Growth prediction /certified fixed orthodontic courses by Indian dental academy

Growth prediction&
Age Estimation

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Contents
 Introduction
 Methods

of growth prediction
 Gnomic growth and logarithmic spiral
 Arcial growth
 Rickett’s cepahlometric prediction
 Parental data to predict craniofacial growth
 Johnston method
 FEM
 Prediction of mandibular growth rotations
 Mathematical model for prediction of
craniofacial growth

 VTO
 Tooth

mineralization
 Skeletal maturity indicator
 Symphysis morphology
 Pubertal growth spurt
 Third molar prediction


Introduction

 It

is not possible to predict how a patient is
going to respond to a particular treatment.
 Variability is expected


Patient’s growth pattern
Variability
Effect of treatment on
growth

In the absence of growth, treatment
responses are reasonably predictable
GROWTH IS NOT…….


 The

goal of growth prediction is to reduce
the clinician’s ignorance of the future…


What are we interested in predicting in
the craniofacial complex?
 1. Future size of a part -The prediction of

future size is primarily a problem of predicting
future increments which are to be added to a
size that is already known.
 Eg:

prediction of length of the mandible


2. Relationship of parts –
 The most important prediction for the
clinician is the future relationship of parts,
that is the future facial pattern.


Timing of growth events – Because growth
does not proceed evenly, certain facial dimensions
demonstrate marked change in their velocity
curves. These spurts make predictions much more
difficult.

 3.

 If one were to predict a “spurt”, we might want to

predict the a) time of onset. b) duration of
increased rate of growth c) rate of growth during
the spurt.

 4.

Vectors of growth- Most predictive method
presume a continuation of the pattern first
seen.The presumption is made that the vectors
of the growth present at the time of prediction
will remain.

However this is not true…..
Mandible which grow vertically for a
period of time can start to grow
horizontally!!!
Can such changes in growth direction be
predicted???

5. Velocity of growth- It would be of use to know the
future expected rate of growth especially during pubescent
spurt.
6.Effect of orthodontic therapy on any of the
above predicted parameters
What effect therapy is having on the predicted and
actual growth of one specific face


How

well can we predict these
parameters???

 Future

Size

Complex craniofacial growth
Any simple series of size prediction is not
clinically useful.


 Relationship

of parts

Harvold, Johnston, Ballach –
predicted maxillo mandibular relationship.
None were accurate…
 Timing

and growth events

 Hunter

& Miller reported the shape of the face as
roughly related to the timing of the pubuscent
spurt.
 Frisancho- predict the individual spurt in stature
from noting the time of calcification of the
sesamoid bone

Vectors of growth
There is no means of anticipating change in the
direction of growth
Predicting vector is not same as predicting
changes in the vector….

Velocity
Not much attention is given to this


 The

effect of orthodontic therapy on
growth
Ricketts’ method- sets the prediction and
then works to make them come true


Methods of prediction of
craniofacial growth




William J Hirschfeld AJO Vol 60 no 5
1971
Several predictive methods that are used
can be grouped as followsA) Theoretical B) Regression
C) Experiential D) Time Series


 1.Theoretical methods of prediction-

A theoretical model is constructed mathematically,
and a test for hypothesis is devised.
 Theoretical models of craniofacial growth have not
yet been defined mathematically in terms precise
enough to permit the application of the method to
prediction



Regression methods- These methods serve to
calculate a value for one variable, called
dependent, on the basis of its initial state and
degree of its correlation with one or more
independent variables
 However Johnston evaluated and revised this
method and concluded1.The ultimate accuracy of cephalometric prediction
may be limited by intrinsic error within the
cephalometric method itself.
2. These methods seem inadequate to provide an
efficient estimate of individual change attributable to
growth only.
 2.


 3. Experiential method- These methods are based

on the clinical experience of a single investigator
who attempts to quantify his observations of
practice in such a way that they can be modified for
use by others.

 4. Time series methods- 2 types

A) Time series analysis- it extracts in a
mathematical form the fundamental nature of the
process as it relates to time.
B) Smoothing methods –it gives representative or
average values to the parameters of a previously
derived time series equation.

