1.  Occlusion- contact of opposing surface of
teeth of two jaws.
 Centric relation- untranslated hinge position
of mandible to maxilla
 Centric occlusion - occlusion of teeth as the
mandible closes in centric relation. This is the
reference position from which all the horizontal
position are eccentric.

2.  Disclusion- contacting of designated groups of teeth in order to
disallow any contacting of other groups of teeth.
 Anterior disclusion describe contacting of anterior teeth to prevent
occlusion of posterior teeth during eccentric closures of mandible.
 During lateral movement, orbiting(non-working) condyle revolves in
orbit around rotational center of opposite rotating(working) condyle
Eg.during right lateral movement right condyle is working or rotating
condyle and left condyle is orbiting or non-working condyle.
 Vice versa in left lateral movement.

4.  Maximum intercuspation - most closed complete interdigitation of
mandibular and maxillary teeth irrespective of condyle centricity.
 Protrusion- forward movement of mandible.
 Retrusion- backward movement of mandible.
 Transtrusion- total lateral translation or side shift of mandible.
 Mediotrusion- lateral movement towards midline of head of orbiting
or non working condyle.
 Laterotrusion- lateral movement away from midline of working
condyle.

5.  Sur trusion- upward movement of working
condyle from its centric position.
 Detrusion- downward movement of either
condyle from its centric position.
 Hinge axis- imaginary line connecting rotational
center of one condyle and around which mandible
makes opening and closing rotational movement.

6.  The TMJ is a synovial joint further
classified as ginglymus joint.
(sliding hinge)
 The articulation consists of a single
bone, the mandible articulating by
bicondylar synovial joints with
temporal bones of the cranium
 ALSO CALLED AS
GINGLYMODIARTHROIDAL TYPE OF
JOINT,
 MEANING IT HAS A RELATIVELY
SLIDING TYPE OF MOVEMENT
BETWEEN BONY SURFACES IN
ADDITION TO HINGE MOVEMENT.

7. Components of the joint:
 Articular surface of
the temporal bone
 The Condyle
 Cartilage and
Synovium
 The Interarticular
disc/ Meniscus
 Ligaments

9. It is in the Sqamous temporal portion of
temporal bone.
Consists of 3 parts:
Mandibular or glenoid fossa.
Articular eminence
Preglenoid plane.

10. It is the concave portion of the temporal bone.
Boundaries:
Posteriorly: Squamotympanic or Petrotympanic fissure
Medially: Spine of sphenoid
Laterally: Root of zygomatic process of temporal bone
Anteriorly : Articular eminence
The glenoid fossa is covered by a dense, avascular fibrocartilage consisting
largely of bundles of collagen fibres with occasional elastic fibres.

11. It is a small prominence on the zygomatic arch.
It is thick and serves as functional component of TMJ
On its lateral aspect, articular tubercle is present which
serves as the point of attachment for the collateral
ligaments.
It is a cylindrical bony projection and covered with a
thin layer of fibro cartilage.

13. The mandible is a U shaped
bone that articulates with the
temporal bone by means of
the articular surface of its
condyle.
The head is covered with
fibrocartilage and articulates
with temporal bone to form
TMJ.

14. The constriction below the head is the neck.
The lateral surface of the neck provides
attachment to the lateral ligament of the TMJ.
Its anterior surface presents a depression
called Pterygoid fovea for the attachment of
lateral pterygoid.
Two condyles of the same patient may be
asymmetrical.

15. The TMJ is a diarthroidal paired joint, means that there
are two joint movements, which occur in separate
compartments of this synovial joint and that one joint
cannot operate without the other.
The disc divides the articular space into two
components.
The lower or inferior compartment- condylodiscal
compartment between condyle and disc.
The upper or superior compartment- temporodiscal
between the disc or temporal bone or glenoid fossa.

16. The articular disc seperates the mandibular
condyle from direct articulation with mandibular
fossa of temporal bone.
It is composed of dense fibrous connective tissue,
for the most part devoid of any blood vessels and
nerve fibres.

