1. Growth and Development
Dr.Omar S.M.J.Ali
PhD Orthodontic

2. Growth and Development
Growth : increase in size or number
Development : an increasing degree of organization
Growth is largely an anatomic phenomenon,
whereas development is physiologic and behavior

3. Growth
increase in size
8 cm3
1 cm3

4. Development
Change in the ratio
1 cm3
1 cm3

5. Human G & D
8 cm3
1 cm3

6. GROWTH DEVELOPMENT Growth may or may not bring development
E.g.: A child may growth fat but becoming fat no functional improvement may take place
Development is possible without growth.
E.g.: A person may not gain height, weight or size but can functional improvement in other aspects.

7. In fetal life, at about the third month of intrauterine development,
the head takes up almost 50 % of the total body length
In contrast, the limbs are still rudimentary and the trunk is underdevelope

8. By the time of birth,
the trunk and limbs have grown faster than the head and face, so that the proportion of the entire body devoted to the head has decreased to about 30%.

9. Changes in proportions of the head and face during growth At birth, the face and jaws are relatively underdeveloped compared with their extent in the adult. As a result there is much more growth of facial than cranial structures postnatally

10. Teeth are unique: no change or growth after eruption.

11. The Nature of Skeletal Growth
At the cellular level, there are only three possibilities for growth;
Hypertroph: an increase in the size of individual cells
Hyperplasia: increase in the number of the cells
Secretion of extracellular material : contributing to an increase in size independent of the number or size of the cells themselves

12. secretion
HYPERPLASIA
proliferating cells
(cell division)
HYPERTROPHY
Increase in cell size
Extracellular matrix

13. Secrete extracellular material
Hypertroph
Hyperplasia
Secrete extracellular material
Skeletal
growth
Occur in

14. Growth and Development
Hyperplasia is a prominent feature of all forms of growth
Hypertrophy occurs in a number of special circumstances but is a less important mechanism than hyperplasia in most instances
Although tissues throughout the body secrete extracellular material, this phenomenon is particularly important in the growth of the skeletal system, where extracellular material later mineralizes.

15. Growth and Development
The fact that the extracellular material of the skeleton becomes mineralized leads to an important distinction between growth of the soft or non mineralized tissues of the body and the hard or calcified tissues.

16. Interstitial growth If the extracellular matrix is NOT mineralized,
secretion
HYPERPLASIA
proliferating cells
(cell division)
HYPERTROPHY
Increase in cell size
Extracellular matrix
If the extracellular matrix is NOT mineralized,
interstitial growth may continue in soft tissues and cartilages.

17. Growth and Development
Hard tissues are bones, teeth, and sometimes cartilages. Soft tissues are everything else. In most instances ,cartilage, particularly the cartilage significantly involved in growth, behaves like soft tissue and should be thought of in that group, rather than as hard tissue.

18. Growth and Development
Interstitial growth
Growth of soft tissues occurs by a combination of hyperplasia and hypertrophy.
These processes go on everywhere within the tissues, and the result is what is called interstitial growth, which simply means that it occurs at all points within the tissue.

19. Growth and Development Interstitial growth
Secretion of extracellular material can also
accompany interstitial growth, but hyperplasia primarily and hypertrophy secondarily are its characteristics

20. Growth and Development
Interstitial growth
Interstitial growth is a prominent aspect of overall skeletal growth because a major portion of the skeletal system is originally modeled in cartilage. This includes the basal part of the skull as well as the trunk and Iimbs.

21. Growth and Development
Development and maturation of the chondrocranium (cartilage: light blue, bone: stippled dark blue)
A , Diagrammatic representationa t about 8 weeks
B. , Skeletal development at 12 weeks.

22. Growth
Development
Hypertroph
Hyperplasia
extracellular material
Interstitial growth