anatomy of tmj.pptx

PRESENTED BY:
Dr. CH.PRAVEENA,
PG STUDENT,
DEPT. OF PROSTHODONTICS &
CROWN AND BRIDGE
INCLUDING IMPLANTOLOGY,
SIBAR INSTITUTE OF DENTAL
SCIENCES,
GUNTUR.

 Describe the functional anatomy & biomechanics
of the TMJ.
-NTRUHS, 1999, 2001 & 2012 (25 Marks)
 Give description on the development & anatomy
of TMJ. Discuss the functions in application of
mastication.
-NTRUHS, 2012 (20 Marks)
 Prosthodontic considerations of TMJ.
-NTRUHS, 2000 (10 Marks)
11/17/2022
FUNCTIONAL .ANATOMY,GROWTH,AGE
CHANGES & BIOMECHANICS OF TMJ -91 2

 INTRODUCTION
 DEFINITION & SYNONYMS
 FUNCTIONAL ANATOMY OF TMJ
 HISTOLOGY OF THE JOINT
 GROWTH & DEVELOPMENT OF THE JOINT
 AGE CHANGES IN TMJ
 BIOMECHANICS OF TMJ
 EXAMINATION OF TMJ
 DIAGNOSTIC IMAGING OF TMJ
11/17/2022

 CLASSIFICATION OF TEMPOROMANDIBULAR
DISORDERS
 FACTORS AFFECTED BY TMJ IN PROSTHODONTIC
REHABILITATION
 CONCLUSION
 BIBLIOGRAPHY & REFERENCES
11/17/2022

 TMJ is the unique and most complex joint in
the body and is the area in which the mandible
articulates with the cranium .
 The TMJ’s are one of the only synovial joints in
the human body with an articular disc.
 The name is derived from the two bones which
form the joint : the upper temporal bone which
is part of the cranium and the lower jaw bone
called the mandible.
11/17/2022

“The articulation between the temporal bone & the
mandible. It is a bilateral diarthroidal, bilateral
ginglymoid joint.”
“The articulation of the condylar process of the
mandible & the intra-articular disk with the
mandibular fossa of the squamous portion of the
temporal bone; a diarthroidal , a sliding hinge (
ginglymus) joint. Movement in the upper joint
compartment is mostly transitional, whereas that in
the lower joint copartment is mostly rotational. The
joint connects the mandibular condyle to the articular
fossa of the temporal bone with the
temporomandibular disk interposed.”
-GPT-8,2005.
11/17/2022

11/17/2022

This is a synovial joint of condylar variety.
Articular surfaces-
A. Upper surface:
a) Articular eminence
b) Anterior part of
mandibular fossa.
B. Inferior surface :
a) Mandibular Condyle
11/17/2022

 There are six main
components of the TMJ.
1. Mandibular condyles
2. Articular surface of
the temporal bone
3. Articular disc
4. Joint Capsule
5. Ligaments
6. Lateral pterygoid
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The condyle is the portion of mandible that
articulates with the cranium around which the
movement occurs.
 Bulbous semicylindrical extremity of the
mandibular ramus.
 Angle between the axes of two condyles is 135˚.
 The posterior articular surface of is greater than the
anterior surface.
 Consists of medial and lateral poles.
 Convex mesio-distally and anterior-posteriorly.
11/17/2022

 Dimensions:
 Mediolateral length: 18-23 mm
 Anteroposterior width: 8-10 mm
 Intercondylar distance: 100 mm
 Angle with frontal plane: 13˚ (0-30 ˚)
 Lateral tip lies about 13 mm beneath the skin & is
palpable.
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FUNCTIONAL .ANATOMY,GROWTH,AGE CHANGES &
BIOMECHANICS OF TMJ -91
11
ANTERIOR VIEW POSTERIOR VIEW

 The mandibular condyle articulates
at the base of the cranium with the
sqamous portion of the temporal
bone.
 This portion is called articular fossa
or glenoid fossa or mandibular
fossa.
 Divided by tympanosqamosal
fissure.
 Anterior portion forms the TMJ.
 Part of sqamous temporal bone.
 Modified to facilitate movement of
disc condyle complex.
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 Immediately anterior to the fossa is a convex bony
prominence called articular eminence.
 Lies at inferior base of zygomatic process of
temporal bone.
 Antero-posterior convexity and transverse
concavity of the eminence is highly variable.
Covered by dense fibrous tissue.
 It dictates the path of condyle when mandible is
positioned anteriorly.
11/17/2022

