tmj

1. TEMPOROMANDIBULAR
JOINT

2. • INTRODUCTION
• DEVELOPMENT
• GROWTH
• PARTS OF TMJ
• BLOOD SUPPLY
• INNERVATION
• LYMPHATICS
• TMJ IN FUNCTION
• TMJ IMAGING
• DEVELOPMENTAL ANOMALIES
• TMJ DISORDERS AND MANAGEMENT
• CLINICAL IMPLICATIONS
• REFERENCES

3. INTRODUCTION
• The TMJ is one of the most complex joints in
the body. It is the area where the mandible
articulates with the cranium.
• It is considered to be a
GINGLYMOARTHRODIAL JOINT.
Ginglymoid- hinging
Arthrodial- gliding.
COMPOUND JOINT- 3 bones
SYNOVIAL JOINT.
• Growth center present within
the joint capsule.

4. DEVELOPMENT
• Meckel’s cartilage provides the skeletal support
for development of the lower jaw.
• Extends from the midline - backwards and
dorsally; terminates as the malleus.(Articulare)
• It articulates with the incal cartilage; thus early
jaw movement occurs between these 2
cartilages.
• This primary jaw joint exists for 4 months until
ossification.

5. • The first evidence of joint development is seen at
3 months.
• Here the 2 condensations
TEMPORAL
CONDYLAR
• The temporal blastema - 1st to appear - separated
from condylar blastema by some distance.
• The condylar blastema’s rapid growth, in the
dorsolateral direction - reduces the gap - band of
uncondensed mesenchyme persists.
(Form in the mesenchyme lateral
to the primary joint.)

6. • Membranous ossification center appears in the middle
of the temporal blastema.
appearance of a cleft immediately above the condylar
condensation
cartilage appears in the condylar blastema to form the
condylar growth cartilage.
• Second cleft appears below the bone forming in the
temporal blastema- creating upper joint cavity.

7. GROWTH OF TMJ
• Neonatal tmj.
• Tmj adopts it’s general postnasal form and
composition around 12th week in utero.
• At birth, the entire masticatory complex -
skeletal structures and musculature -
diminutive relative to craniofacial complex.
• Condyle – immature small in size and
essentially rounded.

8. • Temporal component- essentially flat- with
very small manidibular fossa.
• Articular disk is prominent – uniform
thickness- conforms to flat temporal joint.
• Mandibular condyle is highly vascular
throughout the cartilage layers- Active
proliferation and maturation.

9. • Changes in the temporal component of tmj –
(birth to end of mixed dentition)
• By 8 months - articular surface shows enlargement
of the eminence and post-glenoid region.
• 2.5 years - increase in size of articular eminence
from 2mm to 5mm.
• Temporal component achieves a s-shape; para
sagittal. Contributed by articular eminence, fossa,
post - glenoid process.
• Early mixed dentition 6-7yrs - condyle thickens and
cartilage thins

10. • Articular disk- highly vascularised- rich in
fibroblasts- first few years of life.
• After which- central part becomes avascular -
less cellular.

11. • Adult Tmj - complete replacement of cartilage
by bone- by 4th decade.
• 5th decade - deeper articular fossa - growing
eminence.
• There is flattening of eminence in partial or
complete edentulous states.

12. Parts of tmj
bony
GLENOID
FOSSA
CONDYLE
ARTICULAR
EMINENCE
Soft
tissue
ARTICULAR
DISC
CAPSULE LIGAMENTS

13. Articular fossa /glenoid fossa
Articular eminence ; An anterior
protuberance continuous with the fossa
The condylar process - rests within the
fossa
Articular Disc: divides articular
compartment into upper and lower
spaces
The articular capsule envelopes the
above structures.
The lateral and accessory ligaments
protect the joint.

14. • Laterally-root of zygomatic
process.
• Medially -spine of sphenoid-
anteriorly foms the articular
eminence.
• Posteriorly-separated by sqaumo
tympanic and petrotympanic
fissures, from tympanic plate.
• Superiorly -separated form
middle cranial fossa by a thin
plate of bone at apex.
Glenoid fossa

15. • Glenoid fossa posterior margin-
defined by lateral post glenoid
process-continues medially as
a post glenoid ridge in the
tympanic plate.
• The median glenoid plane defines the medial and the
anteromedial boundary of the articular area.
• Between the zygomatic root and median glenoid plane
there is an extension of the articular surface, anterior to
the crest of the articular slope- the pre-glenoid plane.

