Growth prediction /fixed orthodontic courses

GROWTH PREDICTION
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•

Introduction
Definition
Uses
Methods
Limitation

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GROWTH PREDICTION
• Introduction
•
•
•

Scammon’s curve
Cephalocaudal gradient
Data from various studies
Bolton brush study
Iowa growth study


GROWTH PREDICTION
Definition

• Assumption of ability to estimate

practically future growth.
• Asserting on the basis of theory, data or
experience but in advance of proof.


GROWTH PREDICTION
Why it is necessary ?

• Helps in diagnosis
• Development of satisfactory treatment
plan


Growth prediction
Methods of predicting facial growth change
 According Bjork
 Computerized prediction methods
 Logarithmic spiral
 Arcial growth of the mandible
 Visual treatment objective
• Jacobson and Sadowsky
• Ricketts
• Holdways

GROWTH PREDICTION
According Bjork
• Longitudinal approach
• Metric approach
• Structural approach


Growth prediction
• Longitudinal approach
-

Tweed on growing pt.
2 lateral ceph. 12-18 months apart
3 categories
Type A
Type B
Type C


Growth prediction
type A – middle & lower face growth in
unison + equal change in vertical &
horizontal dime.
Type B – middle face > lower face
Type C – lower face < middle face


Growth prediction
Tweed – growth pattern remain constant.
- Moore et al
- No use in predicting changes.
• Limitation
Accurate in Retrospective.
• Conclusion –
Not accurate method.

Growth prediction

• Metric approach

- consist of measuring different structure on a single
radiograph & then relating these measurement to
future growth changes .

Correlation coefficient =r
- Association b/w 2 variable
- Direction either positive or negative of the
relationship
- It is used in prediction by Squaring the value of ‘r’ = coefficient of determination
( amount of www.indiandentalacademy.com
variation of 2nd variable )

Growth prediction
• Bjork ,Harvold ,Lande, Solow ,others
- Correlation Coefficient not more 0.4 or 0.5
- 16% to 25% variation
Conclusion

this methods is least clinically siginificant


Growth prediction
• Structural approach

- To predict mandible growth
direction
- Superimposition on
metallic implant
- 7 areas
1. Inclination of condyle
2. Curvature of the
mandibular canal
3. Inclination of symphysis


Growth prediction
4. Shape lower border of
5.
6.
7.

the mandible
The interincisal angle
The interpremolar or
molar angle
The anterior lower facial
height

Conclusion

This is also least clinically
siginificant

Growth prediction
• Skeiller ,Bjork, and Linde – Hansen
•
1.
2.
3.
4.

(Tried to quantify it)
4 variable
MP inclination - Anterior cranial base (MP:SN)
or Ratio of posterior & anterior facial height
The intermolar angle
Shape of lower border of the mandible
(GO - ME to lower border of the mandible)
Symphysis inclination (sym. Anterior surface –SN)

Growth prediction
• Measurement of these variables were
included

R squar = 0.8612 = 86% variation in direction of
mandibular growth

• But 86% was high value


Growth prediction
 According Bjork
 Computerized prediction methods
 Logarithmic spiral
 Arcial growth of the mandible
 Visual treatment object


Growth prediction
• Computerized prediction methods
•
•
1.
2.

Tool of analysis not a method
Advantage
Facilitates testing
Complex formulas to growth prediction


Growth prediction
• Ricketts 1970 – potential of computerization
- Cephalogram (diagnosis ,T/P)

• Greenberg & Johnston

- Computer forecasts not better than the
assumption of average growth
- No difference bet. this & method based on
simple addition of the average changes.

