Space analysis /certified fixed orthodontic courses by Indian dental academy

Space analysis
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Space analysis
• Space analysis is one of the essential diagnostic
aids
• Helps to visualize patients occlusion from all
aspects & also make necessary measurements
of teeth & dental arches & basal bones
• Study cast analysis is a three – dimension
assessment of the maxillary and mandibular
dental arches and the occlusal relationships.

Advantages of study cast analysis
1. Degree of Malocclusion can be diagnosed in the dimensions..
a) Midsaggital plan – Transverse plane
b) Tuberosity plan – A-P plane
c) Occlusal plan – Vertical plane
2. Inter arch irregularities. Inter arch relationship
3.To view lingual occlusion
4. Transverse discrepancies.
5. Motivation of patient.
6. Prognosis of the case – patient and doctor.
7. Treatment planning – must surgery.
8. Dental health education.
9. Assessment of the palatal vault.

Preparation of study models
• Study models are reasonably accurate
positive replica of teeth & the associated
structures used primarily for the purpose
of display &demonstration

Trimming of study models

Gnathostatic model by simon 1922
• The gnathostatic method of trimming casts was, in part,
an effort to respond to this problem by relating the
models to the orientation of the dentition in the head
with reference to the Frankfort plane, the mid-sagittal
plane and the preauricular plane.
• The method fell into disuse partly because Simon was
discredited, partly because the method was more
sophisticated than orthodontic treatment at that time,
and partly because it was too difficult and time-
consuming.
• Making models from plaster impressions and the
gnathostatic technique probably did more to discourage
careers in orthodontics than any other single factor.

Principles of space analysis
Space analysis requires a
comparison between the amount
of space available for the
alignment of the teeth & the
amount of space required to align
them properly

Principles of space Analysis
Space analysis requires a comparision between the amount
of space available for the alignment of the teeth and the
amount of space required to align them properly .
Space available space required
Compare
Space excess ok space deficiency

ANTERIOR DENTAL ARCH LENGTH.
• The anterior arch length
according to Korkhaus (Lu in
the maxilla,Ll in the mandible)
is definded as the
perpendicular from the most
anterior labial surface of the
central incisors to the
connecting line of the
referance points of the anterior
arch width . The measurement
should reveal the
anteroposterior malpositioning
of the anterior teeth.

CORRELATION BETWEEN MAXILLARY AND
MANDIBULAR ANTERIOR ARCH LENGTHS.
• The anterior arch length of the
mandible (LL) by the
labiolingual width of the incisal
edge of the upper central
incisor.
• As a rule the following
relationship applies:
• LL = LU – 2mm

INTRAMAXILLARY SYMMETRY.
• These symmetry
analyses estimate the
right-left differences
in transverse and
anteroposterior tooth
positions
(Korbitz1909)
• Midpalatal raphe &
tuberosity plane

Symmetrograph of Bernklau

Analysis of Transverse symmetry
• Symmetric / asymmetric width
development between right & left sides of
the arch
• Congruence / incongruence between
dental midline & skeletal midline

Midline
• Dental midline deviation in the
upper arch.
• The contact point of the upper
central incisors is shifted to the
right, in relation to the midsagittal
plane, i.e. to the side with lack of
space for the canine.
• Reichenbach and Bruckel, 1967).
dental midline shift in the mandibular
arch.The contact point of the
lower central incisors is deviated
to the left as the result of tooth
drift: in an otherwise well aligned
arch, the lower right lateral

Mixed dentition analysis
• Huckabas analysis
• Hixon&Oldfathers analysis
• Nance Caryes analysis
• Moyers Mixed dentition analysis
• Tanaka johnstone
• Total space analysis

Mixed dentition
• Three approaches have been employed to estimate the
mesiodistal crown widths of unerupted canines and
premolars:
• (1) use of measurements from erupted teeth
• (2) use of measurements from radiographs
• (3) use of a combination of measurements from erupted
teeth and from radiographs of unerupted teeth
• This last approach is considered to be the most accurate
since it generally has the lowest standard error of
estimate.

• The Moyers' 1967 probability tables for computing the
sizes of unerupted canines and premolars were
formulated at the University of Michigan from a sample
consisting of northern European white subjects and are
currently used worldwide.

• According to Proffit and Fields, the accuracy with
Moyers' method is fairly good for northern European
white children on which the data is based, despite a
tendency to overestimate the size of unerupted teeth.
• Sexual dimorphism has also been confirmed in several
studies, with specific teeth statistically significantly larger
in males than females.

Hixon & Oldfather
• 1977 Kaplan, Smith, and Kanarek compared the prediction methods
of Hixon and Oldfather, Moyers, and Tanaka and Johnston by
regression analysis and found the Hixon and Oldfather estimate to
be the most accurate in their sample of 104 white children.
• 1979 Gardner found that the methods of Nance, Moyers, and
Tanaka and Johnston tended to overpredict by 1 to 3 mm, whereas
the Hixon and Oldfather technique was more likely to underpredict
by about 0.5 mm
• Hixon and Oldfather prediction did not appear to be seriously
influenced by sex or the type of dental occlusion.

