Growth & development of tooth & tongue/ dental crown & bridge courses

GROWTHGROWTH
ANDAND
DEVELOPMENTDEVELOPMENT
OFOF
TOOTH AND TONGUETOOTH AND TONGUE
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

ContentsContents
 Introduction
 Development of tooth (Odontogenesis)
 Dentinogenesis
 Amelogenesis
 Development of pulp
 Cementogenesis
 Development of periodontal ligament
Developmental anomalies of tooth
Development of tongue
Anatomy
Developmental anomalies of tongue
Prosthodontic considerations
References www.indiandentalacademy.com

INTRODUCTIONINTRODUCTION

OFOF
TOOTHTOOTH

NEURAL CREST CELLS – they are the cells which are
derived from the neural crest.
The neural crest is the region of ectoderm adjacent to the
neural ectoderm which breaks off when the neural tube
forms
The neural crest cells have the capacity to divide
extensively
ECTOMESENCHYME - embryonic connective tissue
Due to its origin from neural crest, is termed
ectomesenchyme.
It consists of a few spindle shaped cells
Separated by a gelatinous ground substance.

PRIMARY EPITHELIALPRIMARY EPITHELIAL
BANDBAND
After 37 days of development, a continuous band of
thickened epithelium forms around the mouth
In the upper and lower jaws from the fusion of separate
plates of thickened epithelium.
These bands are roughly horseshoe shaped
correspond in position to the future dental arches .

The formation of these thickened epithelial
bands
Change in the orientation of the cleavage
plane cells
Proliferation of the cells .
This primary epithelial band gives rise to 2
subdivisions i.e.
Vestibular lamina
Dental laminawww.indiandentalacademy.com

VESTIBULAR LAMINAVESTIBULAR LAMINA
At 6 weeks of development , no sulcus can be seen
between the cheek and tooth bearing areas
The vestibule forms as a result of the proliferation
of vestibular lamina into the ectomesenchyme.
Its cells rapidly enlarge and then degenerate to
form a cleft that becomes the vestibule between
the cheek and tooth bearing areas.

DENTAL LAMINADENTAL LAMINA
Continued and localized proliferative activity
leads to the formation of a series of epithelial
ingrowths into the ectomesenchyme
At sites corresponding to the positions of the
future deciduous teeth
Tooth development now proceeds in three stages
the bud stage
the cap stage
the bell stagewww.indiandentalacademy.com

BUD STAGE ( PROLIFERATION)BUD STAGE ( PROLIFERATION)
Represented by the first epithelial incursion into
the ectomesenchyme of the jaw
Epithelial cells show little change in shape or
function.
Supporting ectomesenchymal cells are closely
packed beneath & around the epithelial bud.

CAP STAGE (PROLIFERATION)CAP STAGE (PROLIFERATION)
As the epithelial bud continues to proliferate into the
ectomesenchyme, cellular density increases
immediately adjacent to the epithelial ingrowth.
This process called as condensation of the
ectomesenchyme, results, from a local grouping of
cells that have failed to produce extracellular substance
and have thus not separated from each other

The different formative elements of the
tooth are
1. The epithelial ingrowth, which
superficially resembles a cap sitting on a
ball of condensed ectomesenchyme, is
called the dental organ,- it forms the
enamel of the tooth.

The ball of condensed ectomesenchymal cells, are
called the dental papilla, form the dentin and
pulp.
The condensed ectomesenchyme limiting the
dental papilla and encapsulating the dental organ
is called the dental follicle or sac, it gives rise to
the supporting tissues of the tooth
The dental organ, dental papilla, and dental
follicle together constitute the tooth germ.

Enamel knot
Enamel niche
Enamel cord

BELL STAGE (HistodifferentiationBELL STAGE (Histodifferentiation
And Morphodifferentiation)And Morphodifferentiation)
The dental organ comes to resemble a bell as
the undersurface of the epithelial cap
deepens.
Through these developmental changes,
termed histodifferentiation, a mass of
similar epithelial cells transforms itself into
morphologically and functionally distinct
components.