 TMJ contains fibrous disc
interposed between the
articular surfaces
 It functions as a shock
absorber
 It is biconcave with a thin
intermediate zone ,thick
anterior and posterior bands.
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 Anterior band - is continuous
into loose fibro elastic
connective tissue also known as
anterior foot extension or
anterior ligament.
 Posterior band- is continuous
with lose connective tissue rich
in elastic fibers called
retrodiscal tissue or posterior
attachachment.
11/17/2022

 It is loosely organized system of collagen fibers ,
branching elastic fibers , fat , blood,lymph vessels
and nerves .
 Superior retrodiscal lamina:
a)attaches to squamotympanic
fissure consists primarily of
elastin.
 Inferior retrodiscal lamina:
a) attaches to posterior articular slope
of condyle.
b)consists primarily of collagen
fibers.
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 Joint capsule is fibro elastic sac.
 BOUNDARIES:
 Inner surface of the capsule is smooth and
glistening.
 It is lined by synovial membrane.
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Anteriorly Ascending slope of articular eminence
Posteriorly Lips of squamotympanic fissure
Superiorly Glenoid fossa
Inferiorly Neck of the condyle

 Synonyms: Synovial lining or synovial fringe
 Specialized endothelial cells.
 Anterior border of retrodiscal tissue forms synovial
fluid.
 Main constituent of synovial fluid is Hyaluronic
acid.
 Functions : Lubrication & providing metabolic
requirements.
 Mechanism of Lubrication:
 Boundary lubrication
 Weeping lubrication
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The disc divides the space into two compartments
1. Condylodiskal 2. temporodiskal
(hinge movement) (translatory movement)
Passive volume -0.9mL Passive volume -1.2mL
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 Made of collagenous connective tissue of particular
length .
 They do not stretch ,act as passive restraining devices to
limit and restrict border movements .
 3 Functional ligaments
Collateral ligament
Capsular ligament
Temporomandibular ligament
 2 Accessory ligaments
Sphenomandibular ligament
Stylomandibular ligament
11/17/2022

 Two discal ligaments– Medial & lateral.
 Divides the joint.
 Functions:
 Restrict movement of disc
away from condyle.
 Hinge movement.
 Innervation of ligaments
determine:
 Joint position.
 Movement.
 Strain produces pain.
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FUNCTIONAL
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CHANGES & BIOMECHANICS OF
TMJ -91 22

It surrounds and
encompasses the entire TMJ.
Thus it retains synovial
fluid.
Well innervated and
provides proprioceptive
feedback regarding position
and movement of joint.
Action : resists medial,
lateral, or inferior forces that
tend to separate or dislocate
articular surfaces.
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 Lateral aspect of capsular ligament is reinforced by
strong tight fibers that makeup temporomandibular
ligament
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Temporomandibular
ligament
outer oblique
portion
Inner horizontal
portion
Resists excessive
dropping of
condyle
Limits extent of
mouth opening
Limits posterior
movement of
condyle and disc

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.ANATOMY,GROWTH,AGE
TMJ -91 25

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Accessory ligaments

 Arises from spine of sphenoid bone and extend
downward to the lingula .
 It does not have any significant limiting effect on
mandibular movements.
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Arises from styloid
process and extends
downward & for to
the angle and
posterior border of
the ramus.
Limits excessive
protrusive
movement of the
mandible.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 28

 Collateral ligaments allow
disk to rotate from top of
condyle to front and back.
 Posterior ligament
prevents disk from
rotating too far forward.
 It also prevents the disk
from being displaced
anteriorly.
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 Superior elastic stratum
maintain constant
tension on the disk
toward the distal.
 Superior lateral
pterygoid the only
forward pulling force.
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ᵜ A – Articular zone
ᵜ B - Reserve zone
ᵜ C - Proliferative zone
ᵜ D - Hypertrophic zone
ᵜ E - Calcifying zone
ᵜ F - Bone
11/17/2022

 Most superficial.
 Utmost functional surface.
 Made of dense fibrous
connective tissue.
 Collagen fibers are parallel
to articular surface and
tightly packed to with stand
forces.
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 Mainly cellular.
 Undifferentiated
mesenchymal tissue is
found .
 Responsible for
proliferation of articular
cartilage in response to
functional demands .
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 33

 Collagen fibers are
arranged in bundles in a
crossing pattern.
 Offers resistance against
compressive forces and
lateral forces.
Calcified zone
 Deepest zone.
 Made up of chondrocytes
and chondroblasts
distributed throughout
the articular cartilage.
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 Composed of chondrocytes and inter
cellular matrix.
 Chodrocytes produce collagen,
proteoglycons , glycoprotiens and
enzymes that form matrix.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 35

