Methods of growth study,theories /certified fixed orthodontic courses by Indian dental academy

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INDIAN DENTAL ACADEMY
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METHODS OF STUDYING
PHYSICAL GROWTH
 MEASUREMENT APPROACHES
-Craniometry
-Anthropometry
- Cephalometric radiography
 EXPERIMENTAL APPROACHES
-Vital staining
-Autoradiography
-Radioisotopes
-Implant radiography

 Measurement approach –
Based on techniques of measuring living
animals ( including humans ) , with the
implication that measurement itself will do no
harm that the animal will be available for
additional measurements at another time.
 Experimental approach -
This approach uses experiments in which
growth is manipulated in some way . The
study may destructive . For this reason it
restricted to non human species.

Experimental Approaches
1. Vital staining .
2. Radio isotopes .
3. Implants .
4. Autoradiography .
5. Micro-radiography .
6. Comparative anatomy .
7. Genetic study .
8. Natural markers .
9. Split – line technique .
10. Laminography .
11. Photographic analysis .
12. Study models .
13. Facial masks .
14. Silhouette method .
15. Hand – wrist radiograph .
16. Physioplanes .
17. Stereophotographmetry .www.indiandentalacademy.com

Experimental Approaches
1. Vital staining –
- originated by John Hunter .
- Belcher 1736 reported that bones of animals which have eaten matter plant were stained red.
growth is studied by observing the pattern of stained mineralized tissue after the injection of
dyes into the animals .
- commonly used dyes – Alizarin red 5
Acid alizarin blue
Trypon blue
Tetracycline
Lead acetate
99mTc ( recently used radio tropic tracers )
- Alizarin reacts strongly with calcium at sites where bone calcification is occurring and thus
marks the location where active growth was occurring.
- advantage – reveals the manner in which bone is laid down , the site of growth , the direction of
growth , relative duration at different sites and timings of growth.
- disadvantage – does not provide direct evidence of bone resorption.

CRANIOMETRY
 Involves measurement of skulls found among
human skeletal remains.
 Advantage-precise measurements can be
made on dry skulls.
 Disadvantage-growth study can only be cross
sectional.

ANTHROPOMETRY
 Involves measurement of skeletal dimensions
on living individuals.
 Various landmarks established in the studies
of dry skull are measured in living individuals
by using soft tissue points overlying these
bony landmarks.
 Advantage-Longitudinal study, hence growth of
an individual can be followed directly over a
period of time.

CEPHALOMETRIC
RADIOGRAPHY
 Technique that depends on a precise
placement of the individual in a cephalostat so
that the head can be precisely oriented.
 Advantage-combines the advantages of both
Craniometry & anthropometry in that direct
bony measurements as seen on the
radiograph can be made over a period of time
for same individual.
 Disadvantage-produces 2D image of 3d
object.

AUTORADIOGRAPHY
- It is a technique in which a film emulsion is
placed over a thin section of tissue
containing radioactive isotopes and then
exposed in the dark by radiation. After the
film is developed , the location of the
radiation that indicates where growth is
occurring can be observed by looking at
the tissue section through the film .

RADIOISOTOPES
- these elements when injected into the
tissues , get incorporated in the developing
bone and act as in vivo markers and can be
located by means of a Geiger counter .
- e.g. 99mTc .
Ca-45 labeled protein – proline .
Phosphorus – 32 .
Technitium – 33 .

IMPLANTS
- Bjork and co-workers extensively used this
technique .
- Here in , inert metal pins ( generally made of
titanium ) are inserted in the bone anywhere
in bony skeleton including face and jaws .
- These serve as reference markers during
superimposing of radiographs and allow
precise observation of both changes in the
position of one bone relative to another and
changes in the external contour of individual
bone

Site for Implant Placement
 In mandible –
1. Midline below root tips of anterior teeth.
2. Two pins on either side of the mandibular
body , one pin 1st premolar and other
below 2nd premolar .
3. On ramus at level with occlusal surfaces
of molars.

Methods of Collecting Growth Data
1. Longitudinal Study –
- involves gathering data of a given individual or subject
over varying periods of time at regular intervals .
- advantages –
1. serial comparisons can be done .
2. any mistakes in measuring at a given time are seen
more easily and corrections can be made more
properly .
- disadvantages –
1. time – lengthy .
2. expenses - costly .www.indiandentalacademy.com

2. Cross – Sectional study –
- involves gathering data from observing different samples
studied at a particular time .
- advantages –
1. time - faster .
2. cost – less expensive .
3. method allow repeating studies more easily .
- disadvantages –
1. it must be assume that the groups being measured are
similar .
2. this type of study tends to obscure individual variation .

