by dr rupali , pediatric dentist

1. GOOD MORNING

2. Dr. Rupali M Athawale
IInd Yr MDS

3.  Definition
 Fundamentals of growth & development
• Prenatal Growth
• Postnatal Growth
 Methods for studying physical growth
 Genetic influences on growth
 Nature of skeletal growth
 Sites and Types of Growth in Craniofacial
Complex
 Theories of Growth Control
 Clinical considerations

4.  Stewart (1982) : Developmental increase in mass
 Profitt (1986) : Increase in size or number
 Moyer (1988) : Changes in amount of living
substance
 Moss () : Change in any morphological
parameter which is measurable

5.  Todd (1931) : Increase in size
 JS Huxley : Self multiplication of living
substance
 Stedman (1990) : Increase in a size of a living
being or any of its parts, occuring in the
process of development
 Pinkham (1994) : Growth signifies an increase,
expansion of any given tissue

6.  Todd (1931) : Increase in complexity
 Moyers (1988) : Naturally occuring unidirectional changes
in the life of an individual from its existence as a single cell
to its elaboration as a multifunctional unit terminating in
death
 Pinkham (1994) : Development addresses the progressive
development of tissue
 Enlow () : A maturational process involving progressive
differentiation at the cellular & tissue levels

7.  Growth is basically an anatomic phenomenon &
quantitative in nature
 Development is basically a physiologic
phenomenon & qualitative in nature

8.  Prenatal growth
1) Period of ovum: From time of fertilization till 1 week
2) Period of embryo: 2-8 week
3) Period of fetus: 9th week onwards till birth
 Postnatal growth
 Maturity
 Old age

9. • After fertilization of ovum, a series of cell divisions give rise
to an egg cell mass – MORULA
• Outer cell layer (trophoblast)
• Inner cell mass (embryoblast):
Epiblast  embryo Hypoblast  placenta

10. • Anterior end of primitive
streak  ENDODERM
(lower germ layer)
• Perspective mesodermal cells
migrate from epiblast through
primitive streak to form
MESODERM (middle germ
layer)
• Cells remaining in epiblast
form ECTODERM, completing
formation of 3 germ layers
Ps : primitive streak
Pp : prechodral plate
N : notochord
Op : olfactory placode
Ef : eye field
B : buccal plate

11. • Median strip of mesoderm cells (chordamesoderm)
extending throughout length of embryo induces
NEURAL PLATE formation within overlying ectoderm
• Chordamesoderm also responsible for developing
organizational plan of head
• Mesodermal portion  somites  myoblasts  skeletal
& CT of head

12. • Unique population of cells
develop from ectoderm
along lateral margins of
neural plate – NEURAL
CREST CELLS
• Migrate in the trunk region
form mostly neural,
endocrine & pigment cells
• Migrate in head & neck
also contribute to skeletal
& connective tissues
(cartilage, bone, dentin,
dermis, etc)

13. (In the trunk all skeletal & connective tissues are formed
by mesoderm)
• Of the skeletal or CT of facial region, tooth enamel
(acellular skeletal tissue) is the only one not formed by
crest cells
• Enamel forming cells - derived from ectoderm lining oral
cavity

14. • Pharyngeal region is then
characterized by grooves
(clefts & pouches) in
lateral pharyngeal wall
endoderm & ectoderm
that approach each other,
appear to segment
mesoderm into a number
of bars that become
surrounded by crest
mesenchyme
• Trailing edge of crest cell
mass appears to attach
itself to neural tube at
locations where sensory
ganglia of 5th, 7th, 9th, 10th
cranial nerves will form

15. • Capillary endothelial cells derived from mesoderm cells
invade crest cell mesenchyme from which supporting cells
of developing blood vessels are derived
• Later additional crest cells differentiate into fibroblasts &
smooth muscle cells that will form vessel wall
• Developing blood vessels become interconnected to form
vascular networks

16. • All myoblasts that subsequently
fuse with each other to form
multinucleated striated muscle
fibres derived from -- mesoderm
• Myoblasts that form hypoglossal
muscles derived from ---- somites
located besides developing
hindbrain (Mesodermal portion 
somites  myoblasts  skeletal & CT of
head)
• Myoblasts of extrinsic ocular
muscles originate from --
prechordal plate (pp)

