Grwoth prediction

Growth prediction
‫الرحيم‬‫الرحمن‬‫هللا‬ ‫بسم‬
Mohanad Elsherif
BDS (U of K), MFD RCSI, MFDS RCPS(Glasg), MSc (Orthodontics), M.Orth. RCSEd
University of Khartoum
Faculty of Dentistry
Department of Orthodontics

Outlines
 Introduction.
 Importance of growth prediction.
 Prediction parameters.
 Difficulties in growth prediction.
 Methods of growth predictions.
 Comparison between methods.
 Conclusions.
 References.

Introduction
 Every child has a unique pattern of
development.
 To achieve a successful orthodontic or
surgical result, the orthodontist must have
some understanding of the patient’s future
facial growth potential.

Why should we predict growth?
 Diagnosis.
 Treatment planning.
 Treatment success.
 Retention planning.

What do we want to predict?
1. Amount of growth “Future size of a part”.
2. Direction of growth.
3. Relationship of parts.
4. Timing of growth events.
5. Velocity of growth.
6. Effect of orthodontic therapy on any of the above
predicted parameters.

Why it is difficult?
 Complexity.
 Variability.
 Extreme cases.

How to predict growth?
 Prediction methods.
 Johnston’s grid.
 Bjork’s structural method.
 Fishman’s method.
 Rickett’s arcial method.

Prediction in science
A) Theoretical method.
B) Regression method.
C) Experiential method.
D) Time Series method.
Hirschfeld AJO 1971

Methods of growth
prediction
• Morrees mesh
• Johnston’s grid
• Jacobson’s grid
• Broadbent’s method
• Fishman’s method
• Sneath’s grid
• Bjork’s implant growth
rotation studies
• Rickett’s arcial growth
of the mandible.
• VTOs (Holdaway’s,
Rickett’s and other)
• Moss’s logarithmic
spiral
• Hirschfield and Moyers
method.
• Mickewn’s allometric
methods
• Todd’s equation
• Finite element method

 In 1975 Johnston introduced a “forcast grid” to predict
future growth.
 He developed a gender and age specific templates for boys
and girls with normal occlusion, class I and class II
malocclusion.
 Each gender specific template has an oriented set of rulers
which are graded in years (form 6-16 years thus growth can
be analyzed for children in this group directly from this
template.
Johnston grid

Technique
 The cephalogram is oriented on sella nasion line and registered at
sella.
 Five landmarks are located these are; tip of the nose, PNS, Point A,
Point B and maxillary first molar.
 The direction of growth is established from the group average age and
gender.
 Johnston assumed that every patient grows in exactly the same
direction and at the same rate.
 Each point is advanced one grid unit per year using the SN line
registered at “S”.

Drawbacks:
 It uses the chronological age rather than the
skeletal age.
 It assume that the patient grow in a fixed
direction.
 The growth increment constant are for fixed
population.
Johnston grid

Bjork structural
method
 Developed by Bjork in 1986.
 His aim was to predict mandibular growth
rotation from a single cephalometric
radiograph.
 Certain morphologic criteria were observed
in the radiograph and related to the type of
rotation.

Bjork structural
method
 A sample of 21 subjects ( 9 girls and 12 boys) were chosen.
 These subjects were followed for 6 years (3 years before puberty
and 3 years after puberty).
 2 cases showed backward growth rotation and the rest showed
forward growth rotation.
 The mandibular rotation was used as the dependent variable in the
following multivariate statistical analysis.
 44 morphologic variables ( 4 linear, 35 angular and 5 indices) were
registered on the first radiograph and used as an independent
variables.

Bjork structural
method
 The purpose was to select those independent variables
which, alone or in combination, could explain as much as
possible of the variability of the dependent variable.
 In this procedure there were two principle purposes:
1. attainment of the greatest possible correlation.
2. selection among morphologic variable with equivalent
effect of those easiest to apply clinically.

Bjork structural
method
 The profile radiographs were superimposed
according to the stable structures in the
anterior cranial base. Nasion Sella line was
transferred form the first film to the last
film.
 The growth rotation was measured form
the first to he last stage as the change in
the inclination of the implant line (IPLi) in
relation to NSL. (negative values indicate
forward growth rotation while positive
values indicates backward growth rotation).

