TMJ EVALUATION AND ITS ANATOMY

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TMJ EVALUATION AND ITS ANATOMY
Dr SIDHARTH R PILLAI
Dr SIDHARTH RAVI PILLAI
PG 1ST YEAR
ORTHODONTICS AND DENTOFACIALORTHOPEDICS

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CONTENTS
• Introduction
• Development of TMJ
• Peculiarity of TMJ
• General Anatomy of TMJ
• Functional anatomy of TMJ
• Mandibular movements and
Muscle activity

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• Examination & Diagnosis of TMJ Disorders
• TMJ disorders
• Treatment modalities
• Recent Articles
• Conclusion
• References

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INTRODUCTION
• The Temperomandibular Joint is formed by articulation between
the Articular Eminence and the anterior part of the Glenoid
Fossa of the squamous part of temporal bone above and the
condylar head of the mandible below.
• It’s a Synovial Joint of condylar variety.

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• TMJ is considered as a Compound joint.
• By definition, compound joint is articulation of atleast 3 bones
yet the TMJ is made up of only Two bones.
• But functionally, the articular disk serves as a non-ossified bone
which permits the complex movements of the joint.
• Thus the TMJ is considered as a compound joint.

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PECULIARITY OF TMJ
• Bilateral diarthrosis.
• Articular surface covered by fibrous cartilage instead of
hyaline cartilage.
• Only bilateral joint that crosses the midline.
• Only joint in the human body with rigid end point due to
occlusion.
• TMJ develops from distinct blastoma.

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DEVELOPMENT OF TEMPOROMANDIBULAR
JOINT
• The early TMJ structures emerged progressively from a block of
embryonic mesenchymal cells interposed between the
developing temporal bone and mandible.

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• This early block of mesenchymal tissue is a “developmental
field” whose normal morphogenesis into discrete anatomic
parts can be interfered with, in some significant and timely
manner resulting in the anomalous development of one or more
structures evolving from that “developmental field”

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PRIMARY JOINT
• At about 7th week of intrauterine life, the Meckel's
cartilage extends from the midline backward and dorsally,
acting as a scaffold to the developing mandible.
• It terminates at the malleus and articulates with the incal
cartilage forming the primary joint and any movement of
the early jaws occur between them

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SECONDARY JOINT
• Two distinct regions of mesenchymal condensation (blastoma)
appear at three months of gestation
• Temporal Blastoma
• Condylar Blastoma

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TEMPORAL BLASTOMA
• The first appearance of the temporal bone articular fossa
occurs at 7 to 7.5 weeks.
• The shape of the articular fossa is initially convex during the
first weeks of its development up to 9 week. After that time,
the fossa progressively takes on its definitive concave shape,
which matches the shape of the condylar head.

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. CONDYLAR BLASTOMA
• The condensation and shaping of the mandibular condyle occur
at about the same time as for the articular fossa. This mass is
superiorly convex.
• Condylar cartilage cells first appear between 9 and 10 weeks .
The shape of this early cartilaginous condyle is that of the
mesenchymal mass from which it arises.

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• After the 10th week, the continuing ossification of the articular
fossa appears more advanced in terms of increased cortical
thickness and density of bony trabeculae.

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The upper and lower joint cavities
• They progressively appear as a group of small spaces or clefts.
• mesenchymal tissue block that had earlier given rise to the articular
fossa, disk, and condyle.

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PARTS OF THE TMJ
• Mandibular fossa
• Condylar process
• Joint capsule
• Articular disc
• Synovial fluid
• Muscles and ligaments

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MANDIBULAR FOSSA
• Oval or oblong depression in the temporal bone just anterior
to auditory canal.

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CONDYLAR PROCESS
• Convex on all bearing surfaces although somewhat
flattened posteriorly
• Its knob like form is wider latero-medially (20mm) than
antero-posteriorly(8-10mm).
• Its long axis is in a lateral plane.
• Condyle is perpendicular to the ascending ramus of the
mandible

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JOINT CAPSULE
• Temporomandibular joint is enclosed in a capsule that is attached at
the borders of articulating surfaces of the mandibular fossa and
eminence of the temporal bone and the neck of mandible.
• The Capsule contains-
• Internal Synovial layer
• External fibrous layer containing veins, nerves and collagen
fibers.

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JOINT CAPSULE

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ARTICULAR DISC

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• Articular disc is hypovascular, fibro-cartilaginous intra-
articular sheet separating the condylar head from the glenoid
fossa.
• Divides the joint space into two compartments – the larger
superior (1.2ml) and the smaller inferior (0.5ml) joint spaces.
• Gliding movements and Hinge movements take place in the
upper and lower compartments, respectively.

