Growth and development of jaws 1

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GROWTH ANDGROWTH AND
DEVELOPMENT OF JAWS:DEVELOPMENT OF JAWS:
CAUSE AND EFFECTCAUSE AND EFFECT

The development of the human embryo occurs in
three stages they are:-
Pre-implantation period (1st 7 days)
Embryonic period (next 7 weeks)
The fetal period (next 7 calendar months)
During the embryonic period that is from the first
to 8th week, the first signs of the development of jaw
bones occur
1. Pre-somite (8-21 days post conception)
2. Somite (21-31 days) and
3. Post somite (35-36 days post conception)
Embryonic period is further divided into 3 stages:-

During the pre somite period primary germDuring the pre somite period primary germ
layer of the embryo and the fetallayer of the embryo and the fetal
membranes are formed. Somite period ismembranes are formed. Somite period is
characterized by the appearance ofcharacterized by the appearance of
prominent dorsal metameric segments andprominent dorsal metameric segments and
organs. During the post somite period theorgans. During the post somite period the
formation of the body’s external featuresformation of the body’s external features
occurs.occurs.
During the late somite period the mesoderm
of the ventral foregut region becomes
segmented to form 5 distinct bilateral
mesenchymal swelling called the branchial
arches

The branchial arches are divided byThe branchial arches are divided by
branchial groove which corresponds to the 5branchial groove which corresponds to the 5
pharyngeal pouches internally. The firstpharyngeal pouches internally. The first
branchial arch which is other wise called asbranchial arch which is other wise called as
the mandibular arch is the precursors of thethe mandibular arch is the precursors of the
jaws, both maxillary and mandibularjaws, both maxillary and mandibular
The cartilage of the first arch is called as
the meckels cartilage. Meckels cartilage arises
at 41st to 45th day of intra uterine life. Most
of the cartilage disappears in the mandible
development. The mental ossicle is the only
portion of the mandible derived from meckels
cartilage by endochondral ossification

MAXILLAMAXILLA
The maxilla develops from a centre ofThe maxilla develops from a centre of
ossification in the mesenchyme of theossification in the mesenchyme of the
maxillary process from the first arch whichmaxillary process from the first arch which
begins at the 4th week of intra uterine life.begins at the 4th week of intra uterine life.
The centre of ossification appears in theThe centre of ossification appears in the
angle between the division of a nerve i.e.angle between the division of a nerve i.e.
where the anterosuperior dental nerve iswhere the anterosuperior dental nerve is
giving off from the inferior branch of infragiving off from the inferior branch of infra
orbital nerve. From this centre, the boneorbital nerve. From this centre, the bone
spreads to:-spreads to:-
Posteriorly: - Below the orbit toward the
developing zygoma
Anteriorly: - Towards the future incisor region
Superiorly: - To form the frontal processwww.indiandentalacademy.comwww.indiandentalacademy.com

As a result of this pattern a bony trough isAs a result of this pattern a bony trough is
formed for the infra orbital nerve. From thisformed for the infra orbital nerve. From this
trough a downward extension of bones formstrough a downward extension of bones forms
the lateral alveolar plate for the maxillarythe lateral alveolar plate for the maxillary
tooth germs. The medial alveolar platetooth germs. The medial alveolar plate
develops from the junction of palatal processdevelops from the junction of palatal process
and the main body of developing maxillaand the main body of developing maxilla
which form a trough of bone around thewhich form a trough of bone around the
maxillary tooth germs with its counterpart andmaxillary tooth germs with its counterpart and
later become enclosed in bony crypts. Alater become enclosed in bony crypts. A
secondary cartilage and zygomatic or malarsecondary cartilage and zygomatic or malar
cartilage also contributes to the developmentcartilage also contributes to the development
of maxilla.of maxilla.

PALATEPALATE
Initially there is a common oronasal cavityInitially there is a common oronasal cavity
bounded anteriorly by the primary palatebounded anteriorly by the primary palate
and occupied mainly by the developingand occupied mainly by the developing
tongue. Primary palate develops from thetongue. Primary palate develops from the
frontonasal processes. The medial growthfrontonasal processes. The medial growth
of maxillary process pushes the medialof maxillary process pushes the medial
nasal processes toward the midline wherenasal processes toward the midline where
it fuses with its anatomical counterpart.it fuses with its anatomical counterpart.
The formation of the secondary palateThe formation of the secondary palate
occurs between the 7th to 8th week ofoccurs between the 7th to 8th week of
development and results from the fusiondevelopment and results from the fusion
of shelves formed from each maxillaryof shelves formed from each maxillary
processes.processes.

The three elements that makes up secondaryThe three elements that makes up secondary
palate are:-palate are:-
1) Two lateral maxillary swelling1) Two lateral maxillary swelling
2) A primary palate of the frontonasal2) A primary palate of the frontonasal
processes.processes.
As the enlarging tongue pushes dorsally into theAs the enlarging tongue pushes dorsally into the
nasal cavity the palatal shelves develop in anasal cavity the palatal shelves develop in a
wedge shape and because of the presence ofwedge shape and because of the presence of
the tongue, palate grow downward into thethe tongue, palate grow downward into the
floor of the mouth along either side of thefloor of the mouth along either side of the
tongue. By 8th week of developmenttongue. By 8th week of development
movement of the palatal shelves changes frommovement of the palatal shelves changes from
a vertical position beside the tongue to aa vertical position beside the tongue to a
horizontal position overlying the tongue. Thishorizontal position overlying the tongue. This
growth will change the position of tongue andgrowth will change the position of tongue and
palatal shelves.palatal shelves. www.indiandentalacademy.comwww.indiandentalacademy.com

As the shelves roll over the tongueAs the shelves roll over the tongue
posteroanteriorly, the tongue may glideposteroanteriorly, the tongue may glide
anteriorly to offer less resistance to the shelfanteriorly to offer less resistance to the shelf
movement. Closure of the palatal shelvesmovement. Closure of the palatal shelves
separates the oral and nasal cavities. Theseparates the oral and nasal cavities. The
tongue may press upward against the palataltongue may press upward against the palatal
shelves, helping to bring them in closershelves, helping to bring them in closer
approximation to facilitate their contact in theapproximation to facilitate their contact in the
mid line. The nerve supply of the tongue andmid line. The nerve supply of the tongue and
cheeks are sufficiently developed to providecheeks are sufficiently developed to provide
some neuromuscular guidance to the intricatesome neuromuscular guidance to the intricate
activity of palatal closure.activity of palatal closure.
By 81/2 prenatal week the palatal shelves
appear above the tongue and in near contact
with each other. During 9th and 10th week they
come in contact and the fusion begins.

First the epithelial covering of the shelves joinFirst the epithelial covering of the shelves join
to form a single layer of cells. Nextto form a single layer of cells. Next
degeneration occurs as the connective tissue ofdegeneration occurs as the connective tissue of
the shelves penetrates this midline epithelialthe shelves penetrates this midline epithelial
barrier and intermingles across the area.barrier and intermingles across the area.
In few cases the two shelves have reported
separate after initial fusion, with resulting
epithelially covered connective tissue bands
stretching across the palate between the
shelves.