16. Articular eminence
• A transversely elliptical region, sinuously curved in
the sagittal plane- tilted forwards at 25 degrees to
the occlusal plane.
• Forms most of the articular surface of the fossa.
• Variable steepness ; flatter in edentulous.
• Anterior limit is the summit of the articular
eminence which is a transverse ridge that extends
as far as articular tubercle.

17. Condyle
• Articular surface of the mandible
represented by the mandibular
condyle.
• 15-20mm long; 8-120mm thick
• Articulating surface strongly
convex; anteroposterior and
mediolateral(elongated): thus has
2 poles
• Lateral pole: more pointed and
does not extend far beyond the
lateral surface of mandible.
• Medial pole: projects further
medially; thicker smoother more
rounded.

18. Articular disc
• Transversely oval-predominantly
dense fibrous connective tissue.
• Divides the joint cavity into 2
compartments.
• Thick margin forming peripheral
annulus; central depression holds
articular surface of condyle.
• Lower surface convex; concavo-
convex upper surface.
• Upper surface: thickened
posteriorly and anteriorly,
delimits a central thinner
component.

19. In the sagittal section
• Disc appears to posses a
thin intermediate zone –
thickened anterior &
posterior bands.
• Upper surface concavo-
convex- fits against convex
articular eminence and
concave articular fossa.
Posteriorly disc attached to
loose vascular and nervous
tissue- splits into 2
laminae. UPPER & LOWER

20. • Upper lamina - fibroelastic
tissue - attached to
squamotympanic fissure
• Lower lamina - fibrous non
elastic tissue - attached to
back of condyle.
• The bilaminar region
consists of venous plexus -
central part avascular.
• Space between the two –
filled with loose highly
vascular connective tissue
Upper lamina-
Lower lamina

21. • Type I collagen comprise the disk – loosely
arranged and poorly oriented- central region
tightly bound, more organized.
• Crimped nature of collagen – serves to absorb
energy when sudden tensile force is applied.
• Protects the disc from potential rupture.

22. Cells in the disc secrete chondroitin sulphate-
heavily concentrated in central portion.
Gives the disc resilience and compressive
strength.

23. Functions of articular disc.
• Helps stabilize tmj.
• Acts as a shock absorber.
• Shape and thickness - governed by muscle forces
controlling position of mandible and condyle
• It reduces wear. Frictional wear is halved by
separating sliding and rotating movements .

24. Synovial membrane
• Lines the inner surface of the capsule -
relatively delicate.
• Finger like projections – villi - anterior and
posterior limits of the joint
• Consists of 2 layers: cellular intima which rests
on vascular subintimal layer.

25. • Subintimal layer – loose connective tissue – blood
vessels, scattered fibroblasts, macrophages, mast
and fat cells & elastic fibers.
• Intimal layer - 2 types of cells –
type A(macrophage like) & type B(fibroblast like).
Type A : phagocytic, have filopodia
Type B : Adds protein to fluid & synthesize
hyaluronate

26. Synovial fluid
• Filtrate of plasma- contains protein and
sodium hyaluronate-
• Total volume- 1ml
• A non-newtonian fluid i.e decreased viscosity
with increased shear rate’.
• May also fulfill metabolic needs of avascular
fibrous tissue of joint.

27. Synovial fluidSynovial cavities

28. Capsule
• Fibrous- surrounds the joint-
extends from margin of glenoid
fossa, including articular
eminence (anteriorly), envelopes
head of the condyle
• Fuses inferiorly with the
periosteum of the condylar
process.
• It encloses- a joint cavity-
divided into 2 compartments by
a fibrous disk.

29. • Origin – temporal - petrosquamosal and
squamotympanic fisure;
• Posteriorly - medial and lateral margins of the
glenoid fossa
• Anteriorly - periosteum of the anterior slope of
the articular eminence.
Here the capsule is lax up to the margins of the
disk.
From here it moves downwards (taut) - fuses with
periosteum of condylar process.

30. Temporomandibular ligament
• Also called lateral ligament
• broad fan shaped – reinforcement
of lateral wall of capsule.
• Has two parts outer and inner
surface
• Outer surface-oblique arises from
articular eminence- extends
downwards and backwards
attaches to outer surface of neck
of condyle.
• Inner horizontal portion (same
origin)- inserts into lateral pole of
the condyle and lateral margin of
disk

31. • Prevents lateral dislocation thus also prevents
medial dislocation of the opposite side.
• Oblique portion limits inferior displacement
and horizontal portion limits posterior
displacement of condyle.