Growth prediction
According Bjork
Computerized prediction methods
Logarithmic spiral
Arcial growth of the mandible
Visual treatment object


Growth prediction
• Logarithmic spiral

Golden triangles
Why
 how the position of 3 foramina on the

unitary , logarithmic spiral in anterior open
bite and deep bite pt. (Melvin. Moss )


Logarithmic spiral


Evolution of logarithmic spiral
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Sectioning of a line
Smaller section is proportional to large section
Larger portion is called ‘golden section’
Larger section is Phi /


• Small section is 1
• Larger = 1.618 times
•

the smaller
The smaller is 0.618
the length of the
larger


• Phi relationship

- Plants, animals, human body , face
• Golden progression – series of these
proportions
- Symbols -

2

3

, ,

4


• Golden triangle
•
•
•

Base of a triangle 1.0
Sides of equilateral
triangle 1.618
Forms a 72 – 72 -36
degree


• Bisection of one base

angle cross the opposite
side

• Divide that side into a
golden section

• Form new golden
triangle


• Bisection of golden triangle can be made in a series


• Curve used to connect

the points on a series of
the triangles

• Form Logarithmic spiral.


Logarithmic spiral
• So human mandible

grows as a logarithmic
spiral on the arc.


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•
•
1.
2.
3.

Logarithmic spiral
Melvin Moss
Aim - determine the position of 3 foramina on the
unitary , logarithmic spiral in anterior open bite and
deep bite pt.
These conditions can be anticipated at young age
even before orthodontic diagnosis
Foramen
Foramen ovale
Mandibular foramen inferior alveolar nerve
Mental foramen

Logarithmic spiral
• Introduction

Studied the position of the inferior alveolar
nerve

• Conclusion

These foramina , at all ages fit precisely
upon a single mathematically defined
logarithmic spiral

Logarithmic spiral
Foramen “moved” down
along this same
logarithmic spiral in
geometric fashion

The gradient of motion

directly increasing with the
distance of the foramina
from cranial base.

Logarithmic spiral
• Method and materials

2 group of pt.

Columbia university

University of utah

16 pt - 3 m & 4 f
4 groups
(Ant
Open bite)
10 pt Normal swallowers
-4m&5f
10 pt Tongue thrust
(Deep bite)
5 pt Angle II div 1
5 pt Ant open bite

Logarithmic spiral
• Tracing of cranial base & mandibular outline
from films

• Superimposed the logarithmic spiral
• Position of 3 foramen marked on it.

Logarithmic spiral
• Result

 Singular position of

foramen ovale in
anterior open bite.
 Foramen ovale located
farther down the spiral.
Help in diagnosis
 No sexual dimorphism

Logarithmic spiral
 Mandibular & mental




foramen also further
down the logarithmic
spiral in AOB
Not as diagnostically
unique
Distance between
these not decreased.


Logarithmic spiral
 Foramen oval cluster

relatively ‘high’ up on
the spiral in deep bite.


Logarithmic spiral
Discussion
Mandibular shape - inferior alveolar nerve
- 2 factors

foramina position on the spiral
distance between them.

• Fetal & circumnatal periods

- All foramina placed near the origin of spiral and
nearer to each other
- Flatter curvature
- Mandible gonial angle relatively obtuse or flat.

Logarithmic spiral
With growth , all foramina moved down along
the spiral and distance

• Ramus becomes more erect relatively to
corpus

• Gonial angle becomes acute

Logarithmic spiral
• Anterior open bite

 Foramen ovale down
along the spiral

Distance mand. &mental
foramen not decrease

Course of inferior alveolar
nerve flatter

 Ramus & corpus more
obutse


Logarithmic spiral
• Deep bite

‘Higher’ up on the spiral
 3 neural foramina

distance not decreased

 Inferior alveolar nerve
curvilinear course

 Ramus & corpus more
acute


Logarithmic spiral
• Anterior cranial base – Richardson
Sella - NA

Deep bite
Anterior
open bite


Logarithmic spiral
Anterior open bite

• Gonial angle
Ar –Go-Me

Obtuse

• Mandibular size
Ramus
Corpus

Shorter
Normal length

• Anterior cranial base
(S-Na)

