Growth of Maxilla and Mandible Prenatal

1. PRENATAL GROWTH
OF MAXILLA AND
MANDIBLE
DR.DHARATI PATEL
NPDCH

2. content
 Introduction – growth and development
 Anatomy of maxilla
 Prenatal growth of Maxilla
 Development of palate
 Development of Maxillary sinus
 Anatomy of mandible
 Prenatal growth of Mandible
 Meckel’s cartilage
 Endhochondral bone formation
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3. GROWTH
Growth is the self multiplication of living substance
J.S. Huxley
Increase in size, change in proportion and progressive
complexity
Krogman
Change in any morphological parameter which is
measurable.
Moss
Entire series of sequential anatomic and physiologic changes
taking place from the beginning of prenatal life to senility
Meredith
Increase in size
Todd - 1931
Growth usually refers to an increase in size and
number
Profit – 1986
Quantitative aspect of biologic development per unit of
time
Moyers-1988
Growth is an increase in size of living being or any of
its parts, occurring in the process of development
Stedman- 1990
Growth signifies an increase, expansion or extension
of any given tissue
Pinkham -1994
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4. Development
Todd
1931
Development is progress towards maturity
Profit
1986
Development refers to increase in complexity
Moyer
1988
Development refers to all the naturally occurring
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
Stedman
1990
The act or process of natural progression from a
previous, lower, or embryonic stage to a later, more
complex, or adult stage.
Pinkham
1994
Development addresses the progressive evolution
of a tissue.
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5. Correlation between Growth and
Development
Growth is basically anatomic
phenomenon and quantitative
in nature
Development is basically
physiologic phenomenon
and qualitative in nature
• Morphogenesis – “A
biologic process having an
underlying control at the
cellular and tissue levels”
• Differentiation – “It is a
change from generalized
cells or tissues to a more
specialized kinds during
development”
• Maturation – The term
maturation is sometimes
used to express qualitative
changes which keep with
ripening or aging.
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6. Classification of growth
Prenatal growth
 Period of ovum-from fertilization to 14th day
 Embryonic period-14th day to 56th day (8th week)
 Fetal period-56th day to 270th day (19th week till the term)
Postnatal growth
Post natal growth is the first 20 years of growth
after birth
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7. The prenatal life may arbitrarily
divided into 3 periods
The period of
ovum
(fertilization to
2 weeks)
The period of
embryo
2 weeks to 8th
week(56th day)
The period of
fetus
(8th week to
9th month)
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8. Importance of growth and
development to Pedodontist
Etiology of
malocclusion
Health and
nutrition of
children
Comparison
of growth
Identification
- abnormal
occlusal
development
at an earlier
stage
Use of
growth
spurts
Surgery
initiation
Planning of
retention
regime
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9. Maxilla
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10. Introduction
 Second largest bone of the facial skeleton.
 The maxilla is attached to the neurocranium directly with
fronto-maxillary suture.
 Maxilla is indirectly attached to various facial structure
such as - nasal, lacrimal and ethmoid bones ,nasal
septum including vomer, palatine bone and zygomatic
arch
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11. 11

12. Anatomy of maxilla
 Parts of maxilla
1. Body – large and pyramidal
2. Four processes
1. Frontal
2. Zygomatic
3. Alveolar
4. Palatine
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13.  Maxilla are a pair of pneumatic bones and join together
to form the upper jaw
 They house the largest sinus in the body- the maxillary
sinus
 Each maxilla assists in forming the boundaries of three
cavities:
 the roof of the mouth
 the floor and lateral wall of the nasal antrum
 the wall of the orbit
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14. 14

15. Pre-natal growth of
maxilla
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16. Prenatal embryology of
maxilla
 4th week in IUL
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17.  Around the 4th week of intra-uterine life,
the developing brain and the
pericardium form two prominent bulges
on the ventral aspect of the embryo.
 These bulges are separated by the
primitive oral cavity or stomodeum.
 The floor of stomodeum is formed by
the bucco-pharyngeal membrane which
separates it from the foregut.
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18.  The mesoderm covering the developing fore brain proliferates & forms a
downward projection that over laps the upper part of stomodeum .
 This downward projection is called “FRONTO-NASAL PROCESS”.
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19.  By around the 4th week of IUL
 The pharyngeal arches are laid down
on lateral and ventral aspects of the
cranial most part of the foregut which
lies in close approximation with the
stomodeum
 Each of these arches gives rise to
muscles, connective tissue,
vasculature, skeletal components &
neural components of the future face.
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20.  Initially, there are 6 pharyngeal
arches, but the 5th one usually
disappears as soon as it is formed
leaving only five
 They are separated by 4 branchial
grooves.
 The first arch is called
MANDIBULAR ARCH and second
arch is called HYOID ARCH.
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21.  The mandibular arches of both sides form the lateral walls of the
stomodeum.
 The mandibular arch gives off a bud from its dorsal end called the
“MAXILLARY PROCESS”
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22. 22
 The maxillary process grows Ventro
medially cranial to the main part of the
mandibular arch which is now called
the “MANDIBULAR PROCESS".
 Thus at this stage the primitive mouth
or stomodeum is overlapped from
above by the frontal process, below by
the mandibular process &on either side
by the maxillary process.