32. Sphenomandibular ligament
•Medial to and separate from
the capsule.
•A flat thin band descends from
the spine of sphenoid-widens
reaching lingula. Fibers attach to
the anterior malleolar process.
•Lateral : Lateral pterygoid and
Auriculotemporal nerve.
• Upper end: Chorda tympani
• Inferomedial: Medial pterygoid

33. Stylomandibular ligament
• Thickened band of deep
cervical fascia -stretches
from the apex ,adjacent
to the anterior aspect of
styloid process-to the
angle & posterior border
of mandible.
• Cannot mechanically
constrain any normal
mandibular movements.

34. Blood supply
• Superficial temporal artery
laterally and anterior
tympanic branch of maxillary
artery medially( terminal
brch of ECA).
• Venous drainage –
retromandibular vein-
anterior aspect -plexus
around lateral pterygoid
• Posteriorly – vascular region
that separates 2 laminae of
the retrodiscal tissue.

35. • Auriculotemporal and
massetric nerves;
mandibular division of
trigeminal nerve.
• Postganglionic
sympathetic nerves-
tissue associated with
the capsular ligament &
bilaminar disc

36. Lymphatic drainage
• Drain into the upper deep cervical lymph
nodes around IJV.

37. Tmj in Function
Functional elements
Glenoid fossa;Posterior surface of articular
eminence.
Entire superior surface of Condylar head.
Capsule and ligament.
Articular disc.
Non functional element
Glenoid fossa; posterior half, attachment to
superior layer of lamina.

38. Jaw movements
 During mouth opening- incisors separated
upto 50-60mm- 35˚ rotation.
 Adult range of movements- 10y (F) 15y(M).

39. Protruders
Retractors
Elevators
Depressors
Lateral movers
Lateral & medial
pterygoids
Temporalis,digastric
geniohyoid
Temporalis,masseter
medial pterygoid
Lateral pteygoid,
digastric, geniohyoid,
mylohoid
Medial & lateral pterygoids

40. Movements of condyle
• Major function of mandible- exerts force to
break down food.
• Pure vertical movements - ineffective in breaking
tough fibrous food.
• Lateral movements - create a shear component-
enhances power stroke of mastication.
• Extensive lateral movements - jaw rotated about
one condyle-other condyle slide backward and
forward.
• Sliding movement - capsular ligament around
upper joint is loose- tight around lower
compartment.

41. • 3 phases in symmetrical opening:
• Early phase- controlled by temporomandibular
ligament and articular eminence
• Short middle phase- constriction of movements
by Temperomandibular ligament &
Sphenomandibular ligament.
• Late phase: controlled by sphenomandibular
ligament and articular eminence.

42. Imaging
• Hard Tissue
• Panoramic projection
• Lateral tanscranial view
• Transpharyngeal view
• Antero-posterior
projection
• Tomography.
• Soft Tissue.
• Arthrography.
• CT scan.
• MRI.

43. TEMPOROMANDIBULAR
DISORDERS

45. • Various terms have been used to describe
disturbances of the masticatory system.
• 1934 James costen described group of symptoms
centering around ear and TMJ- Costen
syndrome.
• 1959 Shore introduced TMJ Dysfunction
• Ash & Ramfjord- functional TMJ disturbances
Terminology

46. • Limited nature of these terms lead to a
broader term- Craniomandibular disorders.
• Bell coined the term Temporomandibular
disorders.
• Describes both problems associated with the
joint & disturbances associated with function
of masticatory system.

47. Activities of system/ function
• Chewing, clenching
• Speaking, grinding
• Swallowing
• Influenced by peripheral
input - inhibitory
• Influenced by CNS
• excitatory
Functional Parafunctional

48. Etiologic considerations for TMD.
• 5 major factors associated with TMD
1. Occlusal condition:
2. Trauma
3. Emotional stress
4. Deep pain input
5. Para-functional activities.

49. Occlusal condition
• Excessive load on the system due to
orthopedic instability may lead to
intracapsular disorders.
• 2 factors that determine it are: degree of
instability and amount of loading.
• Changes can be acute/ sudden or chronic.

50. • Chronic interference affects functional activity
by altering muscle;
• avoids potentially damaging contact and gets
on with task of function

51. Trauma
• Macro and micro
• Macro: sudden force that can result in
structural alterations. Eg blow to face.
• Micro : small force applied repeatedly to
structures over a long periods. Bruxism/
clenching.

