Model analysis.ppt

Model analysis

2. Model analysis
DR SUGAREDDY
PROFESSOR HOD, DEPT OF
ORTHODONTICS
NAVODAYA DENTAL
COLLEGE, RAICHUR

3. INTRODUCTION
Model analysis is one of the essential diagnostic
aids in orthodontics practice.
•Help us to visualize the patient’s occlusion from all
aspects.
•In making the necessary measurements of teeth, the
dental arches and the basal bone.

4. •The study models provide a three dimensional view of
the maxillary and mandibular dental arches.
•Valuable tool in orthodontic diagnosis and treatment
planning.

5. Armamentariumformodelanalysis
Commonlyusedarmamentariumformodel
analysisare,
Divider
Ruler/Wedgeruler
VerniercalipersorBoleygauge
Brasswires
Electronicdigitaldialcalipers

7. Analysis used in permanent dentition
•PONTS ANALYSIS
•LINDER HARTH INDEX
•KORKHAUS ANALYSIS
•ARCH PERIMETER ANALYSIS (upper cast)
•CAREY’S ANALYSIS
•BOLTON'S ANALYSIS
•ASHLEY HOWE'S ANALYSIS
•PECK AND PECK INDEX
•SANIN –SAVARA ANALYSIS

8. Analysis used in mixed dentition
•MOYERS MIXED DENTITION ANALYSIS
•HUCKBA’S ANALYSIS
•HIXON AND OLDFATHER’S METHOD
•NANCE CAREY’S ANALYSIS
•TANAKA AND JOHNSTON

9. PONTS ANALYSIS
Ponts(1909)
Helps in:
a. Determining dental arch width.
b. Determining the need of arch expansion.
c. Determining amount of possible expansion.
Measurements:
a.Determination of sum of incisors (SI)
b.Determination of calculated premolar value (CVP)
c.Determination of calculated molar value (CMV)
d.Determination of measured premolar value (MPV)
e.Determination of measured molar value (MMV).

10. Procedure
a. Determination of sum of incisors (SI)
Sum of mesio-distal width of the 4 maxillary incisors

11. b. Determination of calculated premolar value (CPV)
CPV or the expected arch width in the premolar region is
determined by the formula
S.I. x 100
80
c. Determination of calculated molar value (CMV)
CMV or the expected arch width in the molar region is
determined by the formula
S.I. x 100
64

12. d.Determination of measured premolar value (MPV)
Width of the arch in the premolar region from the distal pit of
one upper first premolar to the distal pit of the opposite first
premolar

13. e. Determination of measured molar value(MMV)
The width of the arch in the molar region from the mesial pit
of one upper first molar to the mesial pit of the opposite first
molar

14. Inference
•calculated value is greater than the measured value
then the arch is narrow and there is scope for
expansion.
•If the measured value is greater than the calculated
value then the arch is wider and there is no scope for
expansion.

15. Draw back of Pont’s analysis
A)Analysis is based on the study of French population.
B)Analysis does not consider the alignment of teeth.
C) Analysis does not consider malformations of tooth.

16. LINDER HARTH INDEX
This analysis is very similar to Pont's analysis except that
a new formula has been proposed to determine the
calculated premolar value.
The calculated premolar value is determined using the
formula,
S.I. x 100
85

17. KORKHAUS ANALYSIS
This analysis is also similar to Pont's analysis.
lt makes use of the Linder Harth's formula to determine the
ideal arch width in the premolar and molar region.
In addition with this Korkhaus analysis uses a new third
measurement

18. That is from the midpoint of the inter-premolar line to a
point in between the incisal edges of two maxillary
incisors called incision.

19. According to Korkhaus, for a given width of upper incisors a
specific value of the distance between the midpoints of
inter-premolar line to the point between the two maxillary
incisors should exist.
Inference
An increase in this measurement denotes proclined upper
anterior teeth while a decrease in this value denotes
retroclined upper anteriors.

20. Arch perimeter analysis
(Carey’s analysis)
Many malocclusions occur as a result of discrepancy
between arch length and tooth material. Carey’s analysis
helps in determining the extent of discrepancy. It is
performed on the lower cast.
The same analysis on the upper arch called Arch
Perimeter Analysis.

21. Procedure
a.Determination of arch length
measured using a soft brass wire.From the mesial surface of
the first permanent molar of one side to the opposite first
permanent molar.

22. In case of proclined anteriors the wire is passed along the
cingulum of anterior teeth.
If the anterior teeth are retroclined, the brass wire in the
anterior segment passes labial to the teeth.
If the anterior teeth are well aligned the wire passes over the
incisal edge of anteriors.

23. b.Determination of tooth material
The mesio-distal width of the teeth anterior to the first molars
is measured and summed up.

24. Inference
If tooth material is more than the space available then there
can be crowding due to space shortage.
If tooth material is less than the space available then there
can be spacing due to excess space.

25. Depending on this suggested treatment planning is,
a.If the discrepancy is 0 to 2.5 mm, it indicates minimum
tooth material excess. In such cases proximal stripping
can be carried out to reduce the tooth material.
b. If the discrepancy is between 2.5 to 5mm it indicates the
need to extract the second pre molars.
c.If the discrepancy of more than 5mm indicates the need
to extract the first pre molars.