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SYNOVIAL FLUID
• High amount of hyaluronic acid, giving it more viscosity.
• The internal surface of the cavities are surrounded by
specialized endothelial cells which forms a synovial lining.
• This lining along with synovial fringe produces synovial
fluid which fills both the joint cavities.

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BOUNDARY LUBRICATION
• It’s the primary mechanism of joint lubrication and prevents
friction.
• It occurs when the joint is moved and the synovial fluid is
forced from one area of the cavity into another.

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WEEPING LUBRICATION
• It’s a secondary lubricating system and provides metabolic
exchange.
• Refers to the ability of the articular surfaces to absorb small
amounts of synovial fluid.
• During function, forces are created between articular surfaces
which drive a small amount of synovial fluid in and out of
the articular surfaces. Thus metabolic exchange occurs.

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MUSCLES AND LIGAMENTS
MUSCLES OF MASTICATION
• Temporalis
• Medial pterygoid
• Lateral pterygoid
• Masseter
• Digastric

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MASSETER
• The masseter is a rectangular muscle that originates from
the zygomatic arch and extends downward to the lateral
aspect of the lower border of the ramus of the mandible.
• Its insertion on the mandible extends from the region of
the second molar at the inferior border posteriorly to
include the angle.

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• It has two portions, or heads:
(1) The superficial portion consists of fibers that run
downward and slightly backward,
(2) The deep portion consists of fibers that run in a vertical
direction.

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TEMPORALIS
• The temporalis is a large, fan-shaped muscle that originates from
the temporal fossa and the lateral surface of the skull.
• Its fibers come together as they extend downward between the
zygomatic arch and the lateral surface of the skull to form a
tendon that inserts on the coronoid process and anterior border of
the ascending ramus. It can be divided into three distinct areas
according to fiber direction and ultimate function.

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• The anterior portion consists of fibers that are directed almost
vertically. The middle portion contains fibers that run
obliquely across the lateral aspect of the skull (slightly
forward as they pass downward).
• The posterior portion consists of fibers that are aligned almost
horizontally, coming forward above the ear to join other
temporalis fibers as they pass under the zygomatic arch.

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MEDIAL PTERYGOID
• The medial (internal) pterygoid originates from the
pterygoid fossa and extends downward, backward, and
outward to insert along the medial surface of the
mandibular angle along with the masseter.
• It forms a muscular sling that supports the mandible at the
mandibular angle.

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• When its fibers contract, the mandible is elevated and the
teeth are brought into contact. This muscle is also active in
protruding the mandible.
• Unilateral contraction will bring about a mediotrusive
movement of the mandible.

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LATERAL PTERYGOID
• For many years the lateral (external) pterygoid was
described as having two distinct portions or bellies: an
inferior and a superior.
• Since the muscle appeared anatomically to be as one in
structure and function, It is now appreciated that the two
bellies of the lateral pterygoid function quite differently

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The muscles will be described as Two Types-
(1)The inferior lateral pterygoid
(2) The superior lateral pterygoid.

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INFERIOR LATERAL PTERYGOID
• The inferior lateral pterygoid originates at the outer surface of
the lateral pterygoid plate and extends backward, upward, and
outward to its insertion primarily on the neck of the condyle.

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SUPERIOR LATERAL PTERYGOID
• The superior lateral pterygoid is considerably smaller than
the inferior and originates at the infratemporal surface of the
greater sphenoid wing, extending almost horizontally,
backward, and outward to insert on the articular capsule, the
disc, and the neck of the condyle.

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DIGASTRIC MUSCLE
• Although the digastric is not generally considered a muscle
of mastication, it does have an important influence on the
function of the mandible.
• It has two bellies- Anterior belly and posterior belly

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ARTICULAR LIGAMENTS

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ARTICULAR LIGAMENTS

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ARTICULAR LIGAMENTS
• Ligaments are made up of collagenous connective tissues fibers
that have particular lengths.
• Three functional ligaments support the TMJ: (1) the collateral
ligaments, (2) the capsular ligament, and (3) the
temporomandibular ligament. There are also two accessory
ligaments: (4) the sphenomandibular and (5) the
stylomandibular.

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COLLATERAL LIGAMENTS
• The collateral ligaments attach the medial and lateral borders of
the articular disc to the poles of the condyle.
• The discal ligaments are true ligaments, composed of
collagenous connective tissue fibers; therefore they do not
stretch.
• They function to restrict movement of the disc away from the
condyle

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Medial discal ligament
• Attaches the medial edge of the disc to medial
pole of condyle
Lateral discal ligament
• Attaches the lateral edge of disc to lateral pole of
condyle.

