Growth prediction

Growth prediction&Growth prediction&
Age EstimationAge Estimation
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ContentsContents
 IntroductionIntroduction
 Methods of growth predictionMethods of growth prediction
 Gnomic growth and logarithmic spiralGnomic growth and logarithmic spiral
 Arcial growthArcial growth
 Rickett’s cepahlometric predictionRickett’s cepahlometric prediction
 Parental data to predict craniofacial growthParental data to predict craniofacial growth
 Johnston methodJohnston method
 FEMFEM
 Prediction of mandibular growth rotationsPrediction of mandibular growth rotations
 Mathematical model for prediction ofMathematical model for prediction of
craniofacial growthcraniofacial growth

 VTOVTO
 Tooth mineralizationTooth mineralization
 Skeletal maturity indicatorSkeletal maturity indicator
 Symphysis morphologySymphysis morphology
 Pubertal growth spurtPubertal growth spurt
 Third molar predictionThird molar prediction

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

Patient’s growth patternPatient’s growth pattern
VariabilityVariability
Effect of treatment onEffect of treatment on
growthgrowth

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

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

What are we interested in predicting inWhat are we interested in predicting in
the craniofacial complexthe craniofacial complex??
 1.1. Future size of a partFuture size of a part --The prediction ofThe prediction of
future size is primarily a problem of predictingfuture size is primarily a problem of predicting
future increments which are to be added to afuture increments which are to be added to a
size that is already known.size that is already known.
 Eg: prediction of length of the mandibleEg: prediction of length of the mandible

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

 3.3. Timing of growth eventsTiming of growth events – Because growth– Because growth
does not proceed evenly, certain facial dimensionsdoes not proceed evenly, certain facial dimensions
demonstrate marked change in their velocitydemonstrate marked change in their velocity
curves. Thesecurves. These spurtsspurts make predictions much moremake predictions much more
difficult.difficult.
 If one were to predict aIf one were to predict a “spurt”,“spurt”, we might want towe might want to
predict the a)predict the a) time of onsettime of onset. b) duration of. b) duration of
increased rate of growthincreased rate of growth c)c) rate of growthrate of growth duringduring
the spurt.the spurt.

 4.4. Vectors of growth-Vectors of growth- Most predictive methodMost predictive method
presume a continuation of the pattern firstpresume a continuation of the pattern first
seen.The presumption is made that the vectorsseen.The presumption is made that the vectors
of the growth present at the time of predictionof the growth present at the time of prediction
will remain.will remain.
However this is not true…..However this is not true…..
Mandible which grow vertically for aMandible which grow vertically for a
period of time can start to growperiod of time can start to grow
horizontally!!!horizontally!!!
Can such changes in growth direction beCan such changes in growth direction be
predicted???predicted???

5.5. Velocity of growth-Velocity of growth- It would be of use to know theIt would be of use to know the
future expected rate of growth especially during pubescentfuture expected rate of growth especially during pubescent
spurt.spurt.
6.Effect of orthodontic therapy on any of the6.Effect of orthodontic therapy on any of the
above predicted parametersabove predicted parameters
What effect therapy is having on the predicted andWhat effect therapy is having on the predicted and
actual growth of one specific faceactual growth of one specific face

How well can we predict theseHow well can we predict these
parameters???parameters???
 Future SizeFuture Size
Complex craniofacial growthComplex craniofacial growth
Any simple series of size prediction is notAny simple series of size prediction is not
clinically usefulclinically useful..

 Relationship of partsRelationship of parts
Harvold, Johnston, BallachHarvold, Johnston, Ballach ––
predicted maxillo mandibular relationship.predicted maxillo mandibular relationship.
None were accurate…None were accurate…
 Timing and growth eventsTiming and growth events
 Hunter & MillerHunter & Miller reported the shape of the face asreported the shape of the face as
roughly related to the timing of the pubuscentroughly related to the timing of the pubuscent
spurt.spurt.
 FrisanchoFrisancho-- predict the individual spurt in staturepredict the individual spurt in stature
from noting the time of calcification of thefrom noting the time of calcification of the
sesamoid bonesesamoid bone

Vectors of growthVectors of growth
There is no means of anticipating change in theThere is no means of anticipating change in the
direction of growthdirection of growth
Predicting vector is not same as predictingPredicting vector is not same as predicting
changes in the vectorchanges in the vector….….
VelocityVelocity
Not much attention is given to thisNot much attention is given to this

 The effect of orthodontic therapy onThe effect of orthodontic therapy on
growthgrowth
Ricketts’ method-Ricketts’ method- sets the prediction andsets the prediction and
then works to make them come truethen works to make them come true

Methods of prediction ofMethods of prediction of
craniofacial growthcraniofacial growth
 William J Hirschfeld AJO Vol 60 no 5William J Hirschfeld AJO Vol 60 no 5
19711971
 Several predictive methods that are usedSeveral predictive methods that are used
can be grouped as follows-can be grouped as follows-
A) Theoretical B) RegressionA) Theoretical B) Regression
C) Experiential D) Time SeriesC) Experiential D) Time Series

