Mixed Dentition Analysis

1. 1
Good morning

2. QUESTIONS
• Mixed dentition analysis with relevant articles 2006, 2012
2

3. MODELANALYSIS
Presented by
Dr Ramesh R
3

4. CONTENTS
• Introduction
• Definition
• Objectives
• Uses, Advantages & Disadvantages
• Model analysis
1) Permanent Dentition 2) Mixed Dentition
- Pont’s Index - Moyer’s
- Linder Harth’s - Hixon & Old Father’s
- Korkhaus - Nance carey’s
- Arch Perimeter - Huckaba’s
- Bolton’s - Total Space analysis etc.
- Ashley Howe’s etc.
Recent Advances
Conclusion
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5. REFERENCES
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6. INTRODUCTION
6
• Early intervention of space discrepancies can prevent a potential
dental irregularity from progressing into a more severe form, thus,
preventing future malocclusions in children.
• One of the pre-requisites for diagnosing these discrepancies is
model analysis, which ideally possess the character to accurately
predict the dimensions of the un-erupted permanent teeth
• Success in orthodontic treatment – Diagnosis.
• Many diagnostic aids are available today but study models are
oldest.
• Model analysis is an adjunct in diagnosis and treatment planning. It
should hence be correlated with the other data in the diagnosis
before formulating any treatment plan.

7. 7
Comprehensive diagnosis
Clinical
Examination
Functional
Analysis
Roentgeno-
Cephalo-
MetricAna-
lysis
Photographic
Analysis
Radiographic
Examination
Study Cast
Analysis
Case History

8. 8

9. DEFINITION
Study models are plaster
reproduction of teeth and their
surrounding soft tissues that
provide a reasonable ‘facsimile’
of the occlusion of the patient
(T. Graber’s definition).
It is also defined as the sum of
maxillary and mandibular arches
in all 3 planes
9

10. OBJECTIVES OF IDEAL
ORTHODONTIC STUDY MODELS
•Models accurately reproduce the teeth and their
surrounding soft tissues.
•Models are to be trimmed so that they are symmetrical
and also the asymmetrical arch form can be readily
recognized.
•Models should trimmed so to meet the proposed ideal
measurement.
10

11. •Models are to be trimmed in such a way that the
occlusion shows by setting the models on their backs.
•Models are to have clean, smooth, bubble free surfaces
with sharp angles where the cuts meet.
•The finished models will be treated with a soap solution
to give a glassy mar-proof finish.
11

12. USES OF STUDY MODELS
1. Provide a 3 D precise record of the teeth and their supporting
structures.
2. Essential diagnostic aid in diagnosis and treatment planning.
3. Valuable aids in patient education and communication.
4. To evaluate the treatment progress.
5. Intraarch irregularities in shape, symmetry, width and
alignment of the dental arches can be analysed on the study
casts.
6. Interarch relationships in all three planes can be evaluated
from study casts.
7. Arch length deficiencies and excesses can be evaluated
12

13. 8. To assess and record the curves of
occlusion.
9. Evaluation of occlusion with the
help of articulators.
10. Used in mixed dentition
analyses along with charts and
radiographs.
11. Surgical repositioning of jaws
can be mimicked on the study
casts.
12. To detect abnormalities like
localized enlargements.
13. Help in communication between
orthodontists regarding nature of
malocclusion.
13

14. ADVANTAGES
1. Study casts permit a more objective assessment of
malocclusion than clinical examination or photographs.
2. They make it possible to view the patient’s occlusion
from the lingual aspect; something which is impossible in
patient’s mouth.
3. Study casts are a permanent record of the patient’s
malocclusion.
4. Can be duplicated easily when needed.
14

15. DISADVANTAGES
1. Occupy considerable storage space.
2. Retrieval takes time with mass storage.
3. Possibility of breakage of study models.
4. No detailed information obtained about soft tissues in the
oral cavity
5. Relationship of teeth to the facial profile cannot be elicited
15

16. CAST SHOULD BE OBSERVED FOR
FOLLOWING
[Nanda]
1. Occlusion
2. Tooth alignment
3. Arch form
4. Midline alignment
5. Overbite and overjet
6. Posterior and anterior crossbite
7. General arch form and symmetry
8. Rotated and malposed tooth
16