26. BOLTON'S ANALYSIS
Tooth size is an important factor to be taken into
consideration in orthodontic diagnosis and treatment
planning.
According to Bolton there exists a ratio between the
mesio-distal widths of maxillary and mandibular teeth. The
Bolton's analysis helps in determining disproportion in size
between maxillary and mandibular teeth.

27. Procedure
a. Sum of mandibular 12
The mesio-distal width of all the teeth mesial to the
mandibular second permanent molars is measured and added

28. b. Sum of maxillary 12
The mesio-distal width of all the teeth mesial to the maxillary
second permanent molars is measured and summed up.

29. c.Determination of overall ratio
The overall ratio of maxillary tooth to mandibular tooth is
determined by using the formula
Overall ratio =Sum of mandibular 12 x 100
Sum of maxillary 12

30. According to Bolton, the sum of mesio-distal widths of the
mandibular teeth anterior to the second permanent molars
is 91.3% the mesio-distal width of the maxillary teeth
mesial to the second molars.

31. If overall ratio is less than 91.3%, it indicates maxillary tooth
material excess. The amount of maxillary excess is determined
using the formula :
Sum of mandibular 12 x 100
Sum of maxillary 12 - .
91.3
If the overall ratio is more than 91.3%. It indicates mandibular
tooth material excess. The amount of excess can be
determined by the formula
: .
Sum of maxillary 12 x 91.3
sum of mandibular 12-
. 100

32. d. Sum of mandibular 6
The mesio-distal width of all the teeth mesial to the
mandibular first premolars is measured and summed up.

33. e. Sum of maxillary 6
The mesio-distal width of all the teeth mesial to the maxillary
first premolars is measured and summed up.

34. f. Determination of anterior ratio
The anterior ratio is determined using the following formula:
Sum of mandibular 6 x 100
Anterior ratio = Sum of maxillary 6
According to Bolton sum of mesio-distal width of the
mandibular anteriors should be 77.2% of mesio-distal width of
the maxillary anteriors.

35. If the anterior ratio is less than 77.2% it indicates maxillary
anterior excess. The amount of maxillary anterior excess is
determined by
Sum of maxillary 6-sum of mandibular 6 x 100
77.2
If the anterior ratio is more than 77.2 %, it indicates mandibular
anterior excess. The amount of mandibular anterior excess is
determined by
Sum of mandibular 6-sum of maxillary 6 x 77.2
100

36. ASHLEY HOWE'S ANALYSIS
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 12 teeth
anterior to the second molars and the width of the dental arch
in the first premolar region.

37. Procedure
a. Determination of total tooth material (T.T.M.)
The mesio-distal width of all the teeth mesial to the maxillary
second permanent molars is measured and added

38. b. Determination of premolar diameter (P.M.D.)
The premolar diameter refers to the arch width from the tip of
the buccal cusp of one first premolar to the tip of buccal cusp
of the opposite first premolar.

39. c. Determination of premolar basal arch width
(PMBAW)
The measurement of the width from canine fossa of one side
to the other gives us the width of the dental arch at the apical
base or the junction between the basal bone and alveolar
process.
The canine fossa is found distal to canine eminence.
If the canine fossa is not clearly distinguishable the
measurement is made from a point that is 8 mm below the
crest of the inter-dental papilla distal to the canine.

40. Inference
The P.M.B.A.W. and the P.M.D. are compared.
If the P.M.B.A.W is greater than the P.M.D., then it is an
indication that arch expansion is possible.
If on the other hand the P.M.B.A.W is less than P.M.D., then
arch expansion is not possible.

41. According to Ashley Howe, to achieve normal occlusion with a
full complement of teeth the basal arch width at the premolar
region should be 44% the sum of mesio-distal widths of all the
teeth mesial to the second permanent molar (total tooth
material).
This ratio is called the premolar basal arch width percentage.
It is determined using the formula:
P.M.BA.W% = P.M.BA.W x 100
T.T.M.

42. a. If P.M.B.A.W % is 37% or less, it indicates a need for
extraction.
b. If P.M.B.A.W % is 44% or more, the case can possibly
be treated without extracting any teeth.
c. If P.M.B.A.W % is 37 -44%, the case is referred to as a
borderline case.

43. Peck and Peck analysis index
Itisdoneinlowerarchinpersonswithincisalcrowding.On
basisofobservation,PeckandPecksuggestedcertain
clinicalguidelines.
Procedure
1.calculatemesio-distalwidthsofmandibularincisors
individually(M.D.).
2.calculatelabio-lingualwidthofmandibularincisors
individually(L.L.).

44. 3.Meanvalueiscalculatedbytheformula
M.D.X100
L.L.
According to peck and peck
•Meanvalueforlowercentralincisorshouldbe88to92%.
•Meanvalueforlowerlateralincisorshouldbe90to95%.
Inference
Ifthevalueforagivencaseismorethanthemeanvalue
proximalstrippingisindicated.

