Orthodontic study models

Orthodontic
Study Models
Dr. Maher Fouda
Professor of orthodontics
Mansoura Egypt

Orthodontic study models are essential
diagnostic records, which help to study the
occlusion and dentition from all three
dimensions. They are accurate plaster
reproductions of the teeth and their
surrounding soft tissues.

REQUIREMENTS OF ORTHODONTIC
STUDY MODELS
1. Models should accurately reproduce the teeth and
their surrounding soft tissues.
2. Models are to be trimmed so that they are symmetrical
and pleasing to the eye and so that an asymmetrical arch form
can be readily recognized .
3. Models are to be trimmed in such a way that the dental
occlusion shows by setting the models on their backs.
4. Models are to be trimmed such that they replicate the
measurements and angles proposed for trimming them.
5. Models are to have clean, smooth, bubble-free surfaces
with sharp angles where the cuts meet.
6. The finished models should have a glossy mar proof Finish.

Importance of models
1. They are invaluable in planning treatment, as they are the only three
dimensional records of the patient’s dentition.
2. Occlusion can be visualized from the lingual aspect.
3. They provide a permanent record of the intermaxillary relationships and
the occlusion at the start of therapy: this is necessary for midicolegal
considerations.
4. They are a visual aid for the dentist as he monitors changes taking place
during tooth movement.
5. Help motivate the patient, as the patient can visualize the treatment
progress.
6. They are needed for comparison at the end of treatment and act as a
reference for posttreatment changes. .
7. They serve as a reminder for the parent and the patient of the condition
present at the start of treatment.
8. In case the patient has to be transferred to another clinician, study models
are an important record.

USES OF STUDY MODELS
1. Assess and record dental anatomy
2. Assess and record intercuspation
3. Assess and record arch form
4. Assess and record the curves of occlusion
5. Evaluate occlusion with the aid of articulators
6. Measure progress during treatment
7. Detect abnormality, e.g. localized enlargements, distortion
of arch form, etc.
8. Calculate total space requirements/discrepancies
9. Provide record before, immediately, after and several years
following treatment for the purpose of studying treatment
procedures and stability.

The study models can be divided into two parts for the
purpose of description.
The anatomic portion
2. The artistic portion
.The anatomic portion is that part which is the actual
impression of the dental arch and its surrounding soft
tissue structures. This is the part, which must be
preserved when trimming the model
.The artistic portion is the stone base supporting the
anatomic portion. This portion is trimmed in a manner,
which depicts, in a general way, the dental arch form
and is pleasing to the eye.
PARTS OF THE STUDY MODELS

FABRICATION AND TRIMMING OF
STUDY MODEL
Preliminary procedures in the fabrication of study
models are:
1. Remove any excess flash or obviously excessive
bulk on the periphery of the models.
2. Remove any nodules that may be present on the
occluding surfaces of the teeth.
3. Remove any extensions in the posterior areas
that prevent occluding of the models.
4. Using the wax bite, occlude the models.

STEPS IN ART PORTION FABRICATION
1-Determine the occlusal
plane of the dentition.
Once this has been
determined, the base of
the lower model is
trimmed parallel to the
occlusal plane. The
occlusal plane is
considered to be the
highest three points of
the erupted teeth.

2. Trim the back of the lower model
perpendicular to the base .This is done
on a near symmetrical model by
measuring the distance from the distal
of the first molars or second bicuspids
to the back of the model on both the
left and right sides. On a model that is
not symmetrical, compensation must
be made to keep the back as near
perpendicular to the midline as
possible. The midline of the lower
model should normally correspond
favorably with the upper mid-palatal
raphae. It is generally easier to locate
the midline in the maxillary cast.The
back is trimmed so that it is 90 degrees
to the base of the model.

The posterior surface should not be trimmed
too close to the posterior aspect of the
mandibular teeth, as the hamular notch of the
upper model governs the distance, this surface
'should be from the teeth.
3. To trim the back of the upper model, occlude the
models utilizing the wax bite. The wax bite not
only maintains the correct interrelationship but
will also help to prevent fracturing of the teeth.
Carefully trim the posterior surface of the
occluded models so that the upper model
matches that of the lower model . The back of
the upper and lower models should now be 90°
to the base of the lower model. Trim the
posterior surfaces of both models until you are
just posterior to the hamular notch which
should be several millimeters posterior to the
last tooth.