17. PARTS OF THE STUDY MODELS
• THE ANATOMIC PORTION.
It is the replica of the patient’s
teeth and supporting structures
obtained by impression.
It is further divided into tooth
portion and soft tissue portion
• THE ARTISTIC PORTION.
Artistic portion is made while
basing around the anatomic
portion.
The artistic portion supports the
anatomic portion and orients it in a
manner that is pleasing to eye
17
2
1
1
1
1

18. • The ratio between anatomic portion and artistic portion
should be 2:1 in a well-trimmed study cast.
• The tooth portion, soft tissue portion and the artistic
portion are related in 1:1:1 fashion.
• The completed model should be 13 mm in height in the
anterior and posterior region.
18

19. FABRICATION
•Fabrication of study casts involves the
following steps:
i. Impression making
ii. Disinfection of the impression
iii. Pouring the impression
iv. Basing and trimming
v. Finishing and polishing
19

20. ALGINATE IMPRESSION
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21. DISINFECTION OF IMPRESSION
21
INTERNET JOURNAL OF DENTAL SCIENCE VOL 9
Efficacy of various disinfectants on dental impression materials
Sukhija et al

22. 22

23. 23
COLUMBIAANTERIOR SEGMENT BASE FORMER

24. KINGSLEY-TYPE SCRAPER
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25. 7 sides 6 sides
25

26. TYPES OF MODEL
ANALYSIS
26

27. CLASSIFICATION
I. Analyses to study the size
relationships of groups of
teeth
1. Bolton’s tooth ratio analysis
2. Sanin–Savara analysis
3. Peck and Peck ratio
II. Analyses to study the
relationships of tooth size to
the size of supporting
structures
1. Ashley Howe’s analysis
2. Pont’s analysis
3. Linderhearth’s analysis
4. Diagnostic set-up
5. Korkhau’s analysis
27
III. Analyses to study the
relationships of tooth size
and available space
during the mixed
dentition (mixed dentition
analyses)
1. Moyer’s mixed dentition
analysis b
2. Tanaka–Johnston analysis
3. Staley and Kerber analysis
4. Radiographic method
IV. Analyses to study the
relationships of tooth size
and available space in the
permanent dentition
1. Carey’s analysis
2. Arch perimeter analysis
3. Total space analysis

28. 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
Tweed method
MIXED- DENTION ANALYSIS
(Estimating the size of unerupted
teeth)
Moyer’s analysis.
Tanaka-Johnston analysis.
Hixon-old father method.
Huckaba analysis.
Upper/lower tooth size disharmony
Bolton’s tooth ratio analysis
TOOTH-SHAPE DISHARMONY
Peck & peck index.
PHOTOGRAPHIC ANALYSIS OF
STUDY MODEL
Sterophotogrametry
Occlusograms
Holographic image analysis
COMPUTERIZED ANALYSIS
Oscopo
Reflex metrography
28
CLASSIFICATION

29. ARMAMENTARIUM
a) Divider
b) Ruler
c) Wedge Ruler
d) Vernier Caliper
e) Brass Wire
29

30. MIXED DENTITION
ANALYSIS

31. OBJECTIVE
• The objective of the mixed dentition analysis is to try to
answer the question: "Is there enough room for the unerupted
permanent teeth?"
• Evaluation of the size of the unerupted canines and premolars
is an important factor in the assessment of the child's
occlusion.
31

32. INDICATIONS OF MIXED DENTITION
ANALYSIS
[NANDA]
• Premature loss of primary canines
• Rotation or lateral incisors because of lost space
• Ectopic eruption of permanent first molars
• Distal terminal plane relationship
• Crossbite
32

33. MIXED DENTITION ANALYSIS BASED ON
FOLLOWING PRINCIPLES
[FIELDS AND PROFITT]
• First permanent molars and permanent incisors have erupted
• Succedaneous permanent teeth are forming
• Size relationship between unerupted permanent teeth and
primary teeth
• Size differential between primary canine and molars and
succedaneous teeth.
33

34. FACTORS NOTED TO COMPLETE THE
ANALYSIS
1.The size of all the Permanent teeth anterior to the first
permanent molar.
2.The arch perimeter,
3.Expected changes in the arch perimeter which may occur
with growth and development.

35. • The Mixed Dentition Analysis helps one to estimate the
amount of spacing or crowding which would exist for the
patient if all the primary teeth were replaced by their
successors
• It does not predict the amount of natural decrease in
perimeter which may occur during the transitional period
without the loss of teeth.