52. Deep pain input.
• Centrally excites a brainstem – produces
muscle response- protective co-contraction.
(body’s response to injury or threat of it.)
• Functional disorders of masticatory system
• 2 symptoms: Pain and dysfunction.

53. CLASSIFICATION
OF
TEMPOROMANDIBULAR
DISORDERS

54. I. Masticatory muscle disorders
a. Protective co-contraction
b. Local muscle soreness
c. Myofacial pain
d. Myospasm
e. Centrally mediated myalgia

55. II. Temporomandibular joint disorders
1. Derangement of condyle - disc
complex
a. Disc displacements
b. Disc dislocations with reduction
c. Disc dislocations without
reduction
2. Structural incompatibility of
articular disc
a. Deviation in form
- Disc
- Condyle
- Fossa
b. Adhesions
i. Disc to condyle
ii. Disc to fossa
c. Subluxation
d. Spontaneous dislocation
3. Inflammatory disorders of TMJ
a. Synovitis/ Capsulitis
b. Retrodiscitis
c. Arthritides
i. Osteoarthritis
ii. Osteoarthrosis
iii. Polyarthritides
d. Inflammatory disorders of
associated structures
i. Temporal tendonitis
ii. Stylomandibular ligament
inflammation.

56. III. Chronic mandibular hypomobility
1. Ankylosis
a. Fibrous
b. Bony
2. Muscle contracture
a. Mystatic
b. Myofibrotic
3. Coronoid impedance
IV. Growth disorders
1. Congenital and develpmental bone
disoredrs
a. Agenesis
b. Hypoplasia
c. Hyperplasia
d. Neoplasia
2. Congenital and develpmental bone
disoredrs
a. hypothrophy
b. Hypertrpohy
c. Neoplasis

57. • Conservative reversible
therapy.
• Counsel
• Exercise
• Physical therapy
• Medications
• Appliances
• Selective Grinding
• Bio-feed Back
• TENS
• Non conservative
irreversible therapy.
• High Condylectomy
• Meniscectomy
• Disectomy
• Orthodontic surgery
• High Condylotomy
• Hyaluronic acid
• Reconstruction
• Arthrocentisis
Long term studies for TMD treatment have
given 2 kinds of approaches ;

58. • All treatment methods can be categorized
generally into ;
• Definitive treatment / supportive treatment.

59. Definitive treatment
• Occlusal conditions- occlusal therapy-
• Reversible-stabilization appliance
• Irreversible – selective grinding, restorative procedures.
• Emotional Stress: Restrictive use, Voluntary avoidance,
Relaxation therapy.
• Trauma- microtrauma- curtail it.

60. Supportive therapy
• Directed toward the reduction of pain and dysfunction.
• Pharmacologic or Physical therapy.
• Pharmacologic:
1. Analgesics
2. NSAIDs
3. Corticosteroids
4. Anxiolytics
5. Muscle relaxants
6. Antidepressants.

61. • Physical therapy. Group of supportive actions,
usually instituted as an adjunct to definitive
treatment. 2 types- Modalities & Manual
techniques
• Modalities: Thermotherapy, Coolant, ultrasound,
phonophoresis, iontophoresis, TENS, laser
• Manual techniques: provided by physical
therapist; 3 types- soft tissue & joint mobilization,
muscle conditioning.

62. Local muscle soreness
• Or non-inflammatory myalgia- myogenos pain
disorder.
• First response of muscle tissue to continued
protective co-contraction.
• Cause
• Protracted protective co-contraction
• Local tissue trauma
• Increased emotional stress.

63. • History
• Pain began several hours or days after event -
associated with tissue injury.
• Clinical characteristics
1.Marked decrease in the velocity and ROM
2.Minimum pain at rest.
3.Pain increased with function.
4.Local tenderness when palpated.

64. • Definitive treatment
• As it produces deep pain; primary goal is to
decrease sensory input to CNS.
• Supportive therapy
• Pain reduction; NSAIDS etc
• Relaxation techniques
• Muscle stretching and massage

65. Myospasm
• Cause:
1. Continued deep pain input
2. Local metabolic factors- leads to fatigue.
3. Idiopathic
 History: sudden onset; restricted movement ;
rigidity

66. • Clinical characteristics
1.Marked decrease in the velocity and ROM
2.Minimum pain at rest.
3.Pain increased with function.
4.Local tenderness when palpated.