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ACTIONS:
• Passive movement with the condyle
• Hinging movement

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CAPSULAR LIGAMENTS
• The entire TMJ is surrounded and encompassed by the
capsular ligament.
• Superiorly Temporal bone along the borders of the articular
surfaces of the mandibular fossa and articular eminence and
inferiorly to the Neck of condyle.

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• The capsular ligament acts to resist any medial, lateral, or
inferior forces that tend to separate or dislocate the articular
surfaces
• A significant function of the capsular ligament is to
encompass the joint, thus retaining the synovial fluid.

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TEMPOROMANDIBULAR LIGAMENT
• The lateral aspect of the capsular ligament is reinforced by
strong, tight fibers that make up the lateral ligament or the
temporomandibular ligament.
• The Temporomandibular ligament is composed of two parts,
an outer oblique portion and an inner horizontal portion

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TEMPORO-MANDIBULAR LIGAMENT

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ACTION OF OUTER OBLIQUE
• The oblique portion of the TM ligament resists excessive
dropping of the condyle, therefore limiting the extent of
mouth opening.
• This portion of the ligament also influences the normal
opening movement of the mandible

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ACTION OF INNER HORIZONTAL
• The inner horizontal portion of the Temporomandibular
ligament limits posterior movement of the condyle and disc.
• When force applied to the mandible displaces the condyle
posteriorly, this portion of the ligament becomes tight and
prevents the condyle from moving into the posterior region of
the mandibular fossa.

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CLINICAL IMPORTANCE
• During trauma to the mandible ,effectiveness of this
ligament demonstrated.
• Neck of condyle will be seen to fracture before retrodiscal
tissues are severed or condyle enters the middle cranial fossa.

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SPHENOMANDIBULAR LIGMENT
• Arises from spine of sphenoid bone and extends downwards
to a bony prominence on medial surface of ramus called
lingula.
• Actions: no significant effect on
limiting movements.

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STYLOMANDIBULAR LIGMENT
• The second accessory ligament is the stylomandibular
ligament.
• It arises from the styloid process and extends downward and
forward to the angle of the posterior boarder to the Ramus of
the Mandible.
• The stylomandibular ligament therefore limits excessive
protrusive movements of the mandible.

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RELATIONS OF THE TMJ

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TMJ INNERVATIONS
Predominant vessels for TMJ are:
• Superficial Temporal artery from the posterior
• Middle Meningeal Artery from anterior
• Internal Maxillary from Inferior alveolar artery

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• Other important arteries are: Deep auricular, Anterior
Tympanic and Ascending Pharyngeal arteries.

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Nerve Supply:
• Auriculotemporal nerve
• Masseteric nerve
• Deep temporal nerve

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HISTOLOGY OF THE TMJ

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HISTOLOGY OF ARTICULAR
SURFACE
• The Articular Surfaces of the madibular condyle and fossa are
composed of four distinct layer.
 Articular Zone
 Proliferative Zone
 Fibrocartilaginous zone
 Calcified zone

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74. Clear straw colored viscous fluid.
Diffuses out from the rich capillary network of the synovial
membrane.
It contains:
Hyaluronic acid-highly viscous
May also contain some free cells mostly macrophages.
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HISTOLOGY OF SYNOVIAL FLUID
• Clear straw colored viscous fluid.
• Diffuses out from the rich capillary network of the synovial
membrane.
It contains:
• Hyaluronic acid-highly viscous
• May also contain some free cells mostly macrophages.

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MANDIBULAR MOVEMENTS
• Occurs as a complex series of inter-related 3D rotational
and translational activities.
• It is determined by combined and simultaneous activities
of both TMJs.
• Types of movements are -
1. Rotational movement
2. Translational movement

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1. ROTATIONAL MOVEMENTS
The process of turning around an axis ; movement of a body
About its axis ,called the axis of rotation.
In the TMJ, rotation occurs as movement within the inferior
cavity of the joint. It is thus movement between the superior
surface of the condyle and the inferior surface of the articular
disc

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HORIZONTALAXIS OF ROTATION
• Mandibular movement around the horizontal axis is an
opening and closing motion.
• It is referred to as a hinge movement, and the horizontal
axis around which it occurs is therefore referred to as the
hinge axis

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1.

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VERTICALAXIS OF ROTATION
• Mandibular movement around the frontal axis occurs when one
condyle moves anteriorly out of the terminal hinge position with
the vertical axis of the opposite condyle remaining in the
terminal hinge position .