36. TWO STRATEGIC CATEGORIES-
1.Those in which the size of the unerupted cuspids and
premolars are estimated from measurement of the
radiographic image.
2. Those in which the sizes of the cuspids and premolars are
derived from knowledge of the sizes of the permanent teeth
already erupted in the mouth.

37. PROFITT’S THREE BASIC APPROACHES
1. Estimation from Proportionality Table
Moyers (1967), Tanaka and Johnson.
2. Radiographic Method
Huckaba G.W Analysis(1964).
3. Combined Radiographic–Prediction Table
Hixon and Oldfather (1956)
Modified by Stanley and Kerbers (1980)

38. MOYERS ANALYSIS
Best known prediction table is Moyers(1967)
Moyers follow the second strategic condition-
Mandibular Incisor have been choosen-
a. Eruped early in the mouth.
b. Easily measured accurately.
c. Are directly in the midst of most space management problems.

39. Maxillary Incisors are not chosen-
Variability in size and their co-relation with other group of
teeth are of lower predicted value.

40. PROCEDURE IN MANDIBULAR ARCH
• Measure with tooth measuring gauge or a pointed guage, the
greatest mesiodistal width of each of the four mandibular
incisors.
BOLEY’S GUAGE

41. • Determine the amount of
space needed for alignment
of the incisors.
• Set the Boleys guage to a
value equal to the sum of the
widths of the left central &
lateral incisors .

42. • Place one point of the midline of the crest b/w the central
incisors & let the other point lie along the line of the dental arch
on the left side.
• Mark on the cast the precise point where the distal surface of the
lateral incisor will be when it has been aligned.

43. • From that aligned point measure the sum of mandibular cuspid and
biscupids.
• Record these values on the mixed dentition analysis form

44. • Compute the amount of space
available after incisor
alignment.
• Measure the distance from the
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 Cuspids &
two Bicuspids and for any
necessary molar adjustment
after the incisors have been
aligned.

45. • Predict the size of the combined width of the mandibular
Cuspids and bicuspids.
LONG METHOD-
• An experienced clinician can use 50% prediction since it is more
precise estimate.
• For inexperienced clinicians, they should use the 75% prediction
for combined widths of canines and two premolars.

46. PROBABILITY TABLE FOR PREDICTING THE SIZES OF
UNERUPTED CUSPIDS AND BICUSPIDS
Handbook of Orthodontics 4th edition Robert E Moyers

47. SHORT METHOD-
less precise method
Add the width of the mandibular incisors and divide by
two.
To the value obtained add
10.5mm Mandibular Cuspids and Bicuspids
11.0mm Maxillary Cuspids and Bicuspids

48. • Whether using the long or short method record, the estimated
values for the combined cuspids and bicuspids widths in the
mixed dentition analysis form for both sides and each arch.
 Compute the amount of space left in the arch for molar
adjustment by subtracting the estimated cuspid and
bicuspids size (moyer’s chart) from the measured space
available in the arch after alignment of the incisors.
 Record these values for each side.

49. PROCEDURE FOR MAXILLARY ARCH
Procedure is similar to lower arch except-
1. A different probability chart is used for predicting the upper
cuspid and two Bicuspids sum [widths]
2. Allowance must be made for overjet correction when
measuring the space to be occupied by the aligned incisors.

50. PROBABILITY TABLE FOR PREDICTION
Handbook of Orthodontics 4th edition Robert E Moyers

51. ADVANTAGES
1. It has minimal systematic error and the range of such error is known.
2. It can be done with equal reliability by the beginner or expert as it
does not presume sophisticated clinical judgement.
3. Not time consuming
4. No special instrument or radiographic projection needed
5. Can be done in mouth with reasonable accuracy as done on dental the
cast
6. Used for both the arches
7. Accuracy with this method is fairly good for the northern European
white children on whose data it is based.
51

52. LIMITATIONS
• The Moyer's analysis is a probability diagnosis.
• The Moyer's analysis does not account for tipping of the
mandibular incisor, either lingually or facially.
• There is not a high correlation of size difference between different
groups of teeth
• The maxillary tooth size is predicted from mandibular tooth size
52

53. •Although various methods of estimation have been
proposed, Moyers regression scheme [utilizing the
buccal segments and the mandibular incisors] is widely
used because of its simplicity and ease of application.
Prediction of the size of unerupted canines & Premolars
in a contemporary orthodontic population.
Marvin M Tanaka, Lysle E Johnston
JADA vol 88 April 1974