23.  The ectoderm overlying the Fronto-
nasal process shows bilateral
localized thickenings above the
stomodeum.
 These are called the “NASAL
PLACODES”. These placodes soon
sink and form the nasal pits.
 The formation of these nasal pits
divides the Fronto-nasal process into
two parts:
The medial nasal
process &
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25.  The two mandibular processes grow medially & fuse to form the lower
lip & lower jaw.
 As the maxillary processes under grows growth, the Fronto-nasal
process become narrow so that the two nasal pits come closer.
 The line of fusion of the maxillary process & the medial nasal process
corresponds to the Naso-lacrimal duct.
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26. 26

27.  Starts around – 8th week of IUL
 The maxilla develops from a center of ossification in the
mesenchyme of the maxillary process of the 1st arch.
 Ossification later than mandible
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Ossification of maxilla

28.  Primary ossification center
 It lies between the division of inferior orbital nerve and the
Anterior superior nerve , just above the canine tooth dental
lamina.
 From this center, the bone spreads :-
 Posteriorly: - Below the orbit toward the developing
zygoma
 anteriorly: - Towards the future incisor region
 Superiorly: - To form the frontal process
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29.  The secondary ossification centers are
 Zygomatic
 Nasopalatine
 Orbitonsal areas
 Ossification spreads by
 Palatine process
 Zygomatic process
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30. Development of palate
 Palate is formed by the
Maxillary process
2 palatal shelves
Frontonasal process
 Palatogenesis begins towards the end of 5th week and is
completed by about 12th week.
 The palate develops from two primordia.
Primary palate
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31. Primary Palate
 At the end of 5th wk.
 Develops from deep part of inter maxillary segment of the maxilla
 By fusion of the maxillary and nasal processes in the roof of
stomodeum
 consists of the maxillary and medial nasal prominences.
 Represents only a small part of adult hard palate.
 The lip and primary palate close – 4th to 7th week
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32. Secondary palate
 Begins to develop in the 6th wk., from shelf like structures called
lateral palatine processes.
 Primordium of the hard and soft palate posterior to the incisive
foramen.
 Characterized by formation of two palatal shelves on the maxillary
process
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33.  The Fronto-nasal process gives rise to the pre-maxillary region
while palatal shelves from the rest of palate
 Palatal shelves rows medially but their union is prevented by
presence of tongue around at 7th week
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34.  Initially the palatal shelves grow vertically downwards and
forwards
 At 7th week oh IUL transformation in position of the palatal
shelves occur
 Changes from a vertical to horizontal position and palatal
elevation start to occur
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35. Mechanism of palate elevation
 Shelf elevation is a rapid event,
probably occurring over a matter of
minutes or hours in vivo (Ferguson,
1978; Brinkley, 1980).
 Numerous theories have been
advanced to account for palatal
shelf elevation
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36. 1. Intrinsic force theory
2. Traction theory
3. Mesenchymal cells theory
4. Neurotransmitter theory
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37. Other reasons for palate
elevation
 Biochemical and physical consistency of connective tissue
 Alteration in Vasculature and blood supply
 Myoneural activity in the tongue.
 Rapid differential mitotic activity
 Hydration and polymerization of intracellular substances
producing an elastic elevating force.
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38. Tongue descent theory
 Withdrawal of face from against the heart prominence
results in slight jaw opening
 This result is withdrawal of tongue from between the
palatal shelves and aids in the elevation of the palatal
shelves from vertical to a horizontal position
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40.  By 8-9th week the two palatal shelves get fused
 Initially they are covered by epithelial lining and then this cell get
degenerated as they joins and connective tissue of palatal shelves
intermingle with each other
 Entire palate does not contact and fused at the same time , initial
contact at central region.
 and the fusion is completed posteriorly by the 12th wk.
 The posterior part of palatal processes remains unossified, they
extend posteriorly beyond the nasal septum and fuse to form soft
palate and uvula.
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41. 41

