Methods of studying growth /certified fixed orthodontic courses by Indian dental academy

Methods of
studying growth
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


Introduction:
Study of man’s development is not always
done by studying man himself
It is useful that basic principles of
development are common to many living
organisms since all of man’s development is not
accessible to ready study by experimentation .
different approaches have been utilized for
the study of both normal and abnormal growth.
Each has its own limitations.

TYPES OF GROWTH DATA
Opinions
Observations
Ratings and rankings

1.OPINION
a) crudest method
b)considered as a calculated guess based on
one’s experience.
c) very unscientific and should be avoided
when possible.
For eg. – One may be able to guess which
one of the two siblings may be taller by
assessing their previous growth.

2.) Observations: useful for studying all or

none phenomenon.
For example – in cursory visual examination
of 67 Eskimo children ranging between Class
II malocclusion was observed.
3) Ratings and Rankings:
Rating make use of comparisons with
conventional scales or
classification
normal values ranges between two extreme
ends, the average of which is considered as a

Each individual be compared with these
norms and rated accordingly.
For eg. – This boy is shorter (as compared to
the average height of the boys in that particular
region of his age).
Ranking :method of arranging the data in an
orderly sequences according to its value.
For eg – The ranks of the children was
determined on the basis of their performance in
the annual examination.

METHODS OF GATHERYING GROWTH DATA
A) LONGITUDINAL:

Measurements made of same person/group
at regular intervals time are longitudinal
measurement. These are thus long term studies.
Advantages

a) Variability in development among individuals
within the group is put in proper perspective.

b)The specific development pattern of an

individual can be studied, permitting serial
comparisons
c)Temporary problems in sampling are
smoothed out with time and an unusual event
or mistake is more easily seen and corrections
made.
Disadvantages
a) Time consuming
b)Expense
c)Attrition.
d)Averaging

B) Cross Sectional:
Measurement made of different individuals or
different samples and studied at different periods
are cross sectional measurements.
Thus, one may measure a group of 7yr. old boys
and on the same day, at the same school, measure a
group of 8yr.old boys.
Changes between 7& 8 yrs of age in boys at that
school are thus assumed after study of the data
obtained.

Advantages
1. quicker

2. less costly
3. statistical treatment of the data - made easier.
4. it allows repeating of studies more readily, in
case of any flaw.
5. used for cadavers skeleton and archeological
data.

Disadvantages
It must always be assumed that the group
being measured and compared are similar.
Cross sectional group are averages, tend to
obscure individual variations.


C) Overlapping or semilongitudinal data:
Longitudinal and cross sectional methods
combined to seek the advantages of each.
In this way one might compress 15yrs of
study into 3yrs of gathering data, each sub
sample including children studied for the
same member of years but started at different
ages.

EVALUATION OF GROWTH DATA
I.

Quantitative approach:

A) Direct growth measurementDirect data are derived from measurements
taken on the living person or cadaver by means
of calipers, scales, measuring tapes, and other
measuring devices.various approaches are


a) Craniometry:

Craniometry based on measurements of
skulls found among human skeletal remains.
From such skeletal material it has been
possible to piece together a great deal of
knowledge about extinct populations and to get
some idea of their pattern of growth by
comparing one skull with another.

advantage :
that rather precise measurements can be made
on dry skulls
disadvantage :
that by necessity, all these growth data must be
cross sectional.
b) Anthropometry:
In this technique,various landmarks are est in
studies of dry skulls -measured in living indiv.
by using soft tissue points overlying these bony
landmarks

.

For eg, it is possible to measure the length of
the cranium from a point at the bridge of the
nose to a point at the greatest convexity of the
rear of the skull.
This measurement can be made on either a
dried skull or a living individual, but results
would be different because of the soft tissue
thickness overlying both landmarks.

Advantages:
it is possible to follow the growth of an
individual directly,
same measurements repeatedly
different times.

made at

This produces longitudinal data repeated
measures of the same individual.

B. Indirect growth measurements:
Indirect growth measurements are those
taken from images or reproductions of the
actual person.
For example, measurements made from
- photographs,
-dental casts,
-cephalograms
-skeletal maturity indicators

a)Cephalometric Radiology:
•Cephalometric Radiology is of importance not only in
the study of growth but also in clinical evaluation of
orthodontic patients.
•There is precise control of magnification.
Advantages:
1.This approach can combine the advantage of
craniometry and anthropometry. It allows a direct
measurement of bony skeletal dimensions, since the
bone can be seen through soft tissue covering in a
radiograph.