 1.Theoretical methods of prediction-1.Theoretical methods of prediction-
 A theoretical model is constructed mathematically,A theoretical model is constructed mathematically,
and a test for hypothesis is devised.and a test for hypothesis is devised.
 Theoretical models of craniofacial growth have notTheoretical models of craniofacial growth have not
yet been defined mathematically in terms preciseyet been defined mathematically in terms precise
enough to permit the application of the method toenough to permit the application of the method to
predictionprediction

 2.2. Regression methods-Regression methods- These methods serve toThese methods serve to
calculate a value for one variable, calledcalculate a value for one variable, called
dependent,dependent, on the basis of its initial state andon the basis of its initial state and
degree of its correlation with one or moredegree of its correlation with one or more
independent variablesindependent variables
 HoweverHowever JohnstonJohnston evaluated and revised thisevaluated and revised this
method and concluded-method and concluded-
1.The ultimate accuracy of cephalometric prediction1.The ultimate accuracy of cephalometric prediction
may be limited by intrinsic error within themay be limited by intrinsic error within the
cephalometric method itself.cephalometric method itself.
2. These methods seem inadequate to provide an2. These methods seem inadequate to provide an
efficient estimate of individual change attributable toefficient estimate of individual change attributable to
growth only.growth only. www.indiandentalacademy.comwww.indiandentalacademy.com

 3.3. Experiential method-Experiential method- These methods are basedThese methods are based
on theon the clinical experienceclinical experience of a single investigatorof a single investigator
who attempts to quantify his observations ofwho attempts to quantify his observations of
practice in such a way that they can be modified forpractice in such a way that they can be modified for
use by others.use by others.
 4.4. Time series methods-Time series methods- 2 types2 types
A)A) Time series analysis-Time series analysis- it extracts in ait extracts in a
mathematical form the fundamental nature of themathematical form the fundamental nature of the
process as it relates to time.process as it relates to time.
B)B) Smoothing methodsSmoothing methods –it gives representative or–it gives representative or
average values to the parameters of a previouslyaverage values to the parameters of a previously
derived time series equation.derived time series equation.www.indiandentalacademy.comwww.indiandentalacademy.com

Gnomic growth and logrithmicGnomic growth and logrithmic
spiralspiral
 What is gnomic growth?What is gnomic growth?
 The process where upon the addition to a bodyThe process where upon the addition to a body
leaves the resultant body similar to the original isleaves the resultant body similar to the original is
calledcalled gnomic growthgnomic growth..
 D’Arcy ThompsonD’Arcy Thompson classified the sea shells inclassified the sea shells in
accordance to their pattern of enlargement andaccordance to their pattern of enlargement and
developed an equation.developed an equation.

 The Nautilus offers 2 fundamental characterstics-The Nautilus offers 2 fundamental characterstics-
 1. The shell grows in size but does not change its1. The shell grows in size but does not change its
shapeshape
new growthnew growth
 2. Its gnomic growth can be described by a2. Its gnomic growth can be described by a
particular kind of curve-particular kind of curve- the logarithmic orthe logarithmic or
equiangular spiral.equiangular spiral.

 The spiral is characterized by the movement of aThe spiral is characterized by the movement of a
point away from the pole along the radius vectorpoint away from the pole along the radius vector
with a velocity increasing as its distance from thewith a velocity increasing as its distance from the
polepole

Logarithmic growth of humanLogarithmic growth of human
mandiblemandible
 There are several functional conditions which areThere are several functional conditions which are
not violated during orofacial growth- one of these isnot violated during orofacial growth- one of these is
neural innervations which must never be subjectedneural innervations which must never be subjected
to external loading.to external loading.
 Craniometric studies were performed on AmericanCraniometric studies were performed on American
Indian skull .they are representative of mandibleIndian skull .they are representative of mandible
with fetal, deciduous, mixed and adult dentition.with fetal, deciduous, mixed and adult dentition.
 Small lead shots were fixed to foramen ovale.Small lead shots were fixed to foramen ovale.
Mandibular foramen.& foramen mentalMandibular foramen.& foramen mental

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

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

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

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

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

 LandmarksLandmarks
 Xi point-Xi point-
 The deepest point on the subcoronoid is selected as R1.The deepest point on the subcoronoid is selected as R1.
 R2 is selected directly opposite to it on post border ofR2 is selected directly opposite to it on post border of
ramus.ramus.
 R3 is selected at the depth of the sigmoid notch.R3 is selected at the depth of the sigmoid notch.
 R4 is directly on the lower border of ramus.R4 is directly on the lower border of ramus.
 The centroid of the rectangle formed is called Xi point.The centroid of the rectangle formed is called Xi point.

