Download GROWTH OF MAXILLA

GROWTH OF MAXILLA
Presented by
Neethu Ajith
First Year PG
CONTENTS
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INTRODUCTION
ANATOMY OF MAXILLA
MECHANISMS OF BONE GROWTH
GROWTH PHASES
PRENATAL GROWTH OF MAXILLA
POSTNATAL GROWTH OF MAXILLA
CONCLUSION
REFERENCE
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INTRODUCTION

Craniofacial growth is a complex process .

Facial
growth
morphogenic
is
a
process
interrelationships
requiring
among
all
intimate
of
its
component growing ,changing , and functioning soft and
hard tissue parts
3
GROWTH

“ Growth is an increase in size ; development is
progress toward maturity “ – Todd

Growth is quantitative
Unit of growth : inches per year / grams per day.
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ANATOMY OF MAXILLA


1.
2.
Maxilla is the second largest bone of face.
Parts of Maxilla :Body
Pyramidal in shape
Encloses a large cavity , the Maxillary sinus
Four Processes
Frontal
Zygomatic
Alveolar
Palatine
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MECHANIMS OF BONE GROWTH

Bone deposition & resorption

Cortical drift

Displacement
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BONE DEPOSITION AND RESORPTION
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A)
B)
C)
D)
Bone changes in shape and size by two basic mechanisms : Bone
deposition and bone resorption
Process of bone deposition and resorption together is called
Remodelling
Progressive sequential change in the position of bone as a result of
remodeling is called Relocation.
The changes that bone deposition & resorption can
produce are:
Change in size
Change in shape
Change in proportion
Change in relationship of the bone with adjacent structures.
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CORTICAL DRIFT
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Growth movement of an enlarging portion of bone by the
remodeling action of its osteogenic tissues.
A combination of bone deposition & resorption resulting in a
growth movement towards the deposition surface is called “Cortical
Drift”.
Thickness of bone remains constant if resorption and deposition
take place at the same rate
Whereas the thickness of bone increases if more bone is deposited
than resorbed
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DISPLACEMENT
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
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1.
2.
It is the movement of the whole bone as a unit
It is the translatory movement of the whole bone
Displacement is of 2 types:-
Primary displacement
Secondary displacement
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PRIMARY DISPLACEMENT
If a bone gets displaced as
a result of its own growth,
it is called
“Primary displacement”.
Textbook of orthodontics ; S.Gowri Shankar
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SECONDARY DISPLACEMENT


Displacement of the bone
resulting from the pull or push
of the growth of the peripheral
structures or adjacent bone.
Growth of cranial base pushes
the entire maxilla in forward
and downward direction.
Textbook of orthodontics ; S.Gowri Shankar
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GROWTH PHASES
Growth and development of an individual progress through two
periods : Prenatal and Postnatal period.
 The Prenatal life can be arbitrarily divided into three periods:i.
Period of ovum
ii.
Period of embryo
iii. Period of fetus

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PRENATAL GROWTH OF MAXILLA

Around the fourth week of intra-uterine life, a prominent bulge
appears on the ventral aspect of the embryo corresponding to the
developing brain.
 Below the bulge a shallow depression which corresponds to
the primitive mouth appears called“ stomodeum”.
The floor of the stomodeum is formed the buccopharyngeal
membrane which separates the stomodeum from the foregut.
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In later 4th week, five branchial(pharyngeal)
arches form in the region of the future head &
neck.
 6 branchial arches are formed but 5th arch perishes
1st arch - mandibular arch
2nd arch - hyoid arch

The pharyngeal arches are separated by
pharyngeal grooves on the external aspect of the
embryo, which correspond internally with five
outpouchings of the elongated pharynx of the
foregut, known as the five pharyngeal pouches .
 Each of these arches gives rise to muscles,
connective tissue,vasculature, skeletal
components, & neural components of the future
face
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Between 3rd and 8th week of IU life ,major part of development of face
occurs.
The first branchial arch called the mandibular arch & plays an
important role in the development of the naso- maxillary region.
 The face derives from five prominences that surround the
stomodeum.These are

the single median Frontonasal prominence

the paired maxillary prominences
(derivatives of first brachial arch )