As the bone form the palate the area along theAs the bone form the palate the area along the
midline anteroposteriorly will become a suture.midline anteroposteriorly will become a suture.
The entire palate does not contact and fuse atThe entire palate does not contact and fuse at
the same time, initial contact occurs in thethe same time, initial contact occurs in the
region of the secondary palate just posterior toregion of the secondary palate just posterior to
the anterior or primary palatine processes andthe anterior or primary palatine processes and
continues both anteriorly and posteriorly to thiscontinues both anteriorly and posteriorly to this
point.point.
After the initial contact and fusion, further
closure occurs by a process of “merging” which
result in the medial space between the two
processes being eliminated. The anterior palatal
suture and the foramen remain in the post
natal period as an evidence of the early
existence of primary and secondary palate.

MANDIBLEMANDIBLE
The cartilage of the first arch forms the jaw inThe cartilage of the first arch forms the jaw in
primitive vertebrates. In human it has a closeprimitive vertebrates. In human it has a close
relationship to the developing mandible but notrelationship to the developing mandible but not
makes much contribution to it. At 6 weeks ofmakes much contribution to it. At 6 weeks of
development this cartilage extends a soliddevelopment this cartilage extends a solid
hyaline cartilaginous rod, surrounded by ahyaline cartilaginous rod, surrounded by a
fibrocellular capsule, from the developing earfibrocellular capsule, from the developing ear
region (otic capsule). The two cartilage of eachregion (otic capsule). The two cartilage of each
side do not meet at the midline but areside do not meet at the midline but are
separated by a thin rod of mesenchyme. On theseparated by a thin rod of mesenchyme. On the
lateral aspect of meckels cartilage, during thelateral aspect of meckels cartilage, during the
6th week of embryonic development, a6th week of embryonic development, a
condensation of mesenchyme occurs in thecondensation of mesenchyme occurs in the
angle formed by the division of the inferiorangle formed by the division of the inferior
alveolar and its incisor and mental branchesalveolar and its incisor and mental branches..www.indiandentalacademy.comwww.indiandentalacademy.com

At 7 weeks intramembraneous ossificationAt 7 weeks intramembraneous ossification
begins in this condensation, forming thebegins in this condensation, forming the
1st bone of mandible. From this centre of1st bone of mandible. From this centre of
ossification, bone formation spreadsossification, bone formation spreads
rapidly anteriorly to the midline andrapidly anteriorly to the midline and
posteriorly towards the point where theposteriorly towards the point where the
mandibular nerve divides into its lingualmandibular nerve divides into its lingual
and inferior alveolar branches.and inferior alveolar branches. ThisThis
spread of bone formation occursspread of bone formation occurs
anteriorly along the lateral aspect ofanteriorly along the lateral aspect of
meckels cartilage, forming a trough thatmeckels cartilage, forming a trough that
consists of lateral and medial plates thatconsists of lateral and medial plates that
unite beneath the incisor nerve.unite beneath the incisor nerve.www.indiandentalacademy.comwww.indiandentalacademy.com

This trough of bone extends to the midline,This trough of bone extends to the midline,
where it comes into close approximationwhere it comes into close approximation
with a similar trough formed in thewith a similar trough formed in the
adjoining mandibular processes. The twoadjoining mandibular processes. The two
separate centers of ossification remainseparate centers of ossification remain
separated at the mandibular symphysisseparated at the mandibular symphysis
until shortly after birth.until shortly after birth.

A backward extension of ossification alongA backward extension of ossification along
the lateral aspect of meckels cartilagethe lateral aspect of meckels cartilage
forms a gutter, later converts into a canalforms a gutter, later converts into a canal
that contains inferior alveolar nerve thisthat contains inferior alveolar nerve this
extends till the division of mandibularextends till the division of mandibular
nerve that is the inferior alveolar and thenerve that is the inferior alveolar and the
lingual nerve. From this bony canal,lingual nerve. From this bony canal,
extending from the division of theextending from the division of the
mandibular nerve to the midline, medialmandibular nerve to the midline, medial
and lateral alveolar plates of boneand lateral alveolar plates of bone
develops in relation to the forming toothdevelops in relation to the forming tooth
germs, so that the tooth germs willgerms, so that the tooth germs will
occupy a secondary trough of bone.occupy a secondary trough of bone.

The ramus of the mandible develops by a rapid
spread of ossification posteriorly into the
mesenchyme of the first arch turning away
from meckels cartilage. This point of divergence
is marked by the lingula in adult mandible.
Thus by 10 weeks the rudimentary mandible is
formed almost entirely by membranous
ossification.
The further growth of mandible until birth is
influenced by the appearance of three secondary
cartilages and the development of muscular
attachment; in this the most important cartilage
is the condylar followed by coronoid and
syphysial cartilages.

The condylar cartilage appears during the 12thThe condylar cartilage appears during the 12th
week of development and rapidly forms a coneweek of development and rapidly forms a cone
or carrot-shaped mass that occupies most ofor carrot-shaped mass that occupies most of
the developing ramus. The mass of cartilage isthe developing ramus. The mass of cartilage is
quickly converts to bone by endochondralquickly converts to bone by endochondral
ossification, so that by 20 weeks only a thinossification, so that by 20 weeks only a thin
layer of cartilage remains in the condylarlayer of cartilage remains in the condylar
heads.heads.
The coronoid cartilage appears at about 4 monthsThe coronoid cartilage appears at about 4 months
of development, surrounding the anteriorof development, surrounding the anterior
border and the top of the condylar process. Theborder and the top of the condylar process. The
symphyseal cartilage, two in number appear insymphyseal cartilage, two in number appear in
the connective tissue between the two ends ofthe connective tissue between the two ends of
meckels cartilage, but are entirely independentmeckels cartilage, but are entirely independent
of it. They are obliterated within the first yearof it. They are obliterated within the first year
of birth. The neural, alveolar and muscularof birth. The neural, alveolar and muscular
elements and growth are assisted by theelements and growth are assisted by the
development of these secondary cartilages.development of these secondary cartilages.

Post natal development of maxillaPost natal development of maxilla
A primary intramembraneous ossificationA primary intramembraneous ossification
centre appears for each maxilla in the 7thcentre appears for each maxilla in the 7th
week of I U L. According to “week of I U L. According to “MillsMills” the” the
maxilla is increased in size bymaxilla is increased in size by
subperiosteal activity during post natalsubperiosteal activity during post natal
growth. The entire nasomaxillarygrowth. The entire nasomaxillary
complex is joined to the cranial vault andcomplex is joined to the cranial vault and
the cranial base by the most complicatedthe cranial base by the most complicated
suture system of all. An endochondralsuture system of all. An endochondral
bone mechanism for the long bonebone mechanism for the long bone
growth, as seen in cranium and mandiblegrowth, as seen in cranium and mandible
is not seen in the mid face.is not seen in the mid face.