The cells in the center of the dental organ
continue to synthesize and secrete
glycosaminoglycans into the extracellular
compartment between the epithelial cells
Glycosaminoglycans are hydrophilic and
so pull water into the dental organ.
The increasing amount of fluid increases
the volume of the extracellular
compartment of the dental organ, and the
cells of the organ are forced apart.www.indiandentalacademy.com

Because the cells retain connections with
each other through their desmosomal
contacts, they become star shaped.
The center of the dental organ is thus
termed the stellate reticulum.

At the periphery of the dental organ, the cells
assume a cuboidal shape and form the
external or outer dental epithelium .
The cells bordering on the dental papilla
differentiate into two histologically distinct
components.
Those immediately adjacent to the dental
papilla assume a short columnar shape and
are characterized by high glycogen content
together they form the internal or inner
dental epitheliumwww.indiandentalacademy.com

Between the internal dental epithelium and
the newly differentiated stellate reticulum
some epithelial cells differentiate into a
layer called the stratum intermedium.
The cells of this layer are characterized by
an exceptionally high activity of the
enzyme alkaline phosphatase.
The internal dental epithelium meets thewww.indiandentalacademy.com

Ultastructural changes of theUltastructural changes of the
tooth germ in bell stagetooth germ in bell stage
The dental organ is supported by a basal
lamina around its periphery.
The external dental epithelial cells are
cuboidal and have a high nuclear:
cytoplasmic ratio.
Their cytoplasm contains free ribosomes, a
few profiles of endoplasmic reticulum,
some mitochondria, and a few scattered
tonofilaments.www.indiandentalacademy.com

Adjacent cells are joined by junctional
complexes.
The star-shaped cells of the stellate
reticulum are connected to each other, to
the cells of the external dental epithelium,
and to the stratum intermedium by
attachment plaques known as desmosomes.
Their cytoplasm contains all the usual
cytoplasmic organelles, but they are
sparsely distributed.www.indiandentalacademy.com

The cells of the stratum intermedium are
connected to each other and to the cells of
the stellate reticulum and internal dental
epithelium by desmosomes
Their cytoplasm also contains the usual
complement of organelles and
tonofilaments www.indiandentalacademy.com

The cells of the internal dental epithelium
have a centrally placed nucleus an a
cytoplasm that contains free ribosomes, a
few scattered profiles of rough endoplasmic
reticulum, mitochondria evenly dispersed,
some tonofilaments, a Golgi complex
situated toward the stratum intermedium,
and a high glycogen content.

Breakup of the DentalBreakup of the Dental
LaminaLamina
During the bell stage first, the dental
lamina joining the tooth germ to the oral
epithelium breaks up into discrete islands of
epithelial cells ,thus separating the
developing tooth from the oral epithelium.

Fragmentation of the Dental Lamina results
in the formation of discrete clusters of
epithelial cells that normally degenerate and
are resorbed.
If any persist, they may form small cysts
(eruption cysts) over the developing tooth
and delay eruption.

An important consequence of the
fragmentation of the dental lamina is that
the before the tooth can function, it must
reestablish a connection with the oral
epithelium and penetrate it to reach the
occlusal plane.
This penetration of the lining epithelium
by the tooth is a unique example of a
natural break in the epithelium of the body

CrownCrown Pattern DeterminationPattern Determination
The cessation of mitotic division within
cells of the dental epithelium determines the
shape of a tooth.
When the tooth germ is growing rapidly
during the early bell stage, cell division
occurs throughout the internal dental
epithelium.
As development continues, cell division
ceases at a particular point because the cells
are beginning to differentiate and assume
their eventual function of producing
enamel.
Determination of Tooth ShapeDetermination of Tooth Shape

The point at which internal dental epithelial cell
maturation first occurs represents the site of future
cusp development, or the growth center.
Because the internal dental epithelium is
constrained at the cervical loop and because there
is continued proliferation of cells on each side of
the zone of maturation, the epithelium buckles and
forms a cuspal outline.
Thus the future cusp is pushed up toward the
external dental epithelium.