The paired mandibular prominences
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o
The stomodeum is thus overlapped superiorly by the frontonasal process.
o
The mandibular arches of both the sides form the lateral walls
of the stomodeum.
o
The mandibular arch gives off a bud from its dorsal end called
the “maxillary process”
o
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.
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During 4th week ,ectodermal proliferations are seen on either
side of Frontal prominence called, nasal placodes.
 Later form lining of nasal pits of Olfactory epithelium.
 These placodes soon sink and form the nasal pits.
 The formation of these nasal pits divides the fronto-nasal process
into two parts:
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a)The medial nasal process
b)The lateral nasal process
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The two medial nasal process grows towards each other and fuse at the
midline to form GLOBULAR PROCESS.
The derivatives of medial process are tip of the nose , columella ,
philtrum , prolabium , primary palate.
The maxillary process grows ventromedially to fuse with the medial
nasal process and forms the rest of the upper lip .
The maxillary process joins also with the lateral nasal process, the
junction being marked by the naso-optic furrow.
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
The furrow develops into a canal called nasolacrimal duct
connecting the conjunctival sac to the lateral wall of the nose.

The lateral nasal process provides for the alar portion of the nose.

The maxillary process contributes to the lateral aspect of the upper
lip, cheek, maxilla, rest of the maxillary teeth and secondary palate
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
The nasal septum develops in the midline as a projection from the cranial base
cartilage in the forebrain region.
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The fusion of medial nasal processes into the globular process narrows the
frontonasal process, at the same time lateral aspect of the face is overgrowing,
resulting in the redirection of the optic placode from lateral to frontal direction.
Thus the stomodeum is narrowed further.

In the mean time, stomodeum becomes continuous with the gut by the
disintegration of buccopharyngeal membrane at about 27th day of IUL.

The oral, nasal and pharyngeal cavities are a single chamber .

The mandibular processes grow towards each other and fuse in the midline.
Textbook of Craniofacial growth ;Sridhar Premkumar
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DEVELOPMENT OF PALATE
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Palatogenesis begins towards the end of 5th week and is completed
by about 12th week of IUL.
The palate develops from 2 premordium
1.
Primary palate
2.
Secondary palate
Frontonasal process
Palatal shelves from Maxillary proper
Primary palate
Secondary palate
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PRIMARY PALATE