54. 54
Philip et al
Applicability of the Moyers mixed dentition probability tables and new prediction aids for
a contemporary population in India.
American journal of orthodontics and dentofacial orthopedics. 2010

55. 55
KAMATHAM ET AL
2017 JOURNAL OF OROFACIAL SCIENCES

56. • In the present study all these percentiles were considered for
comparison in the target population, which revealed
overestimation of tooth dimensions with moyers’ at 75% level
and underestimation with 35% level.
• The predictive values at moyers’ 50% level showed a nearly
reliable estimate for boys and 65% for girls only in the
maxillary arch.
56

57. • Study conducted on Nalgonda & patiala population reported Moyers’ at 75%
probability level as a more reliable estimate.
• Studies conducted on bengali and chennai populations reported moyers’ 50% level
as realistic estimate when compared to the recommended 75% level,
57
Kondapaka et al
A comparison of seven mixed dentition analysis methods and to evaluate the most
reliable one in Nalgonda population. Journal of Indian Orthodontic Society. 2015
Mar;49(1):3-9.
Garg et al
Mixed Dentition Analysis: Applicability of Three Non-Radiographic Methods for Patiala
Population. International Journal of Contemporary Medical Research, 2017; 4(9): 2016-
19
Kommineni et al
Mixed dentition analysis − Applicability of two nonradiographic methods for Chennai
school children. J Int Soc Prev Community Dent 2014;4:133-8.
Dasgupta et al
Comparison of two non-radiographic techniques of mixed dentition space analysis and
evaluation of their reliability for Bengali population. Contemp Clin Dent 2012;3 (Suppl
2):S146-50. doi: 10.4103/0976-237X. 101069.

58. • A study conducted on Central Indian population reported
Moyers’ 50 and 65% levels for girls and boys respectively in
the maxillary arch, and 35% level for mandibular arch,
irrespective of the gender
• A study on South Indian population reported Moyers’ 35%
level to be more reliable which is in contradiction to the
finding of the present study.
58
Nayak et al
Evaluation of applicability of Moyer’s mixed dentition analysis for central India
population. J Ind Orthod Soc 2004;37:154-9.

59. 59

60. The differences noted between predicted values of the Moyers
tables and those of the present investigation are the result of racial
and ethnic diversity and tooth dimension showed sexual
dimorphism.
Mesiodistal crown dimension in the buccal segment of the
mandibular arch was larger in males than in females.
With the help of the data obtained, new regression equations were
derived separately for male and female subjects to be used to predict
tooth dimension.
Male:
Maxilla - Y = 10.52 + 0.48x
Mandible - Y = 9.46 + 0.50x
Female:
Maxilla - Y = 11.73 + 0.41x
Mandible - Y = 11.67 + 0.39x
60

61. • Set of four linear regression equations for predicting sum of
mesiodistal width of permanent canine, first premolar and second
premolar in North Indian population from sum of mesiodistal
width of mandibular incisors and mandibular first molars, were
proposed as;
for males
maxillary arch, Y = 2.9 + 0.40X,
mandibular arch Y = 3.91 + 0.37X
for females
maxillary arch Y = 0.56 + 0.45X
mandibular arch Y = 1.14 + 0.42X.
• Moyers and Tanaka-Johnston, mixed dentition analysis, is found to
be overestimating the mesiodistal width of unerupted canine and
premolars in North Indian population.
61
Goyal et al
Evaluation of mixed dentition analyses in north Indian population: A comparative study.
Contemporary clinical dentistry. 2014 Oct;5(4):471.

62. • From this study it was concluded that neither Moyers' mixed
dentition analysis tables nor Melgaço's prediction equation was
completely accurate when applied to the present contemporary
Indian population.
• The Moyer's mixed dentition analysis and Melgaço's prediction
equation overestimated the tooth dimension in this population
and thus a simplified equation, Y = 0.925X, was formulated to
the present Gujarati population without sexual dimorphism
Melgaço et al
Mandibular permanent first molar and incisor width as predictor of
mandibular canine and premolar width.
Am J Orthod Dentofacial Orthop, 2007; 132: 340-5.
62