4. Trim the base of the upper model so
that it is parallel to the base of the
lower model. Trim until the top base is
flat, but leave several millimeters of
extra height so the occlusal plane of
the models can be centered and the
models finished to the specified
dimension.
The occlusal plane should be centered
between the top of the maxillary
model and the base of the mandibular
model, when the models are occluded
without the wax bite, the models
being viewed from the buccaI.

5. Now we have two bases
parallel to each other and to
the occlusal plane . The backs
of both the upper and lower
bases are at right angles to the
bases, the occlusal plane and
to the mid-palatal
aponeurosis.
From here onwards, the upper
and lower models shall be
trimmed independently of
each other.

The Lower Model
1. Make the buccal cuts on the edge of
the vestibule at 60° angle to balk .
The edge of the vestibule is taken as
a point approximately 5 to 6 mm
away from the most prominent point
of the lower canine or first bicuspid
tooth (whichever is more prominent).
The model is trimmed to this point
provided that this does not cut
beyond the deepest point of the
vestibule in the region of the first or
second molar. If this guideline would
place the cut beyond the depth of
the vestibule, then it is advisable to
use the depth of the vestibule to
determine the depth of the buccal
cuts.

2. The anterior segment of the
lower arch is trimmed into a
curve, which should follow the
arc of a circle. The radius of
this segment of the circle shou
Id represent the general
curvature of the lower anterior
teeth. The finished model
should have this curve
trimmed to within 5 to 6 mm
of the anterior teeth.

3. The heels of the lower model
are cut at approximately 115° to
the back of the model. The floor
of the mouth should be leveled
and smoothed to form a flat
surface.
The ideal set of models will have
the art portion representing
approximately l/3rd of the total
height and the anatomic portion
approximately 2/3rd of the
height.

The Upper Model
1. Make the buccal cuts to the
edge of the vestibule at an
angle of 60° to the back of the
model.
2. Make the anterior cuts so that
the ends are at the midline
and approximately in the
canine area . This cut should
be approximately 5 to 6 mm
from the labial surface of the
anterior teeth, with both sides
of equal length and their
intersection on the midline.
Make buccal cuts. at the edge of the vestibule 60°
to back of the model
Make anterior cuts. the ends of which should be at
the midlineand the middle of each canine

3. The heels of the upper
model are formed by
occluding both the
models and finishing
them such that they are
flush with the heels of
the lower to the bite of
the model that they are
flush with the heels of
the lower models at 115°
. The heels of the upper
model may not be the
same length as those of
the lower model.
Occlude models. Trim upper heels so they are flush
with lower heels

4. The finished height of the occluded models
should be 7 cm .
Occluded models should have a sharp 90° angle between
their base and back

Commercially available plastic
bases are now available
which can be used to base
the upper and lower model in
articulation. These bases offer
the advantage that they have
a standard size, made of
plastic and hence are easy to
store. The procedure involved
for using pre formed plastic
bases for basing of models is
as follows:

1. Using a pencil and the
mid-palatal raphe as a
reference, mark the
midline of the maxillary
cast. Match the mid
palatal plane to the
symmetric scribe line on
the positioning plate.
Secure the model in this
position against the
specially provided hooks
using elastics
The positioning plate stabilized using elastics

2. Now take the upper plastic model base and
place the dove tails into the rear guide rails
with the rest point outwards and the beveled
edge upwards. The upper model base is easily
recognizable by the anterior intercanine
square shape. Pour sufficient quantity of well
spatulated plaster into the upper model base
and insert the position plate along with the
stabilized upper model into the guide rails
until the foot of the positioning plate touches
the table top . The excess plaster should be
removed and the surface smoothened. The
elastics can be cut and removed after the
initial setting of the plaster has taken place.
Once the plaster is completely set, the
position plate and the guide rails can be taken
.off
The stabilized upper model placed in the
upper model base loaded with plaster

3. The guides must be seated again
into the seats of the upper
model plaster base with the rest
point directed towards the
model and the edge upwards.
4. Place the lower model into
articulation with the upper
model and stabilize it with
elastics . The lower base is now
loaded with a suitable quantity
of well spatulated plaster and
seated over the lower model
with the guide rails into the
seats of the lower plastic model
base, until they are in contact
with the rest point.
Lower model stabilized in articulation using
elastics
Guides seated into the seats of the upper model
plaster base with the rest point directed towards the
model and the edge upwards

5. The excess plaster can be
removed and the models
finished .
6. The rails can be replaced with
the hinges which keep the
models in occlusion and act as
hinge joints for demonstration
purpose
The based models in occlusion
The based models with hinges act as
joints for demonstration

Finishing the Models
The surface must be made smooth, remaining at the same
time absolutely flat and at right angles to the bases of the
models. The finishing process should not change the
dimensions or any of the angulations of the models. In the
carborandum stone technique, the model is rubbed over the
stone with an even pressure under a stream of water until a
smooth surface results. The method is to rub the model on a
frosted glass surface. After the surfaces have been finished,
and the exact dimensions achieved, the model is set aside to
dry for 48 hours or dried overnight in an orthodontic oven. At
this point the model should be labeled with the patient's
name and date on the backs of both the upper and lower
models.