The growth of cartilaginous part ofThe growth of cartilaginous part of
nasal septum has been regarded asnasal septum has been regarded as
the source of the force that displacesthe source of the force that displaces
maxilla anteroinferiorly. This theorymaxilla anteroinferiorly. This theory
does not hold well in its entirety atdoes not hold well in its entirety at
present. Major part of the bonepresent. Major part of the bone
formation at the mid face is by intraformation at the mid face is by intra
membranous processmembranous process

The suture system is the most complicatedThe suture system is the most complicated
system in the body. The maxilla is connected tosystem in the body. The maxilla is connected to
the cranial base and the cranium by a numberthe cranial base and the cranium by a number
of sutures. They includes:-of sutures. They includes:-
1) Fronto - nasal suture1) Fronto - nasal suture
2) Fronto – maxillary suture2) Fronto – maxillary suture
3) Zygomatico – temporal suture3) Zygomatico – temporal suture
4) Zygomatico – maxillary suture4) Zygomatico – maxillary suture
5) Pterygo – palatine suture5) Pterygo – palatine suture
These sutures are all oblique
or parallel to each other. This allows a
downward and forward repositioning of the
maxilla as growth occurs at this sutures.

Surface growth remodeling is very activeSurface growth remodeling is very active
providing much regional increase andproviding much regional increase and
remodeling which accompany and adapt to theremodeling which accompany and adapt to the
additions taking place in sutures, synchndrosis,additions taking place in sutures, synchndrosis,
condyles and so forth.condyles and so forth.
Most of the bones in the cranial base are formedMost of the bones in the cranial base are formed
by a cartilaginous process. Later the cartilage isby a cartilaginous process. Later the cartilage is
replaced by bone but certain cartilaginousreplaced by bone but certain cartilaginous
bands remain in the junction of various bonesbands remain in the junction of various bones
these are called synchondrosis. The areathese are called synchondrosis. The area
between the bones consists of growingbetween the bones consists of growing
cartilage.cartilage.

Maxilla is joined to the cranial base and theMaxilla is joined to the cranial base and the
position of the maxilla is dependent on theposition of the maxilla is dependent on the
growth at the sphenooccipital and spheno –growth at the sphenooccipital and spheno –
ethmodial synchndrosis.ethmodial synchndrosis.
Maxillary post natal growth occursMaxillary post natal growth occurs
mainly by two methods they are:-mainly by two methods they are:-
Displacement – The shift in position of theDisplacement – The shift in position of the
maxillary complexmaxillary complex
Surface remodeling – The enlargement of theSurface remodeling – The enlargement of the
complex itself.complex itself.

Due to the enlargement of bones in the middle
cranial fossa.The dimensions of the middle
cranialfossa increases by the spheno – occipital
synchondrosis providing endochondral bone
growth in the middle of cranial fossa floor by
resorption on the endocranial surfaces and the
deposition on ectocranial side. All cranial and
facial parts lying anterior to the middle cranial
fossa displaced in a forward direction.

This can be proved by theThis can be proved by the “counterpart“counterpart
theory”theory” put forward byput forward by Enlow.Enlow.
The theory states: - “Growth of any facial orThe theory states: - “Growth of any facial or
cranial part relates specifically to othercranial part relates specifically to other
structures and geometric part of the facestructures and geometric part of the face
and the cranium”.and the cranium”.
According to theAccording to the “V”“V” principle put forward byprinciple put forward by
Enlow and Bang “Growth is a complexEnlow and Bang “Growth is a complex
multidimensional and a dynamic process.multidimensional and a dynamic process.
Apposition of bone on external surfaces ofApposition of bone on external surfaces of
maxilla with resorption on the inner aspectmaxilla with resorption on the inner aspect
causes an expansion of the maxilla in ancauses an expansion of the maxilla in an
expanding V shape.expanding V shape.

Primary displacement can be visualized using twoPrimary displacement can be visualized using two
reference linesreference lines
Vertically – Posterior maxillary planeVertically – Posterior maxillary plane
Horizontally – Functional occlusal plane.Horizontally – Functional occlusal plane.
Bone gets deposited on the posterior, facing
cortical plate surface of the maxillary tuberosity.
The endosteal surface within the tuberosity is
having a resorptive field. The amount of anterior
maxillary shift is equal to the amount of bone
deposited on the posterior surface of the
tuberosity. The anterior part of maxilla the pre-
maxilla region is resorptive in nature. There is
an additive growth on the opposite surface of
the resorptive field.www.indiandentalacademy.comwww.indiandentalacademy.com

The bone resorption on the nasal side of the palate andThe bone resorption on the nasal side of the palate and
the bone deposition on the inferior oral side producethe bone deposition on the inferior oral side produce
a downward growth of the whole palate. In maxillaa downward growth of the whole palate. In maxilla
the palate grows downward by periosteal resorptionthe palate grows downward by periosteal resorption
on the on the nasal side and periosteal deposition onon the on the nasal side and periosteal deposition on
the oral side. This occurs along with the suturalthe oral side. This occurs along with the sutural
growth.growth.
The classic implant studies of bjork and skieller
confirm that maxillary height increases because of
sutural growth towards the frontal and zygomatic bones
and positional growth in alveolar process. Apposition
also occurs on the floor of the orbit with resorptive
modeling of the lower surfaces. The nasal floor is
lowered by resorption while apposition occurs on the
hard palate. www.indiandentalacademy.comwww.indiandentalacademy.com

Growth of the median suture produces more mmGrowth of the median suture produces more mm
of width increases the appositional remodeling,of width increases the appositional remodeling,
but surface remodeling must everywherebut surface remodeling must everywhere
accompany sutural addition. Alveolaraccompany sutural addition. Alveolar
remodeling contributes to a significant earlyremodeling contributes to a significant early
vertical growth is also important to attainmentvertical growth is also important to attainment
of the width because of the divergence of theof the width because of the divergence of the
alveolar process. As they grow vertically theiralveolar process. As they grow vertically their
divergence increases the width. Up to the timedivergence increases the width. Up to the time
that the mandibular condyles have ceased theirthat the mandibular condyles have ceased their
most active growth, maxillary alveolar processmost active growth, maxillary alveolar process
increase constitute nearly 40% of the totalincrease constitute nearly 40% of the total
maxillary height increases.maxillary height increases.

Growth in the median suture is more importantGrowth in the median suture is more important
than apposition remodeling in the developmentthan apposition remodeling in the development
of maxilla. Growth increases at the medianof maxilla. Growth increases at the median
suture mimic the general growth curve for bodysuture mimic the general growth curve for body
height and maximum pubertal growth in theheight and maximum pubertal growth in the
median suture coincides with the time formedian suture coincides with the time for
maximum growth in the facial sutures. There ismaximum growth in the facial sutures. There is
no correlation between growth in width of theno correlation between growth in width of the
median suture and the sutural growthmedian suture and the sutural growth
contributing to the height of the maxilla. Mutualcontributing to the height of the maxilla. Mutual
transverse rotation of the two maxillae resultstransverse rotation of the two maxillae results
in separation of the halves more posteriorlyin separation of the halves more posteriorly
than anterior.than anterior.

