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1. MODEL ANALYSIS IN
ORTHODONTICS
INDIAN DENTAL ACADEMY
c Leader in continuing Dental Education
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2. MODEL ANALYSIS
•MODEL ANALYSIS IS THE STUDY OF
MAXILLARY & MANDIBULAR DENTAL
ARCHES IN ALLTHREE PLANES OF SPACE
(SAGITTAL, VERTICAL, TRANSVERSE
PLANES ) USING STUDY MODELS &
RADIOGRAPHS WHICH IS A VALUABLE
TOOL IN ORTHODONTIC
DIAGNOSIS&TREATMENT PLANNING
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4. DIFFERENT IMPORTANT ANALYSIS ARE AS
FOLLOWS
• TOOTH SIZE-ARCH WIDTH DISCREPANCY
• PONT’S ANALYSIS.
• LINDERHARTH ANALYSIS
• KORKHAUS ANALYSIS
• ASLEY–HOWE ANALYSIS
• ETC .
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5. TOOTH SIZE-ARCH LENGTH DISCREPENCY
• ARCH-PERIMETER ANALYSIS
• NANCE-CAREY’S ANALYSIS
• IRREGULAR INDEX
• REE’S ANALYSIS.
• DIAGNOSTIC SET UP
• LAARRY WHITE ANALYSIS
• SANIN & SAVARA ANALYSIS
• TOTAL SPACE ANALYSIS
• CONVENTIONAL METHOD
• TWEED METHOD
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6. MIXED- DENTION ANALYSIS
(Estimating the size of unerupted teeth)
MOYER’S ANALYSIS.
TANAKA-JOHNSTON ANALYSIS.
HIXON-OLD FATHER METHOD
HUCKABA ANALYSIS
UPPER/LOWERTOOTH SIZE DISHORMONY
BOLTON’S TOOTH RATIO ANALYSIS
TOOTH-SHAPE DISHORMONY
PECK & PECKINDEX.
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7. PHOTOGRAPHIC ANALYSIS OF STUDY
MODEL
• STEROPHOTOGRAMETRY
• OCCLUSOGRAMS
• HOLOGRAPHIC IMAGE ANALYSIS
• COMPUTERIZED ANALYSIS
• OSCOPO
• REFLEX METROGRAPHY
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8. PONT’S ANALYSIS
• Pont’s in 1909 presented a system
whereby mere measurement of Incisors
automatically gives width of the arch in
premolar &molar region
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9. • Pont’s analysis helps in determining whether the
dental arch is narrow or normal, need for lateral
expansion &how much expansion is possible.
• S.I.-sum of m-d width of 4 max. incisor is
determined
• M.P.V.-width from distal pit to distal pit (P.M.)
• M.M.V.-Width from mesial pit to mesial pit. (M)
• C.P.V-- S.I. × 100/ 80
• C.M.V– S.I × 100/64
INFERENCE- if measured value is < then calculated value, it
indicates the need for the expansion, indicating how much
expansion is needed in molar & premolar regions.
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10. Drawbacks of Pont's analysis
1.Study based on French
population,hence universal
validity is questionable.
2.Does not consider the alignment
of teeth.
3.Doesn't consider the
malformation of teeth-e.g, peg
laterals.
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11. • LINDERHARTH INDEX
This analysis is similar to pont’s analysis
except that a new formula has been
proposed to determine the calculated
premolar & molar value.
• C.P.V.– S .I. × 100/85
• C.M.V.--- S.I. × 100/64
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12. • KORKHAUS ANALYSIS-This is similar to pont’s
analysis. According to this,for a given width of upper
incisor,a specific value of the distance b/n midpoint of
inter premolar line to point in b/n the max.incisor exist.
INFERENCE-Increase in this measurement denotes proclined
upper anteriors, while reduced value indicates retroclined upper
anteriors.
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13. ASHLEY-HOWE’S ANALYSIS- Ashley howe
considered tooth crowding to be due to arch width rather
than arch length.he found a r/nship between the total width
of all 12 teeth mesial to second molar and width of the
dental arch in the 1 st premolar region.