Gnomic growth and logrithmic
spiral
 What is gnomic growth?

The process where upon the addition to a body
leaves the resultant body similar to the original is
called gnomic growth.
 D’Arcy Thompson classified the sea shells in
accordance to their pattern of enlargement and
developed an equation.



 The Nautilus offers 2 fundamental characterstics 1. The shell grows in size but does not change its

shape
new growth

 2. Its gnomic growth can be described by a

particular kind of curve- the logarithmic or
equiangular spiral.


 The spiral is characterized by the movement of a

point away from the pole along the radius vector
with a velocity increasing as its distance from the
pole


Logarithmic growth of human
mandible
 There are several functional conditions which are

not violated during orofacial growth- one of these is
neural innervations which must never be subjected
to external loading.
 Craniometric studies were performed on American
Indian skull .they are representative of mandible
with fetal, deciduous, mixed and adult dentition.
 Small lead shots were fixed to foramen ovale.
Mandibular foramen.& foramen mental

 Lateral

x-rays effectively outlined the
pathway of the Inf. Alveolar nerve.
 All the 3 neural foramina at all ages fit
precisely upon a single mathematically
defined, logarithmic spiral.


 Another

longitudinal and cross sectional clinical
growth data showed that these foramina moved
along the same logarithmic spiral in geometric
fashion, with the gradient of motion directly
increasing with the distance of the foramina from
the cranial base. ie mental foramen moves most
and the foramen ovale least.


In the fetal period the 3 foramina are relatively
near the origin of the spiral and at the same time
they are placed nearer to each other than at
later stage. This produces a flatter curvatre
hence gonial angle is relatively flat
With growth due to increase in distance ramus
becomes straight relative to corpus and gonial
angle acute.


 During

all stages of development the corpus
stays in essentially a horizontal position. At the
same time the mandible curves down the
logarithmic spiral course of the inferior alveolar
nerve.


Arcial growth
 Ricketts

in 1972 developed a method to
determine the arc of growth of the mandible.
 PRINCIPLE:
 A normal human mandible grows by superior
anterior apposition at the ramus on a curve or
arc which is a segment formed from a circle. The
radius of this circle is determined by using the
distance from mental protrubence (Pm) to a
point at the forking of the stress lines at the
terminus of the oblique ridge on the medial side
of the ramus( point Eva)










Landmarks
Xi pointThe deepest point on the subcoronoid is selected as R1.
R2 is selected directly opposite to it on post border of
ramus.
R3 is selected at the depth of the sigmoid notch.
R4 is directly on the lower border of ramus.
The centroid of the rectangle formed is called Xi point.




Supra pogonion- It is a point located at the superior
aspect of symphysis.
It is labelled Pm
This is substantiated as a reference point because1. It is the site of a reversal line (Enlow)
2. Stable unchanging bone in this area of bone (Bjork).



Point Dc – It is a point at the bisection of condyle neck








 Point

Eva- it is a biologic point as it is located
over the point of forking of the stress line in the
ramus.
 Ramus reference point (RR) is the point halfway
between Xi point and R3 on the anterior border
of ramus.




1

2

3
4

Construction of growth
arc:
Point RR and R3 are
connected.
Mid point of RR and R3 is pt
Eva
Take pt Eva –Pm as radiuscircle is drawn
1. taking eva as a centre
2. taking Pm as a centre.
The point of intersection is
TR (True radius) taking this
as a centre an arc is drawn.
Where this arc crosses
sigmoid notch is called
Murray point.


 Steps

in growth prediction

Step 1 amount of growth on arc- 2.5mm
From pt Mu the mandible is grown out on the arc at
the sigmoid notch about 2.5mm.
cutoff for males=19yrs
females= 14.5yrs


Step 2
Coronoid –
upwards &outwards – 0.8mm/ yr
Condyle upward & backward - 0.2 mm / yr

Step 3 - Drift of gonial angle
Females- no addition
Males - 0.2 mm / yr

 Step

4 complete forcasting of the
mandibular form
Connections from coronoid process –RR –
0.4mm/yr
determine space available for 3rd molar


 By

constructing the growth arc, growing the
mandible on the arc, extending and drifting the
angular process, this forecasting technique is
tested.