 Supra pogonion-Supra pogonion- It is a point located at the superiorIt is a point located at the superior
aspect of symphysis.aspect of symphysis.
 It is labelled PmIt is labelled Pm
 This is substantiated as a reference point because-This is substantiated as a reference point because-
 1. It is the site of a reversal line (Enlow)1. It is the site of a reversal line (Enlow)
 2. Stable unchanging bone in this area of bone (Bjork).2. Stable unchanging bone in this area of bone (Bjork).
 Point DcPoint Dc – It is a point at the bisection of condyle neck– It is a point at the bisection of condyle neck

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

 Construction of growthConstruction of growth
arc:arc:
11 Point RR and R3 arePoint RR and R3 are
connected.connected.
Mid point of RR and R3 is ptMid point of RR and R3 is pt
EvaEva
2 Take pt Eva –Pm as radius-2 Take pt Eva –Pm as radius-
circle is drawncircle is drawn
1. taking eva as a centre1. taking eva as a centre
2. taking Pm as a centre.2. taking Pm as a centre.
3 The point of intersection is3 The point of intersection is
TR (True radius) taking thisTR (True radius) taking this
as a centre an arc is drawn.as a centre an arc is drawn.
4 Where this arc crosses4 Where this arc crosses
sigmoid notch is calledsigmoid notch is called
Murray point.Murray point.

 Steps in growth predictionSteps in growth prediction
Step 1 amount of growth on arc- 2.5mmStep 1 amount of growth on arc- 2.5mm
From pt Mu the mandible is grown out on the arc atFrom pt Mu the mandible is grown out on the arc at
the sigmoid notch about 2.5mm.the sigmoid notch about 2.5mm.
cutoff for males=19yrscutoff for males=19yrs
females= 14.5yrsfemales= 14.5yrs

Step 2Step 2
Coronoid –Coronoid –
upwards &outwards – 0.8mm/ yrupwards &outwards – 0.8mm/ yr
Condyle -Condyle -
upward & backward - 0.2 mm / yrupward & backward - 0.2 mm / yr
Step 3 - Drift of gonial angleStep 3 - Drift of gonial angle
Females- no additionFemales- no addition
Males - 0.2 mm / yrMales - 0.2 mm / yr

 Step 4 complete forcasting of theStep 4 complete forcasting of the
mandibular formmandibular form
Connections from coronoid process –RR –Connections from coronoid process –RR –
0.4mm/yr0.4mm/yr
determine space available for 3determine space available for 3rdrd
molarmolar

 By constructing the growth arc, growing theBy constructing the growth arc, growing the
mandible on the arc, extending and drifting themandible on the arc, extending and drifting the
angular process, this forecasting technique isangular process, this forecasting technique is
tested.tested.

 Drawbacks of arcial growth predictionDrawbacks of arcial growth prediction
 1. It relies heavily on the operators skill in tracing1. It relies heavily on the operators skill in tracing
the cephalogram.the cephalogram.
 2.2. Mitchell & Jordan (1975Mitchell & Jordan (1975) concluded Ricketts) concluded Ricketts
uses chronological age rather than the skeletaluses chronological age rather than the skeletal
age. If the patient is in a growth spurt or lag phaseage. If the patient is in a growth spurt or lag phase
it will alter the result.it will alter the result.
 3. The growth increments constants are for a fixed3. The growth increments constants are for a fixed
population.population.

Ricketts cephalometric or shortRicketts cephalometric or short
term predictionterm prediction
The changes in the face during treatment wereThe changes in the face during treatment were
thought to be influenced by a phenomenonthought to be influenced by a phenomenon
within TMJ complex.within TMJ complex.
1. The changes in the angle of cranial base to a1. The changes in the angle of cranial base to a
more acute or obtuse relationship.more acute or obtuse relationship.
2. Forward or backward movement of the2. Forward or backward movement of the
condyle that influenced the chin behavior.condyle that influenced the chin behavior.

Procedure for growth estimationProcedure for growth estimation
 Class II Div 1 case was selected to demonstrateClass II Div 1 case was selected to demonstrate
the procedure.the procedure.
 For growth estimation work, the cranial planeFor growth estimation work, the cranial plane
basion-nasion (Ba-Na) plane is employed.basion-nasion (Ba-Na) plane is employed.
 It can be studied in following steps:It can be studied in following steps:
 STEP 1:STEP 1:
1. Projection of probable changes in the basi1. Projection of probable changes in the basi
craniumcranium
It includes Points N, S, & Ba.It includes Points N, S, & Ba.
a.) Sella – starting point.a.) Sella – starting point.
Average expectancy for increase along SNAverage expectancy for increase along SN

 pubertal spurt – 1mm / yrpubertal spurt – 1mm / yr
 Mixed dentition – 0.5 – 0.7 mm / yr.Mixed dentition – 0.5 – 0.7 mm / yr.
 b) Expected changes between sella & Basionb) Expected changes between sella & Basion
change in length is 3/4change in length is 3/4thth
of S-N.of S-N.
 c.) Establish Expected Ba-Nc.) Establish Expected Ba-N
 Connect the new S & N & Ba –formation of newConnect the new S & N & Ba –formation of new
basicranium.basicranium.