The final glazing is put on the models by immersing them in a
commercial gloss. The models are allowed to remain in this
solution for one-half hour. Holding each arch under cold
water, the models are polished and soap solution removed by
buffing with cotton. The models are set on their occlusal
surfaces to dry for another twelve hours, then buffed with a
very light but rapid motion using cotton. The models should
assume a high, even luster which will then resist soiling while
handling.
The models should be placed on a flat surface with their backs
down. They should be picked up together and always
returned together. Individual handling of the models is more
likely to result in damage to the models.

Cast Trimming to Indicate Occlusal Plane Relationships
The gnathostatic technique, was introduced by Simon in 1962.
It reproduces the inclination of the occlusal plane with
reference to the eye-ear (Frankfort horizontal) plane.
Trimmed in this fashion, the casts show the approximate
inclination of the occlusal plane in the face of the patient. This
information is valuable, but can be gained more accurately
with the use of cephalogram. Also the casts so produced are
not esthetically pleasing as they lack symmetry.

MODEL ANALYSIS
Pont’s Analysis
In 1909 Pont presented to the
profession a system whereby
the mere measurement of 4
maxillary incisors automatically
established the width of the
arch in the premolar and molar
region. The greatest width of
the incisors is measured with
calipers recorded on a line, and
their sums then recorded in
millimeters(Sum of Incisors)
Sum of the mesiodistal widths of individual incisor
teeth is added to calculate the arch width in the
posterior region

The distance between the
upper right first premolar and
upper left first premolar (i.e.
the distal end of the occlusal
groove) is recorded and called
as Measured Premolar Value
(MPV).
The distance between the
upper right first molar and
upper left first molar (i.e. the
mesial pits on the occlusal
surface) is recorded and is
termed as Measured Molar
Value whereas on the
mandibular teeth the points
used are the distobuccal cusps
of the first permanent molar
Measured molar value (MMV) in the maxillary arch

Calculated premolar value (CPV) The expected arch width in
the premolar region is calculated by the formula:
SI x 100
80
Calculated molar value (CMV) The expected arch width in the
molar region is calculated by the formula:
SI x 100
64
The difference between the measured and calculated values
determines the need for expansion. If measured value is less,
expansion is required.
Pont's index gives an approximate indication of the degree of
narrowness of the dental arches in a case of malocclusion and
also the amount of lateral expansion required for the arch to
be of sufficient size to accommodate the teeth in perfect
alignment.

Drawback of Pant's Analysis
1. Maxillary laterals are the teeth most commonly missing from the oral
cavity.
2. Maxillary laterals may undergo morphogenetic alteration like 'peg' shaped
latera1.
3. This analysis is derived solely from the casts of the French population.
4. It does not take skeletal malrelationships into consideration.
5. It may be useful to know the desired maxillary dimension for a case, but it
is more difficult to achieve the corresponding mandibular dimensions that
are necessary to maintain a balanced occlusal relationship.
6. Pont's index does not account for the relationship of the teeth to the
supporting bone, or the difficulties in increasing the mandibular
dimensions. It should always be remembered that the patient's original
mandibular and maxillary arch form should be considered as the ultimate
guide for arch width rather than the values arrived at by using the Pont's
index.

LINDER HARTH INDEX
Linder Harth proposed an analysis, which is very similar to
Pont's analysis. However he made a variation in the
formula to determine the calculated premolar and molar
value. The calculated premolar value is determined using
the formula:
SI x 100
85
The calculated molar value is determined using the
formula:
SI x 100
64
where SI = sum of mesiodistal width of incisors.

