TEMPOROMANDIBULAR JOINT

Submitted by:

Batallones, Amery Rose

Galeno, Chris Carlo

Saunar, Maurice Cheekz

Talag,Bryan Matthew

Ursal, Alyssa Mae

Villacorta, Aimee Carmina

TEMPOROMANDIBULAR JOINT

This is the articulation between the condylar head of mandible and the anterior part of

the glenoid fossa of two temporal bones. The mandibular articulation with the skull on each

side is better termed as Craniomandibular Joint since the articulation is between the movable

mandible and the immovable cranium or skull. The articulation is bilateral because the left and

right sides work as a unit and this is the only visible free moving articulation in the head.

Temporomandibular Joint has distinct features compared to the other joints: The

coordinated movements of the right and left joints are complex and usually are controlled by

reflexes. Both the maxillae and mandible carry teeth whose shape and position greatly affect

the most closed portions of mandibular movements. The articulating surface of the TMJ is not

formed of Hyaline cartilage but of a sturdy avascular fibrous layer. TMJ is the only synovial joint

in the body with articulating disc which is present between the joint surfaces of cranium and

mandible which makes it a double joint.

Classification of Joints

Joints are classified in various ways. Most common and simplistic classifications are

Fibrous joints, Cartilaginous joints, and Synovial Joints.

Fibrous Joints

In a fibrous joint two bones are connected by fibrous tissue and 3 types are described

under this classification of joint, the first type is the suture, it is a joint that permits little or no

movement. Articulation by processes and indentations interlocked together. Its histology

clearly indicates that the function is to permit growth, since the articulating surfaces are

covered by an osteogenic layer which is responsible for new bone formation to maintain the

suture as the skull bones are separated by the expanding brain. The second type of fibrous joint

is gomphosis, articulation formed by the insertion of a conical process into a socket. It is seen in

the articulation of the teeth with the alveoli of the maxillary bones. In gomphosis, the

functional movement is restricted to intrusion and recovery in response to biting forces. The

third type of fibrous joint is syndesmosis, surfaces are united by interosseous ligament that

permits limited movement. Common examples are the joints between tibia and fibula, and

radius and ulna.

Cartilaginous Joints

Cartilaginous joints are classified into primary cartilaginous joints or secondary

cartilaginous joints. In a primary cartilaginous joint, bone and cartilage are in direct apposition.

An example is the articulations of the ribs with their cartilages (costo-chondral). In a secondary

cartilaginous joint, the tissues of articulation occur in the sequence bone-cartilage-fibrous

tissue-cartilage-bone. An example is the pubic symphysis. Cartilaginous joints and fibrous joints

permit little if any movement between the bones involved.

Synovial Joints

In synovial joint, which generally permits significant movement, two bones are united

and surrounded by a capsule that creates a joint cavity. This cavity is filled with synovial fluid

formed by the synovial membrane. The cavity may be divided by an articular disk. Various

ligaments are associated with synovial joints to strengthen the articulation and check excess

movement. Synovial joints are further classified by the number of axes in which the bones

involved can move:

uniaxial- all movements take place around one axis. Ex. Ginglymus and Pivot-joint

biaxial- movements around two horizontal axes at right angles to each other or at any

intervening axis between the two. Ex. Condyloid and Saddle-joint

multiaxial/polyaxial- movements around more than two axes.

Ex. Ball-and-socket joint

Synovial joints are also classified by the shapes of the articulating surface:

a. Planar- a synovial joint in which the opposed surfaces are flat or only slightly curved.

b. Ginglymoid- articular surfaces are molded to each other in such a manner as to permit

motion only in one plane, forward and backward.

c. Pivot- movement is limited to rotation; the joint is formed by a pivot-like process turning

within a ring.

d. Condyloid- one in which an ovoid head of one bone moves in an elliptical cavity of

another, permitting flexion, extension, adduction, abduction and circumduction, but not

axial rotation.

e. Saddle- one having two saddle-shaped surfaces at right angles to each other. Same

movement with condyloid articulations.

f. Ball-and-socket- form of joint in which the distal bone is capable of motion around an

indefinite number of axes which have a common center.

Movements of a synovial joint are initiated and affected by muscles working together in

a highly coordinated manner. This coordination is achieved through the joint’s sensory

innervation which establishes Hilton’s Law, the principle that the nerve supplying a joint also

supplies both the muscles that move the joint and the skin covering the articular insertion of

those muscles.