17. • A number of other structures in facial region such as
epithelial components or glands & enamel organ of tooth
bud, are derived from epithelium that grows into
underlying mesenchyme
• CT components (fibroblasts, odontoblasts, cells of tooth
supporting tissues) derived from -- neural crest cells

18. Ectodermal cells
•Nervous system
•Epidermis & its
appendages (hair, nails,
sebaceous -sweat glands)
•Epithelium lining oral
cavity, nasal cavities &
sinuses
•Part of intraoral glands
•Enamel of teeth
Endodermal
cells
•Epithelial lining
of GIT & all
associated
organs
Mesodermal cells
•Muscles & all
structures derived
from connective tissue
(bone, cartilage, blood,
dentin, pulp,
cementum , PDL

19. • On the completion of initial crest cell migration &
vascularization of derived mesenchyme, a series of
outgrowths or swellings termed as facial prominences
initiates next stages of facial development
• Growth & fusion of upper facial prominences produce
primary & secondary palates

20. • After crest cells arrive in future
location of upper face &
midface – frontonasal region
• 1st structures to become evident
: olfactory placode
Thickenings of ectoderm that
appear to be derived atleast
partly from anterior rim of
neural plate

21. • Lateral edges of placodes
actively curl forward, which
enhance initial development of
lateral nasal prominence (LNP)
• High rates of cell proliferation
rapidly brings LNP forward so
that it catches up with medial
nasal prominence (MNP)
• Before that contact has made,
maxillary prominence (MxP)
has already grown forward
from its origin at the proximal
end of 1st visceral arch to merge
with LNP & MNP

22. • All these 3 prominences contribute to initial separation of
developing oral cavity & nasal pit, called as primary palate
• Primary palate forms roof of anterior portion of primitive oral
cavity, as well as forming initial separation between oral and
nasal cavities
• In later development derivatives of primary palate form
portions of upper lip, anterior maxilla & upper incisor teeth

23. • New outgrowths from medial
edges of maxillary prominences
form shelves of secondary palate
• At 9th gestational week, shelves
fuse each other above tongue
• Eventually, most of the hard
palate & all of the soft palate
form from secondary palate

24. • Pituitary gland develops as a
result of inductive interactions
between ventral forebrain & oral
ectoderm , derived in part from
both tissues
• Following initial crest cell
migration, these cells invade area
of developing pituitary gland &
are continuous with cells that will
later form maxillary prominences
• Eventually, crest cells form CT
components of gland

25. • In humans there are total of 6
visceral arches, of which 5th is
rudimentary  Pharyngeal or
branchial arches
• Proximal portion of 1st
(mandibular) arch becomes
maxillary prominence
• As heart recedes caudally,
mandibular (1st) & hyoid (2nd)
arches develop further at their
distal portions to become
consolidated in ventral midline

26. • Mesoderm of mandibular (1st) & hyoid arches (2nd)  5th
(trigeminal) & 7th (facial) nerve musculature
• Mesoderm of less well developed 3rd & 4th arches  9th
(glassopharyngeal) & 10th (vagus) nerve musculature
• Myoblasts from 2nd arch, take branches of 7th cranial nerve
& migrate very extensively throughout head & neck to
form contractile components of muscles of facial
expression

27. • Myoblasts from 1st arch contribute mostly to
muscles of mastication, while those from 3rd &
4th arches contribute to pharyngeal & soft palate
musculature
 Crest mesenchymal cells -
• skeletal components : temporary visceral arch
cartilages, middle ear cartilages & mandibular
bones
• Connective tissue components : dermis & CT of
tongue

28. • Anterior 2/3rd of tongue is covered by ectoderm, posterior
1/3rd by endoderm
• Thyroid gland forms by invagination of most anterior
endoderm (thyroglossal duct)
• Residual pit (foramen caecum) left in epithelium at site of
invagination marks junction between anterior 2/3rd &
posterior 1/3rd of tongue covered by ectodermal &
endodermal origin resp
• CT components -
• Anterior 2/3rd from 1st arch
• Posterior 1/3rd from 3rd arch