2. But it also allows the same individual to be
followed over time. Therefore longitudinal study
possible their serial cephs.
The disadvantages of a ceph:
1. Metric radiograph is that it produces a two
dimensional representation of a three dimensional
structure
2. Magnification errors
.
3. X ray radiation exposure

2)Skeletal maturity indicators:
Because of individual variation,
physiological and anatomical maturity cannot
be accurately assessed by age alone
Other parameters, such as growth velocity,
secondary sex changes, dental development,
and skeletal ossification, have proven of more
value

Various SMIHAND WRIST
CERVICAL VERTEBRAE MATURATION
INDICATOR
MID PALATAL SUTURE
FRONTAL SINUS

A)Hand wrist radiographs:
The underlying premise is that the osseous
changes seen in the hand and wrist are
indicators of more general skeletal changes.
The system uses only four stages of bone
maturation ,all found on six anatomical sites
located on the
-Thumb
-Third finger
-Fifth finger
-Radius

The sequence of the four ossification stages
progresses through:
epiphyseal widening on selected phalanges
the ossification of the adductor sesamoid of
the thumb
the ‘capping’ of selected epiphysis over their
diaphysis ,
the fusion of selected epiphysis and diaphysis

Skeletal Maturity Indicators
(FISHMAN)
Width of epiphysis as wide as diaphysis
1.Third finger – proximal phalanx
2.Third finger – middle phalanx
3.Fifth finger - middle phalanx
Ossification
4.Adductor sesamoid of thumb

Capping of epiphysis
5.Third finger – distal phalanx
7.Fifth finger - middle phalanx
Fusion of epiphysis and diaphysis
8.Third finger – distal phalanx
9.Third finger – proximal phalanx
11. radius

EVALUATION
For both the maxilla and mandible
measurements, acceleration in growth velocity
occurred between skeletal maturation levels
SMI 6 and 7, followed by a deceleration until
level 9.
Mandible and maxilla reached maximum
growth rate at SMI level 7 in males and at SMI
6 in females

Percentage of growth completed
At SMI level 6, the values representing
height, maxilla and mandible all showed
achievement of approximately 50% of
adolescent growth .
as growth velocity decreased during the
later part of adolescence, the maxilla and
mandible tended to lag behind skeletal growth
(taken from AO vol 52 no. 52 april, 1982)

B) MID PALATAL SUTURE

The purpose of this study was to determine
whether a positive correlation exists between
adolescent maturational development and the
approximation of the mid palatal suture.
The mid palatal suture is formed by three
parts .these include
-Interpremaxillary
-Maxillary
-Interpalatine

The following key landmarks and planes were
identified :
•Point A – most ant. point of the premaxilla
•Point B – most post. point on the posterior
wall of incisive foramen
•Point P – point tangent to a line connecting
the posterior walls of the greater palatine
foramens

Key landmarks on midpalatal suture

RESULTS

Stages of ossification of the midpalatal suture
were compared with the fishman’s standards of
skeletal maturation indicators
Very little mid palatal approx. existed during
SMI 1 – 2
At SMI 11 mid palatal suture is only approx.
half the suture distance

Very large increases in appr. from SMI 8 – 11
At same SMI stages posterior portion
demonstrated larger approximation
Maturational development is related to mid
palatal fusion in ways that can provide
information to better time maxillary expansion
It is best to accomplish this before SMI 9 and
ideal time to initiate it is between SMI 1 – 4
(taken from AJO vol 105, no. 3 march 1994).

The Cervical Vertebrae as Maturational
Indicators
To avoid taking an additional x-ray, some
researchers have sought to relate maturation
with dental and skeletal features other than the
bones in the hand and wrist.
In 1972, Lamparski concluded that the
cervical vertebrae, as seen on routine lateral
ceph, were as statistically and clinically reliable
in assessing skeletal age as the hand-wrist
technique.

Hassel and Farman developed modification of
Lamparski's criteria, which assesses
maturational changes on the second, third, and
fourth cervical
vertebrae.
Six distinct stages of growth can be related to
the SMI developed by Fishman:


Initiation (SMI 1 and 2).
The vertebrae are wedge-shaped
superior vertebral borders tapering from
posterior to anterior.
80 to 100 % of adolescent growth can be
anticipated at this stage

Acceleration (SMI 3 and 4).
Growth acceleration begins
65-85% of adolescent growth be anticipated.
Concavities develop on the inferior borders
of C2 , C3.
The bodies of C3 , C4 nearly rectangular
inferior border of C4 is flat.

Transition (SMI 5 and 6).
Adolescent growth accelerates toward peak
velocity 25-65% of adolescent growth
anticipated.
Distinct concavities develop on the inferior
borders of C2 and C3.
A concavity begins to develop on the inferior
border of C4
bodies of C3 and C4 are rectangular.

Deceleration (SMI 7 and 8).
Only 10-25% of adolescent growth remains.
Clear concavities seen on the inferior
borders of C2, C3, and C4
the bodies of C3 and C4 nearly square.