Eventually the zone of maturation sweeps
down the cusp slopes and is followed by the
deposition of dentin and enamel, which fix
as the outline of the amelodentinal junction.
A zone of maturation always precedes the
zone of maturation on the flanks of the
cusp, however, resulting in an emphasis of
cusp outline

The occurrence of a second zone of
maturation within the internal dental
epithelium leads to the formation of a
second cusp, a third zone leads to a third
cusp, and so on until the final cuspal pattern
of the tooth is determined.
Therefore, the crown pattern of the tooth
seems to be determined by differential cell
division within the internal dental
epithelium. www.indiandentalacademy.com

THE FIELD MODELTHE FIELD MODEL
It proposes that the factors responsible for tooth shape
reside within the ectomesenchyme in distinct but graded
fields for each tooth family
The field corresponds to those unknown factors that
control the regional differentiation of dental mesenchyme
In support of this idea is the fact that, each of the fields
expresses differing combinations of patterning homeobox
genes

THE CLONE MODELTHE CLONE MODEL
It describes odontogenesis in terms of cell clones
Homogenous cells have the ability to grow and
differentiate without any supracellular control
Osborn predicted 3 dental clones -1 each for incisors,
canines and molars
In support of this contention-- isolated presumptive
first molar tissues have been shown to continue
development to form three molar teeth in their normal
positional sequence

It may be that both models can be
combined
For instance, the coded pattern of
homeobox gene expression in the
ectomesenchyme might be expressed
following an epithelial signal, as was the
case for tooth initiation.
Furthermore, as with tooth initiation,
ectomesenchyme eventually assumes the
dominant role in crown pattern formation.
Recombination of molar papilla with
incisor dental organ results in molar
development; conversely, recombination of
incisor papilla with molar dental organ
results in incisor developmentwww.indiandentalacademy.com

ROOT FORMATIONROOT FORMATION
Epithelial cells of the external and internal
dental epithelium proliferate from the
cervical loop of the dental organ to form a
double layer of cells known as Hertwig's
epithelial root sheath.
This sheath of epithelial cells grows around
the dental papilla between the papilla and
the dental follicle until it encloses all but the
basal portion of the papilla.www.indiandentalacademy.com

The rim of this root sheath, the epithelial
diaphragm, encloses the primary apical
foramen.
As the inner epithelial cells of the root
sheath progressively enclose more and more
of the expanding dental papilla, they initiate
the differentiation of odontoblasts from
cells at the periphery of the dental papilla.
These cells eventually form the dentin of
the root. In this way a single-rooted tooth is
formed

Multirooted teeth are formed in the same way.
Differential growth of epithelial diaphragm in the
multirooted teeth causes the division of the root
trunk into 2 or 3 roots.
Two such extensions are found in germs of lower
molars and 3 in the germs of upper molar.
Before division of root trunk occurs the free ends
of these horizontal epithelial flaps grow towards
each other and fuse.
The single cervical opening of the coronal enamel
organ is then divided into 2-3 openings.

DENTINOGENESISDENTINOGENESIS
Begin at the cusp tips after the odontoblasts have
differentiated and begin collagen production.
The odontoblast differentiate from an ovoid to a
columnar shape.
Several processes arise from the apical end of the
cell in contact with basal lamina.
As the matrix formation continues, the odontoblast
process lengthens, as does the dentinal tubule.
Initially daily increment of 4µm of dentin is
formed and continues until the crown is formed.
After this dentin production slows to about 1µm/day

Dentinogenesis is a two phase sequence in which
collagen matrix is first found and is then calcified.
As the increment of predentin is formed along the
pulp border, it remains a day before it is calcified
and the next increment of predentin forms.
Korff’s fibers have been described as the initial
dentin deposition along the cusp tips.

Consequently all predentin is formed in the
apical end of the cell and along the forming
tubular wall.
MINERALIZATION
The earliest crystal deposition is in the form
of fine plates of hydroxy apatite on the
surfaces of collagen fibres and in the ground
substances.

Subsequently crystals are laid down within the
fibres themselves.
The crystals are arranged in an orderly fashion with
their long axis paralleling the fibril axes.
The general calcification process is gradual.

Within the globular islands of mineralization,
crystal deposition appear to take place radially
from the common centres, in a SPHERULITE
form.
CALCOSPHERITE mineralization is seen
occasionally along the pulp predentin

AMELOGENESISAMELOGENESIS
2 processes are involved in the development of
the enamel.
ORGANIC MATRIX FORMATION
MINERALIZATION
Formation of enamel matrix:
Ameloblasts begin their secretory activity when
a small amount of dentin has been laid.

