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4. Temporomandibular Joint
• The area where the craniomandibular articulation occurs
is called the temporomandibular joint
• Bilateral diarthrodial joint
• Atypical synovial joint
• Ginglymoarthrodial joint
• Compound joint
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14. DEVELOPMENT
• Articular Disc:Earliest appearance in 6 week old
embryo
• At 7 weeks: the future condyle is still only a
condensation of mesenchyme resting on osseous
lamella, which forms the mandibular ramus.
• 12 week – condylar growth cartilage makes its 1st
appearance and begins to develop a hemi-spherical
articular surface
.
• By 13th week – condyle and articular disc having moved
up into contact with temporal bone.www.indiandentalacademy.com
15. DEVELOPMENT
• Only when such articular contact has been made do the
joint cavities develop.
• Inferior space appearing first.
• Disc begins to get compressed.
• When central portion of disc is compressed this part
becomes avascular.
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16. DEVELOPMENT
By 26th week:
• All components of TMJ present except articular
eminence.
• Meckel’s cartilage still extends through GF, but by thirty-
first week is transformed into sphenomandibular
ligament.
By 39th week:
• Ossification of bones in this region has proceeded to the
point where; ligament gains its apparent attachment to
spine of sphenoid.
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18. HISTOLOGY OF ARTICULAR
SURFACES
• The Articular surface of the condyle and mandibular
fossa are composed of four distinct layers
• Articular zone
• Proliferative zone
• Fibrocartilaginous zone
• Calcified cartilaginous zone
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22. Condylar cartilage
• Similar to epiphyseal cartilage
• Endochondral ossification
• Absence of ordered column of cells
• Unidirectional and multidirectional growth pattern
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23. Bony components
Condylar head
Glenoid fossa
Articular eminence
Muscles
Muscles involved in
mastication.
Facial muscles.
Muscles of the neck
Soft tissue
Articular disc
Joint capsule
Ligaments
Muscles
attached to
joint
FUNCTIONAL ANATOMY
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27. SQUAMOUS PART OF THE
TEMPORAL BONE
• Mandibular or articular or glenoid fossa
• Degree of the convexity- dictates the pathway of the
condyle
• Posterior roof of the mandibular fossa is thin
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33. Condyloid process
• It is the portion of the mandible that articulates with the
cranium around which movement occurs
• Anterior view it has a medial and lateral projection s
which are called as poles
• ML length - 15 to 20 mm
• AP length - 8 to 10mm.
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34. • Posterior articulating surface is greater than anterior
surface.
• The articulating surface of condyle is quite convex
anteroposteriorly and only slightly convex mediolaterally.
• Pterygoid fovea on the antero-medial aspect of the
mandibular neck where inferior head and most fibres of
the superior head and lateral pterygoid muscle insert on
the mandible.
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38. ARTICULAR DISC
• Dense fibrous connective tissue devoid of blood vessels
and nerves
• Sagittal plane divided into three regions according to the
thickness
• Central area is thinnest and it is called intermediate zone
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39. • Anterior is thick
• Posterior is thick
• Articular surface of the condyle located on the
intermediate zone of the disc bordered by the thicker
anterior and posterior regions
• Shape of the disc governed by the morphology of the
condyle and the mandibular fossa
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42. • The articular disc is attached posteriorly to the region of
loose connective tissue that is highly vascularized and
innervated which is called as retrodiscal tissue or
posterior attachments or bilaminar region.
• The articular disc is attached to the capsular ligament
not only anteriorly and posteriorly and also medially and
laterally this divides the joint into two distinct cavities.
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52. Ligaments
• As with any joint system, ligaments play an important
role in protecting the structures
• The ligaments of joints are made up of collagenous
connective tissues which do not stretch.