Type of joint of Temporomandibular Joint

The Temporomandibular joint articulation is a synovial joint and described as synovial

sliding-ginglymoid joint articulation because its movements are combination of gliding

movements and a loose hinge movement and also the condyle undertakes rotational

movements which is the initial movement of the jaw when the mouth opens and translational

movements which is the secondary gliding motion of jaw as it is opened widely.

Innervation and Vascularization

Sensory innervation of the temporomandibular joint is derived from

the auriculotemporal and masseteric branches of mandibular branch of the trigeminal nerve.

The arterial blood supply is provided by branches of the external carotid artery,

predominately the superficial temporal branch. Other branches of the external carotid artery

such as deep auricular artery, anterior tympanic artery, ascending pharyngeal artery,

and maxillary artery also contribute to the arterial blood supply of the joint.

The specific mechanics of proprioception in the temporomandibular joint involve four

receptors. Ruffini endings function as static mechanoreceptors which position the

mandible. Pacinian corpuscles are dynamic mechanoreceptors which accelerate movement

during reflexes. Golgi tendon organs function as static mechanoreceptors for protection of

ligaments around the temporomandibular joint. Free nerve endings are the pain receptors for

protection of the temporomandibular joint.

In order to work properly, there is neither innervation nor vascularization within the

central portion of the articular disc.

ANATOMY AND HISTOLOGY

I. Anatomy (Bony Structures):

The temporomandibular joint (TMJ)

consists of the condylar head of the mandible

articulating with the glenoid or

temporomandibular fossa of the temporal

bone. The articulating surface of the

temporal bone is convex anteriorly at the

tubercle and concave posteriorly at the fossa.

The articulating surface of the condyle and the

opposing surface of the temporomandibular

fossa, including the anterior tubercle, are covered by fibrocartilage. Chondrocytes in the

posterior aspect of the mandibular condyle, a region exposed to greater tensional forces than

compression, express collagen types I and II.

The condyle of the mandible is composed of cancellous bone covered by a thin layer of

compact bone. The trabeculae are grouped in such a way that they radiate from the neck of the

mandible and reach the cortex at right angles, thus giving maximal strength to the condyle. The

large marrow spaces decrease in size with progressing age by a marked thickening of the

trabeculae. The red marrow in the condyle is the myeloid or cellular type. In older individuals it

is sometimes replaced by fatty marrow.

During the period of growth layer of hyaline cartilage lies underneath the fibrous

covering of the condyle. This cartilaginous plate grows by apposition from the deepest covering

connective tissue. At the same time its deep surface is replaced by a bone. Remnants of this

cartilage may persist into old age.

The roof of the mandibular fossa consists of a thin compact layer of bone. The articular

tubercle is composed of spongy bone covered with a thin layer of compact bone. In rare cases,

islands of hyaline cartilage are found in the articular tubercle.

Articular fossa is resembles the long axis of that of the condyle. The root of the fossa is

very thin, indicating that the role of this part of the joint is rather passive. The deeper part of

the fossa apparently acts more or less as a bed for the thicker posterior part of the articular disc

when it is resting in its most posterior position. The articular surface proper is the posterior and

inferior part of the articular eminence , which is a roll of bone, more or less steep in its

posterior slope, with an anteroposterior curvature of variable constricture.

It has already been pointed out that the cranial and mandibular surfaces of the joints

are not congruent. They do not touch each other even when the teeth are in intercuspal

contact. The distance from the articular surface of the condyle to the opposing cranial surface is

filled by an articular disc.

II. Histological Part:

Articular Capsule

It is attached to the fossa, to the tubercle of the temporal bone, and to the neck of the

condyle.

It is consist of an outer fibrous layer that is strengthened on the lateral surface to form

the temporomandibular ligament. The inner or synovial layer is a thin layer of connective tissue.

It contains numerous blood vessels that form a capillary network close to its surface. From its

surface, folds or fingerlike processes (synovial folds or villi) protrude into the articular cavity. A

few fibroblast of the synovial membrane reach the surface and, with some histiocytes and

lymphatic wandering cells, form an incomplete lining of the synovial membrane.

A small amount of a clear, straw-colored viscous fluid, synovial fluid, is found in

the articular space. It serves as a:

1. Lubricant: As it the principal role of synovial fluid is to reduce friction between the

articular cartilage of synovial joints during movement.

2. Nutrition: Providres as fluid for the avascular tissues covering the condyle and the

anterior tubercle and for the disc.

3. Regulatory: Separates the articular disk from the articulating surfaces.

This is elaborated by diffusion from the rich capillary network of the synovial

membrane, augmented by mucin possibly by the synovial cells.