Bjork structural
method
Results
 Four variables which in combination gave the best prognostic
estimate (86%) of mandibular growth rotation are:
 Mandibular inclination.
 Intermolar angle.
 Shape of the lower border.
 Inclination of the lower border.

Bjork structural
method
S
Tgo Gn
N1. Mandibular inclination:
a. Index 1
 It represent the proportion between
posterior and anterior facial height.
 62% of variability of rotation can be
explained by this index (highest
variable).
 It is increased when the patient has
forward growth rotation and decreased
if the patient has backward growth
rotation.

Bjork structural method
Tgo ML2
N
1. Mandibular inclination:
b. Lower gonial angle
explained by this angle.
 It can be used as an alternative to the
facial height index to represent
mandibular inclination.
 It decreased when patient has forward
growth rotation and increased if the
patient has backward growth rotation.

NSL- ML1
NSL1. Mandibular inclination:
c. Inclination of the lower border:
 It can be used as an alternative to the
facial height index and lower gonial
angle to represent mandibular
inclination.
 It decreased when patient has forward
growth rotation and increased if the
patient has backward growth rotation.

MOLs- MOLi
2. Intermolar angle:
 39% of variability of rotation can
be explained by this angle.
 In combination with index 1 it
explained 76% of the variability of
the mandibular growth rotation.
 It tend to increase in forward
growth rotation and decrease in
backward growth rotation.

ML1
ML2
3. Shape of the lower border:
 In combination with index 1 and
intermolar angle it explained 81% of
the variability of the mandibular
growth rotation.
 It tend to increase in forward growth
rotation and decrease in backward
growth rotation.

CTL- NSL
NSL
CTL
4. Inclination of the symphysis:
 In combination with index 1,
intermolar angle and shape of the
lower border it explained 86% of the
variability of the mandibular growth
rotation.
 It tend to increase in forward growth
rotation and decease in backward
growth rotation.

Success of prediction:
 In all forward rotation cases the direction of the growth rotation was predicted
correctly with index 1 alone.
 Backward growth rotation were predicted when at least two variables were
combined.
 Prediction of the amount of rotation was generally improved by the addition of
variables.
 By Index 1 alone the difference between the observed and predicted in forward
growth rotation was 3.7° in average. With all four variables used the average was 1.3°.
 For the case that show the greatest backward rotation the observed rotation was
5.3° while the predicted value when combining the four variables was 3.6°.

Drawbacks:
 Used only to predict mandibular rotation.
 It is difficult to apply it to average cases because
theses features are less developed in children with
normal growth pattern.

Fishman’s method
 It is based on the maturational age rather
than the chronological age.
 The patient maturational level is determined
from the hand wrist radiograph.
 Percentage of total growth completed is
used rather than absolute linear measurement.

Ricketts arcial method
 Developed by Ricketts in 1972.
 This method used the individual’s own mandibular length and ramus height
to predict mandibular growth.
 Ricketts objective was to find a method to predict the future shape and size
of the mandible using only the beginning cephalometric radiograph as a
reference.
 He described a number of internal mandibular cephalometric landmarks
representing the arc of the mandible.
 The initial shape of the mandible is used as predictor of future growth
direction and added the same average of increment of growth to every
individual.

1. Locate the xi point.
2. Locate the supra pogonion
point (Pm): it is a point
located at the superior
aspect of symphysis.
Technique
R2
R1
R3
R4
Xi
Pm

R3
3. Locate point ramus
reference point: it is the
point halfway between
Xi point and R3 on the
anterior border of
ramus. Xi
RR
Technique

4. Locate point Eva: How?
1. point RR and R3 are
connected.
2. point Eva is located on the
mid point on RR and R3.
Technique
R3
Eva
RR

5. Take the patient Eva- Pm
as radius then a circle is
drawn by:
A. taking Eva as a center.
B. taking Pm as a center.
 The point of intersection
is TR (true radius).
Pm
Eva
TR
Technique

TR
Mu6. By taking point TR as a
center an arc is drawn.
 When this arc crosses
the sigmoid notch this
is called Murray point.
Technique

 Sigmoid notch: upward about 2.5
mm/ year
 Coronoid: upward and outwards
about 0.8 mm/year
 Condyle: upward and backward
about 0.2 mm/year
 Gonial angle drift: female no
addition male 0.2mm/ year
From the point Mu the mandible is grown out in average increments up to
age 19 years in male and 14.5 years
in females as follow:
Growth prediction

