Prenatal influence on facial development

1. PRENATAL
INFLUENCE ON
FACIAL development
BY AHMED ALKHAIR

2. prenatal development
•also known as antenatal development.
• is the development of the embryo
following fertilization, and continued as
fetal development.

3. PRENATAL DEVELOPMENT
PHASES
• The prenatal life of an individual can be classified into the
following three phases :-
1. Period of ovum (from fertilization to the 14th day) .
2. Period of embryo (from 14th to 56th day) .
3. late fetal development & birth (56th day to birth).

4. PRENATAL INFLUENCE
•any impact on the growing organism
between conception and birth.

5. IN DENTISTRY !!
•A general understanding of the formation of
the face and the prenatal development are
particularly pertinent to orthodontic problems
later in life

6. Embryologic development
early stages of prenatal development .
Is the process by which the embryo forms and develops..
• nearly all the tissues of the face and neck originate from
ectoderm this include the muscular and skeleton element .
• Most of the facial tissues develop from The neural crest
cells .

7. Stages of embryologic development
stage time Related syndrome
Germ layer formation Day 17 Facial alcohol syndrome
Neural tube formation Days 18-23 anencephaly
Migration of cells population Days 19-28 Hemi facial microsomia
Teacher Collins syndrome
Limb abnormality
Formation of organ system
Primary palate
Secondary palate
Days 28-38
Days 42-55
Cleft lip and or palate
Final differentiation of tissue Day 50-birth Synostosis syndrome

8. FACIAL DEVELLOMENT
• Neural cells migrate downward beside the neural
tube and laterally under the surface ectoderm .
• After the neural cells completed their migration
facial growth dominated by regional growth centers
and the final differentiation of tissue occur .

9. FACIAL DEVELLOMENT
• At the completion of the migration of the neural crest
cells , they form practically all of the loose
mesenchymal tissue in the facial region ,eye and most
of the mesenchyme in the mandibular arch.
• Most of the neural crest cells in the facial area later
differentiate into skeletal and connective tissues,
including the bones of the jaw and the teeth.

10. FIRST STAGE
INFLUENCE
Germ layer formation

11. Facial alcohol syndrome
• Syndrome caused by exposure to very high blood alcohol levels during the first trimester of
pregnancy.
• Features
1. abnormal appearance .
2. short height .
3. low body weight .
4. small head size .
5. behavior problems .

13. THIRD STAGE INFLUENCE
• Many of the problems that result in craniofacial
anomalies arise in the third stage of development !!??
Because most structures of the face are derived from
FORMATION and MIGRATION OF neural crest cells .
• interferences with this migration produce facial
deformities

14. CONT ..
drugs affect the formation and/or migration
of neural crest cells
1. exposure to thalidomide .
2. anti-acne drug (Accutane) .

15. Treacher Collins' syndrome
(mandibulo-facial dysostosis)
• congenital syndrome.
• both the maxilla and mandible -are underdeveloped as a
result of a generalized lack of mesenchymal tissue .
• the problem arises because of excessive cell death in the
trigeminal ganglion, which secondarily affects neural
crest- cells formation.

16. • a generalized lack of
mesenchymal tissue in the
lateral part of the face is the
major cause of this facial
appearance .
• Note the underdevelopment
of the lateral orbital and
zygomatic areas.
• The ears also may be
affected .

17. Hemifacial microsomia
• Unilateral and an asymmetrical problem .
• Characterized by a lack of tissue on the affected side typically ( external
ear , ramus of the mandible and soft tissue ) .
• Arises from early loss of neural crest cells .
• Defect in the great vessels ( aorta , pulmonary artery , aortic arch ) are
common in children with hemifacial microsomia .
• Midline facial defect (including cleft ) rarely are part of this syndrome.

18. The external ear and the ramus of the
mandibular are deficient or absent on the
affected side .

19. 4th STAGE INFLUENCE
Formation of organ system
Primary palate
Secondary palate

20. Cleft lip
• The most common congenital defect involving the face and jaw .
• Clefts arise during the 4th developmental stage when some interference with
development occurred .
• cause failure of fusion between the median and lateral nasal processes .
• Location determined by the site at which various facial process failed to fuse .
• Usually about 60% of individual with cleft lip also have cleft palate .

22. FINAL STAGE
INFLUENCE
Final differentiation of tissue

23. Synostosis syndrome
• Cause early closure of the sutures between the cranial and facial bone .
• Crouzon’s syndrome is the most frequently occurring member of this group
• Characterized by :
1. Underdevelopment of the midface .
2. Eyes that seem to bulge from their sockets .

24. LATE FETAL DEVELOPMENT &
BIRTH
• By the third trimester the fetus Wight is about 1000gms and during the last 3
month continued rapid growth result in tripling of body mass about
3000gms .
• Dental development which begins in the third month proceeds rapidly.
• Development of all primary teeth and the permanent first molar start well
before birth .
• Growth disturbance after birth will leave visible record on enamel .

25. REFERENCE
• TEXTBOOK OF ORTHODONTIC (G.SINGH)
SECOND EDITION .
• CONTEMPARARY OF ORTHODONTIC
(PROFIT) THIRD EDITION.