• They do not enter actively into joint function but instead
act as a passive restraining devices to limit and restrict
border movements
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53. 3 functional ligaments that support the TMJ
• Collateral ligaments
• Capsular ligaments
• Temporomandibular ligament
3 accessory ligaments
• Sphenomandibular ligament
• Stylomandibular ligament
• Retinacular ligament
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54. Collateral ligaments
• Discal ligaments
• They attach the medial and lateral borders of the
articular disc to the poles of the condyle
• Medial discal ligament –attaches the medial edge of the
disc to the medial pole of the condyle
• Lateral discal ligament-attaches the lateral edge of the
disc to the lateral pole of the condyle
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55. • These ligaments are responsible for dividing joint
mediolaterally into superior and inferior joint cavities
• The discal ligaments are true ligaments, composed of
collagenous c.t fibers –they do not stretch
• Restrict the movement of disc away from the condyle
that means they allow the disc to move passively with
condyle as it glides anteriorly and posteriorly
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56. • The attachment of discal ligaments permit the disc to be
rotated anteriorly and posteriorly on the articular surface
of the condyle thus the these ligaments are responsible
for the hinging movements of the TMJ.
• The discal ligaments have a vascular supply and are
innervated
• This innervation provides information regarding joint
position and movement
• Strain on these ligaments produce pain
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58. Capsular ligament
• Entire TMJ is surrounded and encompassed by the
capsular ligament
• The fibers of capsular ligament are attached superiorly to
the temporal bone along the borders of articular surfaces
of the mandibular fossa and articular eminence
• Inferiorly attach to the neck of the condyle
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59. • Capsular ligament acts to resist any medial ,lateral or
inferior forces that tend to separate or dislocate articular
surfaces
• A significant function of the capsular ligament is to
encompass the joint ,thus retaining the synovial fluid.
• The capsular ligament is well innervated and provides
proprioceptive feedback regarding position and
movement of the joint.
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62. Temporomandibular ligament
• The lateral aspect of the capsular ligament is
reinforced by strong,tight fibers that make up lateral
ligament or temporomandibular ligament.
• The temporomandibular ligament is composed of
2parts
1. Outer oblique portion
2. Inner horizontal portion
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63. • Outer oblique portion-extends from the outer surface of
the articular tubercle and zygomatic process
posteroinferiorly to the outer surface of condylar neck.
• Inner horizontal portion-extends from outer surface of the
articular tubercle and zygomatic process posteriorly and
horizontally to the lateral pole of the condyle and the
posterior part of the articular disc.
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64. • The inner horizontal portion of TM ligament limits
posterior movement of the condyle and disc.
• When force applied to the mandible displaces the
condyle posteriorly,this portion of ligament becomes tight
and prevents the condyle from moving into the posterior
region of mandibular fossa by which it protects the
retrodiscal tissues from trauma.
• The inner horizontal portion also protects the the lateral
pterygoid muscle from over lenghtening or over
extension
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68. RETINACULAR LIGAMENTS
• Recently it has been described in association with TM
joint.
• Arises from the articular eminence, descends along the
ramus of the mandible.
• Insertion: fascia overlying the masseter muscle at the
angle of the mandible.
• As the ligament is connected to the posterolateral aspect
of the retrodiscal tissues and contains an accompanying
vein.
• Action: It maintains blood circulation during the
masticatory movements.
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71. Synovial membrane
• Specialized fringe located at the anterior border of the
retrodiscal tissues produces a synovial fluid which fills
the joint cavities thus it is turned as a synovial joint.
• Capsule lined on its inner surface
• Membrane does not cover articular disk except for
posterior bilaminar region
• Consists of 2 layers
1. Cellular intima
2. Vascular sub-intima -prevents folding of membrane
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72. Synovial fluid
• Since articular surfaces of joint are nonvascular, the
synovial fluid acts as a medium for providing metabolic
nutrients to these tissues
• The synovial fluid also serves as a lubricant between
articular surfaces during function
• Composition - dialysate of plasma with some added
protein of mucin
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82. TYPES OF MUSCLES
• Muscle cells are mainly of three types
1. STRIATED MUSCLE
a. SKELETAL OR VOLUNTARY
2. NON-STRIATED,SMOOTH OR
INVOLUNTARY
3. CARDIAC MUSCLE
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93. MUSCLES OF MASTICATION
• Mastication forces The aev maximum
sustainable biting force is 756N{170 pounds}.
