Internal disk derangement/ dental crown & bridge courses

INTERNAL DISK
DERANGEMENT
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

THE ARTICULAR DISC

•The inferior compartment
– Condylodiscal complex between the condyle and the disc.
•The superior compartment
– Temporodiscal complex between the disc and the glenoid
fossa.

Enhances the flexibility
of the disc by allowing
it to twist, flatten or fill
the variable space
The Articular Disc
posterior anterior
ThickThicker Thin
Superior compartment
Inferior compartment
The disk is biconcave in the sagittal section. The
superior surface is concavoconvex to match the
anatomy of the glenoid fossa and the inferior surface
is concave to fit over the condylar head.

RETRUDED OPENING PHASE OR
ROTATION
• The condyle rotates and moves 5 to 6 mm inferior to the
intermediate zone
• 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 rest

• 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 tightening
EARLY PROTRUSIVE OPENING
PHASE OR FUNCTIONAL OPENING

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

• The condyle translates posteriorly, about 6 to 9 mm, to
the intermediate zone
• There is simultaneous reduction of space posteriorly in
the superior compartment
EARLY 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.
RETRUSIVE CLOSING PHASE

INTERNAL DISK DERANGEMENT
Defined as an abnormal relationship of the articular disk
to the mandibular condyle, fossa and articular eminence

ETIOPATHOGENESIS OF
INTERNAL DISC DERANGEMENT

INTERNAL DISK DERANGEMENT
• Disc displacement divided in to stages based On signs
symptoms combined with imaging findings
– Anterior disc displacement with reduction (clicking joint)
– Anterior disc displacement with intermittent locking
– Anterior disc displacement without reduction (closed lock)

ANTERIOR DISK DISPLACEMENT
WITH REDUCTION
• Causes
– loosened because of elongation
– Tearing of restraining ligaments
– Movement from normal position
– Alteration in the form of disc

WITH REDUCTION
• Common problem
• Significant only if associated with pain
• Distinguish from MPDS
• Mechanism click
• Non invasive treatments

WITH REDUCTION

TREATMENT
• No treatment in absence of pain
• Flat plane splints : do not change mandibular position
• Anterior position splints : place condyle anteriorly,
preventing condyle from closing posterior to disc
• Potential side effects : tooth movement and open bite

ANTERIOR DISC DISPLACEMENT
WITHOUT REDUCTION (CLOSED LOCK)
• May be first sign of TMD or bruxism
• Clicking joint --- brief locking --- permanent locking
• Disc interferes with normal translation
• Pain directly over joint
• Limited movement on opposite side
• Mandible will deviate towards affected side

ANTERIOR DISC DISPLACEMENT
WITHOUT REDUCTION (CLOSED LOCK)

TREATMENT
• Manual manipulation
• Increase in the range of movements
– Manually
– Mandibular range of motion devices
• Flat plane devices to prevent bruxism
• Arthrocentesis and arthroscopy
• Intra-articular corticosteroids or sodium hyaluronate to
increase lubrication

POSTERIOR DISC DISPLACEMENT
• Condyle slipping over anterior rim of disc during opening
• Disc brought backward & in abnormal relation to condyle
• Disc is folded in the dorsal part of joint
• Inability to bring upper and lower teeth together
• Forward displacement of mandible on affected side
• Restriction of lateral movement to affected side
• No restriction of mouth opening

WILKE’S STAGING OF INTERNAL DISK
DERANGEMENT
STAGE CHARACTERISTICS IMAGING
I. Early Painless clicking
No restricted motion
Slightly forward disk
Normal osseous contours
II.Early
Intermediate
Painless clicking
Intermittent locking
Headaches
Slightly forward disk
Early disk deformity
III .Intermediate Frequent pain
Joint tenderness,
Headaches, locking
Restricted motion
Painful chewing
Anterior disk displacement
Moderate to marked disk
thickening
IV.Intermediate
late
Chronic pain, headache
Restricted motion
Anterior disk displacement
Marked disk thickening
Abnormal bone contours
V. Late Variable pain, joint crepitus pain Anterior disk displacement with
Disk perforation and gross
deformity
Degenerative osseous changes

Internal disk derangement/ dental crown & bridge courses

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