• The M-D width of the mandibular 1&2 from casts
• Determine width of 3,4,5 from radiograph
• Sum up the width of the central & lateral incisor
along with the width of unerupted premolar of
that side
• The estimated sum total width of the cuspids &
bicuspids of that particular side can be obtained
from the chart
• Every measured sum width of incisors &
bicuspids has corresponding sum width of the
cuspids & bicuspids in the chart
•

Nance Careys analysis
• Measure M-D width of the erupted permanent
teeth
• Measure (3,4,5) from radiographs
• The total M-D width of all the teeth in each
quadrant will indicate space required to
accommodate the permanent
• Using brass wire, measure the arch perimeter
• Compare the space required & space available to
arrive at the arch length discrepancy

Tanaka and Johnston prediction
values 1974
One half
of the
M-D
width of
the four
lower
incisors
+ 10.5 =
Estimated width of mandibular
Canine & premolar in one
quadrant
+ 11.0 =
Estimated width of maxillary
Canine & premolar in one quadrant

Huckaba 1967
True width of primary molar = true width of unerupted premolar
apparent width of primary apparent width of unerupted premolar
molar

Total space analysis-Merrifield1978
Anterior area
Tooth measurement
• Measurement of mandibular incisors
widths on the cast were added to values
obtained from the radio graphic
measurements of the canines.

• Cephalometric correction was
calculated for the Tweed
method
• FMIA was taken into
consideration
• The incisors were repositioned
and the difference in the
actual and proposed FMIA is
determined.
• The difference in angulation is
multiplied by 0.8 to get the
difference in mm

• Soft tissue modification
• Upper lip thickness from the vermilion
border of the upper lip to the greatest
curvature of the labial surface of the
central incisor
• The total chin thickness from the soft
tissue chin to the N-B line

• If the lip thickness is greater than chin
thickness the diff is determined and
multiplied by 2 and added to the space
required. If it is less than or equal to chin
thickness no soft tissue modification is
necessary

• Measure the Z angle of Merrifield and add
the cephalometric correction to it.
• If the corrected Z angle is greater than 80
the mandibular incisor angulation was
modified as necessary upto an IMPA of 92
• If the corrected angle is less than 75
additional uprighting of the mandibular
incisor is necessary

Middle area
• Measure the M-D with of the 1st
permanent molar of the cast
• Curve of SPEE, the deepest point between
the flat surface and the occlusal surface is
measured on both sides

Posterior Area
• MD width of the 2nd and 3rd molar is obtained
from the radiograph.
• Wheelers method is used for calculation
Y – X1
X=
Y1
X –estimated value of 3rd molar
X1 –wheelers value of 3rd molar
Y - actual size of 6
Y 1- wheelers value for 6

Permanent dentition analysis
• Ponts index
• Korkhaus analysis
• Linder Harth index
• Arch perimeter analysis
• Bolton tooth size ratio
• Howes analysis
• Peck& peck index

Ponts index 1909
• Pont in 1909 suggested a method for determining the
ideal dental arch width from the combined M-D width of
the maxillary central incisors
• Ideal arch width in the premolar region
X x 100
80
Ideal arch width in the molar region
X x 100
64

• Inference
• If calculated value is greater than the
measure value ,then arch is narrow for
sum of incisors-needs expansion
• If measured value is greater - arch wide
– no scope for expansion

Linder Harth index
• Similar to Ponts
• Ideal arch width in the premolar region
X x 100
80
• Ideal arch width in the molar region
X x 100
64

Korkhaus analysis 1939
• Using Linder Harth measurement introduced a third
measurement from the midpoint of the inter-premolar
line of upper arch to point incison.
• For a particular width of incisors there is a specific value
of the distance from incison to the inter-premolar line
• An orthometer was devised which directly measures the
ideal arch width in premolar and molar region &also
perpendicular distance from the inter –premolar line to
the incison for a given sum mesio-distal width of the
maxillary incisors (21/12)

Ashleys Howes
• According to Howe, crowding is not only
due to tooth sise ,but as a result when
there is inadequate apical base
• PMBAW x 100
TM

• Inference
• The patient values should fall within the suggested
range
• If PMD>PMBAW, expansion is contraindicated
• If PMBAW>PMD, expansion is indicated
• If PMBAW x 100
TM
Less than 37% -basal arch deficiency—extraction
If 44% --ideal case—extraction not required
If between 37% - 44% boderline case

Arch perimeter analysis
• This analysis helps to find the
difference between the basal
bone & the tooth material.
• The soft wire is
contoured,from the mesio-
buccal line angle of molar &
pass along the contacts of the
premolar& through the incisive
papilla on an imaginary
repositioned arch .
• Tooth material - space
required
• Arch perimeter - space
available