Ameloblasts loose their projections that had
penetrated basal lamina seperating them
from predentin and islands of enamel
matrix.
Enamel Deposition proceeds, a thin layer of
enamel is formed along the dentin termed as
dentoenamel membrane.

Development of Tome’s
Processes:
The surfaces of the ameloblasts
facing the developing enamel
are not smooth.
There is an interdigitation of
the cells and the enamel rods
that they produce.
The projections of ameloblasts
into the enamel matrix are
named as TOME’S processes.
These tomes processes also
contain typical secretion
granules as well as rough
endoplasmic reticulum and
mitochondria. www.indiandentalacademy.com

DISTAL TERMINAL BARS
At time Tome’s processes begin to form, terminal bars
of the ameloblasts separating the Tome’s processes
from cell proper.
Structurally, they are localized condensations of
cytoplasmic substances closely associated with
thickened membrane.
AMELOBLAST COVERING MATURING ENAMEL
In light microscope ameloblasts over the maturing
enamel are shorter than the ameloblasts over
incompletely formed enamel.www.indiandentalacademy.com

These ameloblast have a villous surface near the
enamel and ends of the cells are packed with
mitochondria.
MINERALIZATION AND MATURATION OF
ENAMEL MATRIX
It takes place in 2 stages:
1st
stage immediate partial mineralization occurs
in the matrix segments and the interprismatic
substances are laid down.
This 1st
mineral is in the form of crystallinewww.indiandentalacademy.com

2nd
stage of maturation
Characterized by gradual
completion of mineralization.
Process of maturation starts
from the height of the crown
and progresses cervically.
At each level maturation seems
to begin at the dentinal end of
the rods.
Each rod mature from the depth
to the surface.
And the sequence of maturing
rods is from the cusp towards
the cervical line.
Maturation begins before the
matrix has reached its full
thickness. www.indiandentalacademy.com

DEVELOPMENT OF PULP
During dentogenesis the dental bell grows and reaches
the size and shape of future dental crown. At the same
time the papilla enlarges through cellular proliferation.
This space takenup by papilla is then reduced again by
increasing thickness of dentinal wall.
During root formation the papillary
tissue also proliferates along the
long axis of the tooth, but at the
same time is restricted to a
progressively narrower space by
increasing mass of dentin.

The apical opening of the papilla surrounding by the
dental follicle and the future periodontal ligament,
remains wide as long as root formation continuous.
It is only after formation of root apex this wide open
entrance to pulp is reduced to apical foramen.
The transformation of papilla into pulp is
accompanied by an decrease in concentration of cells
(Mesenchymal and fibroblast) and increase in
precollagenous and collagenous fibrils.

This brings the shift in distribution of fibrillar
elements which, in the papilla have uniform,
loose arrangement but in pulp are found mainly in
root region.
Most of the initially undifferentiated
mesenchymal cells of papilla become fibroblast.
Fibroblast of young pulp are highly active
synthesizing cells.
The network of blood vessel and nerve fibers
become denser.
Some of the mature mesenchymal cells remain in
mature pulp tissue as undifferentiated and later
can replace necrotic odontoblasts.www.indiandentalacademy.com

CEMENTOGENESISCEMENTOGENESIS
Cementum formation in the developing tooth is
preceded by the deposition of dentin along the
inner aspect of the Hertwig’s epithelial root sheath.
Breaks occur in the epithelial sheath once dentin
formation is underway. Allowing newly formed
dentin to come in direct contact with connective
tissue of the dental follicle.
Cells derived from this connective tissue is
responsible for cementum formation.

Breakdown of Hertwig’s
epithelial root sheath involves
degeneration or loss of its basal
lamina on the cemental side.
This is followed by collagen
fibrils and cementoblasts
between epithelial cells of root
sheaths.
Some cells migrate toward the
dental sac, whereas others
remained near the development
tooth. These cells are called
RESTS OF MALASSEZ.www.indiandentalacademy.com

After some cementum matrix has been laid down
its mineralization begins.
The uncalcified matrix is called CEMENTOID.
Calcium and phosphate ions present in the tissue
fluids are deposited into the matrix and are
arranged as unit cells of hydroxyapatite.
Mineralization of cementoid is highly ordered
event.

