Mechanism of palatal shelf elevation
*Intrinsic Force within the shelf
*Accumulation of Glycosaminoglycans
*EGF and TGF stimulate production of Hyluronan
*Increase in vascularity
*Contraction of elastic fibres or muscle fibres.
*Unequal division in the palatal and the oral epithelium
*Neurotransmitters like Serotonin
*Increase in MMP-3
*Increase in Vimentin expression
*Master controlling gene is FSP-1,ssh,
Site of action of teratogens in electron transport system
*Role of Retinoic Acid
Retinoc acid can inhibit the proliferation
of and induce the apoptosis of EMS cells.
*Role of Folic Acid Deficiency
A high dose of 6 mg of folic acid should be
recommended for the reduction of orofacial
clefts during early pregnancy.
Two leading theories proposed for
formation of rare clefts
Classic Theory By Dursy and His:
States that failure of fusion of the facial processes
The Mesodermal penetration theory By Johnston
Recognises the importance of neural creast cells
Cleft 0:*Represents delay in the closure of the anterior
fontanel through the frontal bone,crista galli,
midline of the nose,columella,lip,and maxilla
and may actually involve the tongue,lower lip and
*It may give rise to frontonasal,frontoethmoidal,
or frontal encephaloceles,duplication of the nasal
septum and midline cleft of the lip.
*Its cranial extension is cleft 14
*The cleft courses through the frontal bone and
the olfactory groove of the cribiform plate,
between the nasal and the frontal process of the
maxilla and through the maxilla between the
central and lateral incisor.
*It can cause telorbitism with a deep
invagination of the dura in the area of the
cribiform plate defect,nasoorbital encephalocele,
notching of the nostrils and occasionally a cleft
*Cranial extension is cleft 13
*It runs through the lacrimal bone,the frontal
process of the maxilla and between the lateral
incisor and the canine.
*There is absence of the inferomedial wall of the
orbit and lack of pneumatisation of the
*Medial canthus is displaced inferiorly.There is
coloboma of the lower eyelid,the conjuctiva and
the nasal mucosa being seperated by a thin band
of fibrous tissue.
*Northbound continuation is cleft 11.
*Similar to cleft 3 except that the clefting
between the nose and the cheek is more
laterally,sparing the nostrils.
*The lip cresting take place lateral to the
*It runs through the orbital floor lateral to
the infraorbital nerve and the maxillary sinus
ending behind the canine in the premolar
*The soft tissue deformity involves the
coloboma of lateral third of lower lip,ending
as the cleft of the lip.
*Seperates the maxilla from the malar bone.
*The corresponding soft tissue deformity
consists of coloboma of the lower lid and a
furrow of skin from the coloboma to the
angle of the mandible
*Courses between the malar and the temporal
* The zygomatic arch is usually absent.
*The condyle,coronoid and the ramus suffer
varying degrees of deformity.
*The temporal muscle is either absent or
atrophic forming a contineous
*There may be cleft of the scalp or abnormal
*There may be a degrees of ear malformations
*It is a frontozygomatic cleft extending to the
greater wing of the sphenoid.
*In the soft tissue there may be either a true
cleft or notching of the lower eyelid.
*It is an upper orbital cleft of the superolateral
orbital ridge angle with a corresponding
coloboma of the upper lid.
*It is an upper central orbital cleft of the
frontal bone,supraorbital ridge and the
orbital rod,which is lateral to the supraorbital
neurovascular bundle,causing an encephalocele.
*It should be associated with a coloboma of the
medial of the upper lid.
*It is an upper medial orbital cleft through the
frontal bone,frontal sinus and lateral mass of
*The soft tissue deformity is coloboma of the
medial third of the upper eyelid.