At the end of 5th week
Develops from deep part of inter
maxillary segment of maxilla
Internal merging of medial nasal
prominences
Represents only a small part of
adult hard palate
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SECONDARY PALATE
 Premordium of the hard and soft palate posterior to the
incisive foramen
 Begins to develop in the 6th week, from shelf like
structures called lateral palatine processes
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During 7-8th week of IUL, descent of the tongue leads to elevation
of the lateral palatal shelves.
The elevation of vertical palatal shelves to a horizontal position
starts around 7th week of IUL and the phenomenon has been
ascribed to withdrawal of developing face from the heart
prominence.
Head is bent over the heart prominence; elevation of the face
facilitates growth of mandible thus increasing the volume of oral
cavity. Tongue senses the increase in space and descends down
leading to elevation of palatal shelves
Textbook of Craniofacial growth ;Sridhar Premkumar
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o
The elevation of palatal shelves may also be due to
 the change in the biochemistry of oral cavity
 change in physical consistency of connective tissue
 variation in vasculature and blood flow
 rapid differential mitotic growth
 intrinsic shelf force
 change in pressure between nasal and oral region due to tongue
contraction and movements.
Textbook of Craniofacial growth ;Sridhar Premkumar
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After
palatal elevation, the lateral palatal shelves approximate with
member of the opposite side, the nasal septum above and primary palate
(ingrowth of frontonasal process) in front.
The
palatal shelves swing from vertical to horizontal position.
Fusion
proceeds both anteriorly and posteriorly from that region.
Fusion
starts at 8th week and is complete by about 12th week of IUL.
Nasal
septum fuses with palate only anteriorly, in the posterior region, the
soft palate and uvula remains free.
Fusion
at first is only epithelial, the epithelial layers are thickened and
they approximate and fuse to form a single layer of epithelium
Textbook of Craniofacial growth ;Sridhar Premkumar
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OSSIFICATION OF PALATE
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Ossification starts by 8th week of IUL.
There is only one center of ossification for each maxilla.
Posterior part of the palate receives ossification center from the
palatine bone. Posterior most part remains unossified as soft palate
and uvula.
Palate increases in length from 7 to18 weeks and at 4th month,
palate grows more in width along the midpalatal suture .
Midpalatal suture ossifies by 12-14 years.
Textbook of Craniofacial growth ;Sridhar Premkumar
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CLEFT PALATE
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Delay in shelf elevation
Disturbance in mechanism of shelf elevation
Failure of shelves to contact due to lack of growth
Failure to displace the tongue during closure
[Pierre robin syndrome]
Failure to fuse after contact as epithelium does not break down
Rupture after fusion
Defective merging
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The formation of the palate involves the coordinated outgrowth,
elevation and midline fuion of bilateral shelves leading to the
separation of the oral and nasal cavities.
Reciprocal signaling between adjacent fields of epithelial and
mesenchymal cells directs palatal shelf growth and morphogenesis.
Loss of function mutations in genes encoding FGF ligands and
receptors have demonstrated critical role for FGF signaling in
mediating these epithelial-mesenchymal interactions.
Hence , deletion that removes the FGF signaling will cause cleft
palate
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DEVELOPMENT OF MAXILLARY SINUS
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The maxillary sinus forms sometime
around 3rd month of IUL
It develops by expansion of
the nasal mucous membrane into the
maxillary bone
Later sinus enlarges by resorption of
the internal wall of maxilla
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POSTNATAL GROWTH OF MAXILLA
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Maxilla cannot be considered as a separate bone; instead its growth
is best studied, taken into account the whole nasomaxillary complex
or midface.
Maxillae are attached to other bones by a complex sutural system
Postnatal growth of nasomaxillary complex was extensively studied
by Enlow and Bang
Textbook of Craniofacial Growth ; Sridhar Premkumar
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
The growth of the nasomaxillary complex is produced by the
following mechanisms:
1.
2.
3.
Displacement
Growth at sutures
Surface remodelling
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1.DISPLACEMENT
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Primary displacement of maxilla is due to growth of maxillary
tuberosity. The tuberosity is considered as a major growth site.
Cortical deposition at this site pushes against the posterior structures
with a counter anterior thrust that leads to primary displacement.
The posterior growth only helps to lengthen the dental arch of
maxilla.
Synchondrosis at the cranial base especially sphenoccipital
synchondrosis grows to lengthen the cranial base.This provides
anterior thrust to the midface.This is termed as secondary
displacement.
Textbook of Craniofacial Growth ; Sridhar Premkumar
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
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Until about the age of 6,displacement from cranial base growth
is an important part of the maxilla’s forward growth.
At about the age of 7 ,cranial base growth stops , and sutural
growth is the only mechanism for bringing the maxilla forward.
Contemporary orthodontics 4th ed ,William R.Proffit,Henry W.Fields,David M.Sarver
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2.GROWTH AT SUTURES