29. • Finally a lateral extension from inner groove
between 1st & 2nd arch gives rise to eustachian
tube which connects pharynx with ear
• External ear or pinna is formed atleast partially
from tissues of 1st & 2nd arches

30.  Pattern
• Reflects proportionality
• Physical arrangement of
body at any one time is a
pattern of spatially
proportioned parts
• After 3rd month of fetal
life, proportion of total
body size contributed by
head & face steadily
declines

31. • 3rd month IU development, head - 50%of total body length
• Cranium is large relative to face , >half of total head
• In contrast, limbs are rudimentary & trunk is
underdeveloped
• By birth, trunk & limbs have grown faster than head and
face, so that proportion of the entire body devoted to the
head has decreased to about 30%
• Reflects “Cephalocaudal gradient of growth”
Axis of increased growth extending from head towards feet

32. • Not only within the body, but also within the face, it is
seen
• From that perspective, it is not surprising that mandible,
being farther away from brain tends to grow more &
later than the maxilla, which is closer

33. • Another aspect of normal growth pattern & reason for
gradients of growth is different tissue systems that grow
at different rates are concentrated in various parts of body
Scammon's curves for
growth, 4 major tissue
systems
• Neural tissues : 6 - 7 yrs
• General body tissues (muscle, bone, &
viscera) : S-shaped curve, with a definite
slowing of rate of growth during
childhood & an acceleration at puberty
• Lymphoid tissues : 200% of adult
amount in late childhood, then undergo
involution at the same time that growth
of the genital tissues accelerates rapidly

34.  Second important concept in study of growth &
development is variability ( by evaluating a given child
relative to peers on a standard growth chart )
 A final major concept in physical growth and
development is timing
• All children undergo a spurt of growth at adolescence,
which can be seen more clearly by plotting change in
height or weight, but growth spurt occurs at different
times in different individuals

35. - Defined as periods of sudden growth acceleration
- Sex-linked
 Just before birth
 1 year after birth
 Infantile spurt – 3 years age
 Mixed dentition growth spurt :
Females : 7-9 years, males : 8-11 years
 Pre-pubertal growth spurt :
Females : 11-13 years, males : 14-16 years
• Surgical correction should be carried out only after cessation of growth
spurts

36. Measurement Approaches - Acquiring Measurement Data
 Craniometry –
• Originally used to study Neanderthal & Cro-Magnon
people whose skulls were found in European caves in 18-
19th centuries
• Based on measurements of skull

37. • Anthropometry –
• Landmarks established in studies of dry skulls are
measured in living individuals simply by using soft tissue
points overlying these bony landmarks
• It is possible to measure length of cranium from a point at
the bridge of nose to a point at the greatest convexity of
rear of skull
 Cephalometric Radiology –
• It allows a direct measurement of bony skeletal
dimensions, since bone can be seen through soft tissue
covering in a radiograph
 Three-Dimensional Imaging –
• Computed axial tomography, Cone beam CT

38. Experimental Approaches - Vital Staining
• English anatomist John
Hunter in 18th century
• Alizarin (dye) reacts
strongly with Ca at sites
where bone calcification is
occurring
• Gamma-emitting isotope 99mTc can be used to detect areas
of rapid bone growth in humans, but these images are more
useful in diagnosis of localized growth problems than for
studies of growth patterns

39.  Implant Radiography (Arne Björk)
• Inert metal pins are placed in bones anywhere in the skeleton,
including face & jaws
• These metal pins are well
tolerated by skeleton, become
permanently incorporated
into bone without causing any
problems & are easily
visualized on a cephalogram
• 6 maxillary & 5 mandibular
tantalum implants ->>>>>>

40. • Homeobox Msx genes - Establishment of body plan, pattern
formation & morphogenesis, expressed differentially in
growth of the mandible
• Msx1 - basal bone
• Msx2 - alveolar process
• Decrease in Hedgehog pathway activity causes
holoprosencephaly (failure of the nose to develop) &
hypotelorism
• Excessive activity causes hypertelorism & frontonasal
dysplasia
• It is estimated that about 2/3rd of 25,000 human genes play a
role in craniofacial development