DEVELOPMENT OF PERIODONTAL
LIGAMENT
The cells of periodontal ligament are derived
from dental sac.
The development of periodontal ligament and its
collagen fiber bundle is different for deciduous
teeth and permanent molars.
The development begins with root formation and
always occur in connection with prior
disintegration of Hertwig’s epithelial root sheath
and simultaneous appearance of cementum.

As each collagen fiber bundle is
formed by fibroblast one end
becomes invaded in the newly
formed cementum while the
remainder of the bundle extends
far occlusally within the walls of
bony compartment.
Thus the fiber bundles of the
periodontal ligament are at first
oriented parallel with the excess
of the tooth and run from the
cementum in an occlusal
direction along the crown and
only later are remodelled with
their usual orientation. www.indiandentalacademy.com

DEVELOPMENTAL ANOMALIESDEVELOPMENTAL ANOMALIES
Developmental disturbances in SIZE of teeth:-
1. MICRODONTIA:- Teeth are smaller than normal.
Types- a. True Generalised
b. Relative Generalised
c. Microdontia involving a single tooth.
2. MACRODONTIA: -Teeth are larger than normal.
Types- a. True Generalised
b. Relative Generalised
c. Macrodontia involving a single tooth.

Developmental disturbances in SHAPE of teeth:-
1. GEMINATION:- Occurs by division of a single
tooth germ by an invagination, with resultant
incomplete formation of 2 teeth.
TWINNING:- Designates the production of
equivalent structures by division, resulting in
one normal and one supernumerary tooth.

2. FUSION:- Occurs by the union of
2 normally separated tooth germs.
-Depending upon the stage of
development of the teeth at the time
of union, fusion can be complete or
incomplete.
-If contact occurs early, before
calcification begins- the 2 teeth be
completely united to form single
large tooth.
-If contact occurs later, when a
portion of tooth crown has
completed its formation- there may
be union of roots only.

3. CONCRESCENCE:- Form of
fusion which occurs after root
formation has been completed.
-Teeth are united by
cementum only.
4. DILACERATION:- An
angulation or a sharp bend or
curve in the root or crown of the
formed tooth.
- Caused due to trauma
during the period of tooth
formation, with the result that
the position of the calcified
portion of the tooth is changed
and the remainder of tooth is
formed at an angle.

5. TALON CUSP:- Resembles eagle’s talon.
-Projects from the cingulum areas of a
maxillary or mandibular permanent incisor.
6. DENS IN DENTE(DENS INVAGINATUS):-
-Developmental variation that arise as a
result of an invagination in the surface of a tooth
crown before calcification has occured.
-Causes: Increase localized external pressure,
Focal growth retardation, Focal growth
stimulation in areas of tooth bud.
Radicular ‘dens in dente’ usually results from an
unfolding of Hertwig’s sheath and takes its origin
within the root after development is complete.

DENS EVAGINATUS
Pathogenesis: of the lesion can be the proliferation
and evagination of an area internal enamel
epithelium and subjecent odontogenic
mesenchyme into the dental organ during early
tooth development.
TAURODONTISM
Body of tooth is enlarged at the expense of the
roots.
Cause: Mutations resulting from odontoblastic
deficiency during dentinogenesis of the root.
It can also be cause due to the failure of Hertwig’s
epithelial sheath to invaginate at proper horizontal
level. www.indiandentalacademy.com

Developmental disturbances in number of teeth
ANODONTIA
1.True anodontia:
(a) Total, (b) Partial
2. False anodontia
SUPERNUMERARY TEETH
Cause: they may develop from a 3rd
tooth bud
arising from the dental lamina near the
permanent tooth bud.
PREDECIDIOUS DENTITION
POST PERMANENT DENTITION

Developmental Disturbances in
Structure of Teeth
AMELOGENESIS IMPERFECTA
It is entirely ectodermal disturbance
since the mesodermal components are
normal.
ENVIRONMENTAL ENAMEL
HYPOPLASIA
DENTINOGENESIS IMPERFECTA
Can be a 3 types – Type I, Type II,
Type III
DENTIN DYSPLASIA
REGIONAL ODONTODYSPLASIAwww.indiandentalacademy.com

OFOF
TONGUETONGUE

Tongue arises in the ventral wall of the primitive
oropharynx from the first four branchial arches.

