Development of maxilla

1. DEVELOPMENT
OF MAXILLA
BY – Dr. Vipul Gupta
MDS 1ST YR
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2. CONTENTS
EMBRYONIC DEVELOPMENT
ANATOMY OF MAXILLA
GROWTH AND DEVELOPMENT
CRANIOFACIAL GROWTH DISORDERS
REFERENCES
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3. PRE-NATAL
GORWTH OF
MAXILLA
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4. PRE NATAL EMBROYOLOGY
OF MAXILLA
• Around 4th week of IUL , a prominent bulge
appears on ventral aspect of embryo
corresponding to developing brain.
• Below this bulge a shallow depression which
correspond to the primitive mouth appears
called STOMODEUM.
• The floor of the stomodeum is formed by
BUCCOPHARNGEAL MEMEBRANE that
separate the stomodeum from the foregut.
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5. • By around the 4th week of intra-uterine life ,5 branchial arches
form in the region of future head and neck .Each of these arches
give rise to muscles , connective tissue, vasculature, skeletal
components and neural components of the future face.
• The 1st branchial arch is called the MANDIBULAR ARCH and
plays important role in development of naso-maxillary region.
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6. • The mesoderm covering the developing forebrain proliferates and
forms a downward projection that overlaps the upper part of
stomodeum.
• This downward projection is known as FRONTO-NASAL
PROCESS.
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7. • The stomodeum is thus overlapped superiorly by the fronto-
nasal process.
• Mandibular arches of both the side form the lateral wall of
stomodeum.
• The mandibular arch gives off a bud from its dorsal end called
MAXILLARY PROCESS.
• Maxillary process grows ventro-medial-cranial to the main part
of mandibular arch that is now called as MANDIBULAR
PROCESS.
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8. • The ectoderm overlying the frontonasal process shows bilateral
localized thickening above the stomodeum and these are called
the NASAL PLACODES.
• These placodes soon sink and form the NASAL PITS.
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9. • The formation of these nasal pits divides the fronto-nasal process into 2
parts-
MESIAL NASAL PROCESS
LATERAL NASAL PROCESS
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10. • As the maxillary process undergoes growth fronto-nasal process
becomes narrow so that two nasal pits come closer.
• The line of fusion of maxillary process and medial nasal process
correspond to the naso-lacrimal duct.
• Nasomedial processes grow quickly pushing the frontal
prominence , then fuse with the maxillary process to complete
the arch of upper jaw.
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11. DEVELOPMENT OF PALATE
• The palate is formed by contribution of:
• 1) Maxillary process
• 2) Palatal shelves given off by maxillary
process
3) Fronto-nasal process
The fronto-nasal process gives rise to the
premaxillary region while the palatal shelves
form the rest of the palate
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12. • As the palatal shelves grow
medially their union is prevented
by the presence of tongue .
• Thus initally the developing
palatal shelves grow vertically
downward towards the floor of
the mouth .
• Sometimes during the 7th week of
IUL, a transformation in position
of palatal shelves occurs.
• They change from vertical to
horizontal position.
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13. • This transformation is believed to take place within hours . Various
reasons are given to explain how this transformation occurs.
• A) Alteration in biochemical and physical consistency of the
connective tissue of palatal shelves.
• B) Appearance of an intrinsic shelf area.
• C) Rapid differential mitotic activity.
• D) Alteration in vasculature and blood supply to the palatal shelves.
• E) Withdrawal of embryonic face from against the heart prominence
results in slight jaw opening.
• This results in withdrawal of tongue from between the palatal shelves
and aids in elevation of palatal shelves from vertical to horizontal
positions.
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14. • The two palatal shelves , by 8th weeks of IUL, are in close
approximation with each other.
• Intially the two palatal shelves are covered by an epithelial
lining.
• As they join, the epithelial cells degenerate.
• The connective tissue of the palatal shelves intermingle with each
other resulting in the fusion.
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15. • The entire palate does not contact and fuse at the same time.
• Intially contact occurs in the central region of the secondary
palate posterior to the premaxilla.
• From this point , closure occurs both anteriorly and posteriorly.
• The mesial edges of the palatal processes fuse with the free lower
end of the nasal septum and thus separates the two nasal cavities
from each other and the oral cavity.
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16. • 8th week IUL
• 1) Stomodeum enlarge
• 2) Tongue drops
• 3) Vertically inclined palatal shelves-horizontal
• 4) Shelves contact each other in midline
• 5) By 12th week , fusion of palatal processes is
complete
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17. ANATOMY OF MAXILLA
• BODY- large and pyramidal
in shape
• FOUR PROCESSES-
frontal
zygomatic
alveolar
palatine
• It houses the largest sinus of the face: maxillary sinus
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18. • The maxillary bone is the second largest bone of the face, first
being the mandible.
• Body of maxilla is like hollow pyramid.
• Base of pyramid is formed by nasal surface and apex is directed
towards zygomatic process.
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19. BORDERS OF MAXILLA
• Superiorly: frontal bone
• Posteriorly: sphenoid, palatine,
lacrimal, ethmoid bones
• Medially: nasal bone, vomer
• Inferior: nasal concha
• Laterally: zygomatic bone
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20. POST NATAL
GROWTH OF
MAXILLA
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21. APPOSITION OF
BONE
SURFACE
REMODELLING
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22. SURFACE REMODELLING