Articular Disk

In young individuals, it is composed of dense fibrous tissue. The interlacing fibers are

straight and tightly packed. Elastic fibers are found only in relatively small numbers. The

fibroblast in the disc are elongated and send flat cytoplasmic winglike processes into the

intertices between the adjacent bundles.

With advancing age, some of the fibroblast develop into the chondroid cells, which later

may differentiate into true chondrocytes. Even small islands of hyaline cartilage may be found

in the discs of the older persons. Chondroid cells, true cartilage cells, and hyaline ground

substance develop in situ by differentiatin of the fibroblast. In the disc as well as in the fibrous

tissue covering the articular surfaces this cellular change seems to be dependent upon

mechanical influences. The presence of chondrocytes may increase the resistance and

resilience of the fibrous tissue.

The fibrous tissue covering the articular eminence and mandibular condyle as well as

the large central area of the disc is devoid of blood vessels and nerves and has limited ability.

Articular Surface of the Temporal Bone

The fibrous layer covering the articulating surface of the temporal bone is thin in the

articular fossa and thickens rapidly on the posterior slope of the artcular tubercle. In this region,

the fibrous tissue shows a definite arrangement in two layers, with a small transitional zone

between them.

a. Inner Zone – the fibers are at right angles to the bony surface.

b. Outer Zone – they run parallel to the bony surface.

As in fibrous covering of the mandibular condyle, a variable number of chondrocytes are

found in the tissue on the temporal surface. In adults the deepest layer shows a thin s=zone of

calcification. There is no continuous cellular lining on the free surface of the fibrocartilage. Only

isolated fibrolast are situated on the suface itself. They are characterized by the formation of

long, flat cytoplasmic processes.

Mandibular Condyle

It is composed of a fibrous layer of tissue that is of fairly even thickness. Its superficial

layers consist of a network of strong collagenous fibers. Chondrocytes may be present and they

have a tendency to increase in number with age. They can be recognized by their thin capsule,

which stains heavily with basic dyes. The deepest layer of the fibrocartilage is rich in chondroid

cells as long as growing hyaline cartilage is present in the condyle. It contains only a few thin

collagenous fibers. In this zone the appositional growth of the hyaline cartilage of the condyle

takes place during the period of growth.

Unlike the articulating surfaces in most joints of the body, the mandibular condyle is not

covered by naked hyaline cartilage. Instead, its articulating cartilage surface is covered by a thin

layer of poorly vascularized dense connective tissue with few fibroblasts. Collagen type I is the

major constituent found in this outer layer.

However, during its development phase, the growing condyle is covered by a

perichondrium and its bulk is made up of typical hyaline cartilage. A similar fibrous layer covers

the surface of the temporomandibular fossa and articular tubercle. The inner region of this

fibrous layer retains progenitor cells that give rise to prechondrocytes.

Function of Mandibular Condyle:

1. Adapts the shifting vector of force, such as in chewing.

2. Undergo changes, some of which are related to changes in mandibular function and

occlusion, since throughout life, the shape of the condyle undergo changes.

III. Synovial Tissue

A synovial membrane covers the inner surface of the joint capsule. The synovial

membrane does not cover the articulating surfaces and the corresponding parts of the

articulating disk. The synovial membrane is neither an epithelial lining nor an actual

membrane; rather it is composed entirely of connective tissue rich in collagen V. The

synovial membrane is well vascularized with numerous fenestrated capillaries.

Histopathologic studies indicate that there is substantial variation in the morphology of

the synovial lining of the normal TMJ, and that synovial inflammation of the TMJ tends to be

less severe than that arising in other joints.

IV. Ligaments

1. Lateral Temporomandibular Ligament

- Strengthens the lateral aspect of the capsule, and its fibers run downward

and backward from the tubercle on the root of the zygoma to the lateral

surface of the neck of the mandible. This ligament limits the movement of

the mandible in a posterior direction and thus protects the external auditory

meatus.

2. Sphenoparietal Ligament

- Lies on the medial side of the joint. It is thin band that is attached above to

the spine of the sphenoid bone and below to the lingual of the mandibular

foramen. It represents the remains of the first pharyngeal arch in this region.

3. Stylomandibular ligament

- Lies behind and medial to the joint and some distance from it. It is merely a

band of thickened deep cervical fascia that extends from the apex of the

styloid process to the angle of the mandible.

