2. 1.Introduction
2.Classification
3.Mixed dentition analysis
1. Space analysis
 Mixed dentition period
4.Analysis based on principles:Fields & Profitt
5.Methods of mixed dentition analysis
 Moyer’s mixed dentition analysis
 Tanaka Johnston mixed dentition analysis
 Hixon & Oldfather prediction method


3.  Nance mixed dentition analysis
 Ballard and wylie modification
 Huckaba mixed dentition analysis
6. Referenes

4.  Model analysis is the study of dental casts, which
helps to study the occlusion& dentition from all
three dimensions &analyze the degree & severity of
malocclusion & to derive the diagnosis &plan for
treatment
 Model analysis is an essential diagnostic record that
helps to study the occlusion and the dentition from
a three dimensional aspect.

5.  The study ranges from the metric analysis of the arch
form to the prediction of the sizes of the unerupted
permanent teeth during the mixed dentition.
 They have been the “gold standard” in orthodontic
diagnosis with the advantages ranging from being a
routine dental technique, ease of production,
inexpensiveness and ease in measurement to plaster
casts being able to be mounted on an articulator for
study in three – dimensions14.

6. Model analysis can be classified in the following ways
1.Based on whether the analysis is on the permanent
dentition or on the mixed dentition
a) PERMANENT DENTITION ANALYSES
 Ashley howe’s
 Carey’s / Arch perimeter
 Pont’s
 Linder Hearth’s
 Korkhau’s
 Bolton’s

7.  Moyer’s
 Tanaka Johnston
 Hixon and Old father
 Staley kerber
 Huckaba’s
 Ballard and Willie

8. 2.Based on the arch in which the analysis is carried out
,they can be classified as
 MAXILLARY ARCH
Pont’s
Linder hearth’s
Korkhau’s
Arch perimeter
 MANDIBULAR ARCH
Carey’s
Hixon and Old father
Peck and peck
Total space analysis
Staley Kerber

9. 3.Based on the Parameter determined by the analysis2
 TOOTH SIZE ANALYSES
Bolton’s tooth ration analysis
Sanin Savara analysis
 RELATIONSHIP OF TOOTH SIZES TO THE
SUPPORTING STRUCTURES
Ashley howe’s
Pont’s
Linder hearth’s
Korkhaus

10.  SPACE ANALYSES DURING MIXED DENTITION
 Moyer’s
 Tanaka Johnston
 Ballard and willie
 Hixon and Old father

11. 4)Based on principles of space analysis
NON –RADIOGRAPHIC SPACE ANALYSES
 Moyer’s
 Tanaka Johnston
 Ballard and Wylie
RADIOGRAPHIC ANALYSES
 Nance’s
 Huckaba’s
COMBINATION OF RADIOGRAPHS AND PREDICTION CHARTS
 Hixon and Old father
 Staley kerber

12.  After completion of the dental cast review, depending upon the age
of the pt, a mixed dentition analysis can be completed.
 An early assesment of available space may permit early
intervention /minimise development of malocclusion.
 Prediction of the M-D widths of the unerupted canines and the
premolars is an essential part of the tooth size-arch length analysis
during the mixed dentition period.

13.  Following the eruption of the permanent incisors, the mandibular
arch length and the width have achieved the adult dimensions for
all practical purposes.
 A meaningful mixed dentition tooth size-arch length analysis
depends on an accurate prediction of the mesio-distal widths of the
unerupted permanent canines and the premolars1

14.  Space analysis , using the study casts is valuable in evaluating the
likely degree of crowding for a child in the mixed dentition ; and in
that case,it must include the prediction of the size of the unerupted
permanent teeth.

15. Mixed dentition period
 6-12 years
 Indications- Nanda(1993)
a. Premature loss of primary canine.
b. Rotation or blocking of lateral incisor because of lack of
space.
c. Ectopic eruption of permanent first molars.
d. Distal terminal plane relationships.

16. a) 1st permanent molar and permanent incisors are erupted.
b) The succedaneous permanent teeth are forming.
c) Size relationship between unerupted permanent teeth and
primary teeth.
d) There is size difference in primary canines and molars and
the succedaenous teeth.
e) M-D width of primary canines and molars is greater than perm’
sucessors (leeway space of nance) 2

17. Methods of space analysis

18.  Basis- high co relation among groups of teeth , thus
measuring one group of teeth, prediction of size of other
group of teeth can be done1.
 Armamentarium-
1. Dental cast
2. Boley’s guage
3. Probability chart

19.  Procedure:
1. Measure the widths of each of four permanent
mandibular incisors .
2. Total the M-D widths of mandibular incisors
3. Using prediction chart for space available in mandibular
arch,locate the value closest to the sum of four
mandibular incisors.