45. Sanin-Savara tooth size analysis
Itmakesuseofprecisemesio-distalmeasurementsofthe
crownsizeofeachtoothappropriatetablesoftoothsize
distributioninthepopulationandachartforplottingpatient’s
measurements.
Theteethshouldbemeasuredwithatoothmeasuringgauge
isfinelypointedBoleygaugeandcompared.

46. MIXED DENTITION
ANALYSIS

47. Mixeddentitionperiodisthebesttimetoanalysesandpredict
thefuturedentalarchconditiontherebypreventingany
malocclusionthatmayoccurinpermanentdentition.
Forthispurposevariousauthorshavesuggested
differenttechniquestodeterminethespaceavailableandthe
spacerequiredforthepermanentdentitiontoeruptandthisis
calledmixeddentitionspaceanalysis.

48. Indications for a mixed dentition analysis
Prematurelossofprimarycanine
Rotationorblockingofpermanentteeth
Ectopiceruptionofpermanentfirstmolars.
Distalterminalplanerelationships
Crossbite

49. The purpose of a mixed dentition analysis is to evaluate the
amount of space available in the arch for the erupting
permanent canines and premolars.

50. MOYERS MIXED DENTITION ANALYSIS
In this analysis the size of the unerupted permanent cuspids
and premolars are predicted from the knowledge of the sizes
of certain permanent teeth already erupted in the mouth.
The Moyer's mixed dentition analysis predicts the combined
mesio-distal width of 3, 4 and 5 based on the sum of the
widths of the four lower permanent incisors.

51. The mesio-distal width of the four lower incisors are measured
and summed up.
The amount of space available for the 3, 4 and 5 after incisor
alignment is detetmined by measuring the distance between
the distal surface of lateral incisor and the mesial surface of
first permanent molar.

52. Based on the mesio-distal width of the 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.

53. The predicted tooth size of 3,4 and 5 is compared with the
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.

54. Reason for choosing the mandibular incisors
1. They erupt first and offer the earliestopportunity of
measurement.
2. They are less variable and more reliable
than maxillary incisors.

55. Advantage
1. It has minimal error and the range of possible error
is precisely known.
2. It can be done with equal reliability either by a
beginner or by an expert.
3. It is not time-consuming.
4. It requires no special equipment.
5. It can be done in the mouth as well on the cast.
6. It may be used for both the arches.

56. HUCKBA’S ANALYSIS
He uses both study casts and radiographs 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, such as primary molar tooth.

57. A simple proportional relationship can then be established as
follows:
Actual width of primary molar (Xl)
Apparent width of primary molar (X2)
Actual width of unerupted premolar (YI)
Apparent width of unerupted premolar (Y2)
Xl xY2
YI =
X2

58. 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.

59. HIXON AND OLDFATHER’S METHOD
Procedure
The mesio distal width of the mandibular central and lateral
incisor is obtained from the casts.
Determine the width of the premolars from the intra-oral
periapical radiographs made using long cone technique.

60. Sum up the width of the central and lateral incisor along with
the width of unerupted premolars of that particular side.
The estimated sum total width of the cuspids and bicuspids of
that particular side can be obtained from the given chart.
Every measured sum width of incisors and bicuspids has a
corresponding sum width of the cuspids and bicuspids in the
chart.

61. NANCE CAREY’S ANALYSIS
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.

62. Then add total mesio-distal width of both in each quadrant will
indicate space required to accommodate the permanent teeth.
Then using brass wire, measure the arch perimeter.
Compare the space required and space available to arrive at
the arch length discrepancy.

63. Tanaka and Johnston (1974)
Calculatedbymeasuringteethon506castsofEuropean
patients.
Advantages:
Thisanalysisisconsideredtheeasiestandquickestwayand
mostclinicallyusefulasnoadditionaltablesorx-raysare
required(Moyers,1988;Gardner,1979).

64. Itgivesasimplifiedequationfromtheirstudyforprediction
that,
Sumofwidthsofmaxillarycanineandpremolars=
½sumofwidthofmandibularincisors+11.0mm
Sumofwidthsofmandibularcanineandpremolars=
½sumofwidthofmandibularincisors+10.5mm

65. Procedure
Determinetheavailablearchlengthbymeasuringdistance
frommesialofpermanentfirstmolartothemesialofthe
contralateralpermanentfirstmolarbydividingthearchinto
severalsegment.Eachsegmentismeasuredoverthe
contactpointsandincisaledgesoftheteeth.The
segmentsareaddedtogethertoprovideanapproximation
oftotalarchlength.

66. Secondstepismeasurementofthewidthofthefour
mandibularincisors.
Thenwiththeuseoftheequationwecanfindthespace
available.
Thefinalstepinthespaceanalysisintosubstractthewidthof
thelowerincisorsand2timesthecalculatedpremolarand
caninewidth(bothsides)fromthetotalarchlength
approximation.

67. Iftheresultispositivethereismorespaceavailableinthe
archthanisneededfortheuneruptedteeth.Iftheresultis
negative,theuneruptedteethrequiremorespacethanis
availabletoeruptinidealalignment.

68. Thank you