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SAGITTAL AXIS OF ROTATION
• Mandibular movement around the sagittal axis occurs when one
condyle moves inferiorly while the other remains in the terminal
hinge position

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TRANSLATIONAL MOVEMENTS
• In the masticatory system, it occurs when the mandible
moves forward, as in protrusion. The teeth, condyles, and
rami all move in the same direction and to the same degree

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SINGLE PLANE BORDER MOVEMENTS
• Mandibular movement is limited by the ligaments and the
articular surfaces of the TMJs as well as by the morphology
and alignment of the teeth.
• When the mandible moves through the outer range of
motion, reproducible limits result, which are called border
movements result.

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SAGITTAL PLANE BORDER AND
FUNCTIONAL MOVEMENTS
• Mandibular motion viewed in the sagittal plane can be seen to
have four distinct movement components
I. Posterior opening border
II. Anterior opening border
III. Superior contact border
IV. Functional

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POSTERIOR OPENING MOVEMENT
• Posterior opening border movements in the sagittal plane occur as
two-stage hinging movements.

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ANTERIOR OPENING BORDER MOVEMENTS
• With the mandible maximally opened, closure accompanied by
contraction of the inferior lateral pterygoids (which keep the
condyles positioned anteriorly) will generate the anterior closing
border movement.

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SUPERIOR CONTACT BORDER MOVEMENT
• The superior contact border movement is determined by the
characteristics of the occluding surfaces of the teeth. Throughout
this entire movement, tooth contact is present. Its precise
delineation depends on -
• The amount of vertical and horizontal overlap of the anterior
teeth,
• The lingual morphology of the maxillary anterior teeth.
• The general interarch relationships of the teeth.

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FUNCTIONAL MOVEMENTS
• Functional movements occur during functional activity of the
mandible..
• They usually take place within the border movements and
therefore are considered free movements.
• Most functional activities require maximum intercuspation and
therefore typically begin at and below the ICP.

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HORIZONTAL PLANE BORDER AND
FUNCTIONAL MOVEMENTS
• When mandibular movements are viewed in the horizontal
plane, a rhomboid-shaped pattern can be seen that has four
distinct movement components and a functional component
1. Left lateral border
2. Continued left lateral border with protrusion
3. Right lateral border
4. Continued right lateral border with protrusion

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LEFT LATERAL BORDER MOVEMENTS
• With the condyles in the Centic relation position, contraction of
the right inferior lateral pterygoid will cause the right condyle to
move anteriorly and medially (also inferiorly).
• If the left inferior lateral pterygoid stays relaxed, the left
condyle will remain situated in CR and the result will be a left
lateral border movement

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CONTINUED LEFT BORDER WITH
PROTRUSION
• With the mandible in the left lateral border position, contraction of
the left inferior lateral pterygoid muscle along with continued
contraction of the right inferior lateral pterygoid muscle will cause
the left condyle to move anteriorly and to the right

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RIGHT LATERAL BORDER MOVEMENT
• Contracting of the left inferior lateral pterygoid muscle will cause
the left condyle to move anteriorly and medially (also inferiorly).
• If the right inferior lateral pterygoid muscle stays relaxed, the right
condyle will remain situated in the CR position. The resultant
mandibular movement will be right lateral border

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CONTINUED RIGHT LATERAL BORDER
MOVEMENTS WITH PROTRUSION
• With the mandible in the right lateral border position,
contraction of the right inferior lateral pterygoid muscle
along with continued contraction of the left inferior lateral
pterygoid will cause the right condyle to move anteriorly and
to the left.

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FUNCTIONAL MOVEMENTS
• As in the sagittal plane, functional movements in the horizontal
plane most often occur near the ICP.

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VERTICAL BORDER AND FUNCTIONAL
MOVEMENTS
When mandibular motion is viewed in the frontal plane, a
shieldshaped pattern can be seen that has four distinct movement
components along with the functional component:
1. Left lateral superior border
2. Left lateral opening border
3. Right lateral Superior Border
4. Right Lateral Opening Border

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LEFT LATERAL SUPERIOR BORDER
MOVEMENTS
• With the mandible in maximum intercuspation, a lateral
movement is made to the left.
• The precise nature of this path is primarily determined by the
morphology and interarch relationships of the maxillary and
mandibular teeth that are in contact during this movement

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LEFT LATERAL OPENING BORDER
MOVEMENTS
• From the maximum left lateral superior border position, an
opening movement of the mandible produces a laterally convex
path.