Maturation (SMI 9 and 10).
Final maturation takes place at this stage
only 5-10% of adolescent growth can be
anticipated.
Accentuated cavities are seen on the
inferior borders of C2, C3, and C4,
bodies of C3 and C4 are nearly square.

Completion (SMI 11).
Little to no adolescent growth is expected
Deep concavities seen on the inferior
borders of C2, C3, and C4
vertebral bodies are more vertical than
horizontal.


FRONTAL SINUS
It was found that the frontal sinus dev. showed
a growth rhythm similar to body height
development, with a well-defined pubertal peak.

SOMATIC MATURITY PREDICTION

To use the prediction of somatic maturity
stage on the basis of the analysis of the frontal
sinus growth velocity, the following findings are
pertinent.

Frontal sinus growth shows a well-defined
pubertal peak (Sp), which on the average,
occurs 1.4 years after the pubertal body height
peak (Bp)
.
In male subjects, the average age at frontal
sinus peak is 15.1 years.
In a l-year observation interval, a peak
growth velocity in the frontal sinus of at least
1.3 mm/yr. is

attained by 84% of the subjects
In a 2-year observation interval, a peak
growth velocity in the frontal sinus of at least
1.2 mm/yr. is attained by 70% of the subjects
(Taken from the AJO-DO on CD-ROM (Copyright © 1997
AJO-DO), Volume 1996 Nov (476 - 482): Frontal sinus
development as an indicator for somatic maturity at
puberty)

C) Derived Data:
obtained by comparing atleast two other
measurements
for eg. when we say that a persons mandible
grew 2mm between ages 7 & 8, the 2mm have not
actually been measured rather, the mandibular
length at 7yrs has been subtracted from the
mandibular length at 8yrs.
the increment thus derived is assumed to
represent growth.

Experimental Approach
A) Bimetric Tests:
They are used in which physical characteristics
such as weight, ht. skeletal nature and
ossification are measured and compared with
standards based upon the examination of large
no. of healthy subjects.


B) Vital Staining:

Vital staining is a technique in which dyes that
stain mineralizing tissues are injected into an
animal.
These dyes remain in the bones and teeth
This method was originated by the great
English anatomist John Hunter in the 18 C
. He discovered that the active agent was a
dye called alizarin, which still is used for
vital staining studies.

Alizarin reacts strongly with calcium at
sites where bone calcification is occurring.
Since these are the sites of active skeletal
growth, the dye marks the locations at which
active growth was occurring when it was
injected.
Bone remodels rapidly, and areas from
which bone is being removed also can be
identified by the fact that vital stained
material has been removed from these
locations.

Antibiotic tetracycline is also used as vital
bone markers
Other dyes used are –
(i) Acid alizarin blue
(ii) Trypon blue
(iii) Procion

C) Radioactive tracers:
Radioactivity labeled metabolite becomes
incorporated into the tissues as a sort of vital
stain
.
The location is detected by the weak
radioactivity given off at the site when the
material was incorporated.


The gamma emitting isotope 99m Tc
(TECHNECIUM) can be used to detect areas
of rapid bone growth in humans, but these
images are more useful in diagnosis of
localized growth problems than for studies of
growth patterns.
It is particularly of importance in study of
condylar hyperplasia

D) Molecular genetics:
Rapid advances in molecular genetics are
providing new information about growth and
its control.
For example – the whole family of
transforming growth factor beta genes now
are known to be important in regulating cell
growth and organ development.

.

Definition
Boucher

E)IMPLANTS
(Implant)

:As

defined

by

‘Implants are alloplastic devices
which are surgically inserted into or onto
jaw bone’.


stable reference points are needed for
accurate assessment of longitudinal growth
changes
though some relatively stable bony land
marks are used as a reference but till today
implants are the best means of reference points
for studying the longitudinal growth studies
.
Implant were first used by Bjork and
Skeiller for studying growth changes.

It involves implanting small bits of
biologically inert Tantalum alloy in certain
areas of maxilla and mandible to study growth
of skull.
These are around 1.5mm in length ,and
0.5mm in diameter.


SITES OF IMPLANT PLACEMENT
Maxilla:
Hard Palate behind deciduous canines.
Below the anterior nasal spine.
2 implants on either side of zygomatic process
of maxilla.
Border between hard palate & alveolar process
medial to the first molar.

Mandible:
Anterior aspect of symphysis, in the midline
below the root tips.
2 pins on the right side of the mandibular
body.
One under the first premolar & the other
below the second premolar or first molar.
One pin on the external aspect of right ramus
in level with the occlusal surface of molars.