 Drawbacks

of arcial growth prediction

1. It relies heavily on the operators skill in tracing
the cephalogram.
 2. Mitchell & Jordan (1975) concluded Ricketts
uses chronological age rather than the skeletal
age. If the patient is in a growth spurt or lag phase
it will alter the result.
 3. The growth increments constants are for a fixed
population.



Ricketts cephalometric or short
term prediction
The changes in the face during treatment were
thought to be influenced by a phenomenon
within TMJ complex.
1. The changes in the angle of cranial base to a
more acute or obtuse relationship.
2. Forward or backward movement of the
condyle that influenced the chin behavior.

Procedure for growth estimation
 Class

II Div 1 case was selected to demonstrate
the procedure.
 For growth estimation work, the cranial plane
basion-nasion (Ba-Na) plane is employed.
 It can be studied in following steps:
 STEP 1:
1. Projection of probable changes in the basi
cranium
It includes Points N, S, & Ba.
a.) Sella – starting point.
Average expectancy for increase along SN




pubertal spurt – 1mm / yr
Mixed dentition – 0.5 – 0.7 mm / yr.



b) Expected changes between sella & Basion
change in length is 3/4th of S-N.



c.) Establish Expected Ba-N
Connect the new S & N & Ba –formation of new
basicranium.




 STEP 2:





Predeterming the behaviour of condyle
Condyle position remained same in 60% of cases
Downward & forward movement of Ar & Ba –similar after the age of 6
Superimposing Ba- N and registering Ba will reveal the future
condylar position..


 STEP 3:
 Ptm is outlined-evaluation of maxillary growth, coronoid pr.
 Superimposing of SN and registering at S shows
 Downward dropping of this fissure.
 Tip of the coronoid process is located 3mm forward to ptm

at both start and completion of Treatment.




STEP 4:

 Construction of condylar axis
 From the centre of condyle to antegonial angle.


 STEP 5:






Contemplation of growth of condyle
Estimated on the condyle axis .
During Rx 2mm of growth / yr upto 9yrs
During puberty = 3 or 4 mm / yr may be expected
The assessment of condylar growth permits the construction of the
post. Border, gonial angle, sigmoid notch,& ant. Border of ramus.














STEP 6: assessment of remaining mandible
Rotation of mandibular plane untill the change agrees with the
estimate of change for that case
Forward direction of condyle – lower mandibular plane angle
Backward condylar growth - higher mandible plane angle .
STEP 7:
Lengthening of body of mandible
It is slightly greater than S-N plane
1.5 mm / yr
Changes in the symphysis are
plotted





STEP 8:
Facial plane and Y axis is constructed
Superimposition on the BA-N plane will indicate the direction of
growth of mandible.


Position of Maxilla
 Step1




Increase in face height( vertical changes)

Facial plane is superimposed & registered on N
40% above ANS
60% of TFH increase is due to the denture area ie below
ANS.


 Step





2 Horizontal position of maxilla

It is postulated from the tendency of S-Na to remain
constant to Ba-N
Pt A is dropped parallel with line NA
Great amt of bodily retraction- Pt. A will be moved back
as much as 3-5 degree.


 3.

future facial convexity is determined by
predicted behavior of Pt. A


 4.

Descent of the palate is forecast
 Post nasal spine drops parallel to ptm




Soft tissue behavior

 Nose – superimposing of the palatal bone and registering

on ANS
 2mm of growth of nose
 Profile outlined is then constructed to the area below nose.


 Upper Lip- severely protruding cases- 2-4 mm increase in

thickness
 Moderate protrusion 1-2mm increase in thickness.


Lower lip- bisecting the overbite& overjet
change and drawing sup portion of the lower lip
at this level.


 This

constitutes the complete procedure
for estimating the changes that can be
expected in any given case prior to
treatment.


Prediction of mandible growth
Rotations
 Bjork 1969 gave 3 methods to predict growth.

1.Longitudnal – following the course of development
in annual x –ray
pattern of growth is not constant
2.Metric- prediction of the facial development on the
basis of facial morphology from a single x ray film.