KORKHAUS ANALYSIS
This analysis makes use of the
Linder Harth's formula to
determine the ideal arch width in
the premolar and molar region. An
additional measurement is made
from the midpoint of the inter-
premolar line to a point in between
the two maxillary incisors.
According to Korkhaus, for a given
width of upper incisors a specific
value of the distance between the
midpoint of interpremolar line to
the point between the two
maxillary incisors should exist .
Measurement of anterior arch length (occlusal view)

In case of proclined upper anteriors,
an increase in this measurement is
seen while a decrease in this value
denotes retroclined upper anteriors.
For the values noted the
mandibular value (LI) should be
equal to the maxillary value (Lu) in
millimeters minus 2 mm.
Measurement of anterior arch length (lateral view)

ASHLEY HOWE'S ANALISIS
Ashley Howe considered tooth crowding to be due to
deficiency in arch width rather than arch length. He
found a relationship between the total width of the
mesiodistal diameters of teeth anterior to the second
permanent molars and the width of the dental arch
in the first premolar region.

Definitions
Total tooth material(TIM) Refers to the sum of
the mesiodistal width of the teeth from
first molar to first molar (inclusive of the
first molars), taken on casts of the dental
arches, measured with dividers or a
Boley's gauge .
2. Basal arch length (BAL)In the maxilla the
median line measurement from Downs A
point is projected perpendicularly to the
occlusal plane, then to the median point on
a line connecting the distal surface of first
molars .
In the mandibular arch the measurement is
made from Downs B point to a mark on the
lingual surface of the cast in the same
manner as in the maxilla
Total tooth material
Maxillary basal arch length

3. Premolar diameter(PMD) Is the
arch width measured at the top of
the buccal cusp of the first
Premolar
4. Premolar basal arch width
(PMBAW) Is obtained by
measuring the diameter of the
apical base from canine fossa on
one side to the canine fossa on the
other side or else 8mm below the
chest of interdental papilla
between lOP below the canine and
first premolar with the lower end of
the Boley's gauge.
Premolardiamete
Mandibularbasal arch length

According to Ashley Howe, to determine whether the apical bases of the patient could
accommodate the
patients' teeth, the following measurements have to be obtained:
1. Percentage of premolar diameter to tooth material is obtained by dividing the PMD
by the total tooth
material.
PMD x 100
TTM
2. Percentage of premolar basal arch width to tooth material is obtained by dividing
the premolar basal arch width by the total tooth material.
PMBAW x 100
TTM
Percentage of basal arch length to tooth material is obtained by dividing the basal arch
length by total tooth material.
=BAL x 100
TTM
Comparison between PMBAW and PMD gives an idea of the need and the amount of
expansion required and PMBAW% gives an indication towards an extraction or
non-extraction treatment plan.

Inference
a. If the width between the canine fossa is greater than
the width of the premolars (PMBAW > PMD), it is an
indication that basal arch is sufficient to allow
expansion of the premolars. If the canine fossa width
or PMBAW is less than PMD there can be 3
possibilities:
• Don't treat.
• Move teeth distally to wider part of the arch.
• Extract some teeth.

b. According to Howe, to achieve a normal occlusion with a full
complement of teeth the canine fossa measurement
(PMBAW) should be 44 percent of the sum of the maxillary
tooth diameter. When this ratio is between 37 percent and 44
percent, extraction of first premolars is doubtful, and the case
is considered to be in the borderline category. When it is less
than 37 percent, then it is considered to be definitely a case
for first premolar extraction as it is a basal arch deficiency.
Any value, 44 percent or above indicates a non-extraction
case.
Therefore, this analysis is a useful treatment planning tool and
helps to determine whether to extract or expand.

WAYNE A. BOLTON ANALYSIS
Bolton pointed out that the extraction of one tooth or several
teeth should be done according to the ratio of tooth material
between the maxillary and mandibular arch, to get ideal
interdigitation, overjet, overbite and alignment of teeth. To
attain an optimum inter-arch dental relationship, the
maxillary tooth material should approximate desirable ratios,
as compared to the mandibular tooth material. Bolton's
analysis helps to determine the disproportion between the
size of the maxillary and mandibular teeth.

