Palate/ dental crown & bridge courses

“T āmso Mā J yotirgāmāyā”
From Darkness Towards
Light
INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMY
Leader in continuing Dental EducationLeader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
 IntroductionIntroduction
 Key wordsKey words
 Development of palateDevelopment of palate
palatogenesispalatogenesis
Intermaxillary segmentIntermaxillary segment
secondary palatesecondary palate
palatal closure : elevation & fusionpalatal closure : elevation & fusion
midpalatal suturemidpalatal suture
neurovascular canalneurovascular canal
ossification of palateossification of palate
dev of palatal musculaturedev of palatal musculature
- Growth of palatal arch- Growth of palatal archwww.indiandentalacademy.comwww.indiandentalacademy.com

 Normal anatomy of palateNormal anatomy of palate
oral cavity properoral cavity proper
hard palate- str., nerves n vessels &hard palate- str., nerves n vessels &
lymphatic drainagelymphatic drainage
soft palate- str., nerves n vessels & lymphaticsoft palate- str., nerves n vessels & lymphatic
drainagedrainage
- Anthropological remarksAnthropological remarks
ConclusionConclusion
ReferencesReferences

The evolution of the skull not only involve the
development of a hard palate, but a far-reaching
series of changes in the dentition and the entire
jaw, face, and skull architecture. It is important
to
realize that all these adaptive changes were
interrelated, so that’s why evolution of the
mammalian craniofacial complex was said to be a
“PACKAGED DEAL"

The evolution of the reptilian skull to the mammalian
skull involve certain changes:
# secondary palate developed to completely separate the
oral and nasal cavities;
#the premolars and molars became multicusped,
#the zygomatic arches enlarged, bowing outward, to serve
larger adductor muscles of the jaw;
#lower jaw established articular contact with the squamous
portion of the temporal bone to give rise to the
temporomandibular joint (TMJ); and
#quadrate and articulare bones persisted as the auditory
ossicles, the malleus and the incus.

Hard palateHard palate
Soft palateSoft palate
Mesenchyme – a diffuse network of cells formingMesenchyme – a diffuse network of cells forming
the embryonic mesoderm and giving rise tothe embryonic mesoderm and giving rise to
connective tissues, blood and blood vessels, theconnective tissues, blood and blood vessels, the
lymphatic system, and cells of reticuloendotheliallymphatic system, and cells of reticuloendothelial
systemsystem
SyndesmosisSyndesmosis
SynostosisSynostosis
TeratogensTeratogens
Apoptosis – disintegration of cells into membraneApoptosis – disintegration of cells into membrane
bound particles that are phagocytosed by otherbound particles that are phagocytosed by other
cells. The process is important in limiting tumorcells. The process is important in limiting tumor
growth.growth.
WORDSWORDS

 Crown rump length – is the measurement from theCrown rump length – is the measurement from the
vertex of skull to mid point between the apices ofvertex of skull to mid point between the apices of
buttocks.buttocks.
Actually exact age of embryo can onlyActually exact age of embryo can only
determined if we know the exact day of conception,determined if we know the exact day of conception,
so indirect methods are used.so indirect methods are used.
WORDSWORDS

EMBRYOLOGYEMBRYOLOGY
““ Is the study of formation and developmentIs the study of formation and development
of embryo from the moment of its inception upof embryo from the moment of its inception up
to the time when it is born as an infant”.to the time when it is born as an infant”.
- Descriptive embryologyDescriptive embryology: study of embryos of: study of embryos of
various ages.various ages.
- Comparative embryologyComparative embryology: study of development: study of development
of organs in embryos of different animals.of organs in embryos of different animals.
- Experimental embryologyExperimental embryology: experiments on living: experiments on living
embryo of lower animals like amphibians orembryo of lower animals like amphibians or
chickschicks www.indiandentalacademy.comwww.indiandentalacademy.com

- General embryologyGeneral embryology: study of preliminary: study of preliminary
processes that are essential before theprocesses that are essential before the
formation of individual organ systems andformation of individual organ systems and
several accessory structures that protect theseveral accessory structures that protect the
embryo and provide it with nutrition.embryo and provide it with nutrition.
- Systemic embryologySystemic embryology: the study of the: the study of the
development of particular organs and organdevelopment of particular organs and organ
systemsystem

