tmj ana,phy,dys.pptx

Introduction
• No specialty in dentistry can be effectively
practiced at the highest