The maxilla is connected to the cranium and cranial base by a
number of sutures. These include:-
i.
Zygomatico-maxillary suture
ii.
Zygomatico-temporal suture
iii.
Fronto- maxillary suture
iv.
Frontonasal suture
v.
Pterygo-palatine suture
vi.
Intermaxillary suture
Textbook of Craniofacial growth ;Sridhar Premkumar
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Growth at these sutures allows the downward and forward
repositioning of the maxilla.
Sutural theory proposes that the sutures of the nasomaxillary
complex are centers of growth. Proliferation of osteogenic tissue at
the sutures causes growth movement that pushes the bone apart
with later fill-in.
As sutures are pressure sensitive; they can act only as fill-in areas
in secondary displacement but cannot provide the force for primary
displacement of bone.
Textbook of Craniofacial Growth ; Sridhar Premkumar
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3. SURFACE REMODELING
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Maxilla grows downwards and forwards in response to various
forces.
As maxilla grows forward, the posterior end is depository to
maintain contact with adjacent bones but the entire anterior surface
of maxilla becomes resorptive to maintain the shape and
configuration.
Bone deposition is seen at the entire inner aspect of the maxillary
arch and at the tuberosity.
Textbook of Craniofacial growth ;Sridhar Premkumar
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


At the anterior concave surface of maxilla,
The periosteal concavity from ANS to point ‘A’ is depository
and the periosteal surface from point ‘A’ to alveolar margin is
resorptive (Fig. 6.9).
At the endosteal side of cortex, upper half resorptive and lower
half depository.
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KEY RIDGE
• The key ridge is an important site of reversal and
remodeling.
• The anterior surface of maxilla till the region of
key ridge is resorptive and is concave, facing
downwards and growing inferiorly. It is at the
region of key ridge (approximately first molar
region) that reversal occurs .
•The lateral surface of maxilla posterior to key
ridge and lateral surface of tuberosity are
depository, growing laterally, facing upward.
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ARCH LENGTHENING
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The maxillary dental arch is lengthened by deposition posteriorly at
the tuberosity, the lateral surface also undergoes deposition.
The lengthening of dental arch allows space for the eruption of all
the molars.
The location of tuberosity is marked by the posterior limit of
anterior cranial base called Posterior Maxillary (PM) plane.
The position of posterior limit of anterior cranial base,maxillary
tuberosity and junction of corpus and ramus of the mandible are all
on the PM plane at the end of the growth according to Enlows
counterpart principle.
Textbook of Craniofacial growth ;Sridhar Premkumar
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VERTICAL GROWTH OF MAXILLA
Occurs due to:
i.
inferior displacement
ii.
adaptive apposition at the sutures
The alveolar margin of maxilla undergoes enormous amount of
growth with eruption of teeth.
The downward displacement of maxilla and mandible increases the
interocclusal space, enough for the alveolar growth and eruption of
Teeth.
Textbook of Craniofacial growth ;Sridhar Premkumar
46

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a)
b)
c)
Increase in height of alveolar margin accompanies eruption of
teeth.
Eruption of teeth is different from vertical drift
The downward increase in height of alveolar housing may be due
to:
Tooth eruption
Vertical drift of teeth
Passive movement of dentition along with maxilla.
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VERTICAL DRIFT OF TEETH