• Molar region: Biting force range 400-890N
• Premolar region: Biting force range 222-445N
• Cuspid region: Biting force range 133-334N
• Incisor region:Biting force range 89-111N {20-55
pounds}
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94. PRIMARY MUSCLES OF
MASTICATION
• MASSETER
• TEMPORALIS
• MEDIAL AND LATERAL PTERYGOID
SECONDARY MUSCLES OF MASTICATION
The suprahyoid group of muscles being used as
secondary or supplementary muscles they are
• Digastric
• Mylohyoid
• Geniohyoid
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95. THE MASSETER
• Quadrilateral and and consist of three layers.
ATTACHEMENTS
• Superficial Layer: Arises by thick aponeurosis.
From zygomatic process of maxilla and anterior
2/3 of lower border of zygomatic arch, pass
downward and back wards at an angle of
45degree and inserted into lower part of lateral
surface of ramus of mandible
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96. • MIDDLE LAYER: Arises from anterior 2/3 of the
deep surface and posterior 1/3 of the lower
border of the zygomatic arch,pass vertically
downwards and and inserted into middle part of
ramus.
• DEEP LAYER: Arises from deep surface of the
zygomatic arch, pass vertically downwards and
inserted into the upper part of the ramus and
into the coronoid process.
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100. • Nerve supply:
MASSETRIC NERVE, a
branch of anterior
division of mandibular
nerve (which is the 3rd
part of V cranial nerve-
trigeminal nerve).
• Blood supply:
Maxillary artery, which is a
branch of external
carotid artery.
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101. ACTIONS OF MASSETER
Actions:
• Elevates the mandible to close the mouth
and to occlude the teeth in mastication.
• Its activity in the resting position is
minimal.
• It has a small effect in side-to-side
movement, protraction and retraction.
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102. THE TEMPORALIS
TEMPORAL FASCIAE
• Thick aponeurotic sheet that roofs over the temporal fossa and
covers the temporalis muscle
.
• ATTACHEMENTS
• Fan shaped
• Arises from whole of temporal fossa.(except the part formed by
zygomatic bone) and deep surface of temporal fascia
• Fibers converge and descend into a tendon .
• It passes through the gap between the zygomatic arch and the side
of the skull
• Attached to medial surface,apex,anterior and posterior border of
coronoid process and anterior border of the ramus of the mandible
as far as last molar.
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105. • BLOOD SUPPLY
Deep temporal part
of maxillary artery
• NERVE SUPPLY
Temporalis is
supplied by the
deep temporal
branches of the
anterior trunk of
mandibular nerve.
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106. ACTIONS OF TEMPORALIS
• Elevates the mandible,this movement requires both the
upward pull of anterior fibers and backward pull of the
posterior fibers.
• Posterior fibers draw the mandible backwards after it has
been protruded.
• It is also a contributor to side to side grinding movement.
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109. SIDE TO SIDE GRINDING
MOVEMENT
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110. MEDIAL PTERYGOID
ATTACHEMENTS
• It is a thick quadrilateral muscle
• Attached to medial surface of lateral pterygoid plate and
grooved surface of pyramidal process of the palatine bone.
• A more superficial slip from the lateral surface of pyramidal
process of the palatine bone and tuberosity of maxilla
• Its fibers pass downwards laterally and backwards
• Attached by a strong tendinous lamina ,to the postero-inferior
part of the medial surfaces of the ramus and the angle of the
mandible
• It is attached as high as mandibular foramen and as far forward
as the mylohyoid groove
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112. • NERVE SUPPLY
Branch of the main
trunk of the
mandibular nerve
• BLOOD SUPPLY
Pterygoid branch of
2nd part of
maxillary artery
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113. Actions of medial pterygoid
• Assits in elevating the mandible
• Acting with the lateral pterygoid they protrude it
• Acting with medial pterygoid of same side
advances the condyle ,while the jaw rotates
through the opposite condyle(when the medial
and lateral pterygoid of the two sides contract
alternatively to produce side to side movements
of mandible eg chewing)
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114. Medial and lateral pterygoid act
together to protrude the mandible
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115. LATERAL PTERYGOID
• ATTACHMENTS
It is a short thick muscle with two parts or head
• UPPER head arise from infratemporal surface and
infratemporal crest of greater wing of sphenoid bone
• LOWER head arise from lateral surface of lateral
pterygoid plate.