No difference


Deep bite
Acute
No significant
linear difference

Logarithmic spiral
Anterior open bite

• Periosteal functional matrix
(Massater)

Deep bite

No difference in attachment site

• Capsular functional matrix
Oral functioning space
Abnormal

Normal

Growth prediction
According Bjork
Visual treatment objective


Principal of Arcial growth of the
mandible
Robert M. Ricketts

• Purpose – explain a method for finding the arcial

growth of the mandible and to enumerate some uses of
the principal

• Based on computer study
• Predict long range growth forecast


Arcial growth of the mandible

• Principal – mandible grows by superioranterior apposition at the ramus on a
curve or arc which is a segment formed
from a circle.

• Radius – Pm to point Eva.


• Growth of the mandible
1.
2.
3.

Roentgenographic cephalometric
Bjork
Enlow
Bjork
- variation in the mandibular bending.
- Resorption of lower angular border
- 3rd molar crypt – stable longitudinal reference
Enlow
3D growth pattern
Remodeling area
Reversal areas of stability

Prediction of mandibular growth

• Primary methods
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•
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Long axis of condyle & neck
Lower border of mandible
‘Central core’ cephalomertrically
Search for ‘reference point’
External mandible (mandibular plane,ramus plane,
condyle – symphysis )


• Xi point – center of

ramus
Occlusal plane
Entrance of neurotrophic
bundles


• Bisect the height of ramus from the
sigmoid notch


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Dc point
Condyle axis
Corpus axis
Change in angle - change
in mandibular form

• Second method –
•

Magnitude & angular
relation.
More successful as a
method of forecasting

• Suprapogonion / Pm
Reference point
Ricketts – stress center
Enlow – site of reversal
line
Bjork - cosistent


• The objective of research was still towards
finding a method to critically predict future
form and size of the mandible over the
long range.


computer study

• 5 yrs growth study of mandible & lower
dental arch
• In lateral & frontal head films -362
measurement


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Material
40 pt – lateral & frontal cephalometric film
One group – 8 yrs another group -13 yrs
No orth. t/t
20M & 20F
20 – class I with normal occlusion
20 - class II malocclusion

Findings

• Mandible bend ½
•
•

degree per year.
Bending in an orderly
manner.
Growth arc was
operative.


• To determine the true arc of growth of the
mandible

• First arc – Pm ,Xi ,Dc
• Straightening of the
mandible



• Second arc -

tip of
coronoid , R1 , Pm
• Segment of circle small in
radius.
• Excessive bending of
mandible



• True arc –

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•
•

Condylar &
Coronoid process ,
Ramus center & it’s ant.
Border
Radius increase or
changing with the size of
the mandible
Changing arc or ultimate
spiral would result.
Growth could not be
represented as simple
segment of circle www.indiandentalacademy.com

Stress lines

• 850 yrs. Old mandible –
•
•

William B. Downs
Disintegration of
interprismatic subs.
Stress lines in the outer
& inner plates


• Examination of

stress lines / lateral
surface

Convergence at

protuberance menti
Upward ,backward &
outward from EO
Gnarled area at the
coronoid base.

•

Stress line /medial side

 Mylohyoid ridge
 YM /Y-shaped bony

prominence
- Center of
quadrant of
ramus
- Inner & outer cortical tables
showed confluence
 TP/ Triangular plane –
Nutritive foramina

• 2 new point - Eva &TR
• Eva- forking of stress lines
in ramus

• TR /true radius – center

of circle from Pog through
Eva

• Mu point

• Mandible size increased,
increment added to the
arc at the sigmoid notch.

• Predicted mandible was

almost absolutely correct
in size and form when
compared with the final
composite

• Mandible growth
occurs on a arc

• This method proved

extremely accurate in
50 treated cases
which were predicted
and compared for
periods of as long as
14 yrs later.

• Amount of growth to
forecast on the arc

- 2.5 yearly increase
14.5 F & 19M

• Symphysis lower

border – 1mm each 8
yrs / M

• Coronoid & condylar
process – different

• Coronoid – 0.8mm/yr
• Condylar
1.
2.
3.