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
i.
ii.
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The socket and its resident tooth drift together as a unit.
Even periodontal tissue also undergoes extensive remodeling.
It is this periodontal tissue membrane that
Provides intramembranous bone remodeling that changes location
of socket
Moves the tooth itself
Vertical drift can be used to treat cases by working with growth,
relative intrusion is an example.
Textbook of Craniofacial growth ;Sridhar Premkumar
Essentials of Facial Growth ; Donald H.Enlow ;Mark G.Hans
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PALATE
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Downward drift of palate is extensive.
The newborn's palate is shallow and the horse shoe shaped
dental arch has equal length and width.
As age advances, the palate receives extensive deposition
at the roof.
This is part of the remodeling of the face.
The nasal floor is resorptive, nasal roof is depository. The
length of nasal floor is increased.
Concomitant with the resorption of nasal floor, palatal roof
receives bone deposition
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Palatal growth can be explained with the help of expanding V,
deposition on the inner aspect of V (palatal roof) and resorption
on the outer aspect (nasal floor) expands the V in the direction of
open end.
Increase in width by maxilla due to V principle is evident.
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ZYGOMATIC BONE
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As the maxilla is displaced anteriorly, its anterior surface is
resorptive, the zygomatic bone shifts posteriorly.
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.
Textbook of Craniofacial growth ;Sridhar Premkumar
Essentials of Facial Growth ; Donald H.Enlow ;Mark G.Hans
52
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NASAL CAVITY
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The floor and lateral walls of nasal
cavity are resorptive with deposition
in the medial wall of maxillary sinus.
This expands the nasal cavity.
The portion of roof near the olfactory
fossa is depository because
endocranial surface is resorptive.
This remodeling pattern lowers the
roof of the nose. In turn, the floor of
the nose is lowered by resorption and
concomitant deposition on the palatal
side
Textbook of Craniofacial Growth ; Sridhar Premkumar
54
ORBIT
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The orbit is a complex congregation of bones(
has medial and lateral walls, roof and floor).
Roof of orbit undergoes deposition to
compensate resorption at the endocranial
surface of the anterior cranial fossa.
The floor of orbit also receives deposits of
bone.
As the nasal cavity elongates, medial wall of
orbit receives deposition; it also expands
laterally.
The lateral wall of orbit undergoes resorption
in the medial surface and deposition in the
lateral surface, thereby drifting it outward.
Orbit expands by V principle.
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LACRIMAL SUTURE : KEY GROWTH MEDIATOR
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The entire perimeter of lacrimal bone is bounded by sutures,
separating it from the surrounding bones.
As all these other separate bones enlarge or became displaced in
many directions, the sutural system of lacrimal bone helps them in
the slippage along sutural interfaces.
Thus the lacrimal bone and its sutures is a developmental hub
providing key traffic controls.
Lacrimal also undergoes remodelling rotation along with the
differential expansion of nasal bridge and ethmoidal sinuses.
Essentials of Facial Growth ; Donald H.Enlow ;Mark G.Hans
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GROWTH TIMING
According to Melsen, the intermaxillary suture
a.
In 6-8 years : smooth and open
b.
In 10-12 years : sutural edges are overlapping
(early adolescence)
c. In 14-16 years : sutures become interdigitated and fused
( late adolescence)

Bacetti summarizes Melsen's findings by quoting that maxillary
expansion can be skeletally effective if the treatment is completed
in early adolescence.

Textbook of Craniofacial Growth ; Sridhar Premkumar
57
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Timing of growth varies with individuals and also with gender.
Girls complete growth earlier than boys.
Width increase in maxilla is not possible after 12 to 13 years in
girls, but in boys maxillary intercanine dimension increase is seen
till 18 years of age.
Downward and forward growth of maxilla is seen till 14 to 15 years
in girls. Increase in height is due to separation of the jaws during
displacement, growth of alveolar bone and eruption of teeth.
Textbook of Craniofacial Growth ; Sridhar Premkumar
58
AGE CHANGES IN MAXILLA
1.AT BIRTH
Transverse and anteroposterior diameter > vertical diameter
 Frontal process is well marked
 The tooth sockets close to the floor of orbit
 Maxillary sinus is mere furrow on the lateral wall of the nose

2. IN ADULTS
 Vertical diameter is greatest due to developed alveolar process

Increase in the size of sinus
3.IN OLD
 Infantile condition

Its height is reduced as a result of resorption of the alveolar process
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CONCLUSION
The knowledge of growth-related changes is essential in planning
orthodontic treatment.
It is important to understand and anticipate the amount and relative rate
of growth in different parts of the face, especially during childhood and
adolescence.
The orthodontist needs to assess the developmental status of the
individual and estimate the remaining growth to plan treatment.
Diagnosis and treatment planning of an orthodontic patient must,
therefore, include application of knowledge in craniofacial growth and
dental development
60
REFERENCE




Enlow and Hans “Essentials of facial growth”, 1996 .
Sridhar Premkumar “Textbook of craniofacial growth”, First edition
, 2011.
Sperber “Craniofacial development”, 2001.
Proffit , Fields and Sarver “Contemporary Orthodontics ,Fourth
edition.
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