 Except articular disc the joint tissues are
innervated by
• Auriculotemporal nerve(sensory)
• Massetric nerve and Deep temporal
branches(motor).
 Lymphatic drainage:
• Lateral surface : Preauricular & parotid
nodes
• Posterior surface : Submandibular nodes
• Medial surface : Parotid nodes
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 Arterial supply:
Posteriorly : Superficial temporal artery
Anteriorly : Middle meningeal artery
Inferiorly : Internal maxillary artery
 Venous supply:
Drain into: Superficial temporal,
Pterygoid plexus &
Maxillary veins.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 37

 Depression- Lateral pterygoid with suprahyoid
muscle
 Elevation/Biting- Masseter, temporalis, medial
petygoid of both sides
 Protrusion- Lateral and medial pterygoid.
 Retraction- Posterior fibres of temporalis
 Lateral or side to side movement eg.Turning
chin to left side- left lateral pterygoid and right
medial pterygoid.
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 Primary jaw joint between the malleus (from
Meckel’s cartilage) and incus exists for 4
months.
 Secondary joint forms at 3 months .
 Approximately at 10th week the components of
the future joint become evident in mesenchyme
between the condylar cartilage of mandibular
bone and temporal bone.
 Two slit like joint cavities and an intervening
disk make their appearance by 12th week.
11/17/2022

 The mesenchyme around it forms fibrous
capsule.
 The developing superior head of lateral
pterygoid muscle attaches the anterior portion
of the fetal disk.
 The disk also continues posteriorly through the
petrotympanic fissure and attaches to the
malleus of the middle ear.
 This connection is obliterated by growth of lips
during development.
11/17/2022

The condylar process continues to grow by
endochondral ossification of secondary
cartilage in response to functional demands.
This produces core of fine cancellous bone
located superficially in medulla of condyle.
11/17/2022

 In neonates
 Cartilage layer constitutes major part of condyle.
 Temporal component is flat and lined by vascular
connective tissue.
 At 3years
Articular layer becomes avascular & contains few
cells.
 At 5-6 years
Thin zone on top of condyle.
 At 6 years of age
S-shaped form of fossa and eminence develops
and continues into second decade.
11/17/2022

 The condyle appears flattened in outline and
sometimes remnants of condylar cartilage can be
found in aged joints.
 The fibrous covering of the condyle becomes
thicker.
 Osteoporosis of the underlying bone of the
condyle is a common feature.
 The articular disk becomes thinner and exhibits
hyalinization. Chondroid changes are apparent.
 Tears can be seen in small acellular areas of disk.
11/17/2022

 The synovial folds appear fibrotic with thick
basement membrane.
 Walls of blood vessels become thick, and
nerves decreased in number.
 These age changes in turn could lead to
dysfunction, impairment of motion, affect the
degree of resiliency during masticatory
function, decrease in the formation of synovial
fluid.
11/17/2022

 The movements of the mandible, combining
rotation and translation include:
1. Opening and closing.
2. Protrusion and retrusion.
3. Lateral shifts of the mandible.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 45

Opening
 Initial step = relaxation of Masseter and
Temporalis (closing muscles).
 Intermediate = Inferior head of Pterygoid
pulls disc & condyle down.
 End = Digastric muscle pulls mandible down
& back.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
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Closing
 Superior head of Pterygoid stabilizes disc &
condyle.
 Masseter & Temporalis pull jaw up.
 Posterior movement limited by TML.
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CHANGES & BIOMECHANICS OF TMJ -91
47

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Movement
in
TMJ
Rotatory
&
Translatory
Type
of
Movement
Protrusive
Retrusive
&
Lateral
Movements
Extent
of
movement
Anterior
&
Posterior
Border
movements

 Rotation:
11/17/2022
“The process of turning
around an axis:
movement of a body
around its own axis”.
It occurs when the mouth
opens & closes around a
fixed point or axis with
in the condyles.

 The transverse axis runs horizontally from one side
of the mandible to the other side.
11/17/2022

 When the condyles are in their most superior
position in the articular fossa, the axis around
which pure rotational movement occurs is called
the “terminal hinge axis”.
 Terminal hinge axis was proposed by Mc.Collum &
verified by Kohno.
 This pure rotational movement of the joint
takes place around the horizontal axis till the
patient opens his mouth about 20 to 25 mm.
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 The vertical axis runs through
the condyle and the posterior
border of the ramus of the
mandible.
 The mandible rotates around
this vertical axis during the
lateral movements.