20. 3)On the study cast, determine and mark the midline of
mandibular arch.
4)Total the M-D widths of right mand’ incisors & set the boley’s
gauge to this value.
 Measure from midline to right side. Place one point of the gauge at
the midline bet’n the central incisor and let the other end lie along
the line of the dental arch on the right side.
 Mark on the point where the precise point where the distal tip of
boley’s gauge touched.
 Repeat for the left side.

21. 5) Measure the dist betw the point marked on the
cast to the mesial surface of perm’ 1st
molar.Record that value and calculate the
difference
6) Repeat the process on the maxillary arch.

23. 6)Compute the amt of space available.
Measure the dist’ from the point marked on the
cast to mesial surface of the 1st molar, and
calculate space difference.

24. It is advocated for foll’ reasons:
 Has minimal systemic errors and the range of such errors is known.
 Can be done with equal reliability by the beginner and the expert as it
does not presume sophisticated clinical judgement.
 Not time consuming, simple and easy to perform.
 Requires no special equipment or radiographic projections.
 It can be done with reasonable accuracy in the mouth although it is
best done on the dental casts.
 It may be used for both the arches.

26. Advantages-
 It has minimal error.
 Can be done with equal reliability
 Not time consuming
 No special equipment required
 Can be done in mouth as well as on cast
 Can be used for both arches
Limitations
1. Moyer’s analysis is probability analysis
2. It does not account for tipping of mandibular incisor either lingually or
facially
3. Maxillary tooth size is predicted by mandibular teeth

27. 4. Moyers advised caution in using any analysis, as none was able to
compensate for the biological variation in individuals during the
transition from primary to permanent dentition3.
5. Moyers equation does not mention the population group from
which they were calculated 13
6. Moyer’s method of prediction may have population variations. For
one to be sure of the accuracy while using Moyer’s method it may
be safer to develop prediction tables for specific populations. Thus
Moyer’s method cannot universally be applied12.

28.  Armamentarium-
 Boley guage
 Study cast
 The prediction of the size of the unerupted canines and the
premolars in contemporary orthodontic population can also be
done with the Tanaka Johnston analysis.
 Tanaka and Johnston conducted a study on 506 orthodontic
patients in Cleveland.

29.  They believed that the Moyer’s equations and the size of his
confidence intervals have never been validated on any other samples.
 Also that the possibility of secular changes during the past 20 years cannot
be ruled out.
 Hence they undertook the study in the Orthodontic Department of Case
Western University school of dentistry

30.  They simplified the Moyer’s results and gave regressive equations of
the form
Y = A+B(X)
 Where Y = sum of the mesio distal widths of the unerupted canines
and premolars
X = sum of the mesio distal widths of the lower incisors
A & B are constants.
 For the maxillary arch , Y = 11 + 0.5 ( X )
 For the mandibular arch, Y = 10.5 + 0.5 ( X )

31. Advantages-
• Technique involves simple, easily repeated procedure with minimum
material requirement.
• Prediction chart and radiograph is not required
 Limitations-
• Error in predicted size if patients are not from North western
European descent.
• *John Y. K. Linga; Ricky W. K. Wong concluded constants for males (upper-11.5;
lower-10.5) or females (upper-11.0; lower-10.0) for southern Chinese population

32.  Iowa Facial Growth Study.
 Staley and Kerber in a later study conducted at the Iowa,
significantly reduced the standard error of estimate when they
generated a revised Hixon and Oldfather prediction equation.
 The co-efficient of correlation of the revised equation was
significantly higher than that of the original equation.

33.  The original equation was primarily obtained from the
measurements of the teeth on the left side of the arch of
each subject whereas the revised equation was derived
from the means of measurements taken from both right
and left side teeth in each subject.
Armamentarium-
• Boley guage
• Study cast
• Periapical radiograph
• Hixon- old father prediction chart

34. Procedure( Stanley and Kerber, 1980)
 From the casts, on one side, measure the m-d widths of
the permanent mandibular central and lateral incisor.
 From the periapical radiographs, measure the m-d width
of unerupted first and second premolars
 Total the m-d widths of four(4) teeth. Compare the
measured value to estimated tooth size from the Hixon-
Oldfather chart.
 Repeat steps 1 to 3 for the other side of the arch.