17. In sagittal plane it is divided into 3 planes.
1. Anterior band
2. Intermediate band
3. Posterior band

19. In the normal joint, the articular
surface of the condyle is located
on the intermediate zone of the
disc.
The shape of the disc is
determined by the morphology
of the condyle and mandibular
fossa.
The disc is somewhat flexible
and can adapt to the functional
demands of the articular surface.

20. Ligaments associated with the TMJ are
composed of collagen, which do not stretch and
act predominantly as restraints to motion of the
condyle and the disc.
They play an important role in protecting the
structures of the joint.
The TMJ has support of 3 functional ligaments
and 2 accessory ligaments.

21. • Functional ligaments- Serve as major anatomical
component for the joint.
a] Collateral/Discal ligament
b] Capsular ligament
c] Temporomandibular ligament
• Accessory ligaments-Serve as passive restraints to
mandibular motion.
a] Sphenomandibular ligament.
b] Stylomandibular ligament.

22. COLLATERAL/DISCAL ATTACHMENTS
These ligaments attach the articular disc to the
medial and lateral poles of the condyle.
These are called the discal ligaments.
These are composed of collagenous connective
tissue fibers and they do not stretch.
They function to restrict the movement of the disc
away from the condyle and permit the disc to rotate
anteriorly and posteriorly on the condyle.

23. • The capsule of TMJ is described as fibrous non elastic
membrane surrounding the joint.
• The capsule seals the joint and provides passive stability.
• The active stability is achieved by proprioceptive nerve
endings in the capsule.
• To resist medial, lateral and inferior forces thereby holding
the joint together.
• It offers resistance to movement of joint only in the
extreme range of motion.
• Secondary function of the capsular ligament is to contain
the synovial fluid within the superior and inferior joint
spaces.

24. • It is located on the lateral
aspect of each TMJ.
• This ligament runs
downwards and
backwards from the
lateral aspect of the
articular eminence to the
posterior aspect of the
neck.

25. Its function is to limit
the posterior
movement of the
condyle during pivoting
movements such as,
when the mandible
moves laterally in
chewing position. It
also protects the inner
lateral pterygoid
muscle from over
lengthening or
extension.

26. • The sphenomandibular
ligament arises from the
spine of the sphenoid and
extends downwards to a
small bony prominence on
the medial aspect of the
mandible called the lingula.
• It does not have any limiting
function on TMJ.
• It is a remnant of Meckels
cartilage.
• It assists the lateral pterygoid
in translatory and rotatory
movement.

27. • It arises from the styloid
process and extends
downwards and forwards to
the angle and posterior
border of the ramus of the
mandible.
• It limits the protrusive
movement of the mandible.
• It is taut in protrusion of
the mandible and relaxed
when the mandible is wide
opened.

29. The muscles of mastication are directly concerned
with mandibular movements in mastication and
speech.
4 pairs of muscles make up a group called the
muscles of mastication.
1. Masseter
2. Temporalis Accessory muscles
3. Medial pterygoid 1. Buccinator
4. Lateral pterygoid 2. Digastricus.

31. These four pairs of muscles attached to mandible,
primarily responsible for
Elevating
Depressing
Protruding
Retruding
Lateral movement

32. It is a quadrilateral muscle.
The fibers are arranged in3 layers
Superficial layer:
Origin : anterior 2/3 of inferior
surface of zygomatic arch.
& maxillary process of
zygomatic arch.
Insertion: angle of mandible ,
posterior half of the lateral
surface of mandibular
ramus.

33. Middle layer:
Origin: medial aspect of 2/3 of
zygomatic arch.
Insertion: middle part of ramus.
Deep layer:
Origin: deep surface of
zygomatic arch.
Insertion : upper part of ramus
& coronoid process.
Most powerful closing muscle
of jaw

35. Action :
Elevates the mandible
to close the mouth.
Retraction of mandible
& clenching of teeth.
Superficial fibers help
in protrusion of
mandible.