41. • At the cellular level, there are only 3 possibilities for
growth
1. Increase in the size of individual cells – Hypertrophy
2. Increase in the number of the cells – Hyperplasia
3. Secretion of extracellular material - Contributing to an
increase in size independent of number or size of cells
themselves

42. Growth of soft tissues : Hyperplasia & hypertrophy
Interstitial growth
(characteristic of soft tissues & uncalcified cartilage)
Direct addition of new bone to surface of existing bone can
occur through the activity of cells in periosteum (soft
tissue membrane that covers bone)
Direct or Surface apposition of bone

43. • 3rd month IU - Cartilaginous skeletal development
occurs most rapidly
• A continuous plate of cartilage extends from nasal
capsule posteriorly to foramen magnum at the base of
skull

44. • 4th month IU, ingrowth of blood vascular elements into
various points of chondrocranium -- become centers of
ossification -- cartilage is transformed into bone
Endochondral ossification (mandible)
• Not all bones of the adult skeleton were represented in
embryonic cartilaginous model
• It is possible for bone to form by secretion of bone matrix
directly within connective tissues, without any intermediate
formation of cartilage
Intramembranous ossification
(cranial vault & both jaws)

45. • Development of mandible begins as a condensation of
mesenchyme just lateral to Meckel's cartilage proceeds
entirely by intramembranous bone formation
• Meckel's cartilage disintegrates & largely disappears as the
bony mandible develops
• Remnants -- conductive ossicles of middle ear
• Perichondrium -- sphenomandibular ligament

46. • Condylar cartilage - secondary cartilage, which is
separated by a considerable gap from the body of
mandible
• Early in fetal life, it fuses with developing mandibular
ramus
A) Separate areas of mesenchymal
condensation at 8 weeks
B) Fusion of cartilage with the
mandibular body at 4 months
C) Situation at birth

47. • Maxilla forms from center of mesenchymal condensation
in maxillary process, located on lateral surface of nasal
capsule
• Endochondral ossification does not contribute directly to
formation of maxillary bone
• An accessory cartilage, zygomatic or malar cartilage
totally replaced by bone well before birth, unlike
mandibular condylar cartilage, which persists

48. • Balance of apposition & resorption with new bone being
formed in some areas while old bone is removed in
others, is an essential component of the growth process
• Formation of new bone from a cartilaginous predecessor
or direct bone formation within mesenchyme often is
referred to as modeling
• Changes in shape of this new bone due to resorption &
replacement are referred to as remodeling

49. • Cranial vault (bones that cover upper & outer surface of
brain)
• Cranial base (bony floor under brain, which is dividing
line between cranium face
• Nasomaxillary complex (nose, maxilla & associated small
bones
• Mandible

50.  Cranial Vault
• Intramembranous bone formation
• Remodeling & growth occur primarily at periosteum-lined
contact areas between adjacent skull bones i.e. cranial sutures
• At birth, flat bones of skull are widely separated by loose
connective tissues
• These open spaces, fontanelles, allow considerable amount
of deformation of skull at
birth -important in
allowing relatively large
head to pass through
birth canal

51.  Cranial Base
• In contrast to cranial vault, bones of cranial base are
formed initially in cartilage -- bone by endochondral
ossification
• Centers of ossification appear early in embryonic life
• As ossification proceeds, bands of cartilage (synchondroses)
remain between centers of ossification

52. • Growth sites :
1. Intraoccipital synchondrosis
2. Spheno-occipital synchondrosis (sphenoid & occipital)
3. Intersphenoid synchondrosis (2 parts of sphenoid bone)
4. Spheno-ethmoidal synchondrosis (sphenoid & ethmoid)

53.  Maxilla (Nasomaxillary Complex)
• Postnatally entirely by intramembranous ossification
• Since there is no cartilage replacement, growth occurs
1) Apposition of bone at the sutures that connect maxilla to
cranium & cranial base
2) Surface remodeling
• Growth pattern of face requires that it grows “out from
under the cranium”
1) By a push from behind created by cranial base growth
2) By growth at sutures