DEVELOPMENT OF THE TMJ

The development of the TMJ involves the following structures:

Mandible

Glenoid fossa

Condyle

Articular disc

Upper joint cavity and Lower joint cavity

At 12 weeks of the gestation, the TMJ begins to develop which is marked by the

appearance of two distinct regions of mesenchymal condensation: the temporal/glenoid

blastema and condylar blastema where the glenoid fossa and condyle arise respectively.

Mandible

The Meckel’s cartilage is the one responsible for the skeletal support for the

development of the mandible or the lower jaw that begins from 6th to 7th week. It extends from

the midline that goes laterally and posteriorly.

Formation of the Glenoid Fossa

Between 10th to 11th week, bone formation in the temporal blastema had begun and

continues anteriorly while the condylar blastema remains undifferentiated and in between

them is a gap.

Formation of the Condyle

The condyle, at first is cartilaginous, develops between the 10th and 11th weeks from the

accumulation of mesenchymal cells called condylar blastema that is lateral to Meckel's cartilage.

Enchondral ossification progresses apically, creating a bony fusion with the body of the mandible.

Immediately above the condylar blastema appears a cleft which becomes the lower joint cavity

and then as the condylar blastema differentiates into a cartilage called condylar cartilage. A

second cleft then appears in relation to the ossification of the temporal bone for the glenoid

fossa which becomes the upper joint cavity.

Formation of the Upper and Lower Joint Cavity

The lower joint space appears first at about the 10th week, but later the upper joint

space overtakes it in its development.

The upper joint space appears after about the 12th week and spreads posteriorly and

medially over Meckel's cartilage with its contour corresponding to that of the future fossa. After

13th week the lower joint space is already well formed as the upper joint space continues to

take shape. From its beginning, the upper joint space has fewer individual islands of space and

grows more rapidly than the lower joint space. After 14th week both joint spaces are completely

formed.

Formation of the Articular Disc

With the formation of these two clefts is the formation of the primitive articular disc.

The articular disk can first be identified after 7.5 weeks in utero as a horizontal concentration

of mesenchymal cells. Between weeks 19 and 20 its typical fibrocartilaginous structure is already

evident.

MUSCLES OF MASTICATION

The Masseter is a thick, somewhat quadrilateral muscle, consisting of two portions,

superficial and deep. The superficial portion, the larger, arises by a thick, tendinous

aponeurosis from the zygomatic process of the maxilla, and from the anterior two-thirds of the

lower border of the zygomatic arch; its fibers pass downward and backward, to be inserted into

the angle and lower half of the lateral surface of the ramus of the mandible. The deep

portion is much smaller, and more muscular in texture; it arises from the posterior third of the

lower border and from the whole of the medial surface of the zygomatic arch; its fibers pass

downward and forward, to be inserted into the upper half of the ramus and the lateral surface

of the coronoid process of the mandible. The deep portion of the muscle is partly concealed, in

front, by the superficial portion; behind, it is covered by the parotid gland. The fibers of the two

portions are continuous at their insertion.

The Temporalis (Temporal muscle) is a broad, radiating muscle, situated at the side of

the head. It arises from the whole of the temporal fossa (except that portion of it which is

formed by the zygomatic bone) and from the deep surface of the temporal fascia. Its fibers

converge as they descend, and end in a tendon, which passes deep to the zygomatic arch and is

inserted into the medial surface, apex, and anterior border of the coronoid process, and the

anterior border of the ramus of the mandible nearly as far forward as the last molar tooth.

The Pterygoideus externus (External pterygoid muscle/Lateral pterygoid muscle) is a

short, thick muscle, somewhat conical in form, which extends almost horizontally between the

infratemporal fossa and the condyle of the mandible. It arises by two heads; an upper from the

lower part of the lateral surface of the great wing of the sphenoid and from the infratemporal

crest; a lower from the lateral surface of the lateral pterygoid plate. Its fibers pass horizontally

backward and lateralward, to be inserted into a depression in front of the neck of the condyle

of the mandible, and into the front margin of the articular disk of the temporomandibular

articulation.

The Pterygoideus internus (Internal pterygoid muscle/Medial pterygoid muscle) is a

thick, quadrilateral muscle. It arises from the medial surface of the lateral pterygoid plate and

the grooved surface of the pyramidal process of the palatine bone; it has a second slip of origin

from the lateral surfaces of the pyramidal process of the palatine and tuberosity of the maxilla.

Its fibers pass downward, lateralward, and backward, and are inserted, by a strong tendinous

lamina, into the lower and back part of the medial surface of the ramus and angle of the

mandible, as high as the mandibular foramen.