 STEP 2:STEP 2:
 Predeterming the behaviour of condylePredeterming the behaviour of condyle
 Condyle position remained same in 60% of casesCondyle position remained same in 60% of cases
 Downward & forward movement of Ar & Ba –similar after the age of 6Downward & forward movement of Ar & Ba –similar after the age of 6
 Superimposing Ba- N and registering Ba will reveal the futureSuperimposing Ba- N and registering Ba will reveal the future
condylar position..condylar position..

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

 STEP 4:STEP 4:
 Construction of condylar axisConstruction of condylar axis
 From the centre of condyle to antegonial angle.From the centre of condyle to antegonial angle.

 STEP 5:STEP 5:
 Contemplation of growth of condyleContemplation of growth of condyle
 Estimated on the condyle axis .Estimated on the condyle axis .
 During Rx 2mm of growth / yr upto 9yrsDuring Rx 2mm of growth / yr upto 9yrs
 During puberty = 3 or 4 mm / yr may be expectedDuring puberty = 3 or 4 mm / yr may be expected
 The assessment of condylar growth permits the construction of theThe assessment of condylar growth permits the construction of the
post. Border, gonial angle, sigmoid notch,& ant. Border of ramus.post. Border, gonial angle, sigmoid notch,& ant. Border of ramus.

 STEP 6: assessment of remaining mandibleSTEP 6: assessment of remaining mandible
 Rotation of mandibular plane untill the change agrees with theRotation of mandibular plane untill the change agrees with the
estimate of change for that caseestimate of change for that case
 Forward direction of condyle – lower mandibular plane angleForward direction of condyle – lower mandibular plane angle
 Backward condylar growth - higher mandible plane angleBackward condylar growth - higher mandible plane angle..
 STEP 7:STEP 7:
 Lengthening of body of mandibleLengthening of body of mandible
 It is slightly greater than S-N planeIt is slightly greater than S-N plane
 1.5 mm / yr1.5 mm / yr
 Changes in the symphysis areChanges in the symphysis are
plottedplotted

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

Position of MaxillaPosition of Maxilla
 Step1 Increase in face height( vertical changes)Step1 Increase in face height( vertical changes)
 Facial planeFacial plane is superimposed & registered on Nis superimposed & registered on N
 40% above ANS40% above ANS
 60% of TFH increase is due to the denture area ie below60% of TFH increase is due to the denture area ie below
ANS.ANS.

 Step 2 Horizontal position of maxillaStep 2 Horizontal position of maxilla
 It is postulated from the tendency of S-Na to remainIt is postulated from the tendency of S-Na to remain
constant to Ba-Nconstant to Ba-N
 Pt A is dropped parallel with line NAPt A is dropped parallel with line NA
 Great amt of bodily retraction- Pt. A will be moved backGreat amt of bodily retraction- Pt. A will be moved back
as much as 3-5 degreeas much as 3-5 degree..

 3. future facial convexity is determined by3. future facial convexity is determined by
predicted behavior of Pt. Apredicted behavior of Pt. A

 4. Descent of the palate is forecast4. Descent of the palate is forecast
 Post nasal spine drops parallel to ptmPost nasal spine drops parallel to ptm

 Soft tissue behaviorSoft tissue behavior
 NoseNose – superimposing of the palatal bone and registering– superimposing of the palatal bone and registering
on ANSon ANS
 2mm of growth of nose2mm of growth of nose
 Profile outlined is then constructed to the area below nose.Profile outlined is then constructed to the area below nose.

 Upper Lip-Upper Lip- severely protruding cases- 2-4 mm increase inseverely protruding cases- 2-4 mm increase in
thicknessthickness
 Moderate protrusion 1-2mm increase in thickness.Moderate protrusion 1-2mm increase in thickness.
 Lower lip- bisecting the overbite& overjetLower lip- bisecting the overbite& overjet
change and drawing sup portion of the lower lipchange and drawing sup portion of the lower lip
at this level.at this level.

 This constitutes the complete procedureThis constitutes the complete procedure
for estimating the changes that can befor estimating the changes that can be
expected in any given case prior toexpected in any given case prior to
treatment.treatment.

Prediction of mandible growthPrediction of mandible growth
RotationsRotations
 Bjork 1969Bjork 1969 gave 3 methods to predict growth.gave 3 methods to predict growth.
1.1.LongitudnalLongitudnal – following the course of development– following the course of development
in annual x –rayin annual x –ray
pattern of growth is not constantpattern of growth is not constant
22.Metric.Metric- prediction of the facial development on the- prediction of the facial development on the
basis of facial morphology from a single x ray film.basis of facial morphology from a single x ray film.

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

 Mandible may be regarded as an unconstrainedMandible may be regarded as an unconstrained
bone.bone.
 The site of the center of rotation may be located at:The site of the center of rotation may be located at:
Anterior endsAnterior ends
Posterior endsPosterior ends
Between the endsBetween the ends
Thus center may not necessarily lie at TMJThus center may not necessarily lie at TMJ

 Forward rotation may occur in 3 ways-Forward rotation may occur in 3 ways-
 Type I: Forward rotation centre in TMJType I: Forward rotation centre in TMJ
 It gives rise to deep bite resulting in under development of anteriorIt gives rise to deep bite resulting in under development of anterior
face heightface height
 Cause may be occlusal imbalanceCause may be occlusal imbalance
 powerful muscular pressure.powerful muscular pressure.