- variable
Short & weak – 0.0mm
Long condyles –
0.4mm/yr
Average – 0.2mm /yr

• Gonion angle growth

50% of the total increase
in mandibular growth

• Females - no further
addition

• Males – above +0.2mm


• External oblique ridge
0.4mm/yr.

• RR point – stable bone
Ramal width



• Impaction of third molar and Arcial
growth prognosis –25 adult skull
normal occlusion

1. Lower third molar 50 % ahead the EOR

50% favorable prognosis
2. Mesial to the EOR – 100 % favorable prognosis
3. Distal to the EOR – poorer
45 % of the nonextracted cases required third molar
extraction.

• Bisect the height of ramus from the

sigmoid notch down to the lower border in
a perpendicular plane from FH ,then
bisected the width of the mandible called
XI point


• 2 new point - Eva &TR
• Eva- forking of stress lines in
•
•

ramus
A center of upward & forward
quadrant of ramus
By bisecting R2 & R3 point

• TR /true radius – center of
circle from Pog through Eva

• Mu point

• Class III
The amount of mandibular
growth in the forecast is
one sixth more in the
classIII


• May be occur in

closed bite faces


Growth prediction
According Bjork
Visualized treatment objective


Visualized treatment objective
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Definition
Uses
Jacobson and Sadowsky
Ricketts
Holdways


• Definition

It is a visual plan to forecast the normal
growth of the pt and the anticipated influences
of treatment , to establish the individual
objectives we want to achieve for that pt



• Uses
1.
2.
3.

Predict growth over an estimated T/t time
Analyzes the soft tissue facial profile
Determines favourable incisor repositioning
based on an ‘ideal’ projected soft tissue
profile
4. Determines total arch length discrepancy

5. Aids in determining b/w extraction &
nonextraction treatment
6. Surgical orthodontic correction


•
•
•

Ricketts
Holdways


ALEX JACOBSON &
P.LIONEL SADOWSKY

• All cephalometric headfilms to be taken in the lips
closed position even if they are strained to close

• Construct a VTO by considering average growth for
an estimated 2 yr period of active t/t & the objective
we want to achieve with our mechanics


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•
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Cephalometric tracing for VTO

Anterior & posterior cranial base
Pterygomaxillary fissure
Orbit
Anterior outlines of frontal bone
Nasal bone & Nasion
ANS &PNS ,hard palate
Upper central incisor & it’s alveolar process
Mandible
External auditory meatus
Soft tissue profiles
Upper & lower molar

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•

Cephalometric tracing for VTO
BAN (Basion-nasion line)
Line Na - POINT A
F H PLANE
Occlusal plane
Downs mandibular plane
Facial axis
Holdway’s line
Facial plane

Visual treatment objective
Step of VTO

• Step 1 obj. – To draw frontonasal area , BAN & NA
line.

• Step 2 obj. – Growth in frontonasal area over 2 yr.
- Frontonasal area 1.5 mm growth
- 1/4mm per year ( Dr. Holdway’s studies )


• Step 3 object –

Mandible growth in vertical direc.
- Ant. Portion of mandible
- Soft tissue chin
- Down’s mandibular plane

• Superimpose on the facial axis
• The distance b/w VTO & ceph Ban line should be 3

times the amount of growth expressed previously in
FN area

Step 4 obj. – Mandible growth in horizontal

direction.
- Draw the Post border of mandible
• Forward growth at chin point = Nasion
• Total vertical facial height as well as forward
location of chin established


Step 5 obj. – To locate maxilla & lower half of nose

•
•
•

Superimpose on NA line & move up
There is 40% of total vertical growth above BaN line
& 60% below mandible
Nose growth 1mm/year.