63. • It was found that 50% probability level is more applicable to boys
and 75% probability level to girls than the Moyer’s probability
table.
• The canine premolar segment in both arches was statistically
larger in men than in women and new regression equation was
formulated.
• The sizes of canines and premolars of the Bangalore subjects are
larger than those predicted by the Moyers tables.
The difference is approximately 1mm per quadrant.
The equation is Y = a+b.(x)
For LCPM width
Y= 17.204+0.174.(x)—Males
Y= 13.431+0.330.(x)—Females
For UCPM width
Y=16.904+0.209.(x)—Males
Y=15.627+0.263.(x)—Females.
• Probability tables (males and female) for Bangalore population
were derived.
Thimmegowda et al
Validity of Moyers Mixed Dentition Analysis and a New Proposed Regression
Equation as a Predictor of Width of Unerupted Canine and Premolars in
Children.
Journal of Clinical and Diagnostic Research: JCDR, Aug, 2015; 9(8): ZC01
63

64. OTHER COMBINATIONS OF GROUP OF TEETH
• Used as Predictor Recent studies have reported that sum of mesiodistal
width of permanent mandibular incisors proposed by Moyer is not the
best predictor for estimating mesiodistal width of unerupted permanent
canine & premolars, so other teeth along with incisors also have been
evaluated to predict mesiodistal width of unerupted canine &
premolars.
• Sum of mesiodistal width of permanent mandibular incisors and
mandibular first molar has been used as predictor in Brazilian
population.
• Sum of mesiodistal width of maxillary central incisor and
mandibular first molar is found to be the best predictor to estimate
mesiodistal width of permanent canine & premolars in Spanish and
Egyptian population.
64
Pereira et al
Evaluation of the space in the mixed dentition through the analysis of Moyers and
Tanaka-Johnston. Ortho Sci., Orthod. Sci. pract. 2010:116-20.
Paredes et al
A new, accurate and fast digital method to predict unerupted tooth size. The Angle
Orthodontist. 2006 Jan;76(1):14-9.

65. • Sum of mesiodistal width of maxillary first molar and
mandibular incisors is found to be the best predictor to estimate
mesiodistal width of unerupted canine & premolars by most of the
researchers in Syrian, Croatia and Italian population
Legovic et al
Regression equations for determining mesiodistal crown diameters of
canines and premolars.
Angle Orthod, Jun, 2003; 73(3): 314-18.
Nourallah at al
New regression equations for predicting the size of unerupted canines
and premolars in a contemporary population.
Angle Orthod, Jun, 2002
65

66. 66
TANAKAAND JOHNSTON
PREDICTION

67. PROCEDURE (TANAKA AND JOHNSON, 1974)
• From, the permanent first molar on one side, mark the distances
on the casts in segments to the permanent first molar on the
opposite side.
• Measure these segments over the contact points.
• Measure the mesiodistal widths of the mandibular central and
lateral incisors.
• Subtract this total from the arch circumference measurement.
67

68. TANAKA AND JOHNSTON PREDICTION
One half of the
mesiodistal width
of the four lower
incisors
+ 10.5mm
+ 11.0mm
Estimated width of
mandibular Canine &
Premolars in one
quadrant
Estimated width of
maxillary Canine &
Premolars in one
quadrant

69. • This total gives the estimated size of the mandibular canine
and the two premolars for one quadrant.
• Double the total in above for the canines and four premolars in
the mandibular arch.
• Subtract this dimension from the remaining space available in
the arch to give a positive or negative for total arch space.
• Available arch length= Total arch length – ( Sum of incisors +
2* Predicted width )
69

70. INFERENCE
If the result is positive, there is more space available in the
arch than is needed for the unerupted teeth.
If the result is negative, the unerupted teeth require more
space than is available to erupt into ideal alignment.
70

71. ADVANTAGES
• This method has good accuracy despite a small bias toward
overestimating the unerupted tooth sizes.
• Requires neither radiographs nor reference tables, which
makes it very convenient.
• For children from a European population group, the method
has good accuracy

72. DISADVANTAGES
• Less accurate for other population groups, and appears to have
systematic errors for specific race and gender. (limitation)
• It will over-estimate the required space for Caucasian females
both arches
• Under-estimate the space required in the lower arch for
African-American males.
72

73. • Tanaka and Johnston combined the sexes in their study.
• This is in contrast to Moyer’s analysis which predicted the size of
permanent teeth for males and females separately.
• Tanaka and Johnston originally advocated use of 75th percentile.
• It is now known that even 50th percentile may overpredict the
tooth size a little.
• It is recommended to use 50th percentile as a hedge against
underpredicting tooth size.
73

74. HUCKABAANALYSIS
• Recommended by Huckaba.G.W in 1964.
• He used both study casts and radiographs for determining the
width of unerupted tooth
• Compensates for radiographic enlargement of tooth image in
periapical film.
• It is based on the assumption that degree of magnification for a
primary tooth will be the same as that of its underlying
permanent successor on the same film.