• Shape of bone can be changed through removal
(resorption) of bone in one area and addition
(apposition) of bone in another.
• This balance of apposition and resorption, with
new bone being formed in some areas while old
bone is removed in others known as remodelling.
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23. Cranial
base
growth
Growth at
sutures
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24. • The maxilla develops post natally entirely by
intramembranous ossification
• The growth pattern of the face requires that it grow
"out from under the cranium,"
• It means that the maxilla must move through growth a
considerable distance downward and forward relative
to the cranium and cranial base
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25. • As the maxilla grows downward and forward, its
front surfaces are remodelled, and bone is removed
from most of the anterior surface.
• That almost the entire anterior surface of the maxilla
is an area of resorption, not apposition
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26. DISPLACEMENT
• PRIMARY DISPLACEMENT: The process of
physical carry, takes place in conjunction with a
bone’s own enlargement.
• SECONDARY DISPLACEMENT: The
movement of bone and its soft tissues is not
directly related to its own enlargement. It is a
fundamental part of the overall process of
craniofacial enlargement.
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27. DOWNWARD MAXILLARY
DISPLACEMENT
• New bone is added at the frontomaxillary, zygotemporal,
zygosphenoidal, zygomaxillary, ethmomaxillary, ethmofrontal,
nasomaxillary, nasofrontal, frontolacrimal, palatine, and vomerine
sutures.
• These multiple sutural deposits
accompany displacement.
• The process of displacement
produces the "space" within which remodeling enlargement
occurs.
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28. • The displacement of the bones is produced by the expanding
soft tissues.
• The bones of the ethmomaxillary region are displaced
downward.
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29. Sutural bone growth takes place
at the same time in response to
It.
Thus enlarging the bones as the
soft tissues continue to develop.
This places all the bones in new
positions in conjunction with the generalized expansion
of the soft tissue matrix and maintains continuous
sutural contact.
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30. NASOMAXIlLARY
REMODELING
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31. • Extensive remodeling occurs throughout the nasomaxillary
complex as the entire region undergoes inferior (and anterior)
displacement .
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32. THE BIOMECHANICAL FORCE
UNDERLYING MAXILLARY
DISPLACEMENT
• “Nasal septum" theory-
developed by Scott
• It developed from the criticisms of
the "sutural theory”
• Cartilage is a special tissue
uniquely structured to provide the
capacity for growth in a field of
compression.
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33. • Where as the cartilaginous nasal septum
itself contributes only a small amount of
actual endochondral growth.
• The basis for the “septal” theory is that
the pressure-accommodating expansion of
the cartilage in the nasal septum provides
a source for the physical force that
displaces
(pushes) the whole maxilla anteriorly and
inferiorly.
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34. • This sets up fields of tension in all the
maxillary sutures.
• The bones then secondarily, but virtually
simultaneously, enlarge at their sutures in
response to the tension created by the
displacement process.
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35. • A notable advance was made with the development of
the functional matrix concept, by Moss.
• According to this theory, the course and extent of bone
growth are secondarily dependent upon the growth and
the functioning of pacemaking soft tissues.
• So, the growth expansion of the facial muscles, the
subcutaneous and submucosal connective tissues, the
oral and nasal epithelia lining the spaces, the vessels
and nerves, and so on, all combine to move the facial
bones passively along with them as they grow.
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36. MAXILLARY TUBEROSITY
AND ARCH LENGTENING
• Remodelling of maxillary tuberosity produces horizontal
lenghtening of the bony maxillary arch.
• The backward-facing periosteal surface of the tuberosity
receives continued deposits of new bone as long as
growth in this part of the face continues
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37. • The arch also widens, and the lateral
surface is, similarly, depository.
• The endosteal side of the cortex within the
interior of the tuberosity (the maxillary
sinus) is resorptive.
• The cortex thus moves (relocates)
progressively posteriorly and also, to a
lesser extent, in a lateral direction.
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38. • After closure of mid- palatine suture, increase in the
arch width is due to remodelling of the alveolar
process.
• The whole maxilla undergoes a simultaneous process
of primary displacement in an anterior and inferior
direction as it grows and lengthens posteriorly
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39. THE MAXILLARY
TUBEROSITY AND THE KEY
RIDGE
In the growth of the bony maxillary arch, area A in the fig. is
moving in three directions by bone deposition on the external
surface
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40. • A major change in surface contour occurs
along the vertical crest just below the
malar protuberance.
• This crest is called the "key ridge.“
• A reversal occurs here.
• most of the external surface of the
maxillary arch is resorptive
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41. The Lacrimal Suture: A Key Growth
Mediator
• The lacrimal bone is a diminutive flake of a bony
island with its entire perimeter bounded by sutural
connective tissue contacts separating it from the many
other surrounding bones.
• The sutural system of the lacrimal bone provides for
the "slippage" of the multiple bones along sutural
interfaces as they all enlarge differentially.
• This is made possible by collagenous linkage
adjustments within the sutural connective tissue 41