Careys analysis (1949)
Inference
• If the amount of discrepancy is between
0 to 2.5mm – non-extraction case
• If it is between 2.5 to 5mm –extraction of
second premolars is recommended
• If it is more than 5mm – extraction of first
premolar is recommended

Peck and Peck index
• According to Peck ideal incisal arrangement had smaller
mesiodistal & comparatively larger labio lingual width
than in persons with incisal crowding .
• On the basis of this Peck suggested certain clinical
guidelines.
MD x 100
LL
Mean value for lower central incisor should be 88% to 92%
Mean value for lateral incisors – 90% to 95%

Boltons analysis
• In 1958, Bolton published his work on interpreting
mesiodistal tooth size dimensions and their effect on
occlusion.
• Bolton selected 55 cases with excellent occlusions, most
of which (44) had been treated orthodontically
(nonextraction).
• The mesiodistal widths of the 12 maxillary teeth (first
molar to first molar) were totaled and compared with the
sum derived by the same procedure carried out on the
12 mandibular teeth.
• The ratio derived between the two is the percentage
relationship of mandibular arch length to maxillary arch
length.

• He concluded that an
overall ratio of 91.3 and
an anterior ratio of 77.2
were necessary for
proper coordination of
the maxillary and
mandibular teeth.

• If the overall ratio is greater than 91.3%
,then there is an excess of mandibular
tooth material
• Actual mand 12 – Corrected mand 12 =
• Actual max 12 _ corrected max

• He computed the specific ratios of the
mesiodistal widths must exist between
maxillary and mandibular teeth from both
canine-canine and first molar-first molar to
obtain optimum occlusion and to achieve
proper occlusal interdigitation in the
finishing stages of orthodontic treatment.

• Black was one of the first investigators to measure tooth
sizes and his tables of mean tooth sizes are still used
today.
• The tooth size measurements of Wheeler also are
frequently used.
• Ballard measured 500 sets of models, evaluating
asymmetry in tooth sizes. Ninety percent of his sample
showed a right-to-left discrepancy of 0.25 mm or more
in the mesiodistal width of one or more pairs of teeth.
• His observations led to the conclusion that asymmetry is
the rule, not the exception, and that judicious enamel
reduction or "stripping" is sometimes necessary,
particularly in the anterior segments to gain proper
interdigitation of teeth

Conclusion

• Lundström 1954 studied 319 13-year-old children and
reported on the variation in intermaxillary tooth width
ratio. The mesiodistal widths were recorded and the
dispersion for the three tooth size indices were
calculated:
• His results demonstrated a large biologic dispersion in
the tooth width ratio. It was great enough to have an
impact on the final tooth position, teeth alignment, and
overbite and overjet relationships in a large number of
these patients. This same formula originally was
developed by Bolton to observe mesiodistal tooth size
discrepancies.

Careys analysis

TOTAL DENTITION SPACE ANALYSIS
• Merrifield
• lSince the original diagnosis and treatment plan must accept the
dimensions of the denture presented in the original malocclusion
when musculature is normal (i.e., Class I), a total dentition space
analysis allows the clinician to develop a differential diagnosis that
respects the dimensions of the denture concept during the
treatment planning process.
• (1) anterior, (2) midarch, and (3) posterior.
• (1) simplicity in identifying the area of space deficit or space
surplus,
• (2) a more accurate differential diagnosis.

ANTERIOR SPACE ANALYSIS
• space available in the mandibular arch from canine to canine and a
measurement of the six anterior teeth mesiodistally.
• The difference is referred to as a surplus or a deficit.
• Tweed's diagnostic facial triangle is also used to further analyze this
area.
• A head film discrepancy, based on the amount of mandibular incisor
uprighting that is needed to restore facial balance, is added to the
anterior space measurement. The total, if a deficit, is referred to as
anterior discrepancy. Anterior discrepancies are most easily
resolved, if they are the overriding consideration of the
malocclusion, by removal of the first premolar teeth and by using
the resulting space to move the canines distally to obtain the space
to upright and align the incisors.

MIDARCH ANALYSIS
• Careful analysis of this area can show mesially inclined first molars,
rotations, spaces, deep curves of Spee, crossbites, missing teeth, habit
abnormality, blocked out teeth, and occlusal disharmonies.
• Crowding, deep curves of Spee, end-on, and Class II occlusions not
accompanied by anterior discrepancy, all indicate a need for second
premolar extraction in the lower arch.
• careful measurement of the space from the distal of the canine to the distal
of the first molar should be recorded as available midarch space.
• To this is added the space required to level the curve of Spee. From these
measurements one can determine the space deficit or surplus in this area.
• Many diagnosticians have suggested that they extract second premolar
teeth to eliminate facial retrusion. This is faulty reasoning. These cases
have, as a rule, very little anterior discrepancy, and the second premolars
are removed because their space is most advantageously used for the
midarch problems that these cases usually demonstrate. The midarch space
analysis is critical in proper differential diagnosis.