FORAMEN CAECUM arises
from this pit and is the site of
origin of THYROID
DIVERTICULUM which forms
the THYROID GLAND.
Anterior 23rd of the TONGUE
derived from fusion of lingual
swellings and tuberculum impar.
LINGUAL SWELLING appear on the internal
aspect of the 1st branchial arch during 4thweek i.u
TUBERCULUM IMPAR arises in the midline of
the mandibular process,whose caudal border is
marked by a blind pit.

Epithelial proliferation into the
underlying mesenchyme occurs
around the periphery of lingual
swellings.
Degeneration of the central cells
of the horseshoe-shaped lamina
forms a sulcus,the
LINGUOGINGIVAL GROOVE
which frees the body of the
tongue from the floor of the
mouth except for the midline
FRENULUM of the tongue.
COPULA is a united single
midventral prominence, formed
from the ventral bases of 2nd, 3rd
and 4th branchial arches .

Anterior part gives origin to- mucosa covering the root of
the tongue.
Posterior part (HYPOBRANCHIAL EMINENCE) origin
to- epiglottis.

The endodermally derived mucosa of the 2nd
to 4th
branchial arches and copula provide the covering
for the root of the tongue.
Circumvallate papillae develop at 2-5 months i.u.
Fungiform papillae develop earlier at 11 weeks
i.u.
Filiform papillae develop later and are not
complete until postnatally.

At Birth, root mucosa becomes pitted by deep crypts
that develop into LINGUAL TONSIL.
TASTE BUDS arise by inductive interaction
between epithelial cells(ectodermal and endodermal
cells) and invading gustatory nerve cells from the
chorda tympani, glossopharyngeal and vagus
nerves.
Gustatory cells start to form at 7th week i.u., but
taste buds are not recognisable until 13-15th weeks
i.u.
Initially, only single taste buds are present in the
fungiform papillae, but multiply, by branching in
later fetal life. www.indiandentalacademy.com

MUSCLES OF THE TONGUE arise in the floor of
the pharynx in the occipital somite region, opposite
the origin of the hypoglossal nerve.
Tongue while moving upwards and ventrally into
the mouth, retains its initial nerve supply:-
a. Mucosal contributions of the 1st branchial arch
(trigeminal nerve) are reflected in the lingual
nerve’s tactile sensory supply of the body of the
tongue.
b. The 2nd branchial arch (facial nerve) accounts
for gustatory sensations from the body of the tongue
through the chorda tympani nerve.www.indiandentalacademy.com

c. The 3rd and 4th arches contribute to the mixed
tactile and gustatory glossopharyngeal and vagus
nerve innervation of the mucosa of the root of the
tongue.
d. The palatoglossus muscle- innervated by
pharyngeal plexus,(the fibres derived from the 3rd
and 4th branchial arches) and accessory nerves.
e. Motor innervation of all the musculature of the
tongue,except palatoglossus, by the hypoglossal
nerve reflects its occipital somite origin.

The entire tongue is within the mouth at birth .
Posterior 1/3rd of tongue descends into the pharynx
by the age of 4years.
The tongue normally doubles in length, breadth and
thickness between birth and adolescence, reaching
near maximal size by about 8years but in some
individuals it continues to grow during adulthood.

ANATOMYANATOMY
External Surface:-
1. Root
2. Tip
3. Body
a. Dorsum
Oral Part
Pharyngeal Part
These parts separated by SULCUS TERMINALIS.
b. Inferior surface
Oral Part

ROOT:-
Attached to the mandible above and hyoid
bone below.
Inbetween 2 bones it is related to
geniohyoid and mylohyoid muscles.
TIP:-
It forms the anterior free end which at rest lies
behind the upper incisor teeth.