DEVELOPEMENTDEVELOPEMENT
Todd:Todd:
””Development is progress towards maturity”.Development is progress towards maturity”.
Moyers:Moyers:
““ Development refers to all the naturallyDevelopment refers to all the naturally
occurring unidirectional changes in the life of anoccurring unidirectional changes in the life of an
individual from its existence as a single cell toindividual from its existence as a single cell to
its elaboration as a multifunctional unitits elaboration as a multifunctional unit
terminating in death. Thus it encompasses theterminating in death. Thus it encompasses the
normal sequential events between fertilizationnormal sequential events between fertilization
and death”and death”..

GROWTHGROWTH
J.S.Huxley:J.S.Huxley:
““The self multiplication of livingThe self multiplication of living
substance”.substance”.
Krogman:Krogman:
““Increase in size, change in proportion andIncrease in size, change in proportion and
progressive complexity”.progressive complexity”.
Todd:Todd:
““An increase in size”.An increase in size”.
Meridith:Meridith:
““Entire series of sequential anatomic andEntire series of sequential anatomic and
physiologic changes taking place from beginning ofphysiologic changes taking place from beginning of
prenatal life to senility”.prenatal life to senility”.www.indiandentalacademy.comwww.indiandentalacademy.com

Moyers:Moyers:
““ Quantitative aspect of biologic developmentQuantitative aspect of biologic development
per unit time”.per unit time”.
Moss:Moss:
““Change in any morphological parameter which isChange in any morphological parameter which is
measurable”.measurable”.
Growth is increase in spatial dimensions inGrowth is increase in spatial dimensions in
weight; it may beweight; it may be
multiplicativemultiplicative (increase in no. of cells) or(increase in no. of cells) or
accretionaryaccretionary (increase in the amount of non-living(increase in the amount of non-living
structural matter) orstructural matter) or
auxeticauxetic (increase in the size of cells).(increase in the size of cells).

THEORIES OF GROWTHTHEORIES OF GROWTH
Major theories are:Major theories are:
 Sicher’s hypothesis or sutural dominanceSicher’s hypothesis or sutural dominance
theory.theory.
 Scott’s hypothesis/ cartilagenous theory.Scott’s hypothesis/ cartilagenous theory.
 Moss, Functional matrix theory.Moss, Functional matrix theory.
 Van Limborgh’s theory.Van Limborgh’s theory.
 Enlow’s expanding V principle.Enlow’s expanding V principle.
 Enlow’s counterpart principle.Enlow’s counterpart principle.

PALATOGENESISPALATOGENESIS
It is a complex developmental process that requires two
main events:
elevation and then fusion of the palatal shelves.
Eur J Anat, 7 Suppl. 1: 53-74 (2003)

4 week embryowww.indiandentalacademy.comwww.indiandentalacademy.com

5 week embryo 6 week embryo
Complete cleft lip/ primary cleft:Complete cleft lip/ primary cleft: when the epithelial fusion of the
swellings around the nasal pocket does not occur.
Simple cleft lip: when the epithelial fusion process ceases prematurely
and the epithelial wall is too short as it comes into the nasal cavity.
Simonart's band: epithelial remnant which is seen in a cleft lip when the
epithelial wall is laid down defectively.

By the end of 8By the end of 8thth
week face of embryoweek face of embryo
can be recognized as human facecan be recognized as human face

Intermaxillary SegmentIntermaxillary Segment
 It is comprised of:It is comprised of:
– A labial component : forms the philtrum of upper lip.A labial component : forms the philtrum of upper lip.
– Upper jaw component : Which carries 4 incisorUpper jaw component : Which carries 4 incisor
teeth.teeth.
– Palatal component : Which form the triangularPalatal component : Which form the triangular
primary palate.primary palate.