75. METHOD
Measure-
1. Width of the primary teeth on
the x-ray film: y
2. Width of its underlying
permanent successor y1 on the
x ray film
3. Primary tooth on the cast : x
4. Width of unerupted
permanent tooth is calculated
by x1 = x * y1
y
y1
y
x
x1

76. •The value obtained for the mandibular incisors on
the cast and those for canines and premolars on the
radiographs were added to provide the space
required.
Space available is obtained by extending the brass wire
from the mesio buccal of 1st permanent molar on one side,
passing through the incisal edge of anterior teeth, and to the
buccal cusps of 1st molar on the opposite side.
The difference in the value obtained for space required and
space available is the amount of discrepancy.

77. HIXON & OLDFATHER ANALYSIS
• This procedures combines measurements from the dental
casts and width measurements from the periapical
radiographs.
• This method (1956); modified by Staley & Kerbers(1980)
is restricted to the analysis of in the mandible.

78. • Allows canine width to be read directly from the sum of
incisor and premolar widths.
• Only for the mandibular arch
• For children of European ancestry, it is quite accurate.
78

79. PROCEDURE
• Measure the size of unerupted 1st & 2nd premolar in one
mandibular quadrant from a periapical radiograph.
• Determination of mesiodistal tooth width of the lower central
and lateral incisors on the study cast to the side of the
radiograph.

80. • X-axis : Mandibular incisor
width measured on the dental
cast + total width of 1st & 2nd
premolar on the periapical
radiograph.
• Y-axis : Predicted total width
of permanent mandibular
canine and 1st & 2nd premolar.

81. •The formula for calculation-
Σ3+4+5=[(Σ 1+2+4+5) X 0.7158]+2.1267
•After adding together both figures, the probable
width of the permanent canine and 1st & 2nd
premolars for the corresponding quadrant can be
read off in the prediction graph under the
column of the calculated sum total.

82. COMPARISON OF MIXED DENTITION ANALYSIS
•Which of these methods is best for an individual
patient depends on the circumstances.
• The Moyers, Tanaka-Johnston, and Staley-Kerber
predictions are all based on data from white school
children of northern European descent, fits this
population group
•Staley-Kerber method will give the best prediction,
followed by the Tanaka Johnston and Moyers.
82

83. •The clinical examination record plus data from cast
analysis and radiographs can be used to make a pre-
liminary assessment of the child's occlusal status.
•The data can be used to advise the parents of the
child's growth potential and possible developmental
problems
83

84. TOTAL SPACE ANALYSIS
84

85. 85
PERMANENT DENTITION
ANALYSIS

86. PONT’S ANALYSIS
• In 1909, Pont devised a method of predetermining an
“ideal” arch width based on the mesio-distal widths of
the crowns of the maxillary incisors.
• Pont suggested that the ratio of combined incisor to arch
width (as measured from the center of the occlusal surface
of the teeth) was ideally 0.8 in the bicuspid area and 0.64
in the first molar area.
86

87. Pont also suggested that the maxillary arch be expanded 1 to
2mm more during treatment than his ideal to allow for
relapse.
USES
1. Determining whether dental arch is narrow or is
normal.
2. Determining the need for lateral arch expansion.
3. Determining how much expansion is possible at the
premolar and molar regions.
87

88. • Determination of sum of incisors
(S.I)
• Determination of measured
premolar value (M.P.V)
• Determination of measured molar
value (M.M.V)
• Determination of calculated
premolar value (C.P.V)
• Determination of calculated molar
value (C.M.V)
88

89. 89

90. INFERENCE
•If measured value is less than the calculated value,
then arch is narrow for the sum incisors width and
needs expansion.
•If measured value is greater than the calculated value,
then the arch is wider and there is no scope for the
expansion.
90