 TYPE 2: Rotation centre at the incisal edgesTYPE 2: Rotation centre at the incisal edges
 Marked Development of Post. Facial heightMarked Development of Post. Facial height ++ normalnormal
increase inincrease in Ant. Facial height. The post part of mandibleAnt. Facial height. The post part of mandible
rotates away from maxilla.rotates away from maxilla.
 Increase in post facial height : lowering of middle cranialIncrease in post facial height : lowering of middle cranial
fossafossa
increase height of ramus.increase height of ramus.

 Vertical direction of condylar growthVertical direction of condylar growth
 Mandilble is lowered more than it is carried forwardMandilble is lowered more than it is carried forward
Muscle and ligamnetous attachmentMuscle and ligamnetous attachment
lowering takes place as a forward rotation in relation tolowering takes place as a forward rotation in relation to
maxillamaxilla

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

 BACKWARD ROTATION OF THE MANDIBLEBACKWARD ROTATION OF THE MANDIBLE
 2 types.2 types.
TYPE 1: centre of rotation in TMJTYPE 1: centre of rotation in TMJ
Backward rotation of the mandible about a center in theBackward rotation of the mandible about a center in the
joints also occurs in connection with growth of the cranialjoints also occurs in connection with growth of the cranial
base.base.
In the case of flattening of the cranial base, the middleIn the case of flattening of the cranial base, the middle
cranial fossae are raised in relation to the anterior one,cranial fossae are raised in relation to the anterior one,
and then the mandible is also raised.and then the mandible is also raised.
There may be other causes also, such as an incompleteThere may be other causes also, such as an incomplete
development in height of the middle cranial fossaedevelopment in height of the middle cranial fossae..

 This underdevelopment of the posterior faceThis underdevelopment of the posterior face
height leads to a backward rotation of theheight leads to a backward rotation of the
mandible, with overdevelopment of the anteriormandible, with overdevelopment of the anterior
face height and possibly open-bite as aface height and possibly open-bite as a
consequence. The mandible is, in principle,consequence. The mandible is, in principle,
normalnormal..

 TYPE 2:TYPE 2: Centre at distal occluding molarsCentre 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 chinThe symphysis is swung backward and the chin
is drawn back below the face. The soft tissues ofis drawn back below the face. The soft tissues of
the chin may not follow this movement, and athe chin may not follow this movement, and a
characteristic double chin can form.characteristic double chin can form.
 Basal open-bite may develop,Basal open-bite may develop,
 Difficulty in closing the lips without tension.Difficulty in closing the lips without tension.
 Lower incisors, functionally related to the upperLower incisors, functionally related to the upper
incisors, become retroclined in the mandibleincisors, become retroclined in the mandible
andand
the alveolar prognathism is reducedthe alveolar prognathism is reduced

BJORK & RUNE found a contrast between the positioning ofBJORK & RUNE found a contrast between the positioning of
mandible in a longitudnal series when superimposed onmandible in a longitudnal series when superimposed on
the cranial base and positioning contours resulting fromthe cranial base and positioning contours resulting from
superimposition on metallic implants. They dividedsuperimposition on metallic implants. They divided
rotations into 3 components.rotations into 3 components.
1.1. Matrix RotationMatrix Rotation
2.2. Intramatrix rotationIntramatrix rotation
3.3. Total rotationTotal rotation

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

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

 TOTAL ROTATION :TOTAL ROTATION :
 Combination of the 2 typesCombination of the 2 types
 It is rotation of the mandibular corpus measured as aIt is rotation of the mandibular corpus measured as a
change in the inclination of an implant line in the mandibularchange in the inclination of an implant line in the mandibular
corpus relative to anterior cranial base.corpus relative to anterior cranial base.
 The position of center of rotation of total rotation isThe position of center of rotation of total rotation is
dependent on the other 2 centers of rotation.dependent on the other 2 centers of rotation.

 Structural method of growth predictionStructural method of growth prediction
 STRUCTURAL SIGNS OF GROWTH ROTATIONSTRUCTURAL SIGNS OF GROWTH ROTATION
 7 structural signs of extreme growth rotation7 structural signs of extreme growth rotation
 The greater in number that are present, the more reliable theThe greater in number that are present, the more reliable the
prediction.prediction.
 1) INCLINATION OF CONDYLE HEAD:1) INCLINATION OF CONDYLE HEAD:
 Forward or backward inclinationForward or backward inclination
of the condylar headof the condylar head
 May not be easy to identifyMay not be easy to identify
on the cephalograms.on the cephalograms.