• Its fibers pass backwards and laterally to be inserted into
a depression(pterygoid fovea)on the front of the neck of
the mandible and into the articular capsule and disc of
the temporomandibular articulation.
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119. • NERVE SUPPLY
The lateral pterygoid
is supplied by a
branch of anterior
division of the
mandibular nerv
• BLOOD SUPPLY
Pterygoid branch of
2nd part of
maxillary artery
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120. ACTIONS OF LATERAL
PTERYGOID
• Assists in opening the mouth with suprahyoid muscle.
• Slow elongation while closing the mouth with masseter and
temporalis
• Acting with medial pterygoid of same side advances the condyle
,while the jaw rotates through the opposite condyle(when the medial
and lateral pterygoid of the two sides contract alternatively to
produce side to side movements of mandible eg chewing).
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121. • When the medial and lateral pterygoids of two
sides act together they protrude the mandible so
that the lower incisors project in front of the
other.
• Some authorities have ascribed different actions
to the two parts of pterygoid muscle.
• The upper (superior)head being involved in
chewing
• The inferior in protrusion,electromyographic
records in rhesus monkey favors this view.
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125. Medial and lateral pterygoid act
together to protrude the mandible
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126. Secondary muscles taking part in
the mastication
The 4 primary muscles of mastication are in turn
supported or supplemented by few secondary
muscles known as SUPRAHYOID GROUP of
muscles they are
• DIGASTRIC
• MYLOHYOID
• GENIOHYOID
• STYLOHYOID is other suprahyoid muscle,
which does not take part in mastication
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127. • DIGASTRIC- The muscle has secondary role in mastication
as a depressor muscle adding to the action of lateral
pterygoid muscle when mouth is to be opened against
resistance. Elevation of hyoid bone
• MYLOHYOID- The secondary role of this muscle is evident
as a depressor seen in action when mouth is to be opened
against resistance.
• It elevates the floor of mouth to help in degluttition.
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128. • GENIOHYOID- Geniohyoid elevates the hyoid bone and draws it
forward, thus acting as a partial antagonist to stylohyoid.
• When the hyoid bone is fixed, it depresses the mandible
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129. Cervical Group:
• Indirectly involved in mandibular function
.
• They are Trapezius, Sternocleidomastoid ,Anterior vertebral
muscles,the lateral vertebral muscles and other deep posterior
cervical muscles.
• They act to stabilize head posture during the active contraction
of the masticatory ,suprahyoid and infra hyoid muscles during
the mastication and swallowing
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131. BIOMECHANICS
• Complex joint system.
• Compound joint – Its structure and function can be divided
into 2 distinct system:
• Condyle disc complex.
• Condyle disc complex and articulating surface of mandibular
fossa.
• Constant contact between joint surfaces for stability is
required.
• Disc space more at rest, decreases with an increase in
pressure of the joint
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132. • Movement involving the joints has been divided
different phases
• Occlusal or rest position
• Retruded opening phase or rotation
• Early protrusive opening phase or functional opening
• Late protrusive opening phase or translation
• Early closing phase
• Retrusive closing phase
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133. OCCLUSAL OR REST POSITION
• The rest position is the first step and
involves a static jaw position
• In this, the joint is in loose pack
position,the connective tissue at rest
• The posterior band occupies the
deepest part of the mandible fossa
• The intermediate zone and the
anterior band lies between the condyle
and posterior slope of the eminence
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134. RETRUDED OPENING PHASE
OR ROTATION
• The condyle rotates and moves 5
to 6 mm inferior to the
intermediate zone
• The condyle joint surface glides
forward and the medial pole of the
condyle moves anterosuperiorly
and the lateral pole moves
posteroinferiorly
• The shape of inferior compartment
changes the most
• The upper lateral pterygoid relaxes
and the lower lateral pterygoid
contracts
• The posterior connective tissues is
in a functional state of restwww.indiandentalacademy.com
135. EARLY PROTRUSIVE OPENING PHASE
OR FUNCTIONAL OPENING
• The condyle moves inferiorly
and anteriorly approximately 6
to 9 mm below the
intermediate zone.