67.  Treatment
1. Reducing the pain- passive strecthing of
muscle.
2. Manual massage, vapocolant spray, ice
etc.
3. In case of remission: botulinum toxin A-
neurotoxin – irreversible presynaptic
blockade of Ach at motor end plates.

68. Disc displacements and disc
dislocations with reduction
• Cause:
• Result from elongation of the capsular and
discal ligaments, coupled with thinning of
articular disc.
• Due to macro or micro trauma.
• Micro trauma e.g. Bruxism, class II div 2
,prolonged excessive loading- breakdown

69. • Clinical features.
1.Relatively normal ROM, restricted with pain.
2.Discal movements felt on palpation of joints
• Treatment
1. To re-establish normal condyle – disc
displacement.
2. Done using anterior positioning appliance-
provides occlusal relationship that maintains
mandible in a forward position- least protruded
position.(farrar 1970).

70. Dislocation without reduction
• Disc dislocated anteromedially from condyle
does not return to normal position with
condylar movement.
• Macro/ microtrauma most common causes
• Features: limited ROM (25-30mm)- normal
eccentric movement to ipsilateral side &
restricted ecccentric movement to
contralateral side .

71. • Treatment:
1.Anterior positioning appliance contraindicated
2.Manual manipulation for disc recapture.

72. Subluxation
• Also called hypermobility
• Clinical description of condyle as it moves
anterior to crest of articular eminence.
• Cause: result of anatomic form of fossa; steep
short poterior slope of eminence- longer flat
anterior slope.
• Results when disc is maximally rotated on
condyle before full translation.

73. • History- patient reports a locking sensation
when ever mouth is opened too widely.
Sudden jump of condyle forward with a ‘thud’
sensation.
• Treatment – Eminectomy- reducing steepness
of eminence.

75. Spontaneous Dislocation
• Also referred to as open lock; occurs after wide
opening; spontaneous dislocation of both the
condyle and disc.
• History: patient arrives at office with mouth
open unable to close- following yawn or wide
opening;
• Features: patient remains in a wide open
position

76. Condyle in normal position
Condyle after dislocation

77. • Treatment: directed towards increasing the
disc space, allows retrodiscal lamina to retract
disc.
• Also applying slight posterior pressure to chin
while the patient is opening wide; reduces
dislocation

78. Ankylosis
• Abnormal immobility of the joint.
• Two types fibrous and bony
• Fibrous - occurs between
condyle and disc
disc and fossa
• Bony - condyle and fossa.

80. • Cause: most commonly- hemarthrosis
secondary to trauma.
• Fibrous ankylosis- continued progression of
joint adhesions- also chronic inflammation
aggravates the condition.

81. • Features: condyle can still rotate- some degree
of restriction on inferior surface of disc.
• Patient unable to open 25mm interincisally;
lateral movements restricted. Path of opening
toward ipsilateral side
• Treatment: surgery only definitive treatment
in case of loss of function.

82. Clinical criteria for
Temporomandibular disorders:
• Motion:
• Limitation
• Deviation
• Tenderness
• Joint noise:
• Examination :
Listening
Palpation (over the TMJ or inside the auditory canal) or
asking the patient.
• Additional means - chewing a wax or gum.
Noise:
Clicking (Popping)
Crepitus

83. EXTRA-AURICULAR METHOD

84. INTRA-AURICULAR METHOD

85. TEMPORALIS MUSCLE EXAMINATION

86. MASSETER EXAMINATION

87. • Range of motion
• 1- Active Range Of Motion (AROM): It’s the
opening under voluntary effort , it is measured
by the distance between upper central incisors
and lower central incisors.
• Normal…………………>40 mm
• Restricted……………. Male if less than 35
mm. Female if less than 30 mm.
• Excessive……… it should be considered normal
except when there is a history of locking or
there is a pain or discomfort during opening that
interfere with normal function
• 2-Passive Range Of Motion (PROM) : +(2-3mm)

88. • Deviation
• As the both sides are not affected to the
same extend usually deviation occurs toward
the affected side.

89. • Clicking (popping)
• Reproducible:
reproducible opening
or reproducible closing
• Reciprocal: In both
opening and closing
• Repetitive: At exact
same position
• Clicking suggests disc
disorder
• Crepitus
• Fine crepitus: weak
grating sound suggests
mild bone to bone
contact
• Coarse crepitus: strong
grating sound suggests
gross bone on bone
contact.
• Crepitus suggests
degenerative joint
disease

90. Developmental anomalies
• ANOMALIES OF THE MANDIBLE AND THE TMJ;
• Hypoplasia
• Hyperplasia
• Dysplasia / dysmorphia
• Deformation
• Postembryonic anomalies

91. • Micrognathia- describes an abnormally small mandible.
• Many anomalies have this as one of their features.
• Cause: occurs due to deficiency in the amount of available
mesenchyme during the formation; due to earlier
destruction or absence of undifferentiated cells. Deficiency
is always bilateral and symmetrical.
• Many craniofacial anomalies include hypoplasia; normal
but small mandible; often with an abnormality of TMJ.