SECONDARY PALATESECONDARY PALATE

In the 7In the 7thth
and 8and 8thth
weeks several coordinated thingsweeks several coordinated things
happen:happen:
The transition of palatal process from vertical to horizontal is
completed within hours.
Shelv.avi

Palatal closure:Palatal closure:
touching of palatal shelves at any placetouching of palatal shelves at any place
along the palatal plane / actual fusion of thealong the palatal plane / actual fusion of the
shelves to one another along their entireshelves to one another along their entire
length.length.
It is probable that the initiation of palatalIt is probable that the initiation of palatal
closure occurs when the fetus is 29 to 33closure occurs when the fetus is 29 to 33
mm crown rump length.mm crown rump length.
PALATAL CLOSUREPALATAL CLOSURE

Several mechanisms have been proposed for this rapid
elevation of the palatal shelves, including
1. genetic Master controlling gene is FSP-1,
2. biochemical transformations in the connective tissue matrix
of the shelves,
3. variations in vasculature and blood flow to these structures,
4. a sudden increase in their tissue turgor,
5. rapid differential mitotic growth,
6 an intrinsic shelf-elevating force,
7. Neurotransmitters like Serotonin,
8. Increase in Vimentin expression,
9. sensorimotor stimulus and response, and
10. muscular movements.
PALATALPALATAL
CLOSURECLOSURE

VASCULAR THEORYVASCULAR THEORY
PALATALPALATAL
CLOSURECLOSURE

INTRINSIC SHELF-ELEVATING FORCE
Chiefly generated by the accumulation and
hydration of hyaluronic acid.
Alignment of mesenchymal cells within the palatal
shelves may serve to direct the elevating forces.
PALATALPALATAL
CLOSURECLOSURE

Stark says that the palatal shelves were destined to
meet and fuse in the midline.
"shelf force," implies an intrinsic medial ward
movement,
- growth at free shelf margins or
- by a medial ward compressive force of the maxillary
process
INTRINSIC SHELF-ELEVATING FORCE
PALATALPALATAL
CLOSURECLOSURE

SENSORIMOTOR STIMULUS AND
RESPONSE COMPLEX
-Jaw opening is the earliest reflex
to develop in the facial area(8-
9wk).
- Withdrawal of the embryo's face
from against the heart
prominence by the uprighting of
the head facilitates jaw opening.
PALATALPALATAL
CLOSURECLOSURE

According to Stark, there is a very interesting reversal of
direction in this development:
Elevation Of The Shelves Fusion
The result is of course, a completed bony palate and a
100 per cent separation of the oral and nasal cavities.
Dorsoventral Ventrodorsal
PALATALPALATAL
CLOSURECLOSURE

FUSION OF PALATAL SHELVESFUSION OF PALATAL SHELVES
The fusion is ventrodorsal
Also occurs between the dorsal surfaces of the fusing
palatal shelves and the lower edge of the midline nasal
septum.
The epithelium overlying the edges of the palatal shelves is
especially thickened (fusion upon mutual contact is crucial
to intact palatal development).
Palate1.avi
PALATALPALATAL
CLOSURECLOSURE

A combination of degenerating epithelial cells and a
surfacecoat accumulation of glvcoproreins and
desmosomes facilitates epithelial adherence between
contacting palatal shelves.
Only the medial-edge epithelium undergoes cytodifferentiation
involving a decline of epidermal growth factor receptors that
leads to apoptotic cell death
Programmed cell death fusing epithelia is restricted to the
periderm.
FUSION OF PALATAL SHELVESFUSION OF PALATAL SHELVES
PALATALPALATAL
CLOSURECLOSURE

MID PALATAL SUTUREMID PALATAL SUTURE
-First evident at 10th
weeks, when an upper layer of
fiber bundles develop across midline.
-In infancy, the midpalatal suture in coronal section has
a Y shape, and it binds the vomer with the palatal
shelves.

-In childhood, the junction between the three bones
rises into a T shape, with the interpalatal section
taking a serpentine course.
-In adolescence, the suture become interdigitated that
the mechanically interlocking and interstitial islets of
bone are formed.
-In adulthood, the palatine bone elements of the palate
remain separated from the maxillary elements by the
palatomaxillary sutures.