DORSUM:- convex in all directions
Oral Part:-
Has free margins.
These margins show 4-5 folds, named
FOLIATE
PAPILLAE in front of palatoglossal arch.
a. Superior Surface
b. Inferior Surface
FRENULUM LINGUAE- median fold
DEEP LINGUAL VEINS- on either side of
frenulum
PLICA FIMBRIATA- more laterally

Pharyngeal Part:-
Lies behind the palatoglossal arches and sulcus
terminalis.
Absence of papillae, but presence of many
LYMPHOID FOLLICLES collectively
constitute LINGUAL TONSIL.
Presence of mucous glands.
3 folds of mucous membrane connects tongue to
epiglottis.
VALLECULA - pouch on either side of median
fold. www.indiandentalacademy.com

INTRINSIC
MUSCLES:-
Superior Longitudinal
Muscle
Inferior Longitudinal
Muscle
Transverse Muscle
Vertical Muscle
MUSCLES OF TONGUEMUSCLES OF TONGUE

EXTRINSIC MUSCLES:-
Genioglossus
Hyoglossus
Styloglossus
Palatoglossus

ARTERIAL SUPPLYARTERIAL SUPPLY
Chiefly derived from LINGUAL ARTERY.
TONSILLAR and ASCENDING PHARYNGEAL
ARTERIES supply ROOT of tongue.
VENOUS DRAINAGEVENOUS DRAINAGE
Two Venae comites accompany lingual artery.
One vena comitans accompanies the hypoglossal
nerve.
Deep lingual vein is the largest and principal vein of
the tongue.
These veins unite to form lingual vein which ends
either in common facial or internal jugular vein.

LYMPHATIC DRAINAGELYMPHATIC DRAINAGE
Tip of tongue drains bilaterally into:-
SUBMENTAL NODES
Anterior part drains unilaterally into:-
SUBMANDIBULAR NODES
Posterior part drains bilaterally into:-
JUGULO OMOHYOID NODES

NERVE SUPPLYNERVE SUPPLY
1. MOTOR
SUPPLY
All intrinsic and
extrinsic muscles
except Palatoglossus
supplied by
HYPOGLOSSAL
NERVE.
Palatoglossus supplied
by cranial part of
ACCESSORY NERVE
through the pharyngeal
plexus. www.indiandentalacademy.com

2. SENSORY SUPPLY
LINGUAL NERVE nerve of
general sensation.
CHORDA TYMPANI:-taste
sensation for anterior 2|3 of
tongue.
GLOSSOPHARYNGEAL
:-general sensation and taste for
posterior 1/3
VAGUS NERVE through
internal laryngeal branch:-
posteriormost part

PAPILLAE OF THE TONGUE
Projections of mucous membrane which gives
roughness to anterior 2/3rd of tongue.
TYPES:-
1. FILIFORM
PAPILLAE:-Most numerous
and the
smallest.
-Consists of connective
tissue core covered by
stratified squamous
keratinised epithelium.
-Contains no taste buds.www.indiandentalacademy.com

2. FUNGIFORM PAPILLAE:-Mushroom shaped
projections on dorsal tongue surface.
-Contains connective tissue core, stratified
squamous surface and contain taste buds.
3. CIRCUMVALLATE PAPILLAE:-8-12 arranged in
form of “V” anterior and roughly parallel to the
sulcus terminalis.
-Large and round .
-Von Ebner’s Glands surround circumvallate
papillae. They are serous.
4. FOLIATE PAPILLAE:-Present at edges of tongue.

TASTE BUDSTASTE BUDS
Present on fungiform,
circumvallate and
foliate
papillae and on
mucous membrane of
pharynx.

DEVELOPMENTAL ANOMALIES OFDEVELOPMENTAL ANOMALIES OF
THE TONGUETHE TONGUE
1. Microglossia
2. Macroglossia
3. Ankyloglossia
4. Cleft Tongue
5. Fissured Tongue (scrotal tongue)
6. Median Rhomboid Glossitis
7. Benign Migratory Glossitis
8. Hairy Tongue
9. Lingual Tongue www.indiandentalacademy.com

MICROGLOSSIA:-
-Rare congenital anomaly that manifests a small
and rudimentary tongue.
MACROGLOSSIA:-
-Enlarged tongue.
-Congenital or secondary in type.
a. Congenital Macroglossia:-
-Due to an over development of the musculature,
which may or may not be associated with
generalised muscular hypertrophy or

b. Secondary Macroglossia:-
Causes are:-
-Tumor to tongue.
-Acromegaly.
-Congenital hyperthyroidism.
Leads to:-
- Displacement of teeth.
-Malocclusion