 The anteroposterior axis is an imaginary axis running along
the mid Sagittal plane. When one condyle moves inferiorly ,
the other remains in the terminal hinge position.
 This type of isolated movement
does not occur naturally because
the ligaments & musculature of
TMJ prevents inferior displacement
of condyle.
 The mandible shows slight
rotation around the axis.
11/17/2022

 “Movement in which every point of the
moving object has simultaneously the same
velocity & direction”.
 The mandible moves forward as in protrusion,
the teeth, rami, condyles- all move in same
direction & same degree.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 54

 Translation occurs simultaneously around one
or more of the 3 axis resulting in extremely
complex movements.
11/17/2022

 Mandibular movement is limited by the
ligaments & the articular surfaces of the TMJ as
well as the morphology & alignment of the
teeth.
 When the mandible moves through the outer
range of motion reproducible describable limits
results, which are called border movements.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 56

 Border movements is defined as, “Mandibular
movement at the limits dictated by anatomic
structures, as viewed in a given plane”.
-GPT-8,2005.
 Extreme border movements occur in three
different planes:
 Horizontal/ Transverse plane
 Sagittal plane
 Coronal/Vertical plane
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 57

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Border movements recorded
in horizontal plane produced
characteristic “Diamond
tracing”.

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A characteristic “ Beak Tracing” is
formed while recording border
movements in the Sagittal plane.

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Border movements produced in
this plane produced
characteristic “Shield tracing”.

11/17/2022
By combining mandibular
border movements in
3 planes, a 3 dimensional
envelope of motion
can be produced.
 This represents maximum
range of movement of
mandible.

Protrusive movement:
 This type of movement occurs when the mandible
moves forward from intercuspation.
Ex : while incising and grasping the food.
 This movement is presumed to occur after the
condyle rotates more than 13˚in the
temporomandibular joint.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 62

 Occurs when the mandible moves posteriorly
from intercuspation.
 This movement is restricted by the ligamentous
structures.
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 64

 Bennett movement or laterotrusion is defined as
“The bodily lateral movement or lateral shift of the
mandible resulting from the movements of the
condyle along the lateral inclines along the
mandibular fossae in lateral jaw movements.”
“Condylar movement on the working side in
horizontal plane. This term may be used in
combination with terms describing condylar
movement in other planes, for example,
laterodetrusion , lateroprotrusion, lateroretrusion,
and laterosurtrusion”.
-GPT -8 ,2005.
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FUNCTIONAL .ANATOMY,GROWTH,AGE CHANGES
& BIOMECHANICS OF TMJ -91 65

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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 66

11/17/2022
Based on the timing and amount of
descent of the contralateral condyle.
1. Condylar translation with
rotation about the center of the
opposite condyle.
2. Solid line indicates the change
in the condylar path due to
progressive shifting of the
center of rotation in the opposite
condyle
3. Solid line indicates the condylar
path resulting from the
immediate shifting of the center
of rotation of the opposite
condyle.
4. Observed motion of the condyle
during chewing

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Bolender CL, Zarb GA. Biological Considerations in Jaw Relations
& Jaw movements. In Boucher’s Prosthodontic treatment for
edentulous Patients.12th edition 2005:258.

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CHANGES & BIOMECHANICS OF TMJ -91
69
Definition: “Angle formed by the sagittal plane & the path of
the advancing condyle during
lateral mandibular movements
as viewed in the horizontal
plane”.
 Bennett Angle: 7.5 to 12.8º.
 This angle is used in
articulators with immediate
lateral translation capability.
Bennett Angle(L)=H/8+12

11/17/2022

 Hard tissue imaging
 Panoramic
 Transcranial
 Transpharyngeal
 Transorbital
 SMV
 CT
 Soft tissue imaging
 Arthrography
 MRI
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 Occluso-muscular disorders
 Intracapsular disorders
 Disorders that mimic TMD
11/17/2022

 Intra-articular(intracapsular) pathology
 Articular disk
 Displacement
 Deformity
 Adhesions
 Degeneration
 Injury
 Perforaton
 Anamolous
 Disk attachments
 Inflammation
 Injury
 Perforation
 Fibrosis
 Adhesions
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 Synovium
 Inflammation/effusion
 Injury
 Adhesions
 Synovial
hypertrophy/hyperplasia
 Granulomatous
inflammation
 Infection
 Arthritides(rheumatoid,
degenerative)
 Synovial chondromatosis
 Neoplasia
 Articular Fibrocartilage
 Hypertrophy/
hyperplasia
 Degeneration
(chondromalacia)
 Fissuring
 Fibrillation
 Blistering
 Erosion
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FUNCTIONAL
.ANATOMY,GROWTH,AGE
TMJ -91 76