42. Ossification of palate
 Ossification of the palate occurs from the 8th week of
intra- uterine life.
 This is an intramembranous type of ossification
 The palate ossifies from a single center derived from the
maxilla
 The most posterior part of the palate does not ossify. This
forms the soft palate
 The mid palatal suture ossifies by 12-14 yrs.
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43. Maxillary sinus
 Forms at 3rd month of IUL
 Develops by expansion of the nasal mucous membrane
in to maxillary bone
 Later enlarges by resorption of internal walls of maxilla
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44. Mandible
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45. Introduction
 Mandible or the lower jaw is the largest & strongest
bone of the face.
 It is the immobile bone of craniofacial bones.
 It has a horse shoe shaped body which lodges the
teeth.
 Mandible is a unique bone both by its structure &
function.
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46. Anatomy

47. Pharyngeal arch
 The pharyngeal arch begun to develop in 4th week of
intra uterine life.
 Each of these five arches contain
1. A central cartilage rod that forms the skeleton of the arch
2. A muscular component termed as branchiomere
3. A vascular component
4. A neural element

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49. 49

50. SKELETAL COMPONENTS MUSCULAR
COMPONENTS
NERVE
•Pre-maxilla & Maxilla
•Zygomatic bone
•Part of Temporal bone
•Mandible
•Malleus
•Incus
•Masseter & Temporalis
•Medial & Lateral
pterygoid
•Mylohyoid
•Ant. belly of Digastric
Trigeminal
nerve
FIRST ARCH

51.  The 1st pharyngeal arch is the mandibular arch which contains the
Meckel’s Cartilage.
 It appears at about 6th week of I.U. life.
 Makes little contribution towards the development of the mandible

53. Meckel’s cartilage
 It is derived from the first branchial arch around the 41st
– 45th day of intra-uterine life
 It extends from the cartilaginous otic capsule to the
midline or symphysis
 Provides a Template for subsequent development of the
mandible.
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54. A major portion of this cartilage disappears
during growth and the remaining part
develops into following structures
 The mental ossicles
 Incus and malleus
 Spine of sphenoid bone
 Anterior ligament of malleus
 Spheno-mandibular ligament
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55.  The first structure to develop is mandibular division of trigeminal
nerve.
 A single ossification center for each half of the mandible arises in the
6th week IU, in the region of the bifurcation of the inferior alveolar
nerve and artery into the mental and incisive branches.
 The resulting intra-memberanous bone lies lateral to Meckel's
cartilage of the first arch.
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57.  From this primary center, ossification spread below and
around the inferior alveolar nerve and its incisive brand
and upward to form a trough for a accommodating the
developing tooth bud.
 Spread of the intramembranous ossification dorsally and
ventrally forms the body and ramus of the mandible.

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59. Fate of MECKEL’S CARTILAGE
 As ossification continues, the Meckel’s cartilage becomes
surrounded and invaded by bone.
 Ossification stops at the point, which will later become the
mandibular lingula and, the remaining part of Meckel's
cartilage continues on its own to form Spheno-mandibular
ligament and the spine process of sphenoid ossification.

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61. Endochondral bone
formation
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62.  About the 5th week of IUL, an area of the
mesenchymal condensation can be seen
above the ventral of developing mandible.
 This develops into a cone-shaped cartilage
by about 10th week and starts ossification
by 14th week.
 Then migrates inferiorly and fuses with the
mandibular ramus by about 4th month.
CONDYLAR PROCESS

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64. The coronoid process
 secondary assessory cartilage
appears in the region of
coronoid process at about 10-
14 weeks of I.U.L
 This cartilage becomes
incorporated into expanding
intramembranous bone of
ramus and disappear before
birth.

65. • In mental region, on either side of
symphysis, one or two cartilage appears
and ossify in 7th week of IUL to become
mental ossicles.
• These ossicles becomes incorporated into
intra-membranous bone when symphysis
ossify completely.
The mental region

66. Differential Growth
• 8 weeks - Mandible > Maxilla
• 11 weeks - Mandible = Maxilla
• 13 – 20 weeks -Maxilla > Mandible
During
fetal
life
• Mandible tends to be retrognathic
• Early post natal life - Orthognathic
At
birth

67. Thank you
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