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RIGHT LATERAL SUPERIOR BORDER
MOVEMENTS
• Once the left frontal border movements are recorded, the
mandible is returned to maximum intercuspation.
• From this position, a lateral movement is made to the right that
is similar to the left lateral superior border movement.

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RIGHT LATERAL OPENING BORDER
MOVEMENTS
• From the maximum right lateral border position, an opening
movement of the mandible produces a laterally convex path similar
to that of the left opening movement.

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FUNCTIONAL MOVEMENTS IN FRONTAL
PLANE
• As in the other planes, functional movements begin and end at
the ICP.
• During chewing the mandible drops directly inferiorly until the
desired opening is achieved.
• It then shifts to the side on which bolus is placed and rises up.

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• As it approaches maximum ICP, the bolus is broken down
between the opposing teeth.

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ENVELOPE OF THE MOTION
• Superior surface is determined by tooth contacts, other borders
are determined by ligaments and joint anatomy that restricts the
movement.
• It differs from person to person.

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EXAMINATION AND DIAGNOSIS OF THE TMJ

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HISTORY
• History of onset, duration, frequency and dental treatment
are important to assess the acute or chronic nature of the
disease.
• Factors like pain, click or dysfunction are to be considered
while taking history.

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CLINICAL EXAMINATION
Inspection
• Inter-incisal distance on mouth opening
• facial asymmetry
• deviation of mouth on opening and closing
• preauricular swelling
• Malocclusion or improper prosthesis,
• Attrition of teeth decreasing vertical dimension should be
noted.

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DENTAL EXAMINATION
• Any pre- mature contacts.
• Evaluation for evidence of bruxism such as attrition of teeth,
cheek or lip ridges caused by trapping of mucosa during
clenching.

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• Molar and canine relationship.
• Freeway space, overjet, overbite, prosthesis.
• Other oral habits and their possible effects on dentition,
periodontium or other oral structures.
• Number of missing teeth specially the posterior relationship
which may predispose the TMJ to degenerative joint diseases.

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RANGE OF MANDIBULAR MOVEMENT
• Interincisal distance ranges between 35 to 50mm.
• Lateral deviation of mandible in certain conditions are a
significant sign. Abnormal protrusive movements are
important and frequent, translation of condyles is the initial
movement/sign.
• Lateral motion should be 7 to 10mm in both sides
• Normal protrusive range is between 7 to 10mm.

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• Lateral aspect of TMJ is also palpated while opening and closing
the mouth.
• If the range of motion is limited attempt should be made to
determine the cause:
1. Contracture of one or more muscle associated with jaw
closure.
2. Non reducing anterior displacement of articular disc.
(closed lock).

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• Coronoid process interference.
• Hematoma or infection.
• Any other conditions such Fibrous ankylosis.

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METHOD OF PALPATION

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Palpation -
• Tenderness on palpation suggests the presence of fracture,
synovitis, or capsulitis of the joint.
• Jaw is palpated for evidence of muscle enlargement and any
unusual features such as movement of disc (hypermobility)
during activity.
• Overlying skin is checked for temperature and consistency
in case of any inflammatory condition

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Neurological test-
• Trigeminal nerve supplies sensation to the superficial and deep
structures of the head and face.
• Sensory nerve activity is assessed by applying pressure ,
cotton wool and pin-pricks to the areas of distribution of
trigeminal nerve.
• This test helps in clinical diagnosis of myofascial pain.

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Auscultation :-
• Noise is assessed by stethoscope and classified either click
(open or close click) or crepitus.

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SPECIAL INVESTIGATIONS
Laboratory investigation :-
• Indicated when primary diseases are diagnosed by biochemical
and serological tests. e.g. gout, infectious arthritis/ suppurative
arthritis, rheumatoid arthritis.
Electromyographic investigations :-
• Helps in monitoring the activity of disordered TMJ

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Drugs :-
• Anti-inflammatory , muscle relaxants and antidepressants can
be used to rule out the cause in myofascial dysfunction
syndrome (MPDS).

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Occlusal splints :-
• To diagnose MPDS.
Intermaxillary fixation :-
• When there is pain of uncertain origin, IMF may be applied.
• It is diagnostic as it relieves the pain if the source is the TMJ
(condylar fracture) or masticatory muscles (prevents
overstretching of muscles).

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Local anesthesia :-
To confirm the muscular pain.
E.g. Injection in the masseter muscle

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RADIOGRAPHIC EXAMINATION
PANORAMIC VIEW

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TRANSCRANIAL VIEW

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TRANSPHARYGEAL VIEW

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TRANSMAXILLARY VIEW

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DISORDERS OF TMJ
• The dental profession was first drawn into the area of Temporo-
Mandibular Disorders by Dr. James Costen (1934) who
described a group of symptoms that centered around the ear &
TMJ.