Growth ceases between 1 and 2 years of age, but no
synostosis occurs to signify its cessation.
Growth in the width of the mid-palatal suture is
larger in its posterior than in its anterior part, so
that the posterior part of the nasal cavity widens
more than its anterior part.
Obliteration of the midpalatal suture may start in
adolescence, but complete fusion is rarely before 30
years of age.

INCISIVE NEUROVASCULAR CANALINCISIVE NEUROVASCULAR CANAL
-The site of junction of the three palatal components is
marked by the incisive papilla overlying the incisive
canal it transmits nasopalatine nerves and blood
vessels..

OSSIFICATIONOSSIFICATION
Proceeds during the 8th week post conception
Starts as trabeculae appearing in the primary
palate as "premaxillary centers," all derived from the single
primary ossification centers of the maxillae.
Posteriorly, the hard palate is ossified by trabeculae
spreading from the single primary ossification centers of
each of the palatine bones.
Ossification does not occur in the most posterior
part of the palate, giving rise to the region of the soft
palate.

 Myogenic mesenchymal tissue of the first and
fourth pharyngeal arches migrates into this faucial
region, supplying the musculature of the soft palate
and fauces.
DEVELOPMENT OF PALATALDEVELOPMENT OF PALATAL
MUSCULATUREMUSCULATURE

Tensor veli palatini :
-earliest of the five palatal muscles to
develop,
-forming myoblasts at 40 days post
conception
Palatopharyngeus (45 days),
levator veli palatini (8th week),
palatoglossus and uvular muscle (9th week),
#palatoglossus, derived from the tongue musculature,
attaches to the soft palate during 11th week.

GROWTH OF PALATAL ARCHGROWTH OF PALATAL ARCH
Growth is 3 dimensional-L, W, & H.
PRENATAL GROWTH
In Between 7 to 18 wk IUL: palate's L>>> W,
after 18 wk IUL : W >> L.
AT BIRTH,
L almost =B

POSTNATAL GROWTH
-lateral appositional growth
-posterior appositional growth
-appositional growth of alveolar process
-remodeling
Lateral appositional growth
-at the Intermaxillary and interpalatine suture
-continues until 7 years of age, by which time the
palate achieves its ultimate anterior width.
GROWTH OF PALATALGROWTH OF PALATAL
ARCHARCH

Posterior appositional growth
- mainly in maxillary tuberosity region
- continue even after lateral growth has ceased
ARCHARCH

Appositional growth of the alveolar processes-
- contributes to the deepening and widening of the
vault - adding to the height and breadth of the
maxillae at the same time.
ARCHARCH

Palatal remodeling - during infancy and childhood.
ARCHARCH

PALATAL RUGAEPALATAL RUGAE
- variable number of transverse rugae develop in the
mucosa covering the hard palate.
-They appear even before palatal fusion.
-The rugae hold the nipple while it is being milked by
the tongue.
-well marked during the 1st year of life
-and normally flattens out after 3 to 4 years.

NORMAL ANATOMYNORMAL ANATOMY
ORAL CAVITYORAL CAVITY-Mouth cavity-Mouth cavity
-can be divided into-can be divided into
outer smaller portion : vestibule andouter smaller portion : vestibule and
inner larger part : oral cavity properinner larger part : oral cavity proper
--VestibuleVestibule is a narrow space bounded externally by theis a narrow space bounded externally by the
lips and cheeks and internally by the teeth and gums.lips and cheeks and internally by the teeth and gums.

--Oral Cavity ProperOral Cavity Proper

HARD PALATEHARD PALATE--

HARD PALATEHARD PALATE--
Vessels and nervesVessels and nerves

LymphaticsLymphatics: they drain mostly to the upper deep: they drain mostly to the upper deep
cervical lymph nodes and partly to thecervical lymph nodes and partly to the
retropharyngeal nodes.retropharyngeal nodes.