POSTERIOR SPACE ANALYSIS
• The posterior denture area has great importance, and has at times been
ignored or mistreated by our specialty. The required space in the posterior
space analysis is the mesiodistal width of the second molars and the third
molars in the mandibular arch. The available space is more difficult to
ascertain on the immature patient. It is a measurement in millimeters of the
space distal to the mandibular first molars along the occlusal plane to the
anterior border of the ramus, plus an estimate of posterior arch length
increase, based on both age and sex.
• There are certain variables that must be considered in estimating the
increase in posterior space available. These variables are as follows:
• 1. Rate of mesioocclusal migration of the mandibular first molar.
• 2. Rate of resorption of the anterior border of the ramus.
• 3. Time of cessation of molar migration.
• 4. Time of cessation of ramus resorption.
• 5. Sex.
• 6. Age.

• A review and study of the literature10-12 reveals that a consensus of
researchers suggests 3 mm of increase in the posterior denture area occurs
per year until age 14 years for girls and age 16 years for boys. This is a 1.5
mm increase on each side per year after the full eruption of the first molars.
In the mature patient, girls beyond 15 years and boys beyond 16 years,
one can measure from the distal of the first molar to the anterior border of
the ramus at the occlusal plane and have an accurate determination of the
space available in the posterior area. It is of extreme importance to know
whether there is a surplus or deficit of space in this area during diagnosis
and treatment planning. It is imprudent to create a posterior discrepancy
while making adjustments in other areas— the midarch, or in the anterior
area. It is equally imprudent not to use a posterior space surplus to help
alleviate midarch and anterior deficits. The most easily recognizable
symptom of a posterior deficit on the young patient is the late eruption of
the second molar. If space is not available for this tooth by the age of its
normal eruption, then one can pretty well ascertain that there is a posterior
space problem. A good lateral jaw radiograph can immediately confirm the
clinical observation by using the above-mentioned guidelines.

• In summary, a total space analysis that analyzes the anterior, midarch, and
posterior denture areas is a valuable diagnostic tool. It enables the
orthodontic specialist to treat within the dimensions of the denture in the
case with normal muscular balance. A total dentition space analysis, used
within the dimensions of the denture framework, enables the orthodontist
to make correct differential diagnostic decisions.
• Diagnosis, by definition, is both subjective and objective. Webster defines
diagnosis as a "determination of a disease from symptoms, data, or tests
and the decisions and judgements made prior to treatment." Thus the
determination made in regard to whether, when, and which teeth need to
be eliminated for proper space management is a differential diagnostic
process. When diagnostic guidelines or decisions are suggested, they can
appropriately be called "one man's opinion." The following diagnostic space
management guidelines are suggested for use and should not be
considered as rules. These space management suggestions are based on
space analysis only. Any complete diagnostic scheme has to consider the
facial pattern and the skeletal pattern.

• Lower incisor space analysis - Harris, Vaden, and Williams
• --------------------------------
• The common situation in which the incisors are labially displaced against the cortical
plate is difficult to assess from the casts alone. During uprighting of the incisors, the
radius of the anterior arch decreases and, along with it, the actual space available.
This sort of error can be minimized by inspecting the incisor positions on the lateral
head film and adjusting the space available accordingly. One such method is to
calculate a ''head film discrepancy value." This is the millimetric distance the lower
incisors must be uprighted in order to be placed over basal bone and into a position
of balance with the facial structures.24 Typically this procedure is indicated because
often all six anterior teeth need to be retracted and uprighted— and the increase in
the required space has to be gained from extractions in the midarch. A case in point
has been illustrated (Fig. 2, B); the casts exhibit spacing of the lower anterior teeth,
but they are proclined to an IMPA of 97° and are at the anterior limit of the alveolar
bone. Treatment involved uprighting the lower incisors 9° and retracting them 6 mm
(I to NP decreased 6 mm).

• Source: AJO-DO on CD-ROM (Copyright © 1998 AJO-DO), Volume
1987 Nov (375 - 380): Lower incisor space analysis - Harris, Vaden,
and Williams
• --------------------------------
• One other diagnostic consideration that warrants attention is the
soft-tissue profile and its relation to tooth position. A compensation
should be made in any diagnostic scheme for a maldistribution of
soft-tissue thicknesses. One approach25 is to compare total chin
thickness (Pg' measured normal to the nasion-B-point line) with
upper lip thickness. Integumental compensation is needed in the
direction of more upright lower incisors in those patients possessing
less total chin thickness than upper lip thickness. Compensation is
not indicated when the total chin and upper lip thicknesses are
equal.25

1994 Nov (535 - 542): Dimensions of the denture - Merrifield
• --------------------------------
• INTRODUCTION TO DEFICITS AND DECISIONS Space management
guidance
• A. Anterior surplus or deficit:+ to -2mm Space
Management Nonextraction
• 3 to 5 mm without crowding. Extract:
• 3 to 5 mm with crowding. Extract:
• 5 to 7 mm with less than 3 mm anterior crowding. Extract:
• 5 to 7 mm with more than 3 mm anterior crowding. Extract:
• 7 to 15 mm anterior deficit. Extract:
• 16 mm and above. Extract:

