Transcript Concept of Growth & Development

ORTD 431
2009, Lecture 2
From page 24-35 3dr addition profit
Concept of Growth & Development
part 1
Osama Abualnaja BDS,MS,Cert. Ortho,ABO
Email [email protected]
Lecture Outline
Growth pattern, variability and timing
Methods for studying Physical Growth:
1- Measurement approaches
2- Experimental approaches
Why we are studying growth


We cant comprehend condition observed in
adults without understanding the
development process that product these
problems
To distinguish normal variation from the
effects of abnormal or pathological
processes
Orthodontic treatment often involves
manipulation of skeletal growth, which
requires understanding of the normal general
concepts of physical growth and development
Growth & Development
• Growth is different from development
• Growth : increase in size or number
• Development : increase degree of
organization and specialization (increase in
complexity)
Growth is anatomical phenomena
Development is behavioral and physiological
phenomena
Growth : pattern ,variability &timing
- Pattern : in the general sense, it reflects
proportionality , usually of a complex set of
proportions rather than just a single
proportional relationship.
- In growth it represents proportionality , but in
a still more complex way
- It is the change in these proportions at a
point of time and overtime
Cephalocaudal Gradient of Growth
 It is an axis of increase growth extending from
the head toward the feet.
 It is reflects the normal growth pattern.
Growth pattern of tissue system
 Do all tissue in the body grow at the same
rate?
No
Not all the tissue systems of the body grow
at the same rate
Muscular and skeletal system
 Grow faster than brain and central nervous
systems which is shows in the decrease head
size.
 The overall pattern of growth is a reflection of
the various tissues making up the whole
organism.
 The cephalocaudal gradient in the head leads
to more growth of the facial than cranial
structures , and more of the mandible than
maxilla.
 One important aspect of pattern is
predictability
 Any change in growth pattern is considered as
an alteration in the expected changes in body
proportions.
Growth: pattern ,variability &timing
 Is the law of nature.
 Deviation from usual pattern.
 One way to measure variability in growth is to
compare a given child relative peers on
standard growth chart , which is derived from
large – scale studies of groups of children
Growth charts could be used in two
ways
1- to determine the location of the child relative
to the normal population
2- to follow a child over time so we can evaluate
whether there is unexpected change in
growth pattern
Variability and Timing
 Variability in growth arises from normal
variation , influences Outside the normal
experiences ( serious illnesses ) , and from
timing effect.
 Variation in timing arises because the same
event happens for different individuals at
different times or viewed differently.
 The biological clocks of different individuals
are set differently.
 Timing variation are particularity evident in
human adolescence , especially in girls.
 The onset of menstruation , often referred to
as menarche Gives an excellent indicator of the
arrival of sexual maturity.
Velocity curve Vs. distance curve
- Because of the time and variability ,
chronological age often is not a good indicator
of the individuals growth status
- It is more appropriate to measure age
biologically , in terms of progress toward
various developmental markers
( developmental, skeletal age , dental age)
Methods of studying physical growth
 Measurement approaches:
1- Craniometry : on dry skulls ( cross sectional only)
2- Anthropomtery: on living individuals. Cross
sectional and longitudinal .
3- Cephalometric radiography : more accurate ,
cross- sectional and longitudinal
4- Graphically in the form of the distance or velocity
curves or using various mathematical
transformations
Experimental approaches using
1. Different vital stains such as alizarin stain
2. Autoradiography and radioactive tracers.
3. Implant radiography.
Why do we study growth and
development?
1. Malocclusion and dentofacial deformities
arise through variation in the normal
developmental process , and so must be
evaluated against a perspective of normal
development.
2. Orthodontic treatment often involves
manipulation of skeletal growth, which
requires understanding of the general
concepts of physical growth and
development.