Different theories of growth have been putDifferent theories of growth have been put
forward to explain the growth of maxilla. Thereforward to explain the growth of maxilla. There
is no universally accepted theory concerningis no universally accepted theory concerning
the mechanism of growth.the mechanism of growth.
Genetic control theory: - genotype supplies all
information necessary for phenotype expression
Suture-dominance theory: - by Siecher
supported by wiemann. This theory states that
sutural growth is the primary mechanism for
forward and downward growth of the maxilla.
Cartilage directed growth theory: - by Scott.
It states that cartilage is the primary factor in
the growth of maxilla e.g.: synchondrosis, nasal
septum etc. www.indiandentalacademy.comwww.indiandentalacademy.com

Functional matrix theory: -Functional matrix theory: - byby Moss.Moss. It statesIt states
that the growth of bone is in response to thethat the growth of bone is in response to the
functional relationship established by the sumfunctional relationship established by the sum
of all soft tissues operating in association withof all soft tissues operating in association with
that bone.that bone.
Servo- system theory: - by Stuzmann and
Perrovic. It states that the growth occur due
to the influence of somatotropic hormone (S T
H), sex hormone, thyroxine etc.

Alveolar processes are closely
correlated with the eruption of teeth.
The increase in overall maxillary height
coincides with the vertical growth in
the mandible. There is general pacing
of the growth of maxilla and mandible
and they both are roughly coincident
with the general growth of the body.

The sutural system adapts to posteriorThe sutural system adapts to posterior
forces (extra oral, cranial and cervical),forces (extra oral, cranial and cervical),
anterior forces and transverse forces.anterior forces and transverse forces.
Variation in theVariation in the
maxillary growth and morphology play anmaxillary growth and morphology play an
important role in skeletal malocclusionimportant role in skeletal malocclusion
class ii (extensive mid face growth) andclass ii (extensive mid face growth) and
class iii (decreased mid face growth)class iii (decreased mid face growth)

Post natal growth of mandiblePost natal growth of mandible
The modes, mechanism and sites of mandibularThe modes, mechanism and sites of mandibular
growth are complicated. Mandible is basically agrowth are complicated. Mandible is basically a
slender “slender “UU” shaped bone with an endochondral” shaped bone with an endochondral
bone mechanism at each end andbone mechanism at each end and
intramembraneous growth between just as inintramembraneous growth between just as in
long bones. Both prenatally and postnatallylong bones. Both prenatally and postnatally
very small percentage of the mandible isvery small percentage of the mandible is
endochondrally formed and the majority isendochondrally formed and the majority is
intramembrously developed. Growth and shapeintramembrously developed. Growth and shape
changes of the areas of muscle attachment andchanges of the areas of muscle attachment and
tooth insertion are more controlled by muscletooth insertion are more controlled by muscle
function and eruption of teeth than by intrinsicfunction and eruption of teeth than by intrinsic
cartilaginous or osteogenic factors.cartilaginous or osteogenic factors.www.indiandentalacademy.comwww.indiandentalacademy.com

Condylar cartilageCondylar cartilage
The condyle is of special interest because it is aThe condyle is of special interest because it is a
major site of growth. The condylar cartilage is amajor site of growth. The condylar cartilage is a
secondary cartilage which makes an importantsecondary cartilage which makes an important
contribution to the overall length of mandible.contribution to the overall length of mandible.
It was considered that the condylar cartilage
was the primary growth centre of the mandible.
Proponents of the functional matrix theory
claimed that some mandibles function
adequately and seem to be positioned rather
normally when condyles are absent. They
concluded that soft-tissue development carries
the mandible forward and downward and the
condylar growth fills the resultant space to
maintain the contact with the basicranium.

The growth mechanism of the condylarThe growth mechanism of the condylar
area is fairly clear, the main factor beingarea is fairly clear, the main factor being
the mesenchymal cells i.e. periosteumthe mesenchymal cells i.e. periosteum
present above the cartilage. Anotherpresent above the cartilage. Another
significant fact about the cartilage is that,significant fact about the cartilage is that,
compared with other cartilages it reactscompared with other cartilages it reacts
faster to outside stimuli with a lowerfaster to outside stimuli with a lower
threshold. The condyle does notthreshold. The condyle does not
determine how mandible grows, ratherdetermine how mandible grows, rather
the mandible which determines how thethe mandible which determines how the
condyles grows.condyles grows.

The growth of mandible is determinedThe growth of mandible is determined
by factors outside the mandible-by factors outside the mandible-
muscles, maxillary growth etc.muscles, maxillary growth etc.
An endochondral growth mechanism isAn endochondral growth mechanism is
required because the condyle grows inrequired because the condyle grows in
the direction of articulation in the face ofthe direction of articulation in the face of
pressure, a situation which purepressure, a situation which pure
intramembraneous bone growth couldintramembraneous bone growth could
not tolerate.not tolerate.

Petrovic et al. have noted the hormonal
influences on condylar cartilage growth.
Koski et al. stated that the periosteal tension
in the condylar neck provides a in-built control
for growth of ramus by way of the cartilage and
the other local factors, such as lateral pterygoid
may induce outside control. This indicate the
periosteal integrity is important for normal
proliferative activity of the connective tissue
cells of the condyle apart from the role of lateral
pterygoid muscle.

The condylar region plays an importantThe condylar region plays an important
role in mandibular growth because of therole in mandibular growth because of the
auricular site and because of theauricular site and because of the
extensive remodeling is necessary.extensive remodeling is necessary.
Condylar cartilage plays some role in theCondylar cartilage plays some role in the
translations of the mandible. Thetranslations of the mandible. The
condylar cartilage as well as thecondylar cartilage as well as the
functioning muscle translates thefunctioning muscle translates the
mandible and in the absence of one themandible and in the absence of one the
other compensate. In either event theother compensate. In either event the
periosteum of the condylar neck region isperiosteum of the condylar neck region is
important.important.


Ramus and bodyRamus and body
The addition of new bone provided byThe addition of new bone provided by
the condyle produce a dominantthe condyle produce a dominant
growth movement (translation) ofgrowth movement (translation) of
the mandible. The posterior border ofthe mandible. The posterior border of
the ramus in conjunction with thethe ramus in conjunction with the
condyle also undergoes a majorcondyle also undergoes a major
growth movement (cortical shift)growth movement (cortical shift)
that follows a posterior and somethat follows a posterior and some
what a lateral coursewhat a lateral course

The condylar growth and the ramus growthThe condylar growth and the ramus growth
bring about the following changes: -bring about the following changes: -
1) A backward transposition of the entire ramus
thereby elongating the mandibular body
2) A displacement of the mandibular body in the
anterior direction.
3) Movable articulation during these various
growth changes.
As the ramus grows and is relocated the
lingual tuberosity also moves posteriorly. The
growth movement of the mandible in general is
complemented by corresponding changes
occurring in the maxilla.