3.Structural- based on the information concerning the
remodelling process of the mandible during growth
gained from implant studies.
Principle- to recognize specific structural feature that
develop as a result of remodelling in a paricular
type of mandibular rotation. A prediction of the
subsequent course is then made on assumption
that the trend will continue.

 Mandible

may be regarded as an unconstrained

bone.
 The site of the center of rotation may be located at:
Anterior ends
Posterior ends
Between the ends
Thus center may not necessarily lie at TMJ

 Forward rotation may occur in 3 ways





Type I: Forward rotation centre in TMJ
It gives rise to deep bite resulting in under development of anterior
face height
Cause may be occlusal imbalance
powerful muscular pressure.


 TYPE 2: Rotation centre at the incisal edges

Marked Development of Post. Facial height + normal
increase in Ant. Facial height. The post part of mandible
rotates away from maxilla.
 Increase in post facial height : lowering of middle cranial
fossa
increase height of ramus.



 Vertical direction of condylar growth


Mandilble is lowered more than it is carried forward
Muscle and ligamnetous attachment
lowering takes place as a forward rotation in relation to
maxilla











Type 3: centre at pre molar
In case of large maxillary overjet the center of rotation is displaced
backward in the arch.to the level of premolars
AFH – under developed
PFH - increases.
Dental arches are pressed into each other and basal deep bite
develops.
In Type II & III the mandibular symphysis swings forward to a
marked degree and the chin becomes prominent.





BACKWARD ROTATION OF THE MANDIBLE
2 types.

TYPE 1: centre of rotation in TMJ
Backward rotation of the mandible about a center in the
joints also occurs in connection with growth of the cranial
base.
In the case of flattening of the cranial base, the middle
cranial fossae are raised in relation to the anterior one,
and then the mandible is also raised.
There may be other causes also, such as an incomplete
development in height of the middle cranial fossae.

 This

underdevelopment of the posterior face
height leads to a backward rotation of the
mandible, with overdevelopment of the anterior
face height and possibly open-bite as a
consequence. The mandible is, in principle,
normal.




TYPE 2: Centre at distal occluding molars

. This occurs in connection with growth in the sagittal direction
at the mandibular condyles.
As the mandible grows in the direction of its length it is carried
forward more than it is lowered in the face, and because of its
attachment to muscles and ligaments it is rotated backward.


 The

symphysis is swung backward and the chin
is drawn back below the face. The soft tissues of
the chin may not follow this movement, and a
characteristic double chin can form.
 Basal open-bite may develop,
 Difficulty in closing the lips without tension.
 Lower incisors, functionally related to the upper
incisors, become retroclined in the mandible
and
the alveolar prognathism is reduced

BJORK & RUNE found a contrast between the positioning of
mandible in a longitudnal series when superimposed on
the cranial base and positioning contours resulting from
superimposition on metallic implants. They divided
rotations into 3 components.
1.
2.
3.

Matrix Rotation
Intramatrix rotation
Total rotation


Matrix Rotation: centre in the condyle
 Rotation of bone with its matrix or periosteal
capsule in its articulation with surrounding bone








INTRAMATRIX ROTATION : centre in corpus
Rotation of the mineralized corpus inside the matrix periosteum.
Periosteal cellular activity
rotation of the bony corpus
Surface of bone are remodeled in compensatory fashion
Matrix retains its stable inclination.




TOTAL ROTATION :

 Combination of the 2 types
 It is rotation of the mandibular corpus measured as a

change in the inclination of an implant line in the mandibular
corpus relative to anterior cranial base.
 The position of center of rotation of total rotation is
dependent on the other 2 centers of rotation.


 Structural









method of growth prediction

STRUCTURAL SIGNS OF GROWTH ROTATION
7 structural signs of extreme growth rotation
The greater in number that are present, the more reliable the
prediction.
1) INCLINATION OF CONDYLE HEAD:
Forward or backward inclination
of the condylar head
May not be easy to identify
on the cephalograms.