• Source: AJO-DO on CD-ROM (Copyright © 1998 AJO-DO), Volume 1994
Nov (535 - 542): Dimensions of the denture - Merrifield
• --------------------------------
• B. Midarch surplus or deficit: An anterior deficit or surplus overrides a
midarch deficit so the first determination is a decision on the anterior
deficit.
• + to 3 mm Nonextraction
• 3 to 5 mm without crowding. Extract:
• 3 to 5 mm with Class II molar. Extract:
• 5 to 7 mm with upper anterior protrusion.Extract:
• 5 to 7 mm Extract:
• 8 to 15 mm Extract:
• Over 15 mm Extract:
• *(Use X for all molars: first, second, and third.)

• Source: AJO-DO on CD-ROM (Copyright © 1998 AJO-DO), Volume 1994 Nov (535 - 542): Dimensions of the
denture - Merrifield
• --------------------------------
• C. Posterior surplus or deficit: The space analysis m this area is of great importance, although in corrective
procedures, anterior and midarch deficits are overriding. The posterior space must be carefully measured and
protected. No orthodontic treatment is complete until all decisions and treatment procedures are completed in
this area.
• + to -5 mm with good position of the third molars. Await full development of the third molars.
• + to -5 mm with poor position of third molars. Extract:
• Note: Wait for maxillary third molars until age 16 years. Have the mandibular third molars removed immediately if
other treatment is necessary.
• 5 to 15 mm. Extract:
• (Determine the timing of these third molar extractions in relationship to symptoms and other treatment that is
necessary.)
• Consistent, quality orthodontic treatment results are based on fundamental concepts. The concept of dimensions
of the denture is predicated on the conviction that the teeth and their supporting structures should be in a state
of maximum environmental harmony (dynamic equilibrium). Total dentition space analysis, based on the
dimension of the denture concept, is a valuable tool that can help the orthodontic specialist produce a
consistently high quality result that meets the needs and expectations of the patient.

• Anterior space analysis: Anterior space analysis includes the measurment in
millimeters of the space available in the mandibular arch from canine to
canine and a measurment of the mesiodistal dimension of each of the six
anterior teeth. The difference is referred to as a surplus or deficit. The
Tweed diagnostic facial triangle is also used to further analyze this area.
Lateral headfilm discrepancy is the amount of space required to position the
mandibular incisors for facial balance. This value is added to the anterior
space measurement.
• The thickness of the soft tissue (upper lip versus total chin) must also be
considered as part of the anterior space analysis. Total chin thickness
should equal upper lip thickness. If it is less than upper lip thickness, the
anterior teeth must be uprighted further to create a more balanced profile
because lip retraction follows tooth uprighting.
• The sum of the anterior tooth arch surplus or deficit, the cephalometric
discrepancy, and the soft tissue thickness imbalance is referred to as the
anterior discrepancy. Each of the three values in the anterior discrepancy
calculation has been given a difficult factor so that an anterior space
analysis difficulty value can be calculated.

• Midarch space analysis: The midarch area includes the
mandible first molars and the first and second
premolars. Careful analysis of this area may show
mesially inclined first molars, rotation, spaces, a deep
curve of spee, crossbites missing teeth, habit
abnormality, blocked out teeth, and occlusal
disharmonies. This is an extremely important area of
the dentition. Because it is in the center of the arch, this
area allows the easiest and most direct method of space
management for malocclusion correction when it can be
so used. Crowding, a deep curve of spee, and end – on
or full – step Class II occlusions, not a accomplained by
anterior disctepancy, indicate a need for second
premolar extraction in the mandibular arch.

• These variables are the following:
• 1. Rate of mesio-occlusal migration of the
mandibular first molar.
• 2. Rate of resorption of the anterior border of
the ramus.
• 3. Time of cessation of molar migration.
• 4. Time of cessation of ramus resorption.
• 5. Gender.
• 6. Age.

• A review of the literature 6,22,38 reveals that a
consensus of researchers suggests that 3 mm of
increase in the posterior denture area occurs per
year until age 14 for girsls and age 16 for boys.
This is an increase of 1.5 mm on each side per
year after the full eruption of the first molars.
In the mature patient (girls beyond 15 years and
boys beyond 16 years) a measyrement from the
distal of the first molar to the anterior border of
the ramus at the occlusal plane is a valuable
determination of the space available in the
posterior area.

• Taken from the JCO 1985 Jun (445-448): Analytical Orthodontic
Computer Programs - DENNIS M. KILLIANY, DDS, MSD
• --------------------------------
• Analytical Orthodontic Computer Programs
• DENNIS M. KILLIANY, DDS, MSD
• I have developed a computer program that performs several
diagnostic analyses— cephalometric, mixed dentition, and tooth
size— and a practice management analysis of patient starts. This
program is written in Basica on an IBM PC-XT. It will also run with
GWBASIC on many IBM-compatible computers. The two versions of
the program (ANALYSES.M— monochrome and ANALYSES.C—
color) are available to any interested practitioner.