Bjork 1969 presented a survey of experience
with the implant method in the study of facial
growth ,with particular emphasis on prediction
of mandibular growth rotation.
The three methods discussed were:
Longitudinal Method
Metric Method
Structural Method

1. Longitudinal
It consists of following the course of
development by annual X-ray cephalograms.
Shown to be of limited use for this purpose,
as the remodeling process at the lower border
of the mandible to a large extent masks the
actual rotation.

2) Metric Method
Aims at prediction based on a metric
description of the facial morphology at a single
stage .
Predicting the intensity or direction of
subsequent development from size or shape at
childhood was not feasible with any
cephalometric analysis

3) Structural method
This method was thence described by which
it may be possible to predict, from a single
cephalogram ,the course of rotation, where this
feature is marked.
This method is based on information gained
from implant studies of the remodeling process
of the mandible during growth.

Implant radiography:
inert metal pins are placed in bones anywhere
in the skeleton including face and jaws.
These metal pins are well tolerated by the
skeleton and become permanently incorporated
into the bone without causing any problems.
If metallic implants are placed in the jaws, a
considerable increase in accuracy of a
longitudinal ceph. analysis of growth pattern can
be achieved.

method of study developed by. Arne Bjork
and Coworkens at the Royal Dental College in
copen-hugan Denmark
. Superimposing ceph. radiographs on the
implanted pins allows precise observation of
both changes in the external contours of
individual bones.
Precise evaluation of dentofacial growth in
humans still is done best by implant radiography

Various Growth Studies
Among the main resources of the craniofacial
research community are the collections of
longitudinal growth records that were
accumulated at considerable economic and
human cost by dedicated investigators


1.The Broadbent Bolton Growth Study
it consists of mixed longitudinal records plus
single visit data sets for a total of 5700 subjects.
About 15% of these subjects have been seen
10 times or more, but 47% have been seen only
once.
Thus there are more than 850 longitudinal
record sets.
In addition to lateral head films,
posteroanterior films (PA), and hand-wrist films
are available

. The study casts are trimmed (Kerr

compound bites), and there are height and
weight records
The lateral and PA films have all been
obtained using the Broadbent Bolton
cephalostat
The records were gathered under the
direction of B. Holly Broadbent, Sr., and the
present director is B. H. Broadbent, Jr.

Importance
The Broadbent Bolton collection has played a
major role in the development of
cephalometric techniques and orthodontic
treatment standards, and in recent years has
been the basis of an important longitudinal
study of craniofacial aging


2) The Burlington Growth Study
The Burlington Growth Study is located at
the Burlington, Ontario Orthodontic Research
Centre at the University of Toronto.
Its various longitudinal samples contain
1632 subjects in all


All samples are of the "diminishing"
longitudinal type
The records for the serial experimental and
control subjects include :
a) lateral head films (taken at rest, in occlusion,
and with the mouth open),
b) PA,
c) 45° oblique
d) hand-wrist films,
e) photographs,
f) study casts (with wax

g) height, weight, written treatment records (for
the annual series only),
h) and some medical histories.
The enlargement factor is 9.8% at the
midsagittal plane for all lateral films
The records were gathered under the direction
of Frank Popovich


3) The lowa Child Welfare Study
The Iowa Facial Growth Study is of the
diminishing longitudinal type.
The sample began with 20 male and 15 female
4-year-old subjects.
These sample sizes diminish toward age 17
years; exact figures are not available for each
age.

Most subjects were recalled at age 25 years.

In addition to lateral head films, PA films are
available.
The records were gathered by H. V. Meredith
who pricked the principal landmarks on each
film
Orthodontically treated subjects are not
included in the series.
• (Taken from the AJO-DO on CD-ROM (Copyright © 1997 AJO-DO),
Volume 1993 Jun (545 - 555): An inventory of growth record sets Hunter, Baumrind, and Moyers)
-------------------------------- www.indiandentalacademy.com

Importance of growth studies:

The analysis of many skeletal deformities can be
aided greatly by the application of the methods
referred to for the study of the growth at bones.
Although some of these methods lend
themselves primarily to experimental work on
animals, they nevertheless will contribute to our
fundamental knowledge of the subject and
thereby supply information which can be of
clinical importance. This will lead to both a
better understanding and more intelligent
treatment planning.

References:
1.Contemporary orthodontics: PROFFIT
2.Handbook of orthodontics: MOYERS
3.Dentofacial orthopedics with functional
appliances: GRABER, PETROVIC, RAKOSI
4ARTICLES:
•.Angle orthodontist; vol 52 no 2, april 1982
•AJO;vol 105 no 3, march 1994
•AJO; vol 112 no 1,2 , july 1997

•AJO;vol 56 no 5, 1969
•AJO;vol 55 no 6, 1969
•AJO; june 1993
•AJO;vol 58 no 6 , dec1970


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