A primary function of corpus displacementA primary function of corpus displacement
is continuous positioning of theis continuous positioning of the
mandibular arch relative to themandibular arch relative to the
complementary growth movements ofcomplementary growth movements of
the maxilla. As the maxilla becomesthe maxilla. As the maxilla becomes
displaced anteriorly and inferiorly adisplaced anteriorly and inferiorly a
simultaneous displacement of thesimultaneous displacement of the
mandible in equivalent directions andmandible in equivalent directions and
approximate extent occurs. Muscleapproximate extent occurs. Muscle
attachment also play an important roleattachment also play an important role
localized remodeling and cortical driftlocalized remodeling and cortical drift
accompanying the downward andaccompanying the downward and
forward mandibular displacement.forward mandibular displacement.

Areas of muscle attachment to coronoid andAreas of muscle attachment to coronoid and
gonial region do not develop well if thegonial region do not develop well if the
muscles are removed very early or if themuscles are removed very early or if the
nerves and vessels serving severed.nerves and vessels serving severed.
The mandible appears to grow in a forward andThe mandible appears to grow in a forward and
downward manner when visualized in serialdownward manner when visualized in serial
cephalometric tracing.cephalometric tracing.
The predominant trend of the growth is theThe predominant trend of the growth is the
posterior and superior but the simultaneousposterior and superior but the simultaneous
displacement of the mandible takes place indisplacement of the mandible takes place in
the opposite direction i.e. inferiorly andthe opposite direction i.e. inferiorly and
anteriorly, regardless of the many varyinganteriorly, regardless of the many varying
regional directions of growth, remodeling andregional directions of growth, remodeling and
local drift.local drift.

Alveolar processAlveolar process
The alveolar process is not present whenThe alveolar process is not present when
the tooth is not present. Its formation isthe tooth is not present. Its formation is
controlled by dental eruption and itcontrolled by dental eruption and it
resorbs when the teeth are exfoliated orresorbs when the teeth are exfoliated or
extracted. The alveolar process serves asextracted. The alveolar process serves as
important buffer zones helping toimportant buffer zones helping to
maintain occlusal relationship duringmaintain occlusal relationship during
differential mandibular and midfacedifferential mandibular and midface
growth. Alveolar process growth is mostgrowth. Alveolar process growth is most
active during eruption, plays anactive during eruption, plays an
unimportant role during emergence andunimportant role during emergence and
initial intercuspation.initial intercuspation.www.indiandentalacademy.comwww.indiandentalacademy.com

This continues to maintain the occlusalThis continues to maintain the occlusal
relationship during vertical growth ofrelationship during vertical growth of
mandible and maxilla. When corpusmandible and maxilla. When corpus
growth is essentially over, verticalgrowth is essentially over, vertical
alveolar growth persists as thealveolar growth persists as the
occlusal surfaces wear thus theocclusal surfaces wear thus the
occlusal height is maintained even inocclusal height is maintained even in
adulthood. Adaptive remodeling ofadulthood. Adaptive remodeling of
the alveolar process makesthe alveolar process makes
orthodontic tooth movementorthodontic tooth movement
possible.possible.

Amounts and direction of mandibular growthAmounts and direction of mandibular growth
1) Height1) Height
Ramus height increases correlate well with
corpus length and overall mandibular length.
Anterior process height increases are highly
correlated with eruption. Anterior mandibular
height is related to dental development and
overall mandibular growth downward and
forward. The mandibular anterior height is
directed to the facial type and is quite different
in a skeletal deep bite and a long anterior facial
height

WidthWidth
Bigonial and bicondylar diameterBigonial and bicondylar diameter
increases are functions of growth inincreases are functions of growth in
overall mandibular length andoverall mandibular length and
natural divergence of the mandible.natural divergence of the mandible.
Width increases occurs because ofWidth increases occurs because of
lengthening of mandible althoughlengthening of mandible although
some periosteal deposition occurs.some periosteal deposition occurs.
Mandibular width is generally moreMandibular width is generally more
evenly acquired than those of overallevenly acquired than those of overall
length or height.length or height.

LengthLength
Mandibular length is measured in twoMandibular length is measured in two
ways:ways:
1) Overall length (condyle to gnathion)
2) Corpus length (pogonion to gonion
Both these dimensions show increase in
correlation with ramus height increases and
spurts in mandibular length occurs about the
same time as spurts in stature.

RotationRotation
Serial cephelometric studies keeping the cranialSerial cephelometric studies keeping the cranial
base as reference shows that the mandible isbase as reference shows that the mandible is
carried away in an anterior and downwardcarried away in an anterior and downward
direction. When the mandible is steeply relateddirection. When the mandible is steeply related
to the cranial base and the anterior facialto the cranial base and the anterior facial
height increases are significantly greater thanheight increases are significantly greater than
those posteriorly, the mandible is said to bethose posteriorly, the mandible is said to be
rotated posteriorly. In such cases the increasedrotated posteriorly. In such cases the increased
facial height to a great degree is contributed byfacial height to a great degree is contributed by
the anterior mandibular height and also seenthe anterior mandibular height and also seen
that the alveolar processes is much higherthat the alveolar processes is much higher
anteriorly than in posterior region.anteriorly than in posterior region.

BjorkBjork studied this by use of metallicstudied this by use of metallic
implants and other methods. There is saidimplants and other methods. There is said
to be two types of rotationto be two types of rotation
1) Matrix rotation
2) Intramatrix rotation
Matrix rotation the centre of rotation being at the
condyle and forms a pendulum movement. Intra
matrix rotation is the rotation of the mandibular
corpus, inner half of its matrix within the
mandibular corpus not in the condyle. Most of
the time intramatrix rotation accounts for most
of the total so called mandibular rotation.

TimingTiming
Spurts in mandibular dimensions are commonSpurts in mandibular dimensions are common
occurs approximately one and a half yearsoccurs approximately one and a half years
earlier in females compared to males. Theearlier in females compared to males. The
most important spurt associated withmost important spurt associated with
mandibular growth is that related to puberty.mandibular growth is that related to puberty.
Almost all first pubertal spurts occur afterAlmost all first pubertal spurts occur after
ulnar sesamoid ossification and beforeulnar sesamoid ossification and before
menarchy. The prediction of the timing ofmenarchy. The prediction of the timing of
mandibular growth spurts according to manymandibular growth spurts according to many
research are not sufficient for clinicalresearch are not sufficient for clinical
application.application.