42. • The lacrimal sutures make it possible for
the maxilla to "slide" downward along its
orbital contacts. This allows the whole
maxilla to become displaced inferiorly.
• It is a key midfacial growth event, even
though all the other bones of the orbit and
nasal region develop quite
differently and at different times,
amounts, and directions.
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43. THE NASAL AIRWAY
• The lining surfaces of the bony walls
and floor of the nasal chambers are
predominantly resorptive .
• This produces a lateral and anterior
expansion of the nasal chambers and
a downward relocation of the palate;
the oral side of the bony palate is
depository.
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44. • The breadth of the nasal bridge in the region just
below the frontonasal sutures does not markedly
increase from early childhood to adulthood
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45. PALATAL REMODELLING
• Even though the external (labial) side of
the whole anterior part of the maxillary
arch is resorptive, bone is being added
onto the inside of the arch
• The arch nonetheless increases in width
• The palate becomes wider
• (follows V- Principle)
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46. 46

47. THE CHEEKBONE AND
ZYGOMATIC ARCH
• The posterior side of the malar
protuberance within the temporal fossa is
depository.
• Together with a resorptive anterior
surface, the cheekbone relocates
posteriorly as it enlarges.
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48. • The zygomatic arch moves laterally by
resorption on the medial side within the
temporal fossa and by deposition on the
lateral side
• This enlarges the temporal fossa and
keeps the cheekbone proportionately
broad in relation to face and jaw size
and the masticatory musculature.
• It also moves the arches bilaterally, thus
increasing the space between for overall
head and brain enlargement.
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49. • As the malar region grows and becomes relocated
posteriorly, the contiguous nasal region is
enlarging in an opposite, anterior direction.
• This draws out and greatly expands the contour
between them, resulting in a progressively more
protrusive-appearing nose and an
anteroposteriorly much deeper face
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50. • This is a major topographic maturational change in the
childhood-to-adult face.
• The facial contours become opened, the protrusions more
prominent, and the depths all increased
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51. ORBITAL GROWTH
• The remodeling changes of the orbit
are complex.
• This is because many separate bones
comprise its enclosing walls, including
• Most of the lining roof and the floor are
depository.
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52. As the frontal lobe of the cerebrum expands forward and
downward (until about 5 to 7 years of age), the orbital roof
remodels anteriorly and inferiorly by resorption on the
endocranial side and deposition on the orbital side.
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53. The orbit grows by the V principle
The cone-shaped orbital cavity
moves (relocation by remodeling)
in a direction toward its wide
opening; deposits on the inside
thus enlarge, rather than reduce,
the volume.
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54. Deposition takes place on the
intraorbital (superior) side of
the orbital floor and resorption
on the maxillary (inferior) sinus
side.
This sustains the orbital floor in
proper position with respect to
the eyeball above it
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55. DEVELOPMENTAL
ANOMALIES
AFECTING MAXILLA
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56. Defective fusion of the various
components of the palate gives
rise to clefts in the palate.
Cleft lip and palate occur when
mesenchymal connective
tissues from different
embryologic structures fail to
meet and merge with each
other.
21