According to this analysis to determine
whether the apical bases could accommodate
the teeth ,the following measurements have
to be obtained:
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14. *Determination of premolar diameter (P.M.D.)
The premolar diameter refers to the arch width
from the tip of the buccal cusp of the opposite
first premolar.
*Determination of premolar basal arch width
(P.M.B.W.)
The measurement of the width from canine fossa
To the other gives us the width of dental arch at
basal bone. Or else measurement is made from
a point 8 mm below the crest of inter-dental
papilla to distal of canine.
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15. • INFERENCE-
If PMBAW>PMD-The basal arch is sufficient
to allow expansion of the premolars.
If PMBAW<PMD-
Three possibilities-
No need of treatment
Move teeth distally to wider part of the arch.
Extract some teeth.
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16. • Calculation of premolar basal arch width
percentage:
P.M.B.A.W.%=P.M.B.A.W*100/T.T.M.
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17. • According to Howe, to achieve a normal
occlusion with full complement of teeth
the PMBAW should be 44 percent.
* If percentage is in between 37-44%-
Borderline case.
*Percentage less than 37%- First premolar
extraction.
*Any value above 44%- Non extraction case
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18. CAREY’S ANALYSIS /ARCH PERIMETER ANALYSIS
• Carey’s Analysis helps in
determinining the extent of
discrepancy b/n arch length &
tooth material discrepency.it is
performed in lower cast & same
on upper is called arch –
perimeter analysis.
• The arch anterior to the first
permanent molar is measured
using soft brass wire touching
mesial surface of 1 st molar of
one side and passed over buccal
cusps of the premolar&along
anteriors & is continued
opposite side first molar.
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19. Determination of tooth material: m-d width of teeth anterior
to 1st molar is determined and summed up.
The discrepancy is the difference b/n arch length & tooth
material
DISCREPANCY
0-2.5 mm –In this proximal stripping can be carried out to
reduce T.T.M.
2.5-5mm-Extraction of second premolar is indicated.
>5mm-Extrction of first premolar is indicated.
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20. BOLTON’S ANALYSIS-
According to Bolton there exist a
ratio b/n the m-d widths of max. &
mandibular teeth. Boltan’s analysis
helps in determining disproportion
in size b/n max. & mand. Teeth
procedure-
Determination of overall ratio-
m-d width of teeth ant. to 2nd
molar.
overall ratio=
sum of man.12Χ 100/
sum of max. teeth=91.3
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21. If the ratio is less than 91.3%-Indicates maxillary tooth
material
excess.
The amount of maxillary excess is determined by:
sum of max.12-sum of mandibular 12*100/91.3.
If the overall ratio is more than 91.3- Indicates
mandibular tooth
Material excess.
The amount of mandibular tooth material excess is
determined by:
sum of mandibular 12- sum of maxillary 12*91.3/100
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22. DETERMINATION OF ANTERIOR RATIO
• The sum of mesio-distal width of the
mandibular anteriors should be 77.2% of
m-d width of the maxillary anteriors.
Anterior ratio=sum of mand.6*100/sum of-
-max.6
If the anterior ratio is less than 77.2% it
indicates max. anterior excess.
If the anterior ratio is more than 77.2% it
indicates mandibular anterior excess.
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23. • The amount of maxillary anterior excess is
determined by –
sum of max.6-sum of mand.6*100/77.2
The amount of mandibular anterior excess is
determined by –
sum of mand.6-sum of max.6*77.2/100
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24. Bolton’s analysis:
• The purpose of mixed dentition analysis is evaluate the amount of
space available in arch for erupting permanent. Canines &
premolars
• This analysis predicts the combined m-d width of 3,4&5 based on
the sum of the width of four incisors .
• Space available from distal of lateral incisor to mesial of 1ST
permanent molar is determined
• The expected width of 3,4 & 5 is are predicted by referring the
probability chart. While doing so ,the75%level of probability is
considered more reliable.
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26. Tanaka & Johnston prediction values
• In this analysis one half of m-d width of 4 lower
incisors+10.5mm= estimated width of mandibular
canine+premolars in one quadrant.