2) CURVATURE OF MANDIBULAR CANAL:
Vertical condylar growth
– curvature of canal is more
Sagittal condylar growth
- straight mandibular canal



3) SHAPE OF THE LOWER BORDER OF MANDIBLE
Vertical condylar growth –
apposition below the symphysis
and anterior part of mandible
Sagittal growth –
ant rounding absent
thin cortical layer
jaw angle is convex






4. INCLINATION OF SYMPHYSIS
 Vertical type –
symphysis swings forward
 Sagittal type –
swings backward with receding chin.






5.Position of the lower incisor seems to be functionally related to the
upper incisors
Inter incisal angle undergoes a smaller change than the rotation of
the jaws.










6. INTERMOLAR & PREMOLAR ANGLE:
Forward growth rotation - mandibular post. More upright
increase in inter molar/ premolar angle
Backward rotation - mandibular molar and premolars inclined
forward
small inter molar / premolar angle.




7. LOWER ANT. FACIAL HEIGHT
Forward growth rotation- decrease in lower AFH
Backward rotation
- over development of AFH


 Thus,

from structural method for prediction
of rotation B’jork concluded:
 Forward inclination of condyle- ant rotation
of the mandible
 Backward inclination- post rotation of the
mandible.


 Drawbacks
 There is no absolute correlation between structural growth

prediction and degree of growth rotation in cases showing
average changes.
 The method should be primarily used to determine whether

any typical signs of ant. or post. Growth rotations are
present.


Johnston method of growth
prediction
 This

is a simple method based on the addition of
mean increment by direct superimposing on a
printed grid
 In this regular angular changes in average
direction was shown ie each point advanced
1grid/yr using standard SN orientation registered
at S


Forecast grid


 This

method by using the grid produces a
moderate flattening of the profile and occlusal
plane as well as a slight mesial drift of M.
 This method do not fit a random series of
patients
 It is not easy to evaluate the significance of the
forecasting error.


Mesh analysis
 Coenrad.

F.A moorrees et al

 The mesh diagram is composed of a grid of

rectangular scaled on the pt’s upper facial height
and depth.


 The

face is inscribed in a coordinate system
consisting of 24 rectangles.


 The

length and height of mesh rectangle differs
among individuals.
 The size increases from 8-16yrs.
 Boys-4.5mm- ht
 Girls- 3.5mm-ht
 Length- 3.2mm in boys
 Length 2.4mm in girls
 Shape of mesh rectangle is determined by
shape of the core rectangle- represents the ratio
between face depth and upper facial height.


 In

the original proposal, the grid was
distorted to fit the proportionate location of
pt’s cephalometric landmark as compared
to the norm, thereby graphically
representing how the patient face deviated
from the norm.
 Disadv- complex and laborious method


 Modification

– a norm is superimposed
on the pt’s grid in order to reveal
difference from a normalized mesh
diagram
 Advantages graphically display pt’s deviation
 Normal mesh diag is readily understood
by patient


C- AXIS
M point- by Nanda & Meritt (AJO 1994)


It is a constructed point representing the
center of the largest circle that is tangent
to the superior, anterior & palatal surfaces
of maxilla as seen in the sagital plane .


 C-Axis:

The line from the sella (S) to M- point is
defined as C- axis.


 It

permits the quantification of a complex
maxillary growth process
 Age group -7.4-18.75yrs
 The regression formula is independent of gender
within the chronological age studied.
 Upto age 14, both male and females showgrowth increment of 1.41mm &1.31mm/yr.


 The

mean growth axis angle (C-axis- SN)
 Increased for both males and females.
 Males = 3.98
 Females = 2.25


Palatal plane to C-Axis
 Palatal

plane is geometrically related to C-axis.
 Females= increases from 35.4 – 37.4
 Males =increases from 39.3- 41.6
 These changes tend to flatten the palatal plane.


A

single M point cannot by itself
summarize the growth of dentomaxillary
complex in sagital plane.
 However, when associated with the
palatal plane the downward & forward
migration is more accurately decsribed.


 Quantification

of the displacement of the

mandible???


Y axis !!!

 What

about remodeling of external
symphyseal area….???

G Axis
G –Axis : A growth vector for mandible
Stanley Braun et al , Angle orthodontist, Vol 74
No3 ,2004
G point : it is a point representing the centre of
largest circle that is tangent to the internal inf,
anterior, and post surfaces of the mandibular
symphyseal region as seen on lat
cephalograms.