Procedure for doing Bolton Analysis
The sum of the mesiodistal diameter of the 12 maxillary teeth
(sum of maxillary 12 )and the sum of the mesiodistal diameter
of the 12 mandibular teeth (sum of mandibular 12) including
the first molars are determined. In the same manner, the sum
of 6 maxillary anterior teeth (sum of maxillary 6) and the sum
of 6 mandibular anterior teeth from canine to canine (sum of
mandibular 6) is determined .
Overall ratio The sum of the mesiodistal widths of the 12
mandibular teeth should be 91.3 percent the to Bolton. This
ratio is calculated using the following formula:
Overall ratio = sum of mand. 12 x 100
sum of max.12

Sum of the mesiodistal widths of the maxillary
and mandibular teeth

The sum of the 12 maxillary and 12 mandibular teeth for a
given patient is inserted into the formula and the overall ratio
is determined. If the overall ratio is greater than 91.3 percent,
then the mandibular tooth material is excessive. The amount
of mandibular tooth material excess is calculated by using the
formula:
Mandibular overall excess =
sum of mand.12 - {sum of max.12 x 91.3}
100

If the overall ratio is less than 91.3 percent, then the maxillary
tooth material is excessive. The amount of maxillary tooth
material excess is calculated by using the formula:
Overall maxillary excess =
sum of max. 12{sum of mand.12 x 100}
19.3

Anterior ratio This ratio can be found out using the formula:
Anterior ratio= sum of mand. 6 x 100
sum of max. 6
If the anterior ratio is greater than 77.2 percent, then
the mandibular anterior tooth material is excessive.
The amount of mandibular tooth material excess is
calculated by using the formula:
MandiIbuIar anterior tooth materiaI excess = sum of
mandibuIar 6 - {sum of max. 6 X77.2}
100

If the anterior ratio is less than 77.2 percent,
then the maxillary anterior tooth material is
excessive. The amount of maxillary tooth
material excess is calculated by using the
formula:
Maxillary anteno..r tooth matenal excess =
sum of max 6 - {sum of max.6 x100}
77.2

CAREY'S ANALYSIS
The arch length- tooth material
discrepancy is the main cause for
most mal occlusions. This
discrepancy can be calculated with
the help of Carey's analysis. This
analysis is usually done in the lower
arch. The same analysis when
carried out in the upper arch is
called as arch perimeter analysis.
Methodology;
Determination of arch length The
arch length is measured anterior to
the first permanent molar using a
soft brass wire.
Brass wire measurement and actual
mesiodistal widthsof the teeth
mesialto the firstpermanentmolars

The wire is placed touching the
mesial aspect of lower first
permanent molar, then passed
along the buccal cusps of premolars,
incisal edges of the anteriors and
finally continued the same way up
to the mesial of the first molar of
the contralateral side.
Brass wire measurement and actual mesiodistal Widths of the
teeth mesial to the first permanent molars

The brass wire should be passed
along the cingulum of anterior teeth if
anteriors are proclined and along the
labial surface if anteriors are
retroclined. The mesiodistal width of
teeth anterior to the first molars are
measured and summed up as the
Total tooth material.
The difference between the arch
length and the actual measured tooth
material gives the discrepancy.

The amount of discrepancy between arch length and
tooth material is calculated.
If the arch length discrepancy is
• 0 to 2.5 mm-Proximal stripping can be carried out
to reduce the minimal tooth material excess.
• 2.5 to 5 mm-Extraction of 2nd premolar is
indicated
• Greater than 5 mm-Extraction of first premolar
is usually required.

MOVER'S MIXED DENTITION ANALYSIS
The purpose of a mixed dentition analysis is to evaluate the amount of
space available in the arch for succeeding permanent teeth and necessary
occlusal adjustments. Many methods of mixed dentitions analysis have
been suggested; however, all fall into two strategic categories:
1. Those in which the sizes of the unerupted cuspids and premolars are
estimated from measurements of the radiographic image, and
2. Those in which the sizes of the cuspids and premolars are derived from
knowledge of the sizes of permanent teeth already erupted in the mouth.
The correlation between the sizes of the mandibular incisors and the
combined sizes of cuspids and bicuspids in either arch is high enough to
predict the amount of space required for the unerupted teeth during
space management procedures. The mandibular incisors have been
chosen for measuring, since they erupt into the mouth early in the mixed
dentition. The maxillary incisors are not used in any of the predictive
procedures, since they show too much variability in size, and their
correlations with other groups of teeth are of lower predictive value.

Procedure
a. Procedure in the mandibular arch
1. Measure with the tooth-measuring gauge or a
pointed Boley's gauge, the greatest mesiodistal width
of each of the four mandibular incisors.
2. Determine the amount of space needed for
alignment of the incisors. Set the Boley's gauge to a
value equal to the sum of the widths of the left central
incisor and left lateral incisor. Place one point of the
gauge at the midline of the alveolar crest between the
central incisors and let the other part lie along the line
of the dental arch on the left side.