• Taken from the JCO 1985 Jun (445-448): Analytical Orthodontic Computer
Programs - DENNIS M. KILLIANY, DDS, MSD
• --------------------------------
• It is not the purpose of this seminar to discuss the validity of each analysis.
These analyses, by themselves, may not provide sufficient information upon
which to base a diagnosis and treatment plan. Care must be taken in
applying a mathematical analysis to patients. For example, although a
statistically significant relationship has been shown to exist between the
size of lower incisors and their crowding, the strength of the relationship is
weak. Hence, indiscriminate mesiodistal narrowing of lower incisors based
on their existing faciolingual dimensions may not lead to a clinically
significant increase in stability. Although many of the assumptions made in
these analyses have been exhaustively argued, the analyses can still be
valuable tools for diagnosis when combined with a complete clinical and
cephalometic appraisal of a patient.

• Even in children with well proportional faces, the position of the p[ermanent
molars changes when primary molar are replaced by the problems. If
space analysis is done in the mixed dentition, it is necessary to adjust the
space available measurment to reflect the shift in molar position that can be
anticipated.
• Model Analysis
• Model analysis is one of the essential diagnostic aids. Study models helps
us to visualize the patient’s occlusion from all aspects and also helps us in
making the necessary measurements of the teeth, the dental arches and
the basal bone to carry out the various types of model analysis. Most of
the model analysis suggested by various authors does not correlate the
findings of model analysis with other diagnostic aids such as cephalogram
and panoramic radiographs and hence the diagnostic value of such
independent model analysis is questionable. However, the model analysis
is still used widely in orthodontic practice and provides us with valuable
information and when it is completed with other diagnostic aids will help us
in diagnosing and planning treatment of a case.

• Study models aid diagnosis in the following wasys.
• 1. They enable occlusal relationships to be observed, which might not
otherwise be visible.
• For example, when the overbile is increased, the point of contact of the
lower incisor edges with the opposing arch cannot be determined clinically
and yet can easily be seen on the models.
• Visulize the lingual occlusion.
• Orientetion of study models
• Construction of reference plens.
• 1. Mid palatal reph – is a reference plane for assessing transverse symetry.
• 2. Tuberosly plane – is a refer plann for ass antero posterior symmetry.
• Assement of symmtry
• 3. Symmetrograph according to Bernklace a transparent plastic frid oriented
to the mid palated and tuberosity plane is and for assening symmetical arch
shape.

• Baldridge1969studied the effect of leveling the curve of Spee on
mandibular arch length in thirty adults with exaggerated curves of
Spee and all mandibular teeth anterior to the third molars erupted.
He found that leveling the curve of Spee required an average of 3.5
± 0.14 mm of additional arch length without expansion of the arch
buccally or labially. The range of required additional arch length
varied from 2.3 mm to 5.2 mm. Baldridge developed prediction
equations for estimating the required additional arch length. No
method of prediction is available for the mixed dentition; however,
consideration for the effect of the curve of Spee needs to be part of
an overall mixed-dentition arch length analysis. Merrifield1978
proposed a simplified method of estimating the required space to
level the curve of Spee, based on Baldridge findings. He suggested
averaging the height of the curve of Spee at its greatest curvature
on both sides. The calculated value presents, in millimeters, the
additional arch length required for leveling the curve of Spee.

• Molar relationship
• Lower incisor
inclination
• Curve of spee

•(1) the Hixon and Oldfather
prediction could be performed before
eruption of the lateral incisor
• (2) the method tended to
underestimate the canine and
premolars to the extent that the
clinician would be less likely to embark
on early extraction regimes.

- Bishara and Staley
• Mandibular tooth size— arch length analysis
• A step-by-step chart was developed for use in conjunction with the
prediction graph to estimate the tooth size— arch length discrepancy for
the patient.
• The chart and graph would be part of the clinical record developed for
patients undergoing mixed-dentition evaluation and/or treatment. A copy of
the chart and graph can be obtained by writing to the authors.
• The first four steps in the chart involve taking measurements of the
predictor variables as illustrated in.
• It is important that the periapical radiographs be taken with a long-cone
paralleling technique.
• The sum of the four predictor variables for each side of the arch is entered
in step 5 of the chart.
• This sum is then taken to the horizontal (bottom) axis of the prediction
graph. The vertical line nearest the point along the horizontal axis where
the sum is located is then followed upward to the diagonal prediction line.
The point of intersection of the vertical and diagonal lines is then followed
leftward on a horizontal line to the vertical (left) axis, where the predicted
sum of the unerupted canine and premolars is found.