 Mandibular condyle and glenoid fossa
 Osteoarthritis(osteoarthritis, degenerative
joint disease)
 Avascular necrosis(osteonecrosis)
 Resorption
 Hypertrophy
 Fibrous and bony ankylosis
 Implant arthropathy
 Fractures/dislocations
11/17/2022

 Extra-articular(extracapsular
pathology)
 Musculoskeletal
 Bone(temporal,mandibular
,styloid)
 Anamolous
development(hypoplasia,h
ypertrophy,
malformation, ankylosis)
 Fracture
 Metabolic disease
 Systemic
inflammatorydisease(conn
ective tissue/ arthritides)
 Infection
 Dysplasias
 Neoplasia
 Masticatory muscles and
tendons
 Anamolous development
 Injury
 Inflammation
 Hypertrophy
 Atrophy
 Fibrosis, contracture
 Metabolic disease
 Infection
 Dyspalsisa
 Neoplasia
 Fibromyalgia
 Central nervous
system/peripheral nervous
system
 Reflex sympathetic dystrophy
11/17/2022

 It is an imaginary line passing through the centre of the
condyle when the mandible rotates in the sagittal
plane.
 This rotation is within 5-12 degrees.
 There can be multiple axes of rotation for a single
patient.
 The one which coincides with centric relation is called
true hinge axis.
 This should be accurately determined during full
mouth rehabilitation done with either removable or
fixed partial denture.
11/17/2022

 It is defined as “the postural position of the mandible
when opening and closing muscles are in minimal
tonic contraction”.
 When mandible is not functionally active it adopts a
rest position.
Significane: In healthy TMJ this record is fairly constant
This varies for number of reasons like condyle
head position and levels of muscle activity
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Centric Relation
 “Most posterior relation of the
mandible to the maxilla with
the head of condyle in
unstrained & most retruded
position in the glenoid fossa”.
 Significance:
 Retention & stability will be
lost if CO & CR are not
coinciding.
 Maintains health of TMJ
 Improves masticatory
efficiency
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 Helpful in adjusting condylar guidance to the
articulator to produce balanced occlusion.
 It is the basic point of teeth setting &
adjustment in articulator.
 It is learnable, repeatable & recordable
position which remains constant throughout
life.
 Acts as centre from which all the eccentric
movements can be made.
 Helps to mount maxillary cast onto the
articulator.
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INCREASED DECREASED
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 The position of widest mouth opening is
associated with the condyle moving to the crest
of the articular eminence or beyond.
 A wide variation in mandibular movement
exists
 Incisor displacement remains the most
common diagnostic indicator
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 Reduced number of contacting teeth in
intercuspal position and loss of posterior teeth
are the risk factors for development of TMDs.
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 Mandibular guidance generated by the condyle
and the articular disc traversing the contour of
the glenoid fossa.
11/17/2022

 As the temporomandibular joint is the most
complex and unique joint of the body which is
responsible for all the functional movements of
the mandible there is all the need to know its
anatomy and function in order to establish a
healthy occlusion in prosthodontic
rehabilitation.
11/17/2022

 Okeson JP.Functional Anatomy & Biomechanics of
TMJ .In Management of TMJ disorders and
occlusion;6th edition 2008 : 1-38.
 Dawson PE. The TMJ. In Functional occlusion from
TMJ to smile design 2007,33-45.
 White SC & Pharoah MS. Imaging Principles &
Techniques. In Oral Radiology Principles &
Interpretation.6th edition 2004: 175- 225.
 Greenberg MS,Glick M.Temperomandibular
Disorders. In. Burkit’s Oral medicine diagnosis and
treatment .10th edition :271-300.
 Chaurasia BD. Temporal & Infratemporal Regions. In
Human anatomy:Head & Neck. 4th edition:161-163.
11/17/2022

 Ash MM, Nelson SJ .TMJ’s muscles,teeth & their function.
In Wheeler’s Dental Anatomy Physiology & Occlusion.8th
edition,2005: 411-429.
 Bolender CL, Zarb GA.Biological & Clinical Considerations
in making Jaw Relation Records. In Prosthodontic treatment
for edentulous Patients.12th edition 2005:268-303.
 Roberson TM. Clinical signifance of Dental Anatomy,
Histology, Physiology & Occlusion. In Sturdevant’s Art &
Science of Operative Dentistry 5th edition 2009:48-64.
 Lundeen HC, Shryock EF, Gibbs CH. An evaluation of
mandibular border movements: their character and
significance .J Prosthet Dent. 1978;40:442-452
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 Landa JS. A critical analysis of the bennett movement Part I. J
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11/17/2022

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