Drawbacks:
 It is technically difficult and time consuming.
 It rely on operator skills in tracing.
 It uses the chronological age rather than the
skeletal age.
 The growth increment constant are for fixed
population.
Ricketts arcial method

Which method is the
best?
Facial growth prediction: A comparison
of methodologies
Turchetta et. al AJODO 2007
Aim:
 The purpose of this study was to compare 3 methodologies that
predict facial growth in short- and long-term time periods. (the
Ricketts analysis, the Johnston grid analysis, and the Fishman
maturational analysis.

Which method is the
best?
Method:
 A randomized sample of serial lateral cephalometric head films
and hand-wrist films of 50 untreated subjects from the Burlington
Growth Center at the University of Toronto were used.
 The sample was subdivided by skeletal classification and further
subdivided by gender.
 The sample comprised 19 skeletal Class I subjects (10 female, 9
male), 20 Class II subjects (10 female, 10 male), and 11 Class III
subjects (6 female, 5 male). No subject had a history of orthodontic
treatment.

Which method is the
best?
 Three serial headplates were traced on each subject, and the associated
chronologic and maturational ages were noted.
 The average age of the initial headplate was approximately 9 years (T1).
 The middle headplate was taken at approximately 13 years of age (T2).
 The final headplate was taken at approximately 20 years of age (T3).
 Predictions were made between the time periods and then compared
with actual T2 and T3 records.
Method:

Which method is the
best?
Results and Conclusions:
 Although not the case in every instance, it was demonstrated
that the maturationally oriented Fishman analysis was superior to
both the chronologically based Johnston grid and Ricketts analysis
for short- and long-term predictions.

Conclusions
 Despite these attempts growth prediction remain a difficult task.
 Although it is difficult to predict the growth amount and direction
in numbers it is very important to understand the overall growth
pattern.
 The more the individual whose growth one is attempting to
predict is represented to the sample of population the greater the
chance of success.
 Extreme cases are difficult to predict, that’s why at present and for
the foreseeable future accurate growth prediction simply are not
possible for the children who need it most .

References
 Adolescent maxilllomandibular relationship: growth pattern, inter-indvidual
variability and predictions. Roberts RO 2006.
 Hirschfield WJ Moyers RE. prediction of craniofacial growth (the state of the art).
Am J Orthod. 1971;60;435_444.
 Ricketts RM. A principle of archial growth of the mandible. Angle Orthod
1972;42:368-86.
 Johnston LE. A simplified approach to prediction. Am J Orthod 1975;67:252-7.
 Bjork A. prediction of mandibular growth rotation evaluated from a longitudinal
implant sample. Am J Orthod 1984;86:359-360.
 Turchetta BJ. Facial growth prediction: A comparison of methodologies. Am J
Orthod Dentofacial Orthop 2007;132:439-49
 Textbook of Craniofacial Growth; Sridhar Premkumar

Declaration
 The author wish to declare that; these presentations are his original work, all
materials and pictures collection, typing and slide design has been done by the
author.
 Most of these materials has been done for undergraduate students, although
postgraduate students may find some useful basic and advanced information.
 The universities title at the front page indicate where the lecture was first
presented. The author was working as a lecturer of orthodontics at Ibn Sina
University, Sudan International University, and as a Master student in Orthodontics at
University of Khartoum.
 The author declare that all materials and photos in these presentations has been
collected from different textbooks, papers and online websites. These pictures are
presented here for education and demonstration purposes only. The author are not
attempting to plagiarize or reproduced unauthorized material, and the intellectual
properties of these photos belong to their original authors.

Declaration
 For the purposes of dissemination and sharing of knowledge, these
lectures were given to several colleagues and students. It were also
uploaded to SlideShare website by the author. Colleagues and students
may download, use, and modify these materials as they see fit for non-
profit purposes. The author retain the copyright of the original work.
 The author wish to thank his family, teachers, colleagues and students
for their love and support throughout his career. I also wish to express
my sincere gratitude to all orthodontic pillars for their tremendous
contribution to our specialty.
 Finally, the author welcome any advices and enquires through his
email address: Mohanad-07@hotmail.com

Grwoth prediction

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