• - Bishara and Staley
• If measurements of predictor variables were available for only one side of
the arch, it can be reasonably assumed, on the basis of the high degree of
bilateral symmetry in canine and premolar tooth widths, that the predicted
sum of unerupted canine and premolar widths would be very similar for the
two sides of the arch. Badly rotated premolars on a radiograph are best not
measured. If the antimere tooth is not rotated on the radiograph, its
measurement can be substituted for that of the rotated tooth.
• The standard error of estimate for the prediction graph is 0.44 mm. It is
expected that for approximately 68% of the patients with a particular
estimate the actual widths of the premolars and canine will be within a
range of values as high as 0.44 mm above the estimate to as low as 0.44
mm below the estimate.

• Bishara and Staley
• The estimate of canine and premolar size that is obtained from the
prediction graph is the mean or aver age estimate. The average estimate at
the fiftieth percentile is larger than the true sum of widths for half of all
possible patients and smaller than the true sum of widths for half of all
possible patients. Some clinicians prefer to choose the predicted sum at a
percentile above 50, so that the error or prediction would be on the
overestimation side rather than the underestimation side. Moyers3
recommends prediction at the seventy-fifth percentile as a protection
against underpredicting the true size. Adding one standard error of estimate
to the predicted sum would give a predicted sum of widths at the eighty-
fourth percentile. This would assure the clinician that the predicted sum of
canine and premolar widths is as large as, or larger than, the true sum in
84% of all possible patients. For those who want protection against
underprediction of the tooth widths, we recommend that one standard error
of estimate be added to the predicted sum that is obtained from the
prediction graph. The standard error of estimate is added to the predicted
sum of unerupted canine and premolar widths in steps 7 and 8 of the chart
(Fig. 3).

• Posterior arch length is measured as illustrated in Fig. 5 and is entered in step 9 of
the chart. When the deciduous canine is present in the arch, an additional arch length
measurement in the canine part of the arch is added to the length measured
between the mesial surface of the permanent first molar and the distal surface of the
deciduous canine. The estimate of the unerupted canine and premolar widths is
subtracted from the posterior arch length measurement (step 9, Fig. 3). This step is
repeated for the other side (step 10), and then the estimates for the two posterior
segments are added (step 11).
• Anterior arch length is measured as illustrated in Fig. 6. It is important that the two
anterior segments be measured from the same point in the midline. Marking the
midline point with a pencil is recommended. The sum of the incisor widths, measured
in steps 1 and 2 of the chart, are then subtracted from the anterior arch length. The
remainder of this subtraction is entered in step 12 of the chart (Fig. 3).
• The total arch length— tooth size relationship is summarized in step 13 of the chart,
with a positive number indicating excess arch length and a negative number
indicating an arch length deficiency.
• As suggested by Merrifield,17 other parameters need to be considered in the space
analysis; for example, the anteroposterior relationship of the first permanent molars,
the anteroposterior position of the lower incisors, and the degree of curve of Spee.

• An index for assessing tooth shape deviations - Peck and
Peck.
• . A mandibular central incisor showing the mesiodistal
(MD) and faciolingual (FL) crown diameters. The MD/FL
index (MD/FL ´ 100) is a numerical expression of the
crown's shape as seen from the incisal aspect. For the
incisor shown, the MD diameter approximately equals
the FL diameter, yielding an MD/FL index of 100. If the
MD diameter of this tooth were greater than its FL
diameter, the index would be greater than 100. Similarly,
if the MD diameter were less than the FL diameter, the
index would be less than 100.

1984 Aug (130 - 135): Mixed-dentition mandibular arch length
analysis - Bishara and Staley
• --------------------------------
• The molar relationship in the mixed dentition is very frequently end
to end (Fig. 7, A). The transition to a full Class I relationship will
require either some type of orthodontic intervention or allowing the
mandibular molars to migrate mesially in the leeway space. If the
latter approach is considered, the amount of mesial migration of the
first molars should be estimated by measuring the distance between
the mesiobuccal cusp tip of the upper molar and the buccal groove
of the lower molar as illustrated by the arrow in Fig. 7, A. This
distance, on each side, is then subtracted from the arch length.

• Source: AJO-DO on CD-ROM (Copyright © 1998 AJO-
DO), Volume 1984 Aug (130 - 135): Mixed-dentition
mandibular arch length analysis - Bishara and Staley
• --------------------------------
• To estimate the arch length needed to upright (move
lingually) the mandibular incisors (Fig. 7, B), Tweed18
suggested multiplying the number of degrees of
uprighting by 0.8. The calculated value represents, in
millimeters, the additional arch length required to
upright the teeth. Conversely, if the treatment plan
requires labial movement of the mandibular teeth, the
same formula is used to estimate the additional arch
length to be gained.

• Ingervall and Lennartsson1978 and Zilberman, Koyoumjisky-Kaye,
and Vardimon1977 also concluded that the unerupted canine and
premolars could be predicted more accurately from radiographs than from
dental casts alone.
• , Moyers' technique is still widely accepted because it does not require
radiographs and is, arguably, more readily applied by a spectrum of
clinicians ( Runey , Johnson , Merow 1977)

CORRELATION BETWEEN DENTAL ARCH FORM
AND SUM OF INCISORS.
• The pont –index is based
On various examinations of the
geometry of normal dental arches.
• According tp these graphic
diagrams, the size of the near-
elliptical shape of the maxillary
dental arch is related to the width
of the upper incisor teeth.
• Depending on the sum value of
the upper incisors,the elliptical
forms are of different size but of
similar shape.