Step 6 obj. – To locate and draw the occlusal plane

• Superimpose on NA plane
• Vertical growth is 50% above maxilla & 50% below
mandible


Step 7 obj. – To determine soft tissue lip contour
using the new H-line

• The distance b/w upper lip contour & H-line is
3 - 7mm (Dr. Holdway’s studies )


•

Step 8 obj. – To relocate the maxillary central incisor

Upper lip thickness = Basic upper lip thickness
( within 1 mm )
• Lip strain is difference b/w above measurement
• Maxillary incisor rebound - 0.5mm in class I
- 1.5 mm in class II
In this case
Lip strain
= 4 mm
Lip movement
= 4 mm
Maxillary incisor rebound = 1.5 mm
Total
9.5 mm

Step 9 obj. – To reposition lower incisor
- Calculate resultant arch length change

• Arch length change - measure the distance b/w
•

old and new incisor position (2mm)
Double the above distance

• Arch length change is in this case is 4 mm

Step 10 obj. –To reposition mandibular first molar

• Total arch length discrepancy = arch length loss
+arch length discrepancy / model discrepancy
8 mm = 4 mm + 4mm

• Extraction of 2nd PM on both side - 15 mm space
Step 11 obj. – To reposition the maxillary first

•
•
•

Holdways
Ricketts


A Soft - tissue cephalometric
analysis
Reed A. Holdway

• Based on soft - tissue measurement
Variations

• Sella nasion line is used express forward growth
•

at nasion
Growth on facial axis is 3mm/yr except during
growth spurts


analysis
• Head films should be taken with the pt’s lip
touching position


A Soft - tissue cephalometric analysis

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•

Original tracing – 9 reference line

SN plane
FH plane
Occlusal plane
Nasion to Pog line (hard & soft tissue)
H- line
Nasion to point A line / facial plane
Facial axis
Down’s Mandibular plane

Steps of VTO tracing
Step 1 – Draw Frontonasal area
Sella – nasion line
Nasion- point A line



•
•

Step 2 - Express horizontal growth in the FN
area for the estimated T/t
Growth at nasion is 0.66 to 0.75 mm/yr
Prediction of growth at nasion is an overall
prediction for all midfacial structure


Step 3 – Mandible growth in vertical dire.

• Growth on facial axis is 3 mm/yr except in growth
spurt period

Step 4 – Mandible growth in horizontal dire.

• At this point total vertical height has been forecast


Step 5 – To locate maxilla, the new point A &
lower half of nose

•
•

Vertical growth above the SN line & below the
mandible is in ratio of 40 :60
The vertical growth of the nose over 2 yr period
keeps pace with the growth from the maxilla
vertically to the anterior cranial base


Step 6 - locate and draw the occlusal
plane

• Vertical growth is 50% above maxilla & 50%
•

below mandible
The occlusal plane is located 3 mm below the lip
embrasure


Step 7 – To determine soft tissue lip contour
using the new H-line

• The distance b/w upper lip contour & H-line is
•
•

3 - 7mm
Short & thin lip – 3 mm
Long & thick lip – 5 mm


Step 8 – To relocate the maxillary central
incisor

• Upper lip thickness = Basic upper lip thickness
•
•

( within 1 mm )
Lip strain is difference b/w above measurement
Maxillary incisor rebound - 0.5mm in class I
- 1.5 mm in class II

Step 9 – To reposition lower incisor
- Calculate resultant arch length change

• Arch length change - distance b/w old and new
•

incisor position
Double the above distance

• Arch length change is in this case is 8 mm

analysis
Step 10 – To reposition mandibular first molar

• Total arch length discrepancy = arch length change
•

+arch length discrepancy / model discrepancy
10 mm = 8mm + 2mm
Extraction of 2nd PM on both side - 15 mm space

Step 11 – To reposition the maxillary first

•
•
•
•
•
•
•
•
•

Original tracing

RICKETTS

Nasion
ANS
Point A
PM
POG
CC
Basion
DC
XI


•
•
•
•
•
•

Construction of VTO
Cranial base prediction
Mandibular growth prediction
Maxillary growth prediction
Occlusal plane prediction
The location of the dentition
The soft tissue of the face