91. DRAWBACKS
•Analysis is based on study of French population
and hence, its universal validity is questionable.
•Maxillary laterals are the most commonly missing
and malformed teeth (i,e Peg shaped).
•Does not consider skeletal mal-relationships and
relationship of teeth to the supporting bone.
91

92. • Mandibular arch form and mandibular intercanine diameter
have been repeatedly found to be more reasonable treatment
guides for both maxillary and mandibular ultimate arch
widths than the pont’s index.
• Pont’s index is naive in concept and of little use in rational
treatment planning.
92

93. LINDER HARTH ANALYSIS
Similar to pont’s analysis.
A variation has been proposed to determine the calculated
premolar value and calculated molar value.
Calculated premolar value : S.I x 100
85
Calculated molar value : S.I X 100
64
93
Where S.I is sum of mesiodistal widths of incisors.

94. KORKHAUS ANALYSIS
• Similar to pont’s analysis but he
used linder harth’s formula to
determine the ideal arch width in
the premolar and molar region
• He also uses the measurements
made from the midpoint of the
interpremolar line to a point
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 central
incisors should exist.
94

95. • Korkhaus devised an instrument
“the orthometer”
• Helps to measure the ideal arch
width in premolar and molar region
•
• Also to know the perpendicular
distance from the interpremolar
line to in between the 2 incisors for
a given sum of mesiodistal widths
of the maxillary incisors
95

96. INFERENCE
If there is an increase in the perpendicular measurement than
ideal then the anterior are proclined and if it is less than they
are retroclined.
ADVANTAGES
This analysis not only tells about the ideal arch width but
also about the ideal positioning of the anterior teeth
96

97. ARCH PERIMETER ANALYSIS
• Many malocclusions are as a result of discrepancy
between arch length and tooth material.
• This analysis helps us to find the difference between the
basal bone and the tooth material i,e in determining the
extent of Discrepancy.
• The same analysis is called “Carey’s Analysis” in the
lower cast.
97

98. DETERMINATION OF ARCH
LENGTH.
Arch length anterior to the first
permanent molar is measured using
a soft brass wire.
The wire is placed contacting the
mesial surface of the first
permanent molar of one side and is
passed over the buccal cusps of the
premolars and along the anteriors
and is continued on the opposite
side in the same way upto the
mesial surface of the opposite first
permanent molar
98
.

99. •In case of proclined anteriors, the wire is passed
along the cingulum of anterior teeth.
•If the anterior teeth are retroclined, the brass wire is
passed labial to the teeth.
•If the anterior teeth are well aligned, the wire is
passed over the incisal edges of the anterior teeth.
99

100. • DETERMINATION OF
TOOTH MATERIAL.
The mesio-distal width of the
teeth anterior to the first
molars (second premolars to
second premolars) is
measured and summed up.
100

101. 101
• DETERMINATION OF
THE DISCREPANCY.
The discrepancy refers to
the difference between
the arch length and tooth
material.
INFERENCE.

102. DRAWBACKS
•This procedure of accessing arch length does not
appear to be clear-cut in border line cases.
•The visualized form will vary with the individual who
is contouring the wire.
102

103. ASHLEY HOWE’S ANALYSIS
• According to Ashley Howe crowding is not only due to tooth
size but can also result when there is inadequate apical base,
i.e. crowding is due to deficiency in arch width rather than
arch length
• He found a relationship between total width of 12 teeth
anterior to the second molars and the width of the dental arch
in the first premolar region.
103
Howes AE.
A polygon portrayal of coronal and basal arch dimensions in the horizontal plane.
American Journal of Orthodontics. 1954 Nov 1;40(11):811-31.

104. 104
Howe’s analysis measurements.

105. 105
DETERMINATION OF TOTAL TOOTH MATERIAL.
The Mesiodistal width of all the teeth mesial to the second
permanent molars is measured with the help of dividers and the
values are summed up.
This value is called Total Tooth material (TTM).