• The disk and the condyle
experience the short anterior
translatory glide
• The upper and lower head of
lateral pterygoid contract to
guide the disk and the condyle
shortly forward
• The posterior connective
tissues is in a functional
tightning
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136. LATE PROTRUSIVE OPENING PHASE
OR TRANSLATION
• The condyle moves inferiorly and
anteriorly beneath the anterior band
i.e there is full opening more, space
develops in the superior
compartment
• The upper and lower head of Lateral
pterygoid contract to guide the disk
and the condyle fully forward
• The posterior connective tissues
tightens
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137. EARLY CLOSING PHASE
• The condyle translates posteriorly, about 6 to 9 mm, to the
intermediate zone
• There is simultaneous reduction of space posteriorly in the
superior compartment
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138. RETRUSIVE CLOSING PHASE
• The condyle rotates superiorly but
remains inferior to the posterior band
• This movement reduces the space in
the inferior compartment
• The upper head of the lateral pterygoid
contracts and The lower head of the
lateral pterygoid relaxes
• This tightens the mandibular
attachment, and forces blood from the
posterior compartments
• The posterior connective tissues
returns to the functional rest movements
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141. 1. Is it difficult or painful to open the mouth (e.g.,
yawning)?
2. Does the jaw get stuck, locked, or go out?
3. Is it difficult or painful to chew, talk, or use the jaws?
4. Do the jaw joints make noises?
5. Do the jaws often feel stiff, tight, or tired? Is there pain
in or about the ears, temples, or cheeks?
6. Are headaches, neck aches, or toothaches frequent?
7. Has there been a recent injury to the head, neck, or
jaw?
8. Have there been any recent changes in bite?
9. Has there been previous treatment for any unexplained
facial pain or a jaw joint problem?
QUESTIONAIRE
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154. HORIZONTAL PLANE BORDER &
FUNCTIONAL MOVEMENTS
When mandibular movements are viewed in the
horizontal plane, a rhomboid-shaped pattern can be
seen that has a functional component, & 4 distinct
movement components:-
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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155. Left Lateral Border Movements
• With the condyles in the centric relation position, contraction of the
right inferior lateral pterygoid move the right condyle - anteriorly and
medially.
• If left inferior pterygoid stays relaxed, with the left condyle still in the
CR & result will be left lateral border movement.
• Left condyle- working or rotatory
Right condyle- non-working or
orbiting
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156. Continued Left Lateral Border Movements
With Protrusion
• With the mandible in the left lateral border position, contraction of
the left inferior lateral pterygoid along with continued contraction of
right inferior lateral pterygoid will cause the left condyle to move
anteriorly to the right.
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157. Right Lateral Border Movements
• Left condyle-orbiting
• Right condyle- rotatory
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159. LATERAL MOVEMENT
– When lateral movement is executed the working condyle rotates
& moves outward while, other non working condyle translates
forward, medially downward orbiting around the rotating working
condyle.
– The orbiting condylar path is
known as sagittal lateral
condylar path.
– Lateral condylar path is longer
& more steep than the protrusive
condylar path.