OROLINGUAL PARESTHESIAOROLINGUAL PARESTHESIA
Glossodynia or “painful tongue”
Glossopyrosis or “burning tongue”
-Paresthesia of the oral mucous membrane is a
common clinical occurance.
-It is a symptom rather than a disease entity.
-One of the cause for this can be local dental causes
such as dentures, irritating clasps or new fixed
bridges.
-Sensations most commonly encountered are pain,
burning, itching and stinging of mucous membrane.www.indiandentalacademy.com

PROSTHODONTIC CONSIDERATIONS OF
TOOTH ANOMALIES
1)Microdontia and Macrodontia of localized
nature are usually of no consequence. Crown
and bridge prosthodontic reconstruction may
be employed to achieve an esthetic appearance.
2)In Gemination and fusion depending on the
morphological feature of the tooth, fixed
prosthodontic appliance can be constructed and
tooth can be used as an abutment.
3)Taurodontism – the enlarged pulp chamber
should be taken care of during any
prosthodontic treatment.

4) Anodontia – related to hereditary ectodermal
dysplasia, prosthodontic appliances are the treatment
of choice. Dentures with soft liner maybe employed
in case of xerostomia.
5) Amelogenesis Imperfecta – Full crown prosthesis
are recommended for esthetic reasons and to
eliminate sensitivity.
- In hypomaturation and hypocalcification type
of amelogenesis imperfecta full coverage prosthesis
minimize calculus deposition. Resin restorative
material can help for desirable esthetic appearance.

6) Dentinogenesis Imperfecta – Full crowns can be
fabricated at early age, because of small,
obliterated pulp chambers. When severe abrasion
exists, an overdenture maybe considered.
7) Dentin Dysplasia – No specific treatment.
When teeth are lost as a result of shortened roots,
adjacent teeth should not be used as prosthetic
abutment.
8) Regional Odontodysplasia – The teeth are non
functional, because eruption is not evident or is
only partial. Fabrication of prosthetic appliance is
recommended. www.indiandentalacademy.com

PROSTHODONTIC
CONSIDERATIONS OF TONGUE
Tongue is a powerful factor mitigating against the
stability of the lower denture, so care should be
taken to design denture.
a) The teeth must never be set inside the alveolar
ridge or they will cramp the tongue causing
movement of the denture and irritation to
patient.
b) Lingual flanges present in the low denture
should slopes slightly inward from a abovewww.indiandentalacademy.com

In no circumstances should the lingual cusp of the
posterior teeth overhang the tongue.
c) The occlusal plane of the lower denture should
be kept low, thus align the lateral borders of the
tongue to rest upon the occlusal surface of the
teeth.
d) In upper denture thin posterior border should
be fabricated for a proper seal so as to sink into
the compressible tissue and not irritate the tongue.

REFERENCESREFERENCES
1)Agur M.R. – Grant’s Atlas of Anatomy
9th
Edition, 1991
2) Berkovitz B.K.B. – A Colour Atlas and
Textbook of Oral Anatomy
4th
Edition, 1986
3) Berkovitz B.K.B. – Head & Neck Anatomy
2002
4) Bhaskar S.N. – Orban’s Oral Histology &
Embryology, 10th
Edition, 1990
5) Chaurasia B.D. – Human Anatomy,
3rd
Edition, 1996
6) Eversole L.R. – Clinical Outline of Oral
Pathology Diagnosis &
Treatment, 2nd
Edition, 1984

7) MacGregor A.R. – Clinical Dental Prosthetics,
3rd
Edition, 1989
8) Miller A.S. & Robinson H.B.G. – Colour Atlas of
Oral Pathology, 5th
Edition, 1990
9) Moore & Persaud – The Developing Human,
Clinically Oriented Embryology, 5th
Edition, 1993
10) Ross M.H. & Reith E.J. – Histology, A text &
Atlas, 1985
11) Schroeder H.E. – Oral Structural Biology, 1991
12) Shafer W.G. – Text Book of Oral Pathology, 4th
Edition, 1983
13) Sperber G.H. – Craniofacial Embryology,
4th
Edition, 1989
14) Tencate A.R. – Oral Histology, 3rd
Edition, 1989www.indiandentalacademy.com

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