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• Refers to the group of disorders of the TMJ as a result of
primary or secondary degenerative changes within the joint or
muscle hyperfunction or parafunction.

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CLASSIFICATION OF TMJ DISORDERS
A. STRUCTURAL (DISORDERS ARISING WITHIN JOINT)
1.DEVELOPMENTAL
I. Condylar hyperplasia
II. Hemi mandibular elongation
III.Hemi mandibular hyperplasia
IV.Condylar hypoplasia and aplasia

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2. ACQUIRED
I. Traumatic arthritis
II. Suppurative arthritis
III.Osteoarthritis
IV.Rheumatoid arthritis (RA)
V. Psoriatic arthritis
VI.Infection from disease that spreads from other tissue like TB
, Syphilis

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vii. Metabolic disorders like gout
viii. Condylar fracture
ix. Dislocation : acute , chronic, recurrent (habitual)
x. Posttraumatic – ankylosis
xi. Internal derangement
xii. Tumors
xiii. Synovial fistula and synovial cyst of TMJ
xiv. Ankylosing spondylitis

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B. FUNCTIONAL
I. Disorders arising from structures outside the joint
II. Myofascial pain dysfunction syndrome (MPDS)

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CONDYLAR HYPERPLASIA
• Condition of mandibular condyles creating overgrowth of the
mandible, first described by Robert Adams.

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Treatment :-
• Condylectomy to ensure removal of the growing cartilage.
• More conservative condylar shave (condyloplasty) can also be
performed in certain cases.
• Correction of facial asymmetry by orthognathic procedures or
orthomorphic surgery.

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HEMI MANDIBULAR ELONGATION
• Horizontal displacement of the mandible and chin towards
the unaffected side.
• Lip line slopes towards the affected side.

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• Lateral crossbite on the unaffected side.
• In severe cases lateral open bite is observed on the affected
side & in mild cases it is compensated by supraeruption of the
teeth.
• The displacement of the midline is greater at the anatomical
mid-chin than at the incisor midline, so that there appears to
be an apical drift of the incisors towards the unaffected side.

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Treatment-
• Condylar surgery is not necessary.
• It is advisable to wait till the cessation of mandibular growth
before jumping on surgical approach.
• In addition genioplasty is sometimes necessary to achieve
symmetry

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HEMI MANDIBULAR HYPERPLASIA
• This varies in the degree of development, depending on the age
at which abnormal growth commences, the degree of abnormal
growth and its duration.
• It generally ceases after cessation of general growth but
occasionally it continues for a few years.

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• Inferior border lies at a lower level on the affected side.
• No chin displacement but lip line slopes downwards to the
affected side.
• No midline shift with lateral open bite seen in some cases.
• Downward cant of maxillary plane due to overeruption of teeth
on the affected side.
• Pain in the TMJ of the affected side.

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TREATMENT
During growth period , some form of condylar surgery
(condylotomy, condyloplasty) will arrest and retard growth, thus
limiting the secondary distortion.
Treatment protocols are -
• High condylectomy to arrest the growth.
• Articular disc repositioning.

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CONDYLAR HYPOPLASIAAND APLASIA
• Characterized by facial deformity expressed on the affected side
by a short mandibular ramus.
• It can be Unilateral or Bilateral

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UNILATERAL CONDYLAR HYPOPLASIA-
• Shortening of mandibular vertical height occurs on the affected
side.
• A midline shift towards the same side.
• Shifting of the chin towards the shorter side of the face.
• Deviation of the mandible on mouth opening

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• It can be congenital due to pharyngeal first and second arch
malformation or it may result due to trauma ,infection or
irradiation during growth period

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Bilateral condylar hypoplasia -
• Bilateral condition results in micrognathia or small mandible.
• In congenital cases , it causes respiratory distress due to
obstruction of pharyngeal airway by falling back of tongue.

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Treatment :-
• Severe mandibular dysostosis should be treated in growing
age itself to produce to avoid secondary deformities
because mandibular ramus is lengthened as the secondary
dentition is erupting.

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TRAUMATIC ARTHRITIS
• Any traumatic incident involving the TMJ may lead to acute
arthritis.
• Site of inflammation is capsule.
• Chronic trauma to the joint due to trauma from occlusion is
also responsible for osteoarthrosis.
• Characterised by, tenderness of the affected joint and restriction
of the movement which cause mandible to swing on the affected
side on opening.

