Upload
care
View
225
Download
0
Embed Size (px)
Citation preview
7/30/2019 29416650 Study Cast Analysis
1/31
Study Cast Analysis
7/30/2019 29416650 Study Cast Analysis
2/31
Study casts are the essential diagnostic aids.They provide a 3-D view of the maxillary and mandibular dental arches
7/30/2019 29416650 Study Cast Analysis
3/31
What is Study Cast Analysis ?
Involves the study of maxillary and mandibular dental arches
in all the three planes of space
Valuable tool in orthodontic diagnosis and
treatment planning
7/30/2019 29416650 Study Cast Analysis
4/31
Proper alignment of the teeth requires harmony between the
tooth sizes and the space required within the dental arch.
Sometimes the space available is not similar to the space
required for the alignment of the teeth.
7/30/2019 29416650 Study Cast Analysis
5/31
Space available = the length of the arch
Space required = the total of the mesio distal width of teeth
If space available = space required , then the arch is well aligned
If the space available is less than space required , then the arch is
crowded
If the space available is more than space required , then the arch is
spaced
Spaced dentition
7/30/2019 29416650 Study Cast Analysis
6/31
It is thus important for the clinician to determine
prior to the onset of the orthodontic treatmentthe space requirements necessary forfavorable results.
To accomplish this, a space (study cast) analysis
must be done.
7/30/2019 29416650 Study Cast Analysis
7/31
Measurements: 1. ARCH LENGTH = ARCH PERIMETER = ARCH CIRCUMFERENCE
2. MESIO-DISTAL WIDTH OF TEETH
S1
S2 S3
S4
Arch length = S1 +S2 + S3 +S4OR
Length of the brass wire
7/30/2019 29416650 Study Cast Analysis
8/31
3. ARCH WIDTH Inter premolar width
Inter molar width
7/30/2019 29416650 Study Cast Analysis
9/31
Permanent Dentition study cast analysis
1. Careys Analysis / Arch Perimeter Analysis
2. Ponts Analysis
3. Ashley Howes Analysis
4. Bolton Tooth Size Analysis (Ratio)
7/30/2019 29416650 Study Cast Analysis
10/31
This analysis helps to determine the extent of the space discrepancy.
It is performed on the lower cast.Same analysis on the upper cast is called Arch Perimeter Analysis.
CAREYS ANALYSIS
Space analysis requires a
comparison between the amountofspace availablefor the
alignment of the teeth
and the amount ofspace required
to align them properly
7/30/2019 29416650 Study Cast Analysis
11/31
STEP 1: Calculation of Space Available
This is accomplished by measuring arch
perimeter from the mesial of one first molar to the other,
over the contact points of posterior teeth and incisal edge of
anteriors.
There are two basic ways to accomplish this
manually:(1) by dividing the dental arch into segments
that can be measured as straight line
approximations of the arch or
(2) by contouring a piece of wire to the line of
occlusion and then straightening it out for
measurement.
S1
S2 S3
S4
7/30/2019 29416650 Study Cast Analysis
12/31
STEP 2: calculate the amount of space required
The mesio-distal width of the teeth
anterior to the first molars (secondpremolar to second premolar) is
measured and summed up.
If the sum of the widths of the permanent teeth is greater than the amount of space
available, there is an arch perimeter space deficiency and crowding would occur. I
f available space is larger than the space required (excess space), gaps between some teeth
would be expected.
SPACE REQUIRED GREATER THEN SPACE AVAILABLE = CROWDING (in mm),
negative discrepancy
SPACE REQUIRED LESSER THEN SPACE AVAILABLE = SPACING (in mm)
7/30/2019 29416650 Study Cast Analysis
13/31
The type of discrepancy is noted, i.e., whether positive (spacing)or negative (crowding).
Any of the following methods will have to be adopted
if there is a negative discrepancy between arch length
and tooth material.
a) Proximal stripping...discrepancy up to 2.5mm
b) Extraction of second premolars.... discrepancy between
2.5mm & 5 mm
c) Extraction of first premolars - discrepancy more than 5 mm.
7/30/2019 29416650 Study Cast Analysis
14/31
Example:
7/30/2019 29416650 Study Cast Analysis
15/31
BOLTONS ANALYSIS
There exists a ratio between the mesio-distalwidths ofmaxillary
and mandibular teeth
Malocclusions occur as a result of
abnormalities in tooth size
The Boltons analysis helps in determining disproportion in size
Between maxillary and mandibular teeth.
