Pre-natal Growth Of Maxilla and Mandible

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
2

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
3

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.
4

5. Correlation between Growth and
Development
Growth is basically anatomic
phenomenon and quantitative
in nature
Development is basically
physiologicphenomenon
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.
5

6. Classification of growth
Prenatal growth
Period of ovum-from fertilization to 14
th
day
Embryonic period-14
th
day to 56
th
day (8
th
week)
Fetal period-56
th
day to 270
th
day (19
th
week till the term)
Postnatal growth
Post natal growth is the first 20 years of growth
after birth
6

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(56
th
day)
The period of
fetus
(8th week to
9th month)
7

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
8

9. Maxilla
9

10. Introduction
Secondlargestboneofthefacialskeleton.
Themaxillaisattachedtotheneurocraniumdirectlywith
fronto-maxillarysuture.
Maxillaisindirectlyattachedtovariousfacialstructure
suchas-nasal,lacrimalandethmoidbones,nasal
septumincludingvomer,palatineboneandzygomatic
arch
10

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
12

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
13

14. 14

15. Pre-natal growth of
maxilla
15

16. Prenatal embryology of
maxilla
4
th
week in IUL
16

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.
17

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”.
18

19. By around the 4th week of IUL
Thepharyngealarchesarelaiddown
onlateralandventralaspectsofthe
cranialmostpartoftheforegutwhich
liesincloseapproximationwiththe
stomodeum
Each of these arches gives rise to
muscles, connective tissue,
vasculature, skeletal components &
neural components of the future face.
19

20. Initially,thereare6pharyngeal
arches,butthe5
th
oneusually
disappearsassoonasitisformed
leavingonlyfive
Theyareseparatedby4branchial
grooves.
The firstarchiscalled
MANDIBULAR ARCHandsecond
archiscalledHYOIDARCH.
20

21. Themandibulararchesofbothsidesformthelateralwallsofthe
stomodeum.
Themandibulararchgivesoffabudfromitsdorsalendcalledthe
“MAXILLARYPROCESS”
21

22. 22
ThemaxillaryprocessgrowsVentro
mediallycranialtothemainpartofthe
mandibulararchwhichisnowcalled
the“MANDIBULARPROCESS".
Thusatthisstagetheprimitivemouth
orstomodeumisoverlappedfrom
abovebythefrontalprocess,belowby
themandibularprocess&oneitherside
bythemaxillaryprocess.

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 &
The lateral nasal
23

24. 24

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.
25

26. 26

27. Starts around –8
th
week of IUL
The maxilla develops from a center of ossification in the
mesenchyme of the maxillary process of the 1
st
arch.
Ossification later than mandible
27Ossification 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
28

29. The secondary ossification centers are
Zygomatic
Nasopalatine
Orbitonsal areas
Ossification spreads by
Palatine process
Zygomatic process
29

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
Secondary palate
30

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 –4
th
to 7
th
week
31

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
32

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 7
th
week
33

34. Initially the palatal shelves grow vertically downwards and
forwards
At 7
th
week oh IUL transformation in position of the palatal
shelves occur
Changes from a vertical to horizontal position and palatal
elevation start to occur
34

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
35

36. 1.Intrinsic force theory
2.Traction theory
3.Mesenchymal cells theory
4.Neurotransmitter theory
36

37. Other reasons for palate
elevation
Biochemicalandphysicalconsistencyofconnectivetissue
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.
37

38. Tongue descent theory
Withdrawaloffacefromagainsttheheartprominence
resultsinslightjawopening
Thisresultiswithdrawaloftonguefrombetweenthe
palatalshelvesandaidsintheelevationofthepalatal
shelvesfromverticaltoahorizontalposition
38