35.  Advantage- it is very accurate technique
 Limitation- Can be used only for lower arch.
 CHART
Measured value Estimated tooth size
23mm 18.4mm
24mm 19.0mm
25mm 19.7mm
26mm 20.3mm
27mm 21.0mm
28mm 21.6mm
29mm 22.3mm
30mm 22.9mm

37.  This analysis is similar to arch perimeter analysis of the
permanent dentition
 Armamentarium
 Dental cast
 Boley gauge, millimeter ruler
 Peri-apical radiograph

38.  SPACE REQUIRED:
◦ measure the mesio distal width of the erupted
permanent teeth.
◦ Measure the width of each unerupted tooth, cuspids
and bicuspids from the IOPA.
◦ The total mesiodistal width of all the teeth in each
quadrant will indicate space required to accommodate
the permanent teeth.

39. B = measurement of un-erupted canines
and premolars on radiograph

40.  SPACE AVAILABLE:
◦ using brass wire, measure the arch perimeter
from the mesial surface of permanent first molar
to the mesial surface of the permanent first molar
on the other side.
◦ Compare the space required and space available
to arrive at the arch length discrepancy

41. ADVANTAGES
 It results in minimal errors
 It can be performed with reliability
 It allows analysis of both arches
LIMITATION
 It is time consuming
 Complete mouth radiograph is needed.

42.  Ballard and Wylie were so concerned about the distortions of the X-
ray films that they devised a scheme for estimating the widths of
the mandibular canine and the premolars on the basis of the
combined widths of the four lower incisors.
 Using the plaster models of 441 cases, they measured and recorded
the widths of all the mandibular teeth including the first molars.
 On the average, the sum of the four permanent lower incisors were
23.84 +/- 0.08 mm.
 The average sum of the canine,first and the second premolars
turned out to be 21.97 +/- 0.06mm

43.  Although not particularly high, the co-efficient of correlation of
+0.64 seemed sufficiently high to justify a predicton. They modified
the equation as
Y = 9.41 + 0.527 ( X )
 Testing these calculations on 60 cases , Ballard and Wylie came to a
conclusion that their method had only 2.6% error as compared to
the 10.5% error when using only the X-rays.
 They do indicate that good X rays should be used and suggest that
their method was an adjunct to the Nance’s method.

44.  This analysis makes use of a radiograph and study cast to
determine the width of unerupted teeth
 Armamentarium
 Dental cast
 Boley gauge, millimeter ruler
 Periapical radiograph

45.  With any type of radiograph, it is necessary to
compensate for enlargement of radiographic image.
 This can be done by measuring an object that can be
seen both in the radiograph and on the cast, such as
primary molar tooth.
 It is possible to determine the measurements of un-
erupted teeth by studying the teeth that have already
erupted in a radiograph and on a cast

46.  A simple proportional relationship can be established as
follows:

47.  Hixon and Oldfather: most accurate
 Tanaka and johnston : most practical
 Radiographic Radiographic method: for
population other method: for population other than
Caucasians

48.  They did a review of Methods that have been proposed for mixed
dentition analysis , Studies comparing the different methods have
shown that the method of Hixon & Oldfather (1958), as refined by
Staley & Kerber (1980), is the most accurate.
* Mixed dentition analysis forms an integral aspect of orthodontic
diagnosis to determine whether the treatment plan is going to
involve serial extraction, space maintenance, space gaining or
simply periodic observation of the patient.

49.  Examine and compare the accuracy of the Moyers and
Tanaka & Johnston mixed dentition analyses and to
evaluate its applicability to Indian Marathi population.
 Developed regression analysis-
 Y = a + b (X) where ,
 X= independent variable (mandibular incisors
measurements)
 Y = dependent variable (sum of canine and
premolars).
 For mandibular teeth-
Y = 10.830 + 0.563 (X)
 For maxillary teeth-
Y = 12.143 + 0.481 (X)

50.  They concluded that
a) Both Tanaka Johnson and moyers have comparable
standard errors of estimate,thus their accuracy is fairly
comparable.
b) Moyers chart at 50% confidence level gives more
realistic estimate of width of unerupted canine and
premolars as compared to 75% confidence level for
Marathi population.
c) Sugessted the use of newly developed regression
equations is suggested.

51. THANK YOU

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