G point : it is a point representing the centre
of largest circle that is tangent to the
internal inf, anterior, and post surfaces of
the mandibular symphyseal region as
seen on lat cephalograms.







Length of this axis is determined by Sella & G- point.
Direction is determined by alpha angle
-Mean growth axis vector angle
Theta angle- Mandibular plane & G-axis.
- Mean mandibular plane angle


 Age

group- 6- 19.25yrs.
 G-axis length
Females – 1.6mm/yr
Males – 2.3mm/yr
 Mean

Growth vector angle
Females – decreases 0.02/yr
Males – increases 0.14/yr

 Mean

mandibular plane angle
Females –increases by 0.4/yr
Males – increases by 0.3/yr

 Thus,

G-axis allow for the quantification of
the complex mandibular growth process in
cephalometric terms relative to various
craniofacial structure in the sagittal plane.


VTO









It is completely practical as a treatment planning
procedure to approach the proposed orthodontic
changes from a soft tissue analysis perspective
Possible soft tissue profile is established--- compute the
tooth movements.
It can be done manually or cephalometric tracings.
Tracing represents the expected growth or any growth
changes induced during treatment.
This is especially noticeable when growth over a period
of 5yrs or longer was forecast

Mathematical Model for prediction
of craniofacial growth
 Presented

by James. T. Todd & Leonard Mark

 The

model is derived from the basic
assumptions about the long range effects of
gravitational pressure on the remodelling of
bone and expressed formally on a single
geometric transformation.


 The

validity of the model is examined
empirically using data for 20 individuals
from the Denver Child research Council,
longitudnal growth study.

 It

is based on the following hypothesis “The overall pattern of craniofacial
growth is primarily controlled by
biomechanical influences.” This is known
as Wolf ‘s law.


 The

wolf law’s states- The bone
elements place themselves in the
direction of functional pressure and
increase or decrease their mass to
reflect the amount of functional
pressure.


 Todd

& mark conclude that the mathematical
transformation was shown to make reasonably
accurate prediction over a span of 10-15 yrs.

 REVISED


CARDIOIDAL STRAIN

R’ = R +bP


 Gravity influences the biomechanics of growth

which is exerted on every point with in the
craniofacial complex and it also provides a counter
force for the action of muscles.


 Heads

are not perfectly spherical
 There are other sources of stress operating on
craniofacial complex besides the force gravity
 The orientation of the head with respect to the
gravity does not remain fixed.


 The

predictions that were made were not
accurate because of mechanical errors
 Oral habits
Nevertheless they very closely predict
the actual outcome of growth……


FEM method of craniofacial
growth
Finite element modeling is able to provide
absolute quantitive description of cranial
skeletal size and shape change with local
growth significance, independent of any
external frame of references.


Finite element fundamental attribute its ability
to dicretize or subdivide structures or bodies
into 2-3 dimensional elements by a series
of imaginary lines, called as finite element.
Each line is connected at one end to at least
one other line. The point of connection is
termed as nodes


 Growth

strains –

It is the measurable deformation of a
biologic body resulting from its growth.
The direction and quantification of growth tensor
can be computed and graphically displayed
Finer the discretization of the body , the more
closely the resulting numerical resulting
numerical result will approximate the reality of
growth behavior at each point.


 Growth

tensors define growth changes locally
independent of the body registration methods
The growth tensor describes the relative
displacement of all points in the neighborhood of
the given point.
It may be regarded as specifying transformation
of coordinates from one stage of growth to
another.

Growth tensor and growth prediction
If growth process is prescribed by
-specifying growth tensors at every point of the
body,
-assuming the growth strains are compatible,
- initial shape of the body is given,
The fem is capable of predicting the shape of
the body at any subsequent stage during its
growth.

Advantage

over roentgenographic
cephalometry

1. Growth prediction is independent of any
external frame of reference thus eliminating
the principal source of methodological error in
RCM
2. It describes growth locally

 Limitations

1.The errors of anatomic or material point
imaging, detection and representations.
2. This does not correspond closely to biologic
reality because tissues of different histologic
type and growth process are present,
including the air fluid.