39. 39

40. By8-9
th
weekthetwopalatalshelvesgetfused
Initiallytheyarecoveredbyepithelialliningandthenthiscellget
degeneratedastheyjoinsandconnectivetissueofpalatalshelves
interminglewitheachother
Entirepalatedoesnotcontactandfusedatthesametime,initial
contactatcentralregion.
andthefusioniscompletedposteriorlybythe12thwk.
Theposteriorpartofpalatalprocessesremainsunossified,they
extendposteriorlybeyondthenasalseptumandfusetoformsoft
palateanduvula.
40

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.
42

43. Maxillary sinus
Formsat3
rd
monthofIUL
Developsbyexpansionofthenasalmucousmembrane
intomaxillarybone
Laterenlargesbyresorptionofinternalwallsofmaxilla
43

44. Mandible
44

45. Introduction
Mandibleorthelowerjawisthelargest&strongest
boneoftheface.
Itistheimmobileboneofcraniofacialbones.
Ithasahorseshoeshapedbodywhichlodgesthe
teeth.
Mandibleisauniquebonebothbyitsstructure&
function.
45

46. Anatomy

47. Pharyngealarch
Thepharyngealarchbeguntodevelopin4
th
weekof
intrauterinelife.
Eachofthesefivearchescontain
1.Acentralcartilagerodthatformstheskeletonofthearch
2.Amuscularcomponenttermedasbranchiomere
3.Avascularcomponent
4.Aneuralelement

48. 48

49. 49

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

51. The1
st
pharyngealarchisthemandibulararchwhichcontainsthe
Meckel’sCartilage.
Itappearsatabout6
th
weekofI.U.life.
Makeslittlecontributiontowardsthedevelopmentofthemandible

53. Meckel’s cartilage
Itisderivedfromthefirstbranchialarcharoundthe41st
–45thdayofintra-uterinelife
Itextendsfromthecartilaginousoticcapsuletothe
midlineorsymphysis
ProvidesaTemplateforsubsequentdevelopmentofthe
mandible.
53

54. Amajorportionofthiscartilagedisappears
duringgrowthandtheremainingpart
developsintofollowingstructures
The mental ossicles
Incus and malleus
Spine of sphenoid bone
Anterior ligament of malleus
Spheno-mandibular ligament
54

55. Thefirststructuretodevelopismandibulardivisionoftrigeminal
nerve.
Asingleossificationcenterforeachhalfofthemandiblearisesinthe
6thweekIU,intheregionofthebifurcationoftheinferioralveolar
nerveandarteryintothementalandincisivebranches.
Theresultingintra-memberanousbonelieslateraltoMeckel's
cartilageofthefirstarch.
55

56. 56

57. Fromthisprimarycenter,ossificationspreadbelowand
aroundtheinferioralveolarnerveanditsincisivebrand
andupwardtoformatroughforaaccommodatingthe
developingtoothbud.
Spreadoftheintramembranousossificationdorsallyand
ventrallyformsthebodyandramusofthemandible.

58. 58

59. Fate of MECKEL’S CARTILAGE
Asossificationcontinues,theMeckel’scartilagebecomes
surroundedandinvadedbybone.
Ossificationstopsatthepoint,whichwilllaterbecomethe
mandibularlingulaand,theremainingpartofMeckel's
cartilagecontinuesonitsowntoformSpheno-mandibular
ligamentandthespineprocessofsphenoidossification.

60. 60

61. Endochondral bone
formation
61

62. About the 5
th
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 10
th
week and starts ossification
by 14
th
week.
Then migrates inferiorly and fuses with the
mandibular ramus by about 4
th
month.
CONDYLAR PROCESS

63. 63

64. The coronoid process
secondaryassessorycartilage
appearsintheregionof
coronoidprocessatabout10-
14weeksofI.U.L
This cartilage becomes
incorporated into expanding
intramembranous bone of
ramus and disappear before
birth.

65. •Inmentalregion,oneithersideof
symphysis,oneortwocartilageappears
andossifyin7
th
weekofIULtobecome
mentalossicles.
•Theseossiclesbecomesincorporatedinto
intra-membranousbonewhensymphysis
ossifycompletely.
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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