VTO – Cranial base prediction

•
•
•
•

Mark at CC point
Trace BaN Plane
Nasion -1mm /yr
Basion – 1 mm/yr


VTO –Mandibular growth prediction

• Condylar axis growth
• Corpus axis growth
• Symphysis growth


VTO – Mandibular growth prediction – Rotation
• Mandible rotates open or closed from the effects of
mechanics used & the facial pattern present

• Mechanics

5 mm convexity reduction

Facial axis open 1 degree

4 mm overbite correction

• Facial pattern


VTO – Mandibular growth prediction – Rotation
• Superimpose at Basion
• Rotate VTO tracing up to open the bite at nasion or
•
•

down to open the bite
This rotation depends on treatment effect
Trace condylar axis, coronoid & condylar process


VTO – Mandibular growth prediction
Condylar axis , Corpus axis growth

• Condylar axis moves 1mm /yr down from DC point
• PM moves forward 2mm /yr in normal growth

•
•
•

VTO – Mandibular growth prediction -Symphysis
growth
Coincide old & new PM
Copy the symphysis , mandibular plane
Construct facial plane & facial axis

•
•
•

VTO – Maxillary growth prediction
Superimpose at nasion along the facial plane
Divide the original & new menton into 3 part by using
2 mark
Superimpose mark 1 on original menton , copy the
maxilla


VTO – Maxillary growth prediction
Point A change related to BA – NA

• Position of Point A change with growth & different mechanics
Mechanics
Maximum range
1. HG
- 8 mm
2. Class II elastics
- 3 mm
3. Torque
- 1 to 2 mm
4. Class III elastics
+ 2-3mm
5. Facial mask
+ 2- 4mm
• Point A and APO plane


VTO – Occlusal plane prediction

• Superimpose mark 2 on original menton along facial
•

plane
Copy the occlusal plane

VTO - Dentition - Lower central incisor

•
•

Superimpose on the corpus axis at PM
Place a point 1mm above to occ. Plane &
1mm ahead to APO line

VTO - Dentition -

•
•

Lower first molar
Arch length change is 4mm
Leeway space is 4mm

VTO - Dentition -

Upper first molar
Upper central incisor

VTO – Soft tissue area

Growth prediction
• Overall changes in size and relationship of
human face from childhood to adulthood
are difficult to accurately predict due to
influence of the combined and complex
effects of genetic and environment factor.


Growth prediction
• Facial and dental changes in Adolescent and their clinical
•
•
•
•
•

implication
Samir –E Bishara ,AO 2000,Vol.60,No.6
Difference between functional matrices in anterior open bite
and in deep bite
Melvin L. Moss, AJO 1970, Vol. 42,No.3
A principal of Arcial growth of the mandible
Robert M . Ricketts AJO 1972,Vol .42 ,No.4
Provocations & perception in craniofacial orthopedics
Robert M . Ricketts
Issues related to the prediction of craniofacial growth
James Todd , AJO 1981,Vol .79 ,No. 2
A soft tissue cephalometric analysis and it’s use in
orthodontic treatment planning
Holdway , AJO www.indiandentalacademy.com 4
1984 ,Vol. 84 ,No.

Growth prediction
• A Visulized treatment objective
•
•
•
•
•
•

Alen Jacobson , P Lionel Sadowsky
Prediction of the mandibular growth rotation
Bjork , AJO 1969 , Vol. 39
Bioprogessive Therapy – VTO
Ruel W Bench , James J. Higler , JCO 1977, November
Contemporary orthodontics - William R. Proffit
Orthodontic current principles & techniques
T.M Graber , Robert Vanarsdall
Orthodontic principles & practice
T.M Graber
Ricketts interview ,JCO 1975 ,may, jun ,july

Thank you
• www.indiandentalacademy.com
• Leader in continuing dental education


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