57. •The common form of
cleft lip is a result of
failure of fusion of the
medial nasal process
with the maxillary
process.
•Cleft lip may be
unilateral or bilateral
and may extend into
the alveolar process.
• there may be
unilateral cleft lip with
palate
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Cleft Lip

58. •Cleft palate is the result of failure of the lateral palatine
shelves to fuse with each other, with the nasal septum, or
with the primary palate.
•Failure of mesodermal proliferation of resistant
epithelial covering and retention of epithelial bridges
can cause cleft palate.
•Clefts of the palate result in anomalous
communications between the mouth and the nose.
• These may be unilateral or bilateral.
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CLEFT PALATE

59. 59
Figs 11.20A to E: Varieties of cleft palate. (A) Complete cleft with bilateral
harelip; (B) Unilateral cleft palate and cleft of upper lip. The left maxillary
process has fused with the premaxilla, but not with the right maxillary process.
The cleft is accompanied by unilateral harelip; (C) Midline cleft of hard palate
and soft palate; (D) Cleft of soft palate; (E) Bifid uvula

60. 60
VARIOUS SYNDROMES ASSOCIATED
WITH [CL(P)]
Stickler syndrome Mutations in the specific
collagen gene palatal clefting
Waarnderburg’s syndrome I Mutation in
homeodomain- containing protein (pa x3)
• Mutation in sonic hedgehog (shh)
Holoprosencephalic disorders
• Characterized by severe midline defect(failure of
nose to develop)

61. •van der Woude syndrome is an
autosomal dominant syndrome
typically consisting of a cleft lip or
cleft palate and distinctive pits of the
lower lips.
•These variable manifestations include lip pits
alone, missing teeth or isolated cleft lip, and
palate of varying degrees of severity.
•The van der Woude syndrome can be caused by
deletions in chromosome band 1q32 , and linkage
analysis has confirmed this chromosomal locus as
the disease gene site.
van der Woude Syndrome
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62. NON- SYNDROMIC CLEFT
LIP/PALATE
Mutation in no. of different genes familial CL
and CP
1. Transforming Growth Factor- alpha(TGF-α)
2. Retinoic Acid Receptor- alpha(RAR-α)
3. MSX1 Gene
4. BCL3
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63. The migration of neural crest cells is important for the derivation of
facial structures
DRUG induced impairement of migration:
•exposure to Thalidomide- congenital defects
•Anti-acne drug Isotretinoin- affects the neural crest cells
Dangerous as it affects the embryo before the mother knows she is
pregnant
•Retinoic acid plays crucial role in ontogenesis of midface
Loss of RAR genes affect post migratory activity of crest cells
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64. SMOKING AND CLEFT LIP/ PALATE
• An initial step in development of primary palate is
forward movement of lateral nasal process which
positions it so that it can contact median nasal
process.
• The associated with probably
interferes with this movement
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65. Altered development of cells
derived
from neural crest
TREACHER COLLINS
SYNDROME
Characterised by a generalised
lack of mesenchymal tissue.
Now known to be due to
mutation in a specific gene
(TCOF1, POLR1C, POLR1D)
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66. CROUZON’S SYNDROME
(Craniosynostosis)
Results due to early closure of the superior and
posterior sutures of maxilla along the wall of orbit
Characterised by:
• Frog face
• Underdeveloped midface
• Eyes that seem to bulge out
• Hypertelorism
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67. CLINICAL IMPLICATION
• Because distal movement of the maxillary first molar
is often part of an orthodontic treatment plan, the
maxillary tuberosity is important.
• Every mechanical option designed to move the
maxillary first molar distally exploits the growth
potential of the tuberosity.
• In Rapid Maxillary Expansion (RME), remodelling
of maxilla follows clinically induced displacement.
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68. •Maxilla is formed by Ist brachial arch and
ectomesenchyme of neural crest cells. Any factor
interfering with the formation underdeveloped
maxilla. E.g Craniofacial dysostosis, cleidocranial
dysplasia, achondroplasia, downs syndrome
•Underdeveloped maxilla mid-face deficiency
•If cleft lip and palate forms narrow maxilla with high
arched palate tendency for posterior and anterior
crossbites speech, mastication, hearing is impared
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69. •Headgear is used for restricting the maxillary growth
and reverse pull head gear or facemask with class III
functional appliance for correction of retrognathic
maxilla
•If growth is completed orthognathic surgical
correction
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70. REFERENCES
1. Essentials of facial growth-
Enlows
2. Human Anatomy-I.B SINGH
3. Contemporary Orthodontics-
William R. Profitt
4. Textbook of orthodontics; Bishara
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