Nerves.—The muscles of mastication are supplied by the mandibular nerve.

Actions.—The Temporalis, Masseter, and Pterygoideus internus raise the mandible

against the maxillæ with great force. The Pterygoideus externus assists in opening the mouth,

but its main action is to draw forward the condyle and articular disk so that the mandible is

protruded and the inferior incisors projected in front of the upper; in this action it is assisted by

the Pterygoideus internus. The mandible is retracted by the posterior fibers of the Temporalis.

If the Pterygoidei internus and externus of one side act, the corresponding side of the mandible

is drawn forward while the opposite condyle remains comparatively fixed, and side-to-side

movements. Such as occur during the trituration of food, take place.

Table 1. Muscles of MasticationMuscle Origin Insertion Nerve Supply Action

Masseter Zygomatic archLateral surface ramus of mandible

Mandibular division of trigeminal nerve (V3)

Elevates mandible to occlude teeth

Temporalis Floor of temporal fossa

Coronoid process of mandible

Anterior and superior fibers elevate mandible: posterior fibers retract mandible

Lateral pterygoid(two heads)

Greater wing of sphenoidLateral pterygoid plate

Neck of mandibleArticular disc

Pulls neck of mandible forward

Medial pterygoid(two heads)

Tuberosity of maxillaLateral pterygoid plate

Medial surface of angle of mandible

Elevates mandible

BIOMECHANICS

MANDIBULAR POSITIONS

1. Postural Position of Mandible

Muscles of mastication are relaxed

Teeth are not in contact in mastication, swallowing or

speech

Lips at rest and jaws apart

Free Way Space or Vertical Dimension of Rest

• Space between mandibular and maxillary teeth

when mandible is in postural position. Average space = .3 – .7 mm

2. Centric Occlusal Relation

Position of the mandible with maximum intercuspation of teeth.

3. Right Lateral Occlusal Relation

Points to the right of centric relation.

4. Left Lateral Occlusal Relation

Points to the left of centric relation.

5. Protrusive Occlusal Relation

Anterior upper and lower incisors are into an edge-to-edge contact.

MANDIBULAR MOVEMENTS

It is named after the direction of movement of the mandible takes as it moves from the

intercuspal position.

1. Right Lateral Movement

Jaws move to the right bringing the teeth together in a right lateral occlusal

relation.

2. Left Lateral Movement

Jaws move to the left bringing the teeth in a left lateral occlusal relation.

3. Protrusive Movement

Mandible depressed then moves forward bringing a protrussive occlusal relation.

4. Retrusive Movement

Both condyles are upward and back into the mandible fossa.

Teeth are in a non-functional occlusal relation.

5. Bennett Movement

Movement of the mandible to the right or left during mastication.

CLASSIFICATION OF MANDIBULAR MOVEMENTS:

1. Border Movements

Limits of mandible movement in any direction.

2. Intraborder Movements

Any mandibular movement within the perimeter of border movements and is

chiefly associated with free movements.

3. Contact Movements

Movements which the mandibular and maxillary teeth maintain contact.

4. Free Movements

Movement wherein the reference point failed to reach its border and the teeth

do not come into contact.

ENVELOPE OF MANDIBULAR MOTION (by Posselt)

Mandible follows a curved trajectory in opening and closing.

In closing:

Molars - horizontal path;

Anterior teeth - vertical movement

Curvature of dental arches enables occlusal balance throughout mandibular movement

range.

CLINICAL CONSIDERATIONS (TMJ)

1. Bruxism

- A condition where in you unconsciously grind, gnash or clench your teeth during day or

night time.

- Over a long period of time, it may tend to causes tooth wear and breakage, disorders

of the jaw (pain and limited movement) and headache.

- This is considered parafunctions of the adults and are thought to result from

physiological stress with or without occlusal interference.

- In children, it has alleged associations with allergies, asthma, digestive upsets,

nervousness. Bruxism In primary dentition is a special problem which might termed a

Lateral View

Superior View

Frontal View

“functional malocclusion” and not necessarily pathogenic. Genetic factors and

psychosomatic symptoms is correlated with bruxism in children.

- This can be artificially induced by sustained tooth clenching like mouth guards/night

guard, Mandibular Advancement Devices.

2. Arthritis

- The synovial fluid is reduced in amount and becomes thicker in viscosity. This result in

pain and swelling in joint capsule. Sometimes very small cyst also appears in condylar heads.