7/30/2019 29416650 Study Cast Analysis
16/31
Bolton Tooth Size Analysis
(Ratio)
Overall ratio:
Add the mesio-distal width of themaxillary incisors, canines, premolars
and the first permanent molars =
maxillary tooth size.Add the mesio-distal widths of the
mandibular incisors, canines,
premolars
and the first permanent molars =
mandibular tooth size.
Overall ratio= Mandibular 12 X100
Maxillary 12
The mean value is 91.3%
7/30/2019 29416650 Study Cast Analysis
17/31
If the calculated overall ratio is greater than the mean value (91.3 %)
It indicates that the mandibular tooth size is in excess
To find the mandibular excess, subtract the correct mandibular tooth size (X) from
the calculated mandibular tooth size
Where X = sum of maxillary 12 X 91.3
100
i.e. Sum of mandibular 12 - sum of maxillary 12 X 91.3
100
If the calculated overall ratio is smaller than the mean value than it implies
that the maxillary tooth size is in excess compared to the mandibular tooth
size.
To find the maxillary excess, subtract the correct maxillary tooth size (X) fromthe calculated maxillary tooth size.
where X = Mandibular tooth size X 100
91.3
7/30/2019 29416650 Study Cast Analysis
18/31
Anterior ratio: The mesio-distal width of the maxillary and mandibularincisors and canines, are taken into account.The calculations are done in the same manner as
in the overall ratio. The mean value for the anterior ratio is 77.2%
Inference :If the discrepancy value exceeds 2mm (overall or anterior)
suitable measures should be adopted to correct the discrepancy.
PONTS ANALYSIS
7/30/2019 29416650 Study Cast Analysis
19/31
Method:
a. Measure the mesio-distal width of the upper central and lateral incisors. .,
b. sum of the above = SI
c. Measure the width of the arch in the region of the first premolari.e., the width from the distal pit of the first premolar to the same point on the otherside
d. Measure the width of the arch in the molar region
i.e., the width from the mesial pit of the first permanent molar of one side to the other.
e. The arch width is calculated, for a given mesio-distal width of the
upper incisors, in the premolar and molar region
using the' formulaSI X 100/80and SI X 100/64 for the premolar and molar regions respectively.
f. The measured and calculated widths are compared.
Conclusion:
If the measured arch width is less than calculated width then the arch is
narrow and needs expansion.
PONTS ANALYSIS
Determines whether the dental arch
is narrow or normal
7/30/2019 29416650 Study Cast Analysis
20/31
Mixed Dentition space Analysis
To evaluate the amount of space available in the arch for the
erupting permanent canines and premolars
Mixed Dentition
7/30/2019 29416650 Study Cast Analysis
21/31
MOYERS MIXED DENTITION ANALYSIS
In this analysis size of the cuspids and premolars are
derived from the knowledge of the size of permanent teeth
already erupted in the mouth.
The lower incisors are measured to predict the size of upper
as well as lower posterior teeth.
The Moyers 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
7/30/2019 29416650 Study Cast Analysis
22/31
7/30/2019 29416650 Study Cast Analysis
23/31
7/30/2019 29416650 Study Cast Analysis
24/31
Tanaka and Johnston prediction values
7/30/2019 29416650 Study Cast Analysis
25/31
Measurement from Radiograph
7/30/2019 29416650 Study Cast Analysis
26/31
HIXON AND OLDFATHER PREDICTION
This method of prediction uses both theradiographs and prediction tables. Since the
major problem with using radiographic images
comes in evaluating the canine teeth, it would
seem reasonable to use the size of permanent
incisors measured from the casts and the size of
unerupted premolars measured from the
periapical films to predict the size of unerupted
canines.
7/30/2019 29416650 Study Cast Analysis
27/31
From the prediction table, the predicted size
of the unerupted canines and premolars are
found against the measured value. This
method is restricted to the mandible.
7/30/2019 29416650 Study Cast Analysis
28/31
measured value Estimated tooth
size
23 18.4
24 19.0
25 19.7
26 20.327 21.0
28 21.6
29 22.330 22.9
7/30/2019 29416650 Study Cast Analysis
29/31
7/30/2019 29416650 Study Cast Analysis
30/31
Graph showing relationship between size of lower incisors measured
from cast plus lower first and
second premolars measured from radiographs (x-axis) and size of
canine plus premolars (y-axis)
Digital Cast Analysis
7/30/2019 29416650 Study Cast Analysis
31/31
Digital Cast Analysis