.(for e.g using of
wire osteosynthesis or any other rigid
fixation.)
Key notes in computerized
cephalometric prediction:

The algorithms in the prediction
software should be modifiable by the
clinician.
The type of fixation and procedure
used by the treatment planners and
surgeons should be chosen before
generating the prediction tracings, so
that the odds of the surgical
prediction and the actual out come
matching closely are maximized.

conclusion
A combination of cephalometric
prediction and model surgery
gives the surgeon a satisfactory
idea of the esthetic and occlusal
result of the surgery. This also
helps the team to decide on the
method of combining orthodontics
and orthognathic surgery.

Thank YouThank You

Ceph and model mock surgery for orthodontic surgery planning

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