106. DETERMINATION OF PREMOLAR DIAMETER
This measurement is the distance between the summits of
the buccal cusps of the first bicuspids.
106

107. DETERMINATION OF PREMOLAR BASAL ARCH
WIDTH (P. M.B.A.W)
Above the maxillary first bicuspids and below of mandibular
first bicuspids.
Basal arch width will be greater than the coronal arch.
107

108. •The canine fossa is found distal to the canine
eminence.
•The measurement of the width from canine fossa of
one side to the canine fossa of other gives the premolar
basal arch width ( P.M.B.A.W).
•If the canine fossa is not clearly distinguishable then
the measurement is made from a point 8mm below the
crest of inter dental papilla distal to the canine.
108

109. The percentage relationship
of first bicuspid width to
tooth material.
BIC.W = %
TTM
The percentage relationship
of first bicuspid basal arch
width to tooth material.
B.A.W = %
TTM
109

110. DETERMINATION OF
BASAL ARCH LENGTH.
( B.A.L)
In the maxilla the median line
measurement from Downs A
point perpendicular to the
occlusal plane , then to the
median point on a line
connecting the distal surface of
the first molar.
110

111. • In the mandibular arch the
measurement is made from
Downs B point to a mark
on the lingual surface of
cast as was incase of the
maxilla.
111

112. Determination of the percentage of arch length to the
tooth material.
B.A.L = %
TTM
The percentage relationship is more important than the
actual measurement.
112

113. INFERENCE
•Howe’s believed that the premolar basal arch width
(P. B.A.W) which he called as the canine fossa
diameter should equal approximately 44% of the
mesiodistal widths of the 12 teeth in the maxilla, if
it is to be sufficiently large enough to accommodate
all the teeth.
•When the ratio is less than 37%, he considered this
to be a basal arch deficiency necessitating extraction
of premolars.
113

114. •If the premolar basal arch width is greater than the
premolar coronal arch width (B.A.W>BIC.W), expansion
of the premolars may be undertaken safely.
114

115. ADVANTAGES
Howe’s analysis is useful in treatment planning of
problems with suspected apical base deficiencies and
deciding to whether to,
1. Extract teeth,
2. Widen the dental arch, or
3. Expand rapidly the palate.
Howe’s analysis is applicable to each arch.
115

116. 116

117. PECK AND PECK INDEX
This done on the lower arch.
Persons with ideal incisal arrangement had smaller
mesiodistal width and comparatively larger labiolingual
width than in persons with incisal crowding
117

118. 118

119. INFERENCE
If the value for a given case is more than the mean value then
mesiodistal width of the tooth is more than the labiolingual
width and hence proximal stripping is indicated in such cases.
119

120. 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.
•Bolton’s analysis helps to determine the disproportion
between the sizes of the maxillary and the mandibular
teeth.
120
Disharmony in tooth size and its relation to the analysis and
treatment of malocclusion. Angle orthod (28) 1958.

121. •To attain an optimum inter- arch dental relationship,
the maxillary tooth material should approximate
desirable ratios, as compared to the mandibular tooth
material.
•Average proportion between upper and lower teeth in
overall and anterior region helps to create a normal
overjet and overbite.
121

122. Measurements
122
• Sum of mandibular 12.
• Sum of maxillary 12.
• Sum of mandibular 6.
• Sum of maxillary 6.
• Overall Ratio.
• Anterior Ratio.

123. • Determination of overall Ratio.
According to Bolton, the sum of mesio distal widths
of the mandibular teeth anterior to the second
permanent molar is 91.3% the mesio distal widths
of the maxillary teeth mesial to the second molars.
Overall Ratio = Sum of mandibular 12 X 100
Sum of maxillary 12
1) If ratio is less than 91.3%, maxillary tooth material
excess.
2) If ratio is more than 91.3%, Mandibular tooth
material excess.
123

124. • Determination of anterior ratio.
The sum of mesio distal width of the mandibular
anteriors to the mesio distal width of the maxillary
anteriors should be 77.2%.
Anterior Ratio = Sum of mandibular 6 X 100
Sum of maxillary 6
1) If ratio is less than 77.2%, maxillary anterior excess.
2) If ratio is more than 77.2%, Mandibular anterior
excess.
124

125. 125

126. Advantage & Disadvantages
•When contemplating the extraction of four premolars,
it is useful, before selecting the teeth for extraction, to
ascertain the effects of various extraction
combinations on these ratios.
•Study done on specific population.
•Does not take into account the sexual dimorphism in
the maxillary canine widths.
126

127. CONCLUSION
• There are numerous model analysis based on different
criteria.
• Now it is left to the pediatric dentist to accept which
ever analysis he feels best suits his group of population
and his diagnosis and treatment planning.
• The basis remains the same only the ways to express it
differs.
• So it does not matter which analysis you follow but what
matter is that how efficiently you imply the results of it
to your treatment planning and do justice to your patient.

128. Thank You