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• Oedema around the joint can be seen.
• Pain in movement leads to classic trismus

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Treatment :-
• Treating the cause followed by physiotherapy.
• Long term trismus may require surgical removal of
coronoid processes and temporalis muscle attachment
followed by physiotherapy.

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OSTEOARTHRITIS
• Most common skeletal disease of human body affecting the
TMJ

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• Earliest degenerative changes are seen in articular cartilage as
preoteoglycans are lost at the surface.
• Chondrocytes are stimulated and DNA synthesis increases.
• Growth of surrounding bone is stimulated, resulting in
osteophyte formation

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• Pain in the joint and muscles of mastication, causing limitation of
mandibular motion.
• Joint noises, especially crepitus.
• Osteophyte formation and marginal bone thickening leads to
palpable masses over preauricular region.

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Treatment :-
• Initial intervention should limit excessive and recurrent
trauma.
• Moderate exercise and physical therapy should be started to
strengthen the musculature supporting the joints.
• NSAIDs to reduce pain.
• In severe case, thermal therapy can be obtained with
ultrasonography and infrared heat.

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RHEUMATOID ARTHRITIS
• Autoimmune disease commonly affecting diarthrodial
joints.
• It can affect the joint at any age.
• Juvenile rheumatoid arthritis (Still's disease) may be of
varying severity

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Pathophysiology :-
• Synovial membrane proliferation and outgrowth causes erosion
of articular cartilage and subchondral bone.
• The production of inflammatory mediators, which is stimulated
by the cells, result in the production of proteinases and
prostaglandin. Collagenases are responsible for typical erosions
seen over the joint surface

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Clinical Feature-
• Clicking, crepitus and tenderness of the joint on palpation.
• Limitation of motion occurs as the bone is destroyed and joint
space is filled with scar tissue leading to fibrous ankylosis.
• Progressive class II occlusion develops resulting in
retrognathia,bird-face deformity and apertognathia may result
in young children.

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TREATMENT-
• Anti inflammatory drugs (salicylates, NSAIDs,
corticosteroids), soft diet, avoiding extreme jaw movements.
• If NSAIDs are ineffective, disease modifying anti-rheumatic
drugs like hydroxychloroquine, penicillamine .

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PSORIATIC ARTHRITIS
• Resembles the rheumatoid type, but it is associated with
psoriasis, a dermatologic disease.
• remission of joint disturbances coincident with the skin lesions
differentiate the disease from rheumatoid arthritis.
• There is a high incidence in women

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Clinical features :-
• TMJ involvement is described as episodic, sudden and
usually unilateral.
• Limitation of mandibular movements.
• Morning stiffness, crepitus, eventual loss of interincisal
opening.
• In advanced disease, ankylosis can occur.

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Treatment-
• Systemic treatment should be undertaken.
• Reduce loading on the joint.
• In severe cases, immunosuppressive agents such as
methotrexate have been used.

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TUMOURS
• Any tumour in the area of TMJ and/or muscles of mastication can
significantly cause jaw hypomobility.
• Both benign and malignant lesions affect the condyles and synovial
components of the joint.

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ANKYLOSING SPONDYLITIS
(Marie- Strumpell disease)
• Chronic inflammatory disease involving the articulators of
spine adjacent soft tissues.
• High sex ratio of male:female (8:1)

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Clinical features :-
• Symptoms are due to imperfect head posture caused by the
vertebral lesions.
• The most common complaints are of pain, stiffness,
decreased range of motion and eventually ankylosis.
• Extra-articular manifestations such as cardiac symptoms are
common in patients with TMJ involvement

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Treatment :-
• The load must be reduced across the joint by the use of acrylic
splints.
• The drug with proven efficacy sulphasalazine.
• Surgical intervention should be limited to those patients with
severe crippling disease.

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DISORDERS ARISING FROM
OUTSIDE THE JOINT
• The most common disorders outside the joints that cause
pain around the joints are
• Fibromyalgia
• Polymyalgia rheumatica
• Bursitis or tendinitis
• Bursitis and tendinitis often result from injury, usually
affecting only one joint. However, certain disorders cause
bursitis or tendinitis in many joints.

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MYOFASCIAL PAIN DYSFUNCTION
SYNDROME (MPDS)
• This condition is the most common disorder affecting the
temporomandibular region. It is more common among women .
• In the affected muscle, both pain and trigger points (which cause
referred pain) may result from parafunctional behavior such
as bruxism (clenching or grinding of the teeth), which is regarded
as two distinct entities: sleep or awake bruxism, which have
different etiologies.