36. This is a fan shaped muscle and fills the temporal
fossa. The temporal fascia covers the muscle.

37. Origin:
Temporal fossa &
deep surface of
temporal fascia
Insertion:
Fibers converge to
insert on tip & medial
surface of coronoid
process of mandible
and anterior border
of ramus of mandible

38. Action:
Anterior and middle
fibers elevate mandible.
Posterior fibers
retract the mandible.

39. It is a quadrilateral muscle with 2 heads.
A small superficial head & a large deep head.

40. Origin:
Superficial head: from
maxillary tuberosity and
adjoining pyramidal
process of palatine bone.
Deep head: larger, arises
from medial surface of
lateral pterygoid.
Insertion:
The fibres run
downwards, backwards &
laterally to insert into
medial surface of the
angle and adjoining part
of ramus of mandible.

42. Actions:
When both side muscle
contracts together it
elevates the mandible
When one side muscle
contracts jaw is pulled to
opposite side.
It also helps in protrusion
of the mandible and helps
in lateral movements of the
jaw.

43. It is a short
and thick
muscle with
2 distinct
heads.

44. Origin:
Upper head- small, arises from
infra temporal surface of
greater wing of sphenoid.
Lower head – large, arises from
lateral surface of lateral
pterygoid plate.
Insertion:
Fibres run backwards, laterally,
converge to insert into
pterygoid fovea in the anterior
surface of neck of mandible,
adjoining articular disc and
capsule of TMJ.

45. Actions:
Depresses the mandible.
Lateral and medial
pterygoid muscles of
both sides act together
to protrude the
mandible.
Helps in side to side
movements of the jaw.

46.  Temporalis, masseter, medial pterygoid muscle elevates
the jaw and have great power in keeping the teeth
clenched.
 The mouth opens by relaxation of these muscle and by
weight of mandible cooardinated with contraction of
suprahyoid and infrahyoid group of muscle, platysma
and lateral pterygoid muscle.
 Infrahyoid and suprahyoid muscle also helps in function
of degluttination, phonation and mastication.

48.  Muscle contract iso tonically and iso metrically
 Iso-tonic M.C.- occurs in absence of resistance
with shortening of muscle fibres without increase
in muscle tone making the associated skeletal
parts are moved by this contraction.
 Iso-metric M.C.- occurs in presence of resistance
without shortening of muscle fibres with increase
in muscle tone and it resists the associated
skeletal parts movement.

49.  It is compound diarthrodial joint or
Ginglymoarthrodial articulation
 Mandible has two action –
 Ginglymoid action by rotation.
 Diarthrodial action by translation.

50.  These movements occur in 3 cranial planes
 Transverse
 Saggital
 Frontal

51.  It occurs in lower compartment of TMJ.
 It occurs around 3 axis
 Horizontal- mandible rotates around horizontal or hinge axis to
produce opening and closing movement.
 Frontal- mandiblar rotates around vertical axis of one condyle. It
results in lateral excursion.
 The condyle around which rotation occurs called as rotating or
working condyle and opposite condyle is called orbiting or non-
working condyle.
 Saggital- lateral excursions are made and orbitting condyle travels
downward and forward during rotation around saggital axis.

53.  It occurs in upper
compartment of TMJ.
 It occurs simultaneosly
in all 3 cranial planes.
 In this muscular
contraction makes
change in relationship of
condyle and articular
disc with articular fossa.

54. Stuart describes condylar factors as determinants of
occlusal morpholgy and effect on acceptable cusp
height and fossa depth and allowable ridge and
groove direction of teeth, called as posterior
determinants of occlusion .
These are-
Side shift
Path of rotating condyle
Intercondylar distance
Path of orbiting condyle

55.  This is the detrusion of
orbiting(non working)
condyle in relation to
horizontal cranial
reference plane.
 Greater angle of the
path, greater cusp
height and deeper the
fossa.

56.  Transtrusion or lateral shifting of mandible as lateral
movement is made. This is produced by combination of rotation
and translation in both horizontal and frontal planes.
 Greater the immediate shift, shorter is allowable cusp height.
 Presence if immediate shift also requires mesial positioning of
oblique grooves and ridges of mandibular teeth and more distal
positioning of oblique ridges and grooves of maxillary teeth.
 During right lateral movement, greater mediotrusion of left
condyle that is produced by side shift, greater must lingual
concavity of maxillary canine in order to allow smooth cyclic
chewing movement without conflict.