Theories of mandibular growthTheories of mandibular growth
Genetic theory: -Genetic theory: - States that growth isStates that growth is
inherited through a genetic code.inherited through a genetic code.
Sutural theory: - Proposed by Sicher states
that growth takes place by deposition of
new bone at the suture.
Cartilaginous theory: - Proposed by Scott it
states that cartilage is the primary determinant
of growth while bone responds secondarily and
passively.
Functional matrix theory: - Proposed by Moss.
Servo system theory: -By Petrovic.www.indiandentalacademy.comwww.indiandentalacademy.com

Counterpart theory:Counterpart theory: - By- By EnlowEnlow it states thatit states that
growth of any given function or cranial partgrowth of any given function or cranial part
relates specifically to other structural andrelates specifically to other structural and
geometric counterparts in the face andgeometric counterparts in the face and
cranium.cranium.
Unloaded nerve theory: - Proposed by Moss it
states that mandibular growth is secondary to the
primary growth of the mandibular division of
trigeminal nerve which is the first structure to be
develop in the primodia of the lower jaw.
Trajectories of the jaws: - Proposed by Koch
it states that the bony trabaculae corresponds to
the pathway of maximal pressure and tension
and bony trabaculae are thick there.www.indiandentalacademy.comwww.indiandentalacademy.com

PalatePalate
The palate starts its growth between the 7th andThe palate starts its growth between the 7th and
18th week of intra uterine life. After the first18th week of intra uterine life. After the first
growth the width increases faster than thegrowth the width increases faster than the
length. In early pre natal life the palate islength. In early pre natal life the palate is
relatively long but from the 4th month it widensrelatively long but from the 4th month it widens
as a result of mid palatal suture growth andas a result of mid palatal suture growth and
appositional growth along the lateral alveolarappositional growth along the lateral alveolar
margins. At the birth the length and width ofmargins. At the birth the length and width of
the hard palate is almost equal. The post natalthe hard palate is almost equal. The post natal
increase in palatal length is due to appositionalincrease in palatal length is due to appositional
growth in the maxillary tuberosity region and togrowth in the maxillary tuberosity region and to
some extent at the transverse maxillo-palatinesome extent at the transverse maxillo-palatine
suture.suture. www.indiandentalacademy.comwww.indiandentalacademy.com

Growth of the mid palatal suture occursGrowth of the mid palatal suture occurs
between 1 and 2 years of age. Growth inbetween 1 and 2 years of age. Growth in
the width of mid palatal suture is large inthe width of mid palatal suture is large in
its posterior than in its anterior part, soits posterior than in its anterior part, so
that the posterior part of the nasal cavitythat the posterior part of the nasal cavity
widens more than the anterior part.widens more than the anterior part.
Lateral appositional growth continuesLateral appositional growth continues
until 7 years of age by this time theuntil 7 years of age by this time the
palate achieves its maximum anteriorpalate achieves its maximum anterior
width. Posterior appositional growthwidth. Posterior appositional growth
continues after the lateral growth hascontinues after the lateral growth has
ceased, so that the palate becomesceased, so that the palate becomes
longer and wider during late childhood.longer and wider during late childhood.www.indiandentalacademy.comwww.indiandentalacademy.com

During infancy and childhood boneDuring infancy and childhood bone
apposition also occurs on the entireapposition also occurs on the entire
inferior surface of the palateinferior surface of the palate
accompanied by a simultaneousaccompanied by a simultaneous
resorption from the superior surface; thisresorption from the superior surface; this
result in descent of the palate andresult in descent of the palate and
enlargement of the nasal cavity.enlargement of the nasal cavity.
The appositional growth of the alveolarThe appositional growth of the alveolar
processes contributes to deepening asprocesses contributes to deepening as
well as widening of the vault of the bonywell as widening of the vault of the bony
palate at the same time adding to thepalate at the same time adding to the
height and breadth of maxillae.height and breadth of maxillae.

The lateral alveolar process helps to formThe lateral alveolar process helps to form
an antero posterior palatal furrow whichan antero posterior palatal furrow which
together with a concave floor producedtogether with a concave floor produced
by tongue. The anterior palatal furrow isby tongue. The anterior palatal furrow is
well marked during the first year of lifewell marked during the first year of life
and normally flattens out into a palataland normally flattens out into a palatal
arch after 3 to 4 years of age whenarch after 3 to 4 years of age when
sucking has been discontinued.sucking has been discontinued.
Persistence of thump or finger suckingPersistence of thump or finger sucking
may retain the accentuated palatalmay retain the accentuated palatal
furrow into childhoodfurrow into childhood

Ossification does not occur in theOssification does not occur in the
posterior part of the palate, givingposterior part of the palate, giving
rise to the region of soft palate.rise to the region of soft palate.
Myogenic mesenchymal tissues ofMyogenic mesenchymal tissues of
the I, II and IV branchial archthe I, II and IV branchial arch
migrates into this facial regionmigrates into this facial region
supplying the musculature of facialsupplying the musculature of facial
and palate.and palate.

Congenital malformationCongenital malformation
CausesCauses
Genetic factors
Chromosomal disorder.
Single gene disorder.
Multifactoral disorder (polygenic and
environmental) at birth.
Disorder of late life.
Non genetic factors
Maternal infection.
Maternal use of medicine and toxic materials.
Maternal exposure to radiation.
Disturbance of embryonic differentiation and
fetal growth.

Clefts of maxillofacial skeletonClefts of maxillofacial skeleton
This is the most common defect of theThis is the most common defect of the
maxillofacial region. This major congenitalmaxillofacial region. This major congenital
malformation includes: -malformation includes: -
 Cleft lip.Cleft lip.
 Clefts of primary palate.Clefts of primary palate.
 Clefts of secondary palate.Clefts of secondary palate.
 Clefts of facial skeleton: -Clefts of facial skeleton: -
• Oblique facial clefts.Oblique facial clefts.
• Mandibular clefts.Mandibular clefts.
 Submucous cleft of palate.Submucous cleft of palate.
 Bifid uvula.Bifid uvula.
 Pits in the lips.Pits in the lips. www.indiandentalacademy.comwww.indiandentalacademy.com

Some facial clefts will be so severe andSome facial clefts will be so severe and
may result in health hazards out sidemay result in health hazards out side
the oral cavity also. Early diagnosisthe oral cavity also. Early diagnosis
and treatment of theseand treatment of these
malformations will help in a bettermalformations will help in a better
further development.further development.

Classification of the cleftsClassification of the clefts
Cleft lips: -Cleft lips: -
 Unilateral cleft lip.Unilateral cleft lip.
 Bilateral cleft lip.Bilateral cleft lip.
 Oblique facial cleft and cleft lip.Oblique facial cleft and cleft lip.
 Median cleft lip associated with nasalMedian cleft lip associated with nasal
defects.defects.
 Median mandibular cleft lip.Median mandibular cleft lip.
 Unilateral macrostomia.Unilateral macrostomia.

Cleft palateCleft palate
 Unilateral incomplete cleft of primaryUnilateral incomplete cleft of primary
palatepalate..
 Complete cleft of the primary palate,Complete cleft of the primary palate,
ending at the incisive foramen.ending at the incisive foramen.
 Bilateral complete cleft of primary palate.Bilateral complete cleft of primary palate.
 Incomplete isolated cleft of secondaryIncomplete isolated cleft of secondary
palate.palate.
 Complete cleft of secondary palate; softComplete cleft of secondary palate; soft
and hard palate.and hard palate.
 Bilateral complete cleft of primary andBilateral complete cleft of primary and
secondary palate.secondary palate.
 Incomplete cleft of primary andIncomplete cleft of primary and
incomplete cleft of secondary palate.incomplete cleft of secondary palate.