92. • Hallerman strieff syndrome, Pierre Robin syndrome,
and Treacher Collins syndrome.
• Hallermann Strieff Syndrome: includes a number of
facial defects involving the eyes, nose, maxilla and
mandible giving a distinct facial appearance.
• Features: Small mandible particularly the condyles,
and forward positioning of the condyle out of a
poorly formed fossa is characteristic.
• Positioning partly postural to improve airway;
regularity and symmetry of the condition suggests a
reduction in mesenchyme at an early embryonic
stage.

93. • Pierre robin syndrome; recently referred to as Robin sequence;
Small mandible an essential feature; also one of the causes of
associated cleft palate; more generalised hypoplasia involving facial
and masticatory muscles, maxilla, mandible and palate; thus wide
spread deficiency of mesenchyme.
• Treacher collins syndrome: dysplastic anomalies of eye, zygomatic
arch, temporal bone, ear and mandible; produces a distinct facial
appearance.
• Small mandible including condyle; unusual
TMJ relations; condyle positioned posteriorly
and inferiorly in close relation with the
external auditory canal .
• This may be related to the abnormal muscle
balance in this condition; or anomaly of the
capsule as an unusual discomalleolar ligament.
Treacher collins

94. • Excessive size of the mandible is termed
mandibular prognathism.
• Usual criteria for estimating prognathism is the
amount of anterior protrusion of the chin; length
of the mandible from condyle to symphysis.
• Unilateral hyperplasia is limited to the condyle,
larger than the unaffected side.
• Another form of unilateral hypertrophy is part of
a generalized hemihypertrophy involving many
facial structures and the entire mandible. Tmj on
the affected side is positioned far anterior to the
external auditory canal accounting for midline
deviation.

95. • Dysmorphia- group of anomalies characterized by
partial or complete agenesis or malformation of parts
of the TMJ.
• Agnathia, complete or nearly complete absence of the
mandible and hyoid bone with other branchial arch
defects . Due to failure of neural crest cells to enter
face.
• Orofacial digital syndrome( Type II)- includes absence
of the symphysis(cleft mandible), cleft of lower lip and
macroglosssia, ODS(type I) less sever form.
• Dyspalsias of the TMJ belong to the group of anomalies
most commonly termed hemifacial microsomia(also
termed Lateral facial Dysplasias).
• Features: Complete agenesis of the TMJ, also affects
ramus, condyle, muscle of mastication etc.

96. • Biomechanics of the movement of mandible
takes place with the changes associated with in
the TMJ.
• Usual function never exceeds the integrity or
adaptive limits of the masticatory system.
• Any function which exceeds this limit causes
acute or chronic trauma on the masticatory
system.
Clinical implications

97. • Acute
– Subluxation
– Dislocation
– Trauma
– Displacement of the articular disk
• Chronic
– Bruxism
– Occlusal disharmony
– Intercapsular disorders

98. • Even and simultaneous contacts on all teeth
during centric closure – distributes forces on
all teeth equally.
• During centric closure canine or anterior
guidance is desirable – reduces the ability of
elevator muscles to contract – transfers the
movement onto the anterior teeth – class III
lever system – resulting in anterior teeth
receiving only 1/9th the force.

99. • Anterior guidance needs to be in harmony
with the patient’s neuromuscular envelope of
function.
• The occlusion should have a definite vertical
dimension. Alteration lengthens the
pterygomassetric sling beyond its ability to
adapt causing muscular spasms
• Force management should be considered
while treating mobile teeth.

100. REFERENCES
• Management of temporomandibular disorders and
occlusion: 5th edition; Jeffrey P. Okeson
• Oral Radiology; Principles & interpretation; White &
Pharaoh; 4th Edition.
• Clinical periodontology 10th edition Carranza
• Gray’s anatomy: anatomical basis of clinical practice:
39th edition.
• The anatomical basis of dentistry: Bernard Liebott: 2nd
edition
• Oral histology: Development, structure and function:
Tencate; 5th edition

101. THANK
YOU