Concept of Growth & Development part 1

ORTD 431 2009, Lecture 2From page 24-35 3dr addition profit

Osama Abualnaja BDS,MS,Cert. Ortho,ABOEmail dr.naja@gmail.com

Lecture Outline

Growth pattern, variability and timingMethods for studying Physical Growth:

1 -Measurement approaches2 -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 phenomenaDevelopment 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 stain2 .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.