 2)2) CURVATURE OF MANDIBULAR CANAL:CURVATURE OF MANDIBULAR CANAL:
Vertical condylar growthVertical condylar growth
–– curvature of canal is morecurvature of canal is more
Sagittal condylar growthSagittal condylar growth
- straight mandibular canal- straight mandibular canal
 3) SHAPE OF THE LOWER BORDER OF MANDIBLE3) SHAPE OF THE LOWER BORDER OF MANDIBLE
 Vertical condylar growthVertical condylar growth ––
apposition below the symphysisapposition below the symphysis
and anterior part of mandibleand anterior part of mandible
 Sagittal growthSagittal growth ––
ant rounding absentant rounding absent
thin cortical layerthin cortical layer
jaw angle is convexjaw angle is convex

 4. INCLINATION OF SYMPHYSIS4. INCLINATION OF SYMPHYSIS
 Vertical type –Vertical type –
symphysis swings forwardsymphysis swings forward
 Sagittal type –Sagittal type –
swings backward with receding chin.swings backward with receding chin.
 5.Position of the lower incisor seems to be functionally related to the5.Position of the lower incisor seems to be functionally related to the
upper incisorsupper incisors
 Inter incisal angle undergoes a smaller change than the rotation ofInter incisal angle undergoes a smaller change than the rotation of
the jaws.the jaws.

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

 7. LOWER ANT. FACIAL HEIGHT7. LOWER ANT. FACIAL HEIGHT
Forward growth rotation- decrease in lower AFHForward growth rotation- decrease in lower AFH
Backward rotation - over development of AFHBackward rotation - over development of AFH

 Thus, from structural method for predictionThus, from structural method for prediction
of rotation B’jork concluded:of rotation B’jork concluded:
 Forward inclination of condyle- ant rotationForward inclination of condyle- ant rotation
of the mandibleof the mandible
 Backward inclination- post rotation of theBackward inclination- post rotation of the
mandible.mandible.

 DrawbacksDrawbacks
 There is no absolute correlation between structural growthThere is no absolute correlation between structural growth
prediction and degree of growth rotation in cases showingprediction and degree of growth rotation in cases showing
average changes.average changes.
 The method should be primarily used to determine whetherThe method should be primarily used to determine whether
any typical signs of ant. or post. Growth rotations areany typical signs of ant. or post. Growth rotations are
present.present.

Johnston method of growthJohnston method of growth
 This is a simple method based on the addition ofThis is a simple method based on the addition of
mean increment by direct superimposing on amean increment by direct superimposing on a
printed gridprinted grid
 In this regular angular changes in averageIn this regular angular changes in average
direction was shown ie each point advanceddirection was shown ie each point advanced
1grid/yr using standard SN orientation registered1grid/yr using standard SN orientation registered
at Sat S

Forecast gridForecast grid

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

Mesh analysisMesh analysis
 Coenrad. F.A moorrees et alCoenrad. F.A moorrees et al
 The mesh diagram is composed of a grid ofThe mesh diagram is composed of a grid of
rectangular scaled on the pt’s upper facial heightrectangular scaled on the pt’s upper facial height
and depth.and depth.

 The face is inscribed in a coordinate systemThe face is inscribed in a coordinate system
consisting of 24 rectanglesconsisting of 24 rectangles..

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

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

 ModificationModification – a norm is superimposed– a norm is superimposed
on the pt’s grid in order to revealon the pt’s grid in order to reveal
difference from a normalized meshdifference from a normalized mesh
diagramdiagram
 AdvantagesAdvantages--
 graphically display pt’s deviationgraphically display pt’s deviation
 Normal mesh diag is readily understoodNormal mesh diag is readily understood
by patientby patient

C- AXISC- AXIS
M point-M point- byby Nanda & Meritt (AJO 1994)Nanda & Meritt (AJO 1994)
 It is a constructed point representing theIt is a constructed point representing the
center of the largest circle that is tangentcenter of the largest circle that is tangent
to the superior, anterior & palatal surfacesto the superior, anterior & palatal surfaces
of maxilla as seen in the sagital planeof maxilla as seen in the sagital plane..

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

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

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

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

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

 Quantification of the displacement of theQuantification of the displacement of the
mandible???mandible???
 Y axis !!!Y axis !!!
 What about remodeling of externalWhat about remodeling of external
symphyseal area….???symphyseal area….???

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

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

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

 Age group- 6- 19.25yrs.Age group- 6- 19.25yrs.
 G-axis lengthG-axis length
Females – 1.6mm/yrFemales – 1.6mm/yr
Males – 2.3mm/yrMales – 2.3mm/yr
 Mean Growth vector angleMean Growth vector angle
Females – decreases 0.02/yrFemales – decreases 0.02/yr
Males – increases 0.14/yrMales – increases 0.14/yr
 Mean mandibular plane angleMean mandibular plane angle
Females –increases by 0.4/yrFemales –increases by 0.4/yr
Males – increases by 0.3/yrMales – increases by 0.3/yrwww.indiandentalacademy.comwww.indiandentalacademy.com

 Thus, G-axis allow for the quantification ofThus, G-axis allow for the quantification of
the complex mandibular growth process inthe complex mandibular growth process in
cephalometric terms relative to variouscephalometric terms relative to various
craniofacial structure in the sagittal plane.craniofacial structure in the sagittal plane.