Cleft lipCleft lip
The failure of the facial prominenceThe failure of the facial prominence
to fuse together results in abnormalto fuse together results in abnormal
development of cleft lip. These clefts aredevelopment of cleft lip. These clefts are
due to disruption of the many integrateddue to disruption of the many integrated
processes of induction, cell migration,processes of induction, cell migration,
local growth and mesenchymal merging.local growth and mesenchymal merging.
Unilateral cleft of the upper lip isUnilateral cleft of the upper lip is
the result of the medial nasal prominencethe result of the medial nasal prominence
failure to merge with the maxillaryfailure to merge with the maxillary
prominence on either side of the mid line.prominence on either side of the mid line.
The unilateral is more common on theThe unilateral is more common on the
left side and have a strong familialleft side and have a strong familial
tendency suggesting a genetictendency suggesting a geneticwww.indiandentalacademy.comwww.indiandentalacademy.com

The bilateral cleft lip results in a wide midThe bilateral cleft lip results in a wide mid
line defect of the upper lip and may cause aline defect of the upper lip and may cause a
protuberant proboscis, which are rarely seen.protuberant proboscis, which are rarely seen.
The rare median cleftThe rare median cleft
lip (hare lip) is due to incomplete merging oflip (hare lip) is due to incomplete merging of
two medial nasal prominences and therefore intwo medial nasal prominences and therefore in
most cases, with deep midline grooving of themost cases, with deep midline grooving of the
nose leading various forms of bifid nose.nose leading various forms of bifid nose.
Merging of maxillary andMerging of maxillary and
mandibular prominences beyond or short of themandibular prominences beyond or short of the
site for normal mouth size result in too small orsite for normal mouth size result in too small or
too wide (micro or macrostomia). Rarely thetoo wide (micro or macrostomia). Rarely the
maxillary and mandibular prominences fuse,maxillary and mandibular prominences fuse,
producing a closed mouth (astomia).producing a closed mouth (astomia).

An oblique facial cleft results fromAn oblique facial cleft results from
persistence of the groove between thepersistence of the groove between the
maxillary prominence and the lateralmaxillary prominence and the lateral
nasal prominence running from thenasal prominence running from the
medial canthus of the eye to the ala ofmedial canthus of the eye to the ala of
the nose. Persistence of the furrowthe nose. Persistence of the furrow
between the two mandibularbetween the two mandibular
prominences produces the rare midlineprominences produces the rare midline
mandibular cleft.mandibular cleft.

Cleft palateCleft palate
Cleft palate occurs due to the lack of fusion orCleft palate occurs due to the lack of fusion or
breakdown of the fusion process of thebreakdown of the fusion process of the
palate during the first 6-9 weeks in utero.palate during the first 6-9 weeks in utero.
These deformities occur about in 750These deformities occur about in 750
(Daniel waite). Delay in elevation of the(Daniel waite). Delay in elevation of the
palate shelves from the vertical to thepalate shelves from the vertical to the
horizontal while the head is growinghorizontal while the head is growing
continuously results in widening of gapcontinuously results in widening of gap
between the shelves so that they cannotbetween the shelves so that they cannot
meet and therefore cannot fuse. This leadsmeet and therefore cannot fuse. This leads
clefting of palate.clefting of palate.

Other causes of cleft palate areOther causes of cleft palate are
defective self fusion, medial edge epithelial celldefective self fusion, medial edge epithelial cell
death, post fusion rupture and mesenchymaldeath, post fusion rupture and mesenchymal
consolidation and differentiation. The leastconsolidation and differentiation. The least
severe form of cleft palate is the bifid uvula ifsevere form of cleft palate is the bifid uvula if
the cleft involves the alveolar arch it usuallythe cleft involves the alveolar arch it usually
passes between canine and lateral incisor.passes between canine and lateral incisor.
Within the major constraint ofWithin the major constraint of
the lack of knowledge on the relativethe lack of knowledge on the relative
contribution of genetic and environmentalcontribution of genetic and environmental
factors in the pathogenesis of cleft, it isfactors in the pathogenesis of cleft, it is
possible to postulate a number of disturbancespossible to postulate a number of disturbances
and their consequences for the development ofand their consequences for the development of
clefts in the palate.clefts in the palate.

 Disturbed mesenchymal cell migration orDisturbed mesenchymal cell migration or
proliferation. Small facial growth centers orproliferation. Small facial growth centers or
palatal process impair mesenchymal cellpalatal process impair mesenchymal cell
replacement after palatal fusion.replacement after palatal fusion.
 Suppressed cell division in associatedSuppressed cell division in associated
structures. Reduced growth of cranial orstructures. Reduced growth of cranial or
meckels cartilage.meckels cartilage.
 Impaired intrinsic tissue function.Impaired intrinsic tissue function.
 Reduced tongue mobility and delayed abilityReduced tongue mobility and delayed ability
or inability of palatal processes to elevate.or inability of palatal processes to elevate.
 Disturbance of inductive tissue interactionsDisturbance of inductive tissue interactions
aberrant messages leading to failure of palatalaberrant messages leading to failure of palatal
function.function.
 Suppressed programmed epithelial cell deathSuppressed programmed epithelial cell death
following fusion. Incomplete palatal fusion orfollowing fusion. Incomplete palatal fusion or
opening or fused processes.opening or fused processes.www.indiandentalacademy.comwww.indiandentalacademy.com

Experimental studies and clinical caseExperimental studies and clinical case
reports have shown that certainreports have shown that certain
substances can be regarded assubstances can be regarded as
teratogenic i.e. they cause deformityteratogenic i.e. they cause deformity
after exposure of the embryo toafter exposure of the embryo to
which may or may not be above thewhich may or may not be above the
therapeutic level. It is thus wise totherapeutic level. It is thus wise to
avoid all drugs and source of ionizingavoid all drugs and source of ionizing
radiation during the early months ofradiation during the early months of
pregnancy.pregnancy.

Craniofacial anomaliesCraniofacial anomalies
Pierre robin syndrome: -Pierre robin syndrome: - Pierre robin (1929Pierre robin (1929))
Features are under developed mandible,Features are under developed mandible,
glossoptosis, palatal clefting and respiratoryglossoptosis, palatal clefting and respiratory
troubles. The pathogenesis is due thetroubles. The pathogenesis is due the
disturbance of muscular maturation ofdisturbance of muscular maturation of
nervous origin and the syndrome of Pierrenervous origin and the syndrome of Pierre
robin therefore belongs to the category ofrobin therefore belongs to the category of
muscular dysmaturation which affect themuscular dysmaturation which affect the
masticatory muscles, the tongue and themasticatory muscles, the tongue and the
pharyngeal slings.pharyngeal slings.