• one half of m-d width of 4 lower incisors+11 mm =
estimated width of max. canine+premolars in one
quadrant.
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27. CONCLUSION
• There are numerous model analysis based on different
criteria.it is left to the orthodontist to accept which analysis
he feels best suites his group of population &diagnosis and
treatment planning.
• The basis remains the same only the ways to express it
differs so does not matter which analysis one follows but
what matters is that how efficiently one imply the results
to the treatment planning and do justice to the patient.
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28. MOYERS MIXED DENTITION
ANALYSIS
 The purpose of a mixed dentition analysis is to
evalute the amount of space available in the arch
for the erupting permanent canines and premolars.
In this analysis the size of the unerupted
permanent cuspids and premolars are predicted
from the knowledge of the sizes of certain
permanent teeth that are already erupted in the
mouth.
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29.  The moyers analysis predicts the combined mesio-
distal width of 3,4,5 based on the sum of the widths
of the four lower permanent incisors.
 the mesio-distal width of the four lower incisor are
measured and summed up.the amount of space
available for the 3,4and 5 after incisor alignment is
determined by measuring the distance between the
distal surface of lateral incisor and the mesial surface
of first permanent molar.
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30.  Based on the mesio-distal width of four mandibular
incisors, the expected width of the canines, first and
second premolars are predicted by referring the
probability chart. While doing so,the 75%level of
probability is considered reliable.
 The predicted tooth size of 3,4,5 is compared with
arch length available for them so as to determine the
discrepancy. If the predicted value is greater than the
available arch length,crowding of teeth can be
expected
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31. • Total mandibular width of 345
incisor width
19.5 20.6, 20.1
20.0 20.9,20.4
20.5 21.2,20.7
21.0 21.3,21.0
21.5 21.8,21.3
22.0 22.0, 21.6
22.5 22.3,21.9
23.0 22.6,22.2
23.5 22.9, 22.5
24.0 23.1, 22.8
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32. HUCKABA’S ANALYSIS
• Here both study cast and radiographs are used for
determining the width of unerupted tooth.
• Principle
• with any type of radiograph, it is necessary to
compensate for enlargement of the radiographic
image. This can be done by measuring an object
that can be seen both in radiograph and on the
cast.
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33. • YI= X1 xY2/X2
• y1= width of unerupted tooth whose measurement is to be
determined .
• y2= width of unerupted tooth on radiograph.
• X1=width of a tooth that has erupted measured on the cast.
• X2=Width of a tooth that has erupted,measured on the
radiograph
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34. • Accuracy of this method of determining the
width of the unerupted tooth is fair to good,
depending upon the quality of the radiographs
and their position in the arch
• this technique can be used in maxillary and
mandibular arches for all ethnic groups.
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35. HIXON AND OLD FATHER’S
• The mesio-distal width of mandibular
central and lateral incisor is obtained from
the casts. Determine the width of the
premolars from the intraoral periapical
radiographs made using long cone
technique. Sum up the width of central and
lateral incisor along with the width of
unerupted premolars of that particular side.
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36. • The estimated sum total width of the
cuspids and bicuspids of that particular side
can be obtained from the chart. Every
measured sum width of incisor and
bicuspids has a corresponding sum width of
the cuspids and bicuspids in the chart.
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37. • measured values estimated tooth size
46 18.4
• 47 18.7
• 48 19.0
• 49 19.4
• 50 19.7
• 51 20.0
• 52 20.3
• 53 20.7
• 54 21.0
• 55 21.3
• 56 21.6
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38. Nance careys analysis
This analysis is similar to arch perimeter analysis of
the permanent dentition.
PROCEDURE
measure the mesio-distal width of the erupted
permanent teeth.
measure the width of each unerupted tooth, cuspids
and bicuspids (3,4,5) from the intra-oral periapical
radiographs.
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39.  The total mesio-distal width of all the teeth in
each quadrant will indicate space required to
accommodate the permanent tooth
.
 using brass wire measure the arch perimeter.
 compare the space required and space
available to arrive at the arch length
discrepancy.
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40. Thank you
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