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

Mathematical Model for predictionMathematical Model for prediction
of craniofacial growthof craniofacial growth
 Presented byPresented by James. T. Todd & Leonard MarkJames. T. Todd & Leonard Mark
 The model is derived from the basicThe model is derived from the basic
assumptions about the long range effects ofassumptions about the long range effects of
gravitational pressure on the remodelling ofgravitational pressure on the remodelling of
bone and expressed formally on a singlebone and expressed formally on a single
geometric transformation.geometric transformation.

 The validity of the model is examinedThe validity of the model is examined
empirically using data for 20 individualsempirically using data for 20 individuals
from thefrom the Denver Child research CouncilDenver Child research Council,,
longitudnal growth study.longitudnal growth study.
 It is based on the following hypothesis-It is based on the following hypothesis-
 ““The overall pattern of craniofacialThe overall pattern of craniofacial
growth is primarily controlled bygrowth is primarily controlled by
biomechanical influences.” This is knownbiomechanical influences.” This is known
asas Wolf ‘s lawWolf ‘s law..

 TheThe wolf law’swolf law’s states-states- The boneThe bone
elements place themselves in theelements place themselves in the
direction of functional pressure anddirection of functional pressure and
increase or decrease their mass toincrease or decrease their mass to
reflect the amount of functionalreflect the amount of functional
pressure.pressure.

 Todd & mark conclude that the mathematicalTodd & mark conclude that the mathematical
transformation was shown to make reasonablytransformation was shown to make reasonably
accurate prediction over a span of 10-15 yrs.accurate prediction over a span of 10-15 yrs.
 REVISED CARDIOIDAL STRAINREVISED CARDIOIDAL STRAIN
 R’ = R +bPR’ = R +bP

 Gravity influences the biomechanics of growthGravity influences the biomechanics of growth
which is exerted on every point with in thewhich is exerted on every point with in the
craniofacial complex and it also provides a countercraniofacial complex and it also provides a counter
force for the action of muscles.force for the action of muscles.

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

 The predictions that were made were notThe predictions that were made were not
accurate because of-accurate because of-
 mechanical errorsmechanical errors
 Oral habitsOral habits
Nevertheless they very closely predictNevertheless they very closely predict
the actual outcome of growth……the actual outcome of growth……

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

Finite element fundamental attribute its abilityFinite element fundamental attribute its ability
to dicretize or subdivide structures or bodiesto dicretize or subdivide structures or bodies
into 2-3 dimensional elements by a seriesinto 2-3 dimensional elements by a series
of imaginary lines, called asof imaginary lines, called as finitefinite elementelement..
Each line is connected at one end to at leastEach line is connected at one end to at least
one other line. The point of connection isone other line. The point of connection is
termed astermed as nodesnodes

 Growth strainsGrowth strains ––
It is the measurable deformation of aIt is the measurable deformation of a
biologic body resulting from its growth.biologic body resulting from its growth.
The direction and quantification of growth tensorThe direction and quantification of growth tensor
can be computed and graphically displayedcan be computed and graphically displayed
Finer the discretization of the body , the moreFiner the discretization of the body , the more
closely the resulting numerical resultingclosely the resulting numerical resulting
numerical result will approximate the reality ofnumerical result will approximate the reality of
growth behavior at each point.growth behavior at each point.

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

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

Advantage over roentgenographicAdvantage over roentgenographic
cephalometrycephalometry
1. Growth prediction is independent of any1. Growth prediction is independent of any
external frame of reference thus eliminatingexternal frame of reference thus eliminating
the principal source of methodological error inthe principal source of methodological error in
RCMRCM
2. It describes growth locally2. It describes growth locally

 LimitationsLimitations
1.The errors of anatomic or material point1.The errors of anatomic or material point
imaging, detection and representations.imaging, detection and representations.
2. This does not correspond closely to biologic2. This does not correspond closely to biologic
reality because tissues of different histologicreality because tissues of different histologic
type and growth process are present,type and growth process are present,
including the air fluidincluding the air fluid..

Parental data to predict growthParental data to predict growth
of craniofacial formof craniofacial form
 Akira Suzuki & Yashuhide TakahamaAkira Suzuki & Yashuhide Takahama
Am J Orthod Dentofac Orthop 1991;99 107-121Am J Orthod Dentofac Orthop 1991;99 107-121
 In a family study of craniofacial dimension the mostIn a family study of craniofacial dimension the most
striking feature is the high level of significantstriking feature is the high level of significant
correlation between parents and off springs andcorrelation between parents and off springs and
between siblings especially when they arebetween siblings especially when they are
contrasted with the co-relation of fathers to motherscontrasted with the co-relation of fathers to mothers

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

2)2) The genetic influence of parents on their childrenThe genetic influence of parents on their children
appear to be equalappear to be equal
3)Coefficient of correlation of craniofacial forms3)Coefficient of correlation of craniofacial forms
between children and their parents increased frombetween children and their parents increased from
childhood to adulthoodchildhood to adulthood
4) The heritabilities of variables associated with4) The heritabilities of variables associated with
craniofacial form ranged from 0.5-0.9 exceptcraniofacial form ranged from 0.5-0.9 except
respiratory and masticatory system.respiratory and masticatory system.