54. • Upto about age 6, displacement from cranial base growth is
an important part of maxilla's forward growth
• Failure of cranial base to lengthen normally, as in
achondroplasia & several congenital syndromes  midface
deficiency
• At about age 7, cranial base growth stops, then sutural
growth is the only mechanism for bringing maxilla forward
• The overall growth changes are result of both a downward
& forward translation of maxilla & simultaneous surface
remodeling

55. • As the maxilla is carried
downward- forward, its
anterior surface tends to resorb
• Resorption surfaces - dark
yellow
• Only a small area around
anterior nasal spine – exception
• Maxilla is like platform on
wheels, being rolled forward,
while at the same time its
surface (wall in cartoon) is
being reduced on its anterior
side and built up posteriorly,
moving in space opposite to the
direction of overall growth

56.  Mandible
• In contrast to maxilla, both endochondral & periosteal activity
are important in growth of mandible
• Displacement created by cranial base growth that moves TMJ
-- negligible role

57.  Overall pattern of growth of mandible :
1. If cranium is reference area-- chin moves downward-
forward
2. If data from vital staining experiments -- principal sites of
growth of mandible are the posterior surface of ramus
and condylar & coronoid processes
• There is little change along anterior part of the mandible
(correct)

58. • As a growth site, chin is almost
inactive
• It is translated downward-
forward, as the actual growth
occurs at mandibular condyle &
along the posterior surface of
ramus
• Body of mandible grows longer by
periosteal apposition of bone only
on its posterior surface
• Ramus grows higher by
endochondral replacement at the
condyle accompanied by surface
remodeling
• Conceptually, it is correct to view
mandible as being translated
downward- forward, same time
increasing in size by growing
upward-backward
• Translation occurs largely as the
bone moves downward- forward
along with the soft tissues in
which it is embedded

59. • In infancy, ramus is located at spot where primary first
molar will erupt
• Progressive posterior remodeling creates space for second
primary molar then for sequential eruption of permanent
molar teeth
• However, this growth ceases before enough space has
been created for eruption of third permanent molar,
which becomes impacted in ramus

60. Facial Soft Tissues
 Growth of Lips :
• Lips trail behind growth of jaws prior to adolescence, then
undergo a growth spurt to catch up
• Lip height is relatively short -- mixed dentition years
• Lip separation at rest (lip incompetence) is maximal - childhood
Decreases during - adolescence
• Lip thickness reaches its maximum during - adolescence,
decreases—to the point in their 20s and 30s

61.  Growth of Nose :
• Growth of nasal bone is complete at age 10
• Nose becomes more prominent at adolescence, especially in
boys
• The lips are framed by the nose above & chin below, both of
which become more prominent with adolescent &
postadolescent growth, while lips do not, so relative
prominence of lips decreases
• This can become an important point in determining how
much lip support should be provided by teeth at the time
orthodontic treatment typically ends in late adolescence

62.  Genetic theory (Brodie):
• All growth is controlled by genetic influence & is
preplanned
 Sutural theory (Sicher):
• Craniofacial growth occurs at the sutures
• Paired parallel sutures that attach facial areas to skull &
cranial base region push nasomaxillary complex
forwards to pace its growth that of mandible

63.  Cartilagenous theory ( James Scott) :
• Intrinsic growth controlling factors are present in cartilage &
periosteum with sutures being only secondary
• Acc to scott, nasal septal cartilage is pacemaker for growth of
entire nasomaxillary complex
• Mandible is considered as diaphysis of long bone, bent into
horseshoe shape with epiphysis removed so that there is
cartilage constituting half an epiphyseal plate at the ends,
which are represented by condyles

64.  Functional matrix concept (Melvin Moss) :
• Theorized that growth of face occurs as a response to
functional needs & neurotrophic influences, is mediated by
soft tissue in which jaws are embedded
• In this conceptual view, the soft tissues grow, and both
bone-cartilage react to this form of epigenetic control
• All tissues, organs & functioning spaces taken as a whole
comprise the functional matrix, while skeletal tissues
related to specific tissues related to this specific functional
matrix comprise the skeletal unit