THEORIES OF GROWTH
CONTROL
1. Genetic Theory .
2. Sutural Dominance Theory .
3. Scott’s Hypothesis .
4. Functional Matrix Thoery .
5. Neurotropism .
6. Enlow and Bang’s “V” shaped Principle or
Area Location Theory .
7. Petrovic’s Hypothesis or Servosystem
Thoery .

GENETIC THEORY-Wendell &
Wiley
 One of the earliest theories (early 1900’s ) .
 It states that cranial differentiation is largely
genetically determined and is preplanned .
Cartilages & facial sutures are under genetic control
& brain determines the vault dimensions. This they
termed as Orthodontic calvinism . E.g. Hapsburg jaw
and prognathic mandible.
 Malocclusion could be produced by inherited
characteristics in two major possible ways :
1. An inherited proportion between the size of teeth
and size of jaw producing crowding or spacing of
teeth .
2. Inherited proportion between size or shape of upper
jaw causing improper occlusal relationship .www.indiandentalacademy.com

SICHER’S SUTURAL
DOMINANCE THEORY (1952)
 He believed that most of the cranio-facial growth occurs at the
sutures . The theory implies that genetic control is expressed
directly at the level of bone . The primary event in sutural
growth is proliferation of connective tissue and its replacement
by bone in the sutures .
Following evidences were against the theory :
1. When an area of sutures between two facial bones was
transplanted to another location ( e.g. to a pouch in the
abdomen ) the tissue does not continue to grow . This
indicates the lack of innate growth potential in the sutures .
2. It can be seen that sutures respond to outside influence . If
mechanically pulled apart bone will fill in making them larger
than normal . If compressed growth at that side will be
impeded . Thus sutures must be considered areas that react
and not the primary determinate of growth .
3. In untreated cases of cleft palate , though suture is not present
growth still takes place .
4. Occurrence of microcephaly and hydrocephaly raises the

SCOTT’S CARTILAGENOUS
HYPOTHESIS (1950)
 It stated that the growth controlling factors are
present in the cartilage , periosteum with the
sutures being secondary. According to him
cartilaginous part of the skull must be considered
as primary growth centers with nasal septum
contributing to major portion of the maxilla.
 Following evidences supported the theory :
1. Atraumatic resection of nasal septum ( rabbit ) ,
leads to significant interference in growth of the
midface or maxilla .
2. In cases of cleft palate where there is no suture ,
the growth still takes place .

FUNCTIONAL MATRIX THEORY
(1962)
 It was given by Melvin Moss in 1960’s and was
based on the functional cranial component theory
of Vander Klaauw .
 It states that the form of the cranial skeletal
tissues ( e.g. size and shape ) is always a
response to the spatial , mechanical and energy
demands of all the tissues , organs and cranial
spaces . Here function is dominant .
 He stated that head is the region where relatively
independent functions are carried out by
functional components .
 The functional cranial component is divided into :

Functional Cranial Component
Skeletal Unit Functional Matrices
Micro-skeletal Macro-skeletal Periosteal
Capsular
Unit Unit Matrices Matrices

Functional Cranial Component
(Ex : Mandible )
Skeletal Unit Functional Matrices
Micro-skeletal Macro-skeletal Capsular Periosteal
Unit Unit Matrices Matrices
Ex : Coronoid Ex : Mandible Ex : Oral Capsule Ex :
Muscles
Acts on Acts on
Macro-skeletal Micro-skeletal
Unit Unit
Brings about Brings about
Passive Growth Active Growth
or or
Translation Transformation

Neurotrophism
 It is a non-impulse transmitting neural function that
involves axoplasmic transport , and provides for long
term interactions between neurons and innervated
tissue that homeostatically regulate the morphological ,
compositional and functional integrity if those tissues .
The actual nature of neurotrophic substance and its
mode of action is not known at present .
 Moss indicates three general categories :
1. Neuro-epitelial trophism .
2. Neuro-visceral trophism .
3. Neuro-muscular trophism .

Enlow and Bang’s “V” shaped
Principle
 In “V” shaped theory , when the direction of
movement is towards the wide end of “V” ,
bone deposition occurs on the inner sides of
the “V” and resorption occurs on the outer
surfaces . As growth takes place there is
overall increase in dimensions .

Enlow’s “V” Principle

Petrovic’s Hypothesis (1967)
( Servosystem )
 According to Petrovic using the language of
Cybernetics , he said that it is the interaction of a
series of casual changes and feedback
mechanism which determines the growth of
various craniofacial regions .
 Cybernetics is the science of communication and
control theory that is concerned with the
comparitive study of autonomic control systems .
For ex : as the nervous system and brain ,
mechanical-electrical communication systems .

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