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165. Diagnostic information
• Lateral aspect of joint space , glenoid fossa, articular
eminence, condylar head
• Position of the head of condyle
• Shape of glenoid fossa and articular eminence
• Condition of articular surface
• Gross osseous changes on the lateral aspect of condyle
• Displaced condylar feacture
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172. Diagnostic information
• Entire mediolateral dimension of articular eminence,
condylar head and neck is visible
• Condylar neck fractures
• Morphology of convex surface of condylar head can be
evaluated
• Gross degenerative changes
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175. Diagnstic information
• Shape of the condylar head and condition of articular
surface from posterior aspect
• Direct comparison of both condyles
• Fractures of head and neck
• Condylar hypo/hyper-plasia
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181. Advantages
• Assesment of whole joint
• Position of the head of condyle
• Shape of the head of condyle
• Information of all aspects of joint
• Position and orientation of fracture
fragments
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185. Advantages
• Images both hard and soft tissues
• Disc condyle comlex can be evaluated
• 3 D image
• No physical trauma
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187. MANDIBULAR TRACKING
DEVICES
• Disc displacement with reduction
• Click with deviation
• Exact movement of mandible can be recorded
• Diagnose and monitor TMD
• Sensitivity and specifity
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188. Sonography
• Recording and graphically demonstrating joint sounds
• Audio-amplifying devices
• Ultra-sound echo recordings
• Specific disc derangement
• No additional diagnostic information
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189. Vibration analysis
• Intra-capsular and internal derangement
• Minute vibrations by condyle
• Identifying disc displacement
• Selection of appropriate patient therapy
• Positve finding
• Non reducing derangement
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190. Thermography
• Records and graphically illustrates skin temp.
• Various temperatures recorded by different colors
• Bilateral symmetrical thermogram
• Asymmetric thermogram associated with TMD
• Identifying myo-facial trigger points
• Show greater variability of normal temp. In 2 sides of face
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191. CLASSIFICATION
I Masticatory muscle disorders
1. Protective co-contraction (11.8-4)*
2. Local muscle soreness (11.8.4)
3. Myofascial pain (11.8.1)
4. Myospasm (11.8-3)
5. Centrally mediated myalgia (11.8.2)
II Temporomandibular joint disorders
1. Derangement of the condyle-disc complex
• Disc displacements (11.7.2.1)
• Disc dislocation with reduction (11.7.2.1)
• Disc dislocation without reduction (11.7-2.2)
2. Structural incompatibility of the articular surfaces
a. Deviation in form (11.7.1)
i. Disc
ii. Condyle
iii. Fossa
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192. b. Adhesions (11.7.7.1)
i. Disc to condyle
ii. Disc to fossa
c. Subluxation (hypermobility) (11.7.3)
d. Spontaneous dislocation (11.7.3)
3. Inflammatory disorders of the TMJ
a. Synovitis/capsulitis (U.7-4.1)
b. Retrodiscitis (11.7.4.1)
c Arthritides (11.7.6)
i. Osteoarthritis (11.7.5)
ii. Osteoarthrosis (11.7.5)
iii. Polyarthritides (11.7.4.2)
d. Inflammatory disorders of associated structures
i. Temporal tendonitis
ii. Stylomandibular ligament inflammation
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193. III Chronic mandibular hypomobility
1. Ankylosis (11.7.6)
a. Fibrous (11.7.6.1)
b. Bony (11.7.6.2)
2. Muscle contracture (11.8.5)
a. Myostatic
b. Myofibrotic
3. Coronoid impedance
IV. Growth disorders
1. Congenital and developmental bone disorders
a. Agenesis (11.7.1.1)
b. Hypoplasia (11.7.1.2)
c. Hyperplasia (11.7.1.3)
d. Keoplasia (11.7.1.4)
2. Congenital and developmental muscle disorders
a. Hypotrophy
b. Hypertrophy (11.8.6)
c. Neoplasia (11-8.7)
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194. TMJ DISORDERS
Classification:
1) Growth disorders and the joint
• Developmental disorders.
• Acquired disorders.
• Neoplastic disorders.
2) Masticatory muscle disorders:
• Protective muscle splinting.
• Muscle hyperactivity or spasm.
• Myositis (muscle inflammation).
3) Disk interference disorders (internal derangement)
• Incoordination.
• Deformation of articular disk.
• Partial anterior disk displacement.
• Anterior disk displacement with reduction.
• Anterior disk displacement without reduction.
• Anterior disk displacement with perforation.
• Posterior disk displacement.www.indiandentalacademy.com