 The following hypothesis formed the basis ofThe following hypothesis formed the basis of
parental data to predict growth-parental data to predict growth-
 1. The face of off spring often resemble that of at1. The face of off spring often resemble that of at
least one of his parentsleast one of his parents
 2. if the face of a young offspring resembles the2. if the face of a young offspring resembles the
face of either parent, it will continue to resembleface of either parent, it will continue to resemble
that parent when the off spring becomes an adult .that parent when the off spring becomes an adult .
 3. if the cranio facial type of an off spring resembles3. if the cranio facial type of an off spring resembles
that of the father or of the mother in the earlythat of the father or of the mother in the early
growing stage , its adult craniofacial type will begrowing stage , its adult craniofacial type will be
nearly like that of the same parent.nearly like that of the same parent.

 Equation of the individual growthEquation of the individual growth
Y(t) = CY(t) = C11XX(s)(s)+ C+ C22XX(d)(d) + C+ C33 + C+ C6)6)
1+exp(C1+exp(C44(t-C(t-C55) )) )
Here, CHere, C11XX(s)(s) similiar parentssimiliar parents
CC22XX(d)(d) dissimiliar parentsdissimiliar parents

 There is a high correlation between the craniofacial form ofThere is a high correlation between the craniofacial form of
an off spring and that of his or her parents.an off spring and that of his or her parents.
 The relationship become closer with growth, so its better toThe relationship become closer with growth, so its better to
use the parental information than to use average growthuse the parental information than to use average growth
curves when the individual growth of a child is to becurves when the individual growth of a child is to be
determined.determined.

Computerized growth predictionsComputerized growth predictions
 Cephalometric softwareCephalometric software ((quickceph imagequickceph image,,
dentofacial plannerdentofacial planner)) have replaced manual acetatehave replaced manual acetate
tracings with computer generated tracings derived fromtracings with computer generated tracings derived from
digitized head film. During the process of digitization, the x-digitized head film. During the process of digitization, the x-
y coordinates of cephalometrics landmarks are recordedy coordinates of cephalometrics landmarks are recorded
and stored in data set from which various cephalometricand stored in data set from which various cephalometric
measurements are made.measurements are made.
 Growth and treatment response can be displayed andGrowth and treatment response can be displayed and
measured by longitudnal superimposition of serial datasetsmeasured by longitudnal superimposition of serial datasets
on stable cranial base or regional landmarkson stable cranial base or regional landmarks

Rickett’s technique-Rickett’s technique- It is the mostIt is the most
widely used and the first technique that iswidely used and the first technique that is
implemented in software.implemented in software.
 It assigns mean increments of growth to aIt assigns mean increments of growth to a
series of landmarks along reference linesseries of landmarks along reference lines
determined by the use of growthdetermined by the use of growth
increments that are sensitive to theincrements that are sensitive to the
skeletal age.skeletal age.

Computerized VTO-Computerized VTO-
 The manual method of prediction gives aThe manual method of prediction gives a
reasonable good graphic representation ofreasonable good graphic representation of
growth changes to create a VTOgrowth changes to create a VTO
 Computer offers the added advantageComputer offers the added advantage
 quicker access to informationquicker access to information
 greater accuracy in producing the tracinggreater accuracy in producing the tracing
 useful in pt educationuseful in pt education
 Software used are.Software used are. Rocky Mountain DataRocky Mountain Data
System,System, Quickceph IIQuickceph II

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

Construction of the referenceConstruction of the reference
gridgrid
 Normal reference have been constructed on theNormal reference have been constructed on the
basis of the data bank available at LAFAS, Milanbasis of the data bank available at LAFAS, Milan
with the use of 3D facial morphometry, whichwith the use of 3D facial morphometry, which
detects 3 dimensional coordinates.detects 3 dimensional coordinates.
 The digitized landmarks described the head, theThe digitized landmarks described the head, the
face, the orbits, the nose lips&mouth. Meanface, the orbits, the nose lips&mouth. Mean
values were computed within genders.values were computed within genders.
 A standard lattice of equidistant horizontal,A standard lattice of equidistant horizontal,
vertical,& A-P line was constructed comprisingvertical,& A-P line was constructed comprising
84 parallelopipeds (28 frontal , 21 sagital 1284 parallelopipeds (28 frontal , 21 sagital 12
horizontal tracings)horizontal tracings)

Comparison of the patient to theComparison of the patient to the
norm.norm.
 3 dimensional coordinates of the facial3 dimensional coordinates of the facial
landmarks of each pt were obtained, oriented onlandmarks of each pt were obtained, oriented on
x-y-z axis & a grid is constructed.x-y-z axis & a grid is constructed.
 Step 1.Step 1. std normal reference is superimposedstd normal reference is superimposed
on the patients tracingson the patients tracings
 Size and shape difference is evaluated bySize and shape difference is evaluated by
calculation of new relevant displacement vectorcalculation of new relevant displacement vector
for each landmarkfor each landmark

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

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

Growth prediction

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