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• Symptoms include pain and tenderness of the masticatory
muscles and often pain and limitation of jaw excursion.
• Both sleep bruxism and sleep- disordered breathing (such as
obstructive sleep apnea and upper airway resistance
syndrome) are associated with headache that is more severe
on awakening and gradually subsides during the day.

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• The jaw deviates when the mouth opens but usually not as
suddenly or always at the same point of opening as it does
with internal temporomandibular joint derangement

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DIAGNOSIS
• Clinical evaluation
• Sometimes polysomnography
• A simple test may aid the diagnosis: 2 or 3 tongue blades are
placed between the rearmost molars on each side, and the patient
is asked to close the mouth gently
• The distraction produced in the joint space may ease the
symptoms.

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• X-rays usually do not help, except to rule out arthritis.
• If giant cell arteritis is suspected, erythrocyte sedimentation rate
(ESR) is measured.
• Polysomnography should be done if sleep-disordered breathing is
suspected.

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Treatment
• Mild analgesics
• Oral appliances
• Possibly temporary use of an anxiolytic or cyclobenzaprine at
bedtime
• Trigger point injections and other physical and behavioral therapy
modalities

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ORTHODONTIC TREATMENT AND TMJ
Twin block therapy-
• There was a significant change in the condylar dimensions:
• Increase in length, width, and height by 1.28, 0.88, 1.59 on the
right and by 1.60, 0.53, and 1.10 mm on the left sides,
respectively.
• There was significant forward positioning of the right and left
condyle by 1.5 and 1.3 mm, respectively.
Younes Elfeky et al 4 (2018). Three-dimensional skeletal, dentoalveolar and temporomandibular joint changes produced by Twin Block
functional appliance. Journal of Orofacial Orthopedics / Fortschritte der Kieferorthopädie. 10.1007/s00056-018-0137-1

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Condylar position and joint spaces after maxillary first premolar
extraction in skeletal Class II malocclusion :-
• There was a statistically significant (P≤.05) posterior
positioning of the condyle relative to the vertical plane.
• The distance increased significantly from 5.77 to 6.82 mm as
this plane is anterior to the mandibular condyle.
Alhammadi MS, Fayed MS, Labib A. Three-dimensional assessment of condylar position and joint spaces after
maxillary first premolar extraction in skeletal Class II malocclusion. Orthod Craniofac Res. 2017 May;20(2):71-78.
doi:10.1111/ocr.12141.Epub 2017 Feb 1. PubMed PMID: 28150380.

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• There was an increased anterior joint space (from 3.10
to 3.90 mm) and decreased posterior joint space (from 2.78 to
2.23 mm) following treatment.
• No changes were observed in mediolateral and vertical
condylar positions.

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CONCLUSION
• As dental practitioners, we seldom examine the TMJ during
routine examination. Though treating the cause is important,
it’s also duty of a dentist to thoroughly examine the patient,
identify any underlying asymptomatic disorders, and educate
and motivate the patient to take up preventive measures & early
treatment to avoid further symptoms that serve as precursors to
TMJ disorders.

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REFERENCES
• Management of Temporomandibular Disorders & occlusion-
Jeffrey p. Okeson
• White and Pharoah book of Oral radiology
• Human anatomy 3rd Volume; 3rd edition - B.D.Chaurasia
• Color atlas of dental medicine- tmj disorders and orofacial pain-
alex bumann, ulrich lotzmann
• Human Embryology 8th Edition – Inderbir Singh
• Textbook of Human Histology with Colour Atlas 5th edition -
Inderbir Singh

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REFERENCES
• Wheeler's Dental Anatomy, Physiology and Occlusion 9th edition
- Nelson fausto
• Orbans Oral Histology & Embryology 13th edition – G S kumar
• Younes Elfeky, Hanem & Fayed, Mona & Alhammadi, Maged &
Abou Zeid Soliman, Sanaa & Mohamed El Boghdadi, Dalia.
(2018). Three-dimensional skeletal, dentoalveolar and
temporomandibular joint changes produced by Twin Block
functional appliance. Journal of Orofacial Orthopedics /
Fortschritte der Kieferorthopädie. 10.1007/s00056-018-0137-1.

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REFERENCES
• Alhammadi MS, Fayed MS, Labib A. Three-dimensional
assessment of condylar position and joint spaces after maxillary
first premolar extraction in skeletal Class II malocclusion.
Orthod Craniofac Res. 2017 May;20(2):71-78.
doi:10.1111/ocr.12141.Epub 2017 Feb 1. PubMed PMID:
28150380.