SOFT PALATE-SOFT PALATE-

soft palate has two surfaces -soft palate has two surfaces -
Anterior surfaceAnterior surface
Posterior surfacePosterior surface

soft palate has two borders-soft palate has two borders-

Nerve supply of soft palateNerve supply of soft palate
1.Motor nerves: all are supplied by the pharyngeal1.Motor nerves: all are supplied by the pharyngeal
plexus (XI) except tensor veli palati is supplied byplexus (XI) except tensor veli palati is supplied by
the mandibular nerve.the mandibular nerve.
2.General sensory: middle and posterior palatine nerves2.General sensory: middle and posterior palatine nerves
which are branches of the maxillary nerve andwhich are branches of the maxillary nerve and
glossopharyngeal nerve.glossopharyngeal nerve.

3.Special sensory (gustatory):3.Special sensory (gustatory):
lesser palatine nerveslesser palatine nerves
greater petrosal nervegreater petrosal nerve
geniculate ganglion of the facial nervegeniculate ganglion of the facial nerve
nucleus of the solitary tract.nucleus of the solitary tract.

4.Secretomotor nerves:4.Secretomotor nerves:
lesser palatine nerveslesser palatine nerves
travel through the greater petrosal nervetravel through the greater petrosal nerve
superior salivatory nucleussuperior salivatory nucleus

Blood supplyBlood supply
arteries:arteries: greater palatine branch of maxillary arterygreater palatine branch of maxillary artery
ascending palatine branch of facial arteryascending palatine branch of facial artery
palatine branch of ascending pharyngealpalatine branch of ascending pharyngeal
artery.artery.
veins:veins: pterygoid and tonsillar plexuses of veins.pterygoid and tonsillar plexuses of veins.
lymphatics:lymphatics: drain into the upper deep cervical anddrain into the upper deep cervical and
retropharyngeal lymph nodes.retropharyngeal lymph nodes.

ANTHROPOLOGICALANTHROPOLOGICAL
REMARKSREMARKS
For cephalometric purpose palatine indexes can be used forFor cephalometric purpose palatine indexes can be used for
classifying skull:classifying skull:
1. Palatine index=1. Palatine index=palate breadthpalate breadth× 100× 100
palate lengthpalate length
leptostaphyline = <79.9leptostaphyline = <79.9
mesostaphyline = 80-84.9mesostaphyline = 80-84.9
brachystaphyline = >85brachystaphyline = >85
2. Palate height index=2. Palate height index=palate heightpalate height ×100×100
palate breadth
chamestaphyline = <27.9chamestaphyline = <27.9
orthostaphyline = 28-39.9orthostaphyline = 28-39.9
hypsistaphyline = >40hypsistaphyline = >40

CONCLUSIONCONCLUSION
JUST AS THE CLINICIAN NEEDS THEJUST AS THE CLINICIAN NEEDS THE
MEDICAL HISTORY TO MAKE A LOGICALMEDICAL HISTORY TO MAKE A LOGICAL
DIAGNOSIS, SO TOO THE GROWTH ANDDIAGNOSIS, SO TOO THE GROWTH AND
DEVELOPMENT OF FACE IS ESSENTIAL FOR ADEVELOPMENT OF FACE IS ESSENTIAL FOR A
LOGICAL EXPLANATION OF ANY STRUCTURALLOGICAL EXPLANATION OF ANY STRUCTURAL
AND FUNCTIONAL IMBALANCES IF IT DOAND FUNCTIONAL IMBALANCES IF IT DO
OCCURS.OCCURS.

REFERENCESREFERENCES
1. An introduction to human embryology for medical
students – Inderbir Singh, 5th
Edition.
2. Craniofacial embryology – G.H. Sperber, 4th
Edition.
3. Langman’s medical embryology – T.W. Sadler, 5th
Edition.
4. Human anatomy, Regional and applied – Head, Neck
and Brain – B.D. Chaurasia, 3rd
Edition.
5. Orban’s oral histology and embryology – S.N. Bhaskar,
11th
Edition.

7. Oral histology, development, structure and function –
A.R. Ten Cate, 4th
Edition.
8. Contemporary Orthodontics – William R. Proffit.
9. The development of the palate – a brief review; Eur J
Anat, 7 Suppl. 1: 53-74 (2003)

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MANAGEMENT OF DEFECTS OFMANAGEMENT OF DEFECTS OF
PALATEPALATE

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