Mark on the tooth or the cast the precise point where the
distal surface of the lateral incisor will be when it has been
aligned. Repeat this process for the right side of the arch.
3. Compute the amount of space available after incisor
alignment. To do this, measure the distance from a point
marked in the line of the arch to the mesial surface of the first
permanent molar. This distance is the space available for the
cuspid and two bicuspids and for any necessary molar
adjustment after the incisors have been aligned. Record the
data for both sides on the mixed dentition analysis form.

4. Predict the size of the combined widths of the mandibular cuspid and
bicuspids. Prediction of the combined widths of cuspid, first bicuspid,
and second bicuspid is done by use of probability charts. Locate in
the left column of the mandibular chart the value that most nearly
corresponds to the sum of the widths of the four mandibular
incisors. To the right is a row of figures indicating the range of values
for all the cuspid and bicuspids sizes that will be found for incisors of
the indicated size. The value at the 75 percent level of probability is
chosen as the estimate, since it has been found to be the most
practical from a clinical standpoint.
Procedure in the maxillary arch. The procedure is similar to that for
the lower arch, with two exceptions
1. A different probability chart is used for predicting the upper cuspid
and bicuspid sum.
2. Allowance must be made for overjet correction when measuring
the space to be occupied by the aligned incisors. Remember that the
width of the lower incisors is used to predict upper cuspid and
bicuspid widths

TANAKA AND JOHNSON ANALYSIS
The prediction of the size of unerupted canines and
prernolars in contemporary orthodontic population can
also be done with the Tanaka and johnson analysis.
Tanaka and Johnson did a study to repeat Moyers
observation to validate its equation on a new sample. The
possibility of secular changes within the past 20 years was
to be examined and they found Mover's prediction table to
be equally appropriate for contemporary population.
However they have simplified Moyers 75 percent level of
the prediction table into a formula .
Predicted width of maxillary canine and premolar
{Misiodistal width of four lower incisors}+11
2
= estimated width of maxillarycanine and premolar in one
quadrant

Predicted width of mandibular canine and
premolar
{Mesiodistal width of four lower incisors} +
2
10.5
= estimated width of canine and premolar in
one quadrant

KESLlNG DIAGNOSTIC SET-UP
Kesling introduced the
diagnostic set-up which is
made from an extra set of
trimmed study models . The
diagnostic helps the clinician in
treatment planning as it
simulates various tooth
movements, which are to be
carried out in the patient. The
individual teeth along with
their alveolar process are
sectioned off from the model
using a saw and replaced back
in the desired final position.

The procedure is as follows
Dental cast is related to FMlA
• Constant FMIA = 65° and find
ideal position of mandibular
incisors mesiodistally.
• Align both the lower central
and lateral incisors on the
lower cast at FMTA= 65°
• Mandibular incisors are placed
at right angles to mandibular
plane.
• Canines are the next teeth to
be positioned
Mark the labial position of the
anterior teeth and the canine
width on the artistic portion of
the model
Section individual teeth using a saw-
starting with a vertical cut

First and second premolars are
then set on the model.
• If the remaining space on each
side is adequate to receive the
permanent first molars, then
extraction is not required.
• If space is inadequate and
amounts to more than can be
gained by uprighting the
permanent second molars, then
some teeth must be removed
usually the first premolar .
According to the lower
incisors the posterior
teeth are set with or
without extracting
certain teeth depending
on space requirements
Section individual teeth using
a saw

When the mandibular
set-up is completed, the
maxillary teeth are cu t
from their base and
repositioned, then
articulated to the
mandibular set-up .
The finished set-up with ideal/proposed changes visible

Base the models to be used for Kesling setup
Mark the labial position of the
anterior teeth and the canine
width on the artistic portion of
the model
Section individual teeth
using a saw-starting with a
vertical cut
Section individual teeth using
a saw

Section the teeth molar to molar
Mandibular incisors are
placed with an ideal inclination
and position
According to the lower
incisors the posterior
teeth are set with or
without extracting certain
teeth depending on
space requirements
The maxillary teeth are set
according to the mandibuiar teeth

The finished set-up with ideal/proposed changes visible

Uses of Diagnostic Set-up
1. Aids in treatment planning as it helps to
visualize tooth size-arch length discrepancies and
determine whether extraction is required or not.
2. The effect of extraction and tooth movement
following it, on occlusion can be visualized.
3. It also acts as a motivational tool as the
improvements in tooth positions can be shown to
the patient.

Orthodontic study models

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Orthodontic study models