58.  Distance between the rotational center of one
condyle to the rotational center of the other
side of condyle is called as intercondylar
distance.
 Larger the distance, more distal positioning of
oblique ridges and grooves on mandibular
teeth and mesial positioning of ridges and
grooves of maxillary teeth.
 Smaller the distance vice-versa.

59. Laterotrusion- lateral
movement of rotating
condyle.
Horizontal plane: these
movements give antero-
posterior componet which
effects the ridge and groove
directions of occlusal
surface.
Lateroprotrusion- outward
and forward movement.
Distal positioning of
grooves and ridge is done in
mandibular teeth.

60. Lateroretrusion-
outward and backward
movement
Mesial positioning of
grooves and ridges is
done on mandibular
teeth.
For maxillar y teeth
vice-versa

61.  Frontal plane- it gives
the vertical component
affects the depth of
grooves, height of
cuspsand angle of
ridges.
 Laterosurtrusion-
outward and upward
movement.
 It demands shallower
grooves and less cusp
height.

62.  Laterodetrusion-
outward and
downward movement.
 Demands deeper
grooves and greater
cusp height.

63. Path of rotating
condyle affects the
path of mandibular
canine on working side
and influence the
amount of allowable
lingual contour of
opposing maxillary
canine.

64.  The factors within dentition which influences
the mandidular movement are called as
anterior determinants of occlusion.
 These are –
Occlusal plane
Curve of spee
Facial position of teeth
Vertical and horizontal overlap of anterior teeth

65.  Position of teeth in relation to
rotational centers of condyle
and to horizontal cranial
reference plane is
transferred to articulator by
means of facebow.
 Interocclusal records made in
centric relation are used to
place mandibular cast in
proper relation to rotational
centers and cranial reference
planes.

66.  Effect of curve of
spee is determined
by comparing plane
of each tooth in
curve with path of
orbiting condyle
with same rule as
in occlusal plane.

67.  The more plane of
occlusion diverges from
path of non working
condyle, greater is
allowable cuspal height.
 The more nearly parallel
occlusal plane to path of
non working condyle the
shorter is allowable
cuspal height.

68.  Greater the vertical
height, greater will be
cusp height.
 Greater the
horizontal overlap,
lesser will be cusp
height.

69. Posselt”s
envelope of
motion

70.  The upper extent of posselt”s envelope of
motion is product of tooth contact. The
movements of mandible along all other borders
of envelope and movements within envelope
are without tooth contacts and are controlled
by craniomandibular articulation and the
quantity of muscular activity. If Occlusal
contacts are not created properly with growth
and development will interfere with condylar
controls so that condylar centricity is lost.

72.  Faulty occlusal contours of dental restorations may also
produce deflective occlusal contacts causing mandible
to move away from centric relation closure in order to
allow maximal intercuspation of teeth. This maximum
intercuspal position is an eccentric closure. Premature
contacts occuring on the inclines of cusps produce
lateral forces on teeth that create undesirable lateral
pressure and tension on periodontal tissue. While
occlusal forces donot cause periodontal disease, it
produces increased tooth mobiltybecause of
compensatory widening of periodontal ligament space.

73.  The craniomandibular articulation allows
changes in relation of its parts in order to
accommodate guiding influence of tooth
inclines during mandible”s attempt to reach the
position of maximal intercusping. The
accomodation produces an eccentric maximal
intercusping of teeth. The repeated demands
resulting from this intercusping can produce
hypertonicty in associated muscle beyond their
capacity to adapt and myofacial pain devlops.

74.  Disharmony between condylar centricity and
maximal intercusping may also produce
excessive wear of the teeth that are
responsible for the deflective interferences.

75.  All functions of mandibular movements such as
chewing, speaking and swallowing begin with
opening movement of jaw. For chewing a cycle
of lateral depressing and elevating movement
is generated. The chewing take place within the
envelope of motion and unique for each
individual. Tooth position and tooth morphology
may contribute to development of this cycle,
however extremes in either factor may prevent
a smooth cycle function.