65. • All skeletal tissues originate, grow & function completely
embedded in their several matrices
• Thus, changes in size, shape & spatial position of all
skeletal units including their very maintenance is due to
operational activity of their related functional matrices

66.  Multifactorial theory (Von limborgh) :
• 5 factors –
• Intrinsic epigenetic F, genetic control of skeletal units
themselves
• Local epigenetic F : Bone growth determined by genetic
control originating from adjacent structures like brain,
eyes
• General epigenetic F determining growth from distant
structures. Eg. Sex hormones, growth hormone

67. • Local environmental F : non-genetic factors
from local external environment
Eg. Habits, muscle force
• General environmental F, general non-genetic
influences such as nutrition, oxygen

68.  Enlow’s expanding V principle
• V shaped pattern of growth, result of differential
deposition & selective resorption of bone
• Bone deposition on inner side
• Bone resorption on outer surface
• Eg. Base of mandible, ends of long bones,
mandibular body, palate, etc

69.  Enlow’s counterpart principle
• It states that growth of any given facial or cranial part relates
specifically to other structural & geometric counterparts in
face & cranium
Examples :
• Nasomaxillary complex relates to anterior cranial fossa
• Horizontal dimension of pharyngeal space relates to middle
cranial fossa
• Counterparts : Middle cranial fossa & breadth of ramus,
Maxillary tuberosity & lingual tuberosity
• Mutual counterparts : Maxillary & mandibular arches, Bony
maxilla & corpus of mandible

70.  Neurotrophic process in oro-facial growth :
• Neurotrophism is a non-impulse transmitting neural function
that involves axoplasmic transport & provides for long term
interaction between neurons & innervated tissues that
homeostatically regulates morphological, compositional &
functional integrity of those tissues
Types :
• Neuro-epithelial trophism
• Neuro-visceral trophism
• Neuro-muscular trophism

71. Aberrations in embryonic facial development lead to
wide variety of defects. Defects of primary & secondary
palate development are most common
 Facial celfts
• Increase in clefting rates associated with children born to
epileptic mothers undergoing phenytoin (dilantin)
therapy & to mothers who smoke cigarettes (due to
hypoxia)

72.  Hemifacial microsomia :
• Underdevelopment & abnormalities of TMJ, external &
middle ear, also parotid gland & muscles of mastication
• 3rd most common group of major craniofacial
malformations
• Also found from use of acne drug retinoic acid (accutane)
in pregnant women, also who had taken drug
thalidomide

73.  Treacher collin’s syndrome (mandibulofacial
dysostosis):
• Underdevelopment of tissues derived from maxillary,
mandibular, hyoid prominences
• External, middle, inner ear are often defective, clefts of
secondary palate found
• Excessive doses of retinoic acid (accutane)
 Labial pits :
• Small pits may persist on either side of midline of lower lip
• Due to failure of embryonic labial pits to disappear

74.  Lingual anomalies :
• Median rhomboid glossitis – result of persistance of
tuberculum impar
• Bifid tongue – due to lack of fusion between 2 lateral
lingual prominences
• Thyroid tissue present in the base of tongue

75.  Developmental cysts :
• Branchial cleft (cervical) cysts or fistulas- from rests of
epithelium in visceral arch areas
• Thyroglossal duct cysts at or near midline along course of
duct
• Globulomaxillary cysts arise from epithelial rests after
fusion medial, maxillary, lateral nasal prominences

76. • Anterior palatine cysts from remnants of fusion of 2
processes (midline of maxillary alveolar prominence)
• Nasolabial cysts may be originating from epithelial
remnants in cleft lip line
• Malformations in head indicate defective malformation in
heart as spiral septum which divides cornus codis &
truncus arteriosus, is derived from neural crest cells

77.  Contemporary orthodontics, Proffit 5th ed
 Oral histology & embryology, Orban’s 12th ed
 Orthodontics, Bhalajhi 4th ed
 Textbook of pediatric dentistry, Nikhil Marwah
3rd ed