3. Fractures

- The thinness of the bone in the articular fossa is responsible for fractures if the

Mandibular head is driven into the fossa by heavy blow.

- Patients with fractures of the neck of the condyle usually present history of severe

trauma to the symphysis or directly to the joint. Symptoms are swelling, altered

occlusion and pain in the area of the joint.

- when the dentist places a finger in the external auditory meatus while the patient

moves his mandible, no condylar movement is felt.

4. Structural Changes

- The finer structure of the bone and its fibrocartilaginous covering depends upon

mechanical influences. A change in force or direction of stress, occurring especially

after loss of posterior teeth, may cause structural changes. This frequently occurs

after the loss o posterior teeth. The important change is separation between the

collagen bundles (thin, fragile, and separated from each other). This results in the

pain at the TMJ.

5. Disharmony in the relation of teeth and the Temporomandibular joint.

- Clinical symptoms: pain in the region of joint and pain radiating to the temporal,

infraorbital, supraorbital, and postauricular areas, which may be of such severity as

to produce trismus. The joint has palpable irregularities and produces popping and

clicking noises.

6. Myofacial Pain Dysfunction (MPD) Syndrome characterized by

a. pain (dull ache in ear or preauricular area which may radiate to the angle of

mandible

b. masticatory muscle tenderness, most frequently, the lateral pterygoid, and then,

the temporalis, medial pterygoid, and masseter.

c. limited opening of mandible (<37mm)

d. joint sounds (clicking or popping noise in the TMJ)

These symptoms are seen more often in females. Hypersensitivity and spasm of the

muscles of mastication account for many of the symptoms. Since the condition may be related

to stress, treatment should be as conservative as possible.

7. Luxation or Dislocation of Temporomandibular Joint

- the Dislocation of Temporomandibular Joint is a forward displacement of the head

of condyle in front of the eminence. (during wide opening of mouth like in yawning)

- *very careful external manipulation of mandible in downward and backward

direction for extrusion of mandible at proper place* happens mostly in aged persons

and mostly in females because of (a) wearing and resorption of articular eminence

(b) reducing muscle tone with the advancing age. Treatment: injection of various

sclerosing solutions are given in TMJ capsular lgaments to tone them up with

variable success rate.

- Treatment of luxation consists of reduction and immobilization for a week, using

interdental arch wires and rubber bands, to permit tissue repair. For acute

dislocation, reduction and immobilization for 2 to 3 weeks to prevent secondary

hemorrhage and to permit tissue repair.

8. Ankylosis

- is immobility and consolidation of joint and its most frequent cause is injury to the

joint or infection in or around the joint. It may occur due to (a) intrauterine fetal

abnormality (b) forcep deliveries (c) malunion of condylar fractures (d) metastatic

malignancies (e) rheumatoid arthritis (f) inflammation of joint from infection in ear like

otitis media

- two types:

a. Fibrous ankylosis – also called partial ankylosis, is the result of fibrotic changes in

the joint following hemorrhage caused by external trauma. A slight space can be

seen between the condyle and the fossa in the roentgenogram.

b. Bony ankylosis – is generally the result of infectious or suppurative disease.

Complete bony union between the condyle and the fossa can be seen in the

roentgenogram.

9. Aplasia of condyle

- Failure of development of Mandibular condyle may occur unilaterally or bilaterally. In

unilateral condylar aplasia, there is obvious facial asymmetry toward the affected side.

10. Hypoplasia of Mandibular Condyle

- underdeveloped or defective formation of condyle, which may be congenital or

acquired because of reasons like forceps deliveries in newborns and damage following radiation

therapy of jaws.

11. Hyperplasia of Mandibular Condyle

- Chronic mild inflammation may cause hyperplasia of condyle unilaterally causing

unilateral elongation of face and deviation toward the normal side.

BibliographyJulian B. Woelfel and Rickne C. Scheid : Dental Anatomy: Its Relevance to Dentistry, 5th

Edition

Bertram S. Kraus : Kraus Dental Anatomy and Occlusion

P.R. Grant : Oral Cells and Tissue

Orban : Orban’s Oral Histology and Embryology

Nathan Allen Shore : Temporomandibular Joint Dysfunction & Occlasal Equilibrium 2nd Edition

Henry Gray : Gray’s Anatomy

Richard Snell : Clinical Anatomy by Regions, 8th Edition

Robert E. Moyers : Handbook of Orthodontics

Ten Cate, A.R. : Oral Histology- Development, Structure, and Function, 4th Edition