Swallowing is disturbed and the airwaySwallowing is disturbed and the airway
is obstructed resulting in the aspiration ofis obstructed resulting in the aspiration of
secretion and food. The respiratory difficultiessecretion and food. The respiratory difficulties
are further increased by the low and posteriorare further increased by the low and posterior
position of the tongue. A lateral radiographposition of the tongue. A lateral radiograph
shows the tongue positioned below the level ofshows the tongue positioned below the level of
the mandibular angle, pressing the epiglottis.the mandibular angle, pressing the epiglottis.
Retromandibulism is caused by theRetromandibulism is caused by the
deficient activity of the pterygoid muscle, whichdeficient activity of the pterygoid muscle, which
is unable to bring the mandible forward. Theis unable to bring the mandible forward. The
clinical forms of Pierre robin syndrome areclinical forms of Pierre robin syndrome are
extremely variable. Other mandibularextremely variable. Other mandibular
malformations resemble the syndrome but themalformations resemble the syndrome but the
term Pierre robin should not be applied whenterm Pierre robin should not be applied when
there is no abnormal function.there is no abnormal function.www.indiandentalacademy.comwww.indiandentalacademy.com

Mandibulo facial dysostosisMandibulo facial dysostosis
(Treacher Collins syndrome(Treacher Collins syndrome))
This is an inherited disorder involving theThis is an inherited disorder involving the
structure of the first branchial arch, pouchstructure of the first branchial arch, pouch
and groove. Manifestation includesand groove. Manifestation includes
fish-like mouth, downward sloping offish-like mouth, downward sloping of
palpebral fissure, malar deficiencypalpebral fissure, malar deficiency
receding chin and deformities of the pinnareceding chin and deformities of the pinna
contribute to the characteristic feature.contribute to the characteristic feature.
Open bite malocclusion, deep palatal andOpen bite malocclusion, deep palatal and
occasional cleft palate have been reportedoccasional cleft palate have been reported
as important oral symptoms.as important oral symptoms.

Craniofacial dysostosisCraniofacial dysostosis
(Crouzon syndrome)(Crouzon syndrome)
This occurs due to the prematureThis occurs due to the premature
closure of the cranial and facialclosure of the cranial and facial
suture. There is severe lack of orbits,suture. There is severe lack of orbits,
nasal, zygomatic and maxillary bonenasal, zygomatic and maxillary bone
components. Mandible will be normalcomponents. Mandible will be normal
and they exhibit a class iiiand they exhibit a class iii
malocclusion with a ‘v’ shapedmalocclusion with a ‘v’ shaped
palate. In some cases partialpalate. In some cases partial
anodontia or peg shaped teeth areanodontia or peg shaped teeth are
seen.seen.

Hemifacial macrostomiaHemifacial macrostomia
In this underdevelopment of the bonyIn this underdevelopment of the bony
and soft tissue structure of half ofand soft tissue structure of half of
the face,the face, can occur unilaterally orcan occur unilaterally or
bilaterally. The patients often havingbilaterally. The patients often having
missing portion of mandible likemissing portion of mandible like
condyle, ramus and in severe casescondyle, ramus and in severe cases
even the body of mandible.even the body of mandible.
Malformed ears and zygomaticMalformed ears and zygomatic
arches are the other features.arches are the other features.

Cerebrohepatorenal syndromeCerebrohepatorenal syndrome
(Bowen’s syndrome)(Bowen’s syndrome)
It is occurred in an autosomal recessive way.It is occurred in an autosomal recessive way.
 Oral feature includes micrognathia, protrudingOral feature includes micrognathia, protruding
tongue and high arched palate.tongue and high arched palate.
Trisomy 13 syndromeTrisomy 13 syndrome
This is a chromosomal disorder in whichThis is a chromosomal disorder in which
an extra chromosome number 13 is present.an extra chromosome number 13 is present.
 Oral signs include cleft lip sometime associatedOral signs include cleft lip sometime associated
with cleft palate, small ears and microcephaly.with cleft palate, small ears and microcephaly.

Cleidocranial dysplasiaCleidocranial dysplasia
This is an autosomal dominant condition.This is an autosomal dominant condition.
Oral features: - This includes high archedOral features: - This includes high arched
palate, with or without clefts, delayedpalate, with or without clefts, delayed
eruption of teeth, malformed roots, anderuption of teeth, malformed roots, and
supernumerary tooth.supernumerary tooth.
Radiographic features reveals feature likeRadiographic features reveals feature like
obtuse mandibular angle and lacking ofobtuse mandibular angle and lacking of
cellular cementum in the impacted tooth.cellular cementum in the impacted tooth.

Achondroplasia
It is an autosomal dominant condition,
characterized by dwarfism and short extremities.
Oral features include hypoplastic maxilla with a
relative mandibular prognathism and resultant
malocclusion.
Aperts syndrome
This syndrome is believed to be
transmitted by an autosomal dominant gene. The
essential features of this syndrome include
acrocephaly and syndactaly
Oral features include high palatal vault and
presence of posterior palatal and uvular clefts.
Dental malocclusion is a consistent feature.www.indiandentalacademy.comwww.indiandentalacademy.com

Acroosteolysis(Hajadu-cheney syndrome)Acroosteolysis(Hajadu-cheney syndrome)
Acroosteolysis is a rare autosomalAcroosteolysis is a rare autosomal
dominant disorder with the oral feature ofdominant disorder with the oral feature of
premature loss of teeth.premature loss of teeth.
Blepharonasofacial syndromeBlepharonasofacial syndrome
This is an autosomal dominant disorder.This is an autosomal dominant disorder.
Oral features include malocclusion resulting fromOral features include malocclusion resulting from
mid face hypoplasia.mid face hypoplasia.
Elashy-Waters syndromeElashy-Waters syndrome
It is an autosomal recessive condition.It is an autosomal recessive condition.
Oral features include high arched palate, palatalOral features include high arched palate, palatal
clefts, multiple jaw cysts and bifid uvula.clefts, multiple jaw cysts and bifid uvula.

Craniocarpato tarsal dysplasiaCraniocarpato tarsal dysplasia
This disorder has autosomalThis disorder has autosomal
dominant feature.dominant feature.
Oral feature: This includes macrostomia,Oral feature: This includes macrostomia,
protruding lips, high arched palate andprotruding lips, high arched palate and
retrognathic mandible. Another constantretrognathic mandible. Another constant
feature is the presence of fibrous bandfeature is the presence of fibrous band
demarcated by two grooves extendingdemarcated by two grooves extending
from the midline of the lower lip to thefrom the midline of the lower lip to the
chin, often present in an U or V shape.chin, often present in an U or V shape.

Trisomy syndromeTrisomy syndrome
The trisomy syndromes areThe trisomy syndromes are
 Downs syndromeDowns syndrome
 Edwards syndromeEdwards syndrome
 Patan syndrome.Patan syndrome.
Oral features: -
Downs syndrome- Short mouth, large tongue
with tongue thrust, maxillary lateral incisor shows
abnormality, microdontia, high arch palate, bifid
uvula, delayed eruptions and malocclusions.

Edwards syndrome- Small mandible,Edwards syndrome- Small mandible,
high arch palate, bifid uvula andhigh arch palate, bifid uvula and
occasionally cleft palate.occasionally cleft palate.
Patan syndrome- The features includePatan syndrome- The features include
cleft lip or palate.cleft lip or palate.

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