CORRECTION BETWEEN DENTAL ARCH WIDTH
AND ARCH LENGTH.
• View of a wide, short maxillary
arch. The shape of the normal
arch depends on the
development of width and
length which is in the ratio of
2;1 for example if the arch
width is increased by 2mm,the
arch length is reduced by
1mm.
• The ideal arch width value
determined according to pont
can be individualized if both
parameters (length and width)
are considered.

MEASUREMENTS OF ANTERIOR ARCH
LENGTH.
• Overview of the maxillary and
mandibular arches,with marking
of the referance lines for antrerior
arch length determination.
• The arch length is defined as the
distance perpendicular to the line
connecting the referance points of
anterior arch width in the
midsagittal plane. It is measured
from the intersection of the two
lines to the labial surface of the
most anterior positioned central
incisor.

Analysis of Transverse symmetry

• Neff measured the mesiodistal dimensions of the
maxillary and mandibular teeth of 200 patients.
• He developed an "anterior coefficient" by dividing the
sum of the six maxillary anterior teeth by the mandibular
mesiodistal sum.
• The range was 1.17 to 1.41 mm, but no means were
given.
• Neff then correlated these ratios to the amount of
overbite and concluded that a 20% overbite with a
coefficient of 1.20 to 1.22 mm was ideal; the value of
1.17 mm was associated with an edge-to-edge incisor
relationship (Class I large mandibular teeth) and the
other extreme of 1.41 mm was associated with a deep
overbite relationship (Class I small mandibular teeth).

• The first step in space analysis is calculation of
space available .This is by measuring the arch
perimeter from one first molar to the other ,over
the contact points of posterior teeth & incisal
edge of anteriors.
• The second step is to calculate the amount of
space required for alignment of the teeth.

• The first step is space analysis is calculation of space
available.
• This is accomplished by measuring the arch perimeter
from one first molar to the other, over the contact point
of posterior teeth and incisial edge of anteriors.

Contouring a piece of wire
-

Measured as straight line
approximation of arch

• The second step is to calculate the amount of
space required for alignment of the teeth.
• This is done by measuring the M-D width of
each tooth from contact point to contact point
• If the sum of the width of the permanent teeth
is greater that the amount of space available
there is an arch perimeter space deficiency and
crowding would occur.
• If available space is large then the space
required (excess space) gaps between some
teeth would be expected.

• Space analysis carried out in this way is
based on two important assumption.
1. The A – P position of the incisors is
correct. (i.e) The incisors are neither
excessively protrusive nor retrusive)
2. The space available will not change
because of growth. Neither assumption
can be taken for granted.

• If the incisors flare forward, they can align themselves
along the arc of a larger circle , which provides more
space to accommodate the teeth and alleviates
crowding.
• Conversely, if the incisors move lingually there is less
space and crowding becomes worse.
• For this reason, crowding and protrusion of incisors
must be considered two aspects of the same thing: how
crowded and irregular the incisors are reflects both how
much room is available and where the incisors are
positioned relative to supporting bone.
• For this reason, information about how much the
incisors protude must be available from clinical
examination to evaluate the results of space analysis.

• The second assumption, that space available will
not change during growth, is valid for adults but
may not be for children.
• In a child with a well proportional face, then is
little or no tendency for the dentition to be
displaced relative to the jaw during growth, but
the teeth after shift artcroly or pertrits in a child
with a jaw discrepency.
• For this reason, space analysis is less accurate
and less useful for children with skeletal problem
(class II, Class III, long face , short face) than in
those with good facial proportions.

Shortended arch length
LINGUOVERSION
OF CENTERAL INCISORS
• Shortended anterior arch length in
the maxilla resulting from lingual
inclination of upper central
incisors in a class 11 division 2
• Malocclusion

MESIAL POSITION OF
PREMOLARS
• Markedly shortened
anterior arch length in
the maxilla as the result
of mesial drift of posterior
teeth ollowing early loss
of deciduous teeth in the
supporting zones.
• The axial inclination of
the upper incisors is
approximately corect,in
spite of a reducedLu.

Analysis of anteroposterior symmetry.
• Serves to analyse any mesial tooth
drift.
• Symptoms of mesial position of
posterior teeth
• Crowding and space loss, especialy in
the supporting zones.
• Dental midline shift with crowding and
space loss
• Mesial topping of premolars.
• Rotation of first permanent molars.
• Symmetric / asymmetric width
development between right and left
sides of the arch (malposition:
symmetric, asymmetric, unilateral).
• Congruence/incongruence between
dental midline and skeletal midline of
the arches (dental midline shift).
• Dental midline shift.
• Dental midline shifts are the result of
tooth migration.

Palatal height

Analysis of supporting zones

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