77.  Dental occlusion should be designed so as not
to interfere with these muscle produced and
condylar controlled cyclic actions. This
requirement and the purpose of occluding
teeth to provide a stable closure of mandible in
centric relation are major considerations in an
occlusal scheme that promotes health of
supporting tissues, has a reasonable degree of
permanence and provides efficient comfortable
group uses of teeth.

79.  The protective proprioreceptors responses
minimizes the occurrence of occlusal conflict of
premature contacts by controlling muscle tension
and by developing an adaptive arc of closure into
an eccentric maximal closing. However if damage
resulting from these interferences warrants
change it can be done by following-
 Occlusal adjustments if teeth
 Restoration of form and function by recusping
 Surgical or orthodontic movement of teeth
 Removal of teeth in some cases.

80.  Lingual cusp of maxillary teeth and facial cusp
of mandibular teeth are stamp or centric
holding cusp.
 The facial cusp of maxillary teeth and lingual
cusp of mandibular teeth are shearing cusp.

82.  Development of occlusion can result in fitting
one stamp cusp into fossa and fitting another
stamp cusp into embrasure area of two
opposing teeth.
 It is also called as tooth to two teeth occlusion
or cusp embrassure occlusal pattern.

84.  It produces an interdigitative relation of cusps
and fossa of one tooth with cusps and fossa of
only one opposing tooth.
 This arrangement is also called as tooth to one
tooth occlusion.

86.  Given by stallard and stuart
 In protrusive movement two or more mandibular anterior teeth
occlude with maxillary incisors.
 All mandibular teeth occlude simultaneously with maxillary teeth in
centric relation.
 Maxillary lingual cusp occlude in fossa of each mandibular opponent.
Mandibular facial cusp occlude in fossa of each maxillary opponent.
 The mandibular anterior teeth relate to lingual surface of maxillary
anterior teeth as stamp cusps into fossa.
 In lateral closure only canines on the working side occlude.
 In lateroprotrusive closure, the lateral incisor may share closure
contacts with canines.
 The stamp cusps of premolars and molars occlude with opposing
fossa with 3 point contact in centric relation.

87. Adjustment of occlusion can be done by-
 Selective reshaping of ridges of cusps.
 Changes can be made at angles of marginal ridge.
 Reduction of cusp height can be done.
 Reduction of sulcus by reducing angles of triangular and
oblique ridges.
While reduction do not create flat areas, always
maintain rounded contours polished sur face of
cusps and ridges.
All eccentric inter ferences should be removed first
then only centric relation inter ferences should be
removed.

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89.  It is three point contact of each stamp cusp
into its respective fossa by grinding of tooth
surface.
 It is unrealistic to give 3 point contact but
grinding tooth surface of stamp cusp can be
done in such a manner to give 2 point contact
for stabilty.

91.  If contact occur between premolars or molars
while moving teeth in end to end incisal
relationship, then grind it from distal
inclines of maxillar y facial cusps and
mesial inclines of mandibular lingual
cusps.

93.  If contacts occurs between opposing premolars
or molars on non-working side while moving
mandible in end to end relation of canine on
working side, then make oblique grooves
directed mesially on maxillar y teeth to
ser ve pathway for mandibular facial
cusps and on distal inclination of
mandibular teeth for maxillar y lingual
teeth.

95.  Teeth are moved into extreme lateral position to
extent of end to end relation of canine on
working side. If there are interferences or
simultaneous contact between premolars or
molars on the working side, remove tooth
structure from mesial inclines of facial
cusp of maxillar y teeth and distal
inclines of lingual cusp of mandibular
teeth.

97.  Centric relation occlusal contacts are corrected
only after all eccentric interferences are removed.
 The mandible is closed in centric relationuntil
initial tooth contact is made.if increasing the
closing force deflects mandible to more closed
position , corrections must be made.
 Reductions are made on mesial slopes of
maxillar y teeth and distal slopes of
mandibular teeth.