Parental data to predict growth
of craniofacial form


Akira Suzuki & Yashuhide Takahama
Am J Orthod Dentofac Orthop 1991;99 107-121

 In a family study of craniofacial

dimension the most
striking feature is the high level of significant
correlation between parents and off springs and
between siblings especially when they are
contrasted with the co-relation of fathers to mothers

Twin studies:
- genetic analysis of craniofacial morphology was of
prime concern
 Family studies:

the statistically significant correlations between
parents and their children have been reported.
1) The cranio facial forms of children with a certain
degree of bone maturity were significantly co
rrelated with those of their parents



2) The genetic influence of parents on their children
appear to be equal
3)Coefficient of correlation of craniofacial forms
between children and their parents increased from
childhood to adulthood
4) The heritabilities of variables associated with
craniofacial form ranged from 0.5-0.9 except
respiratory and masticatory system.

 The following hypothesis formed the basis of

parental data to predict growth 1. The face of off spring often resemble that of at
least one of his parents
 2. if the face of a young offspring resembles the
face of either parent, it will continue to resemble
that parent when the off spring becomes an adult .
 3. if the cranio facial type of an off spring resembles
that of the father or of the mother in the early
growing stage , its adult craniofacial type will be
nearly like that of the same parent.

 Equation

of the individual growth
prediction

Y(t) = C1X(s)+ C2X(d) + C3
1+exp(C4(t-C5)

+ C6)

)

Here, C1X(s) similiar parents
C2X(d) dissimiliar parents


 There is a high correlation between the craniofacial form of

an off spring and that of his or her parents.
 The relationship become closer with growth, so its better to
use the parental information than to use average growth
curves when the individual growth of a child is to be
determined.


Computerized

growth predictions

 Cephalometric software (quickceph image,

dentofacial planner) have replaced manual acetate

tracings with computer generated tracings derived from
digitized head film. During the process of digitization, the xy coordinates of cephalometrics landmarks are recorded
and stored in data set from which various cephalometric
measurements are made.
 Growth and treatment response can be displayed and

measured by longitudnal superimposition of serial datasets
on stable cranial base or regional landmarks

Rickett’s

technique- It is the most

widely used and the first technique that is
implemented in software.
 It assigns mean increments of growth to a
series of landmarks along reference lines
determined by the use of growth
increments that are sensitive to the
skeletal age.


Computerized

VTO-

 The

manual method of prediction gives a
reasonable good graphic representation of
growth changes to create a VTO
 Computer offers the added advantage
 quicker access to information
 greater accuracy in producing the tracing
 useful in pt education
 Software used are. Rocky Mountain Data
System, Quickceph II

Computerized mesh analysis
 It

is a quantitative assessment of the direction
and amount of deviation of each facial landmark
of the patient.
 A modified 3 dimensional mesh analysis could
then be used to compare patients values to
reference soft tissue data collected on normal
standard.


Construction of the reference
grid
 Normal

reference have been constructed on the
basis of the data bank available at LAFAS, Milan
with the use of 3D facial morphometry, which
detects 3 dimensional coordinates.
 The digitized landmarks described the head, the
face, the orbits, the nose lips&mouth. Mean
values were computed within genders.
 A standard lattice of equidistant horizontal,
vertical,& A-P line was constructed comprising
84 parallelopipeds (28 frontal , 21 sagital 12
horizontal tracings)

Comparison of the patient to the
norm.
3

dimensional coordinates of the facial
landmarks of each pt were obtained, oriented on
x-y-z axis & a grid is constructed.
 Step 1. std normal reference is superimposed
on the patients tracings
 Size

and shape difference is evaluated by
calculation of new relevant displacement vector
for each landmark

Conclusion
has pointed out “ the knowledge
of prediction might best proceed by learning to
predict untreated growing faces.”
 The clinician must always wonder what
effect his therapy is having on the patient
and actual growth of one specific face.
 Burstone


 Research

work may develop mathematical
models, devise predictive procedures and
test them statistically but the practicing
orthodontist treating one child at a time
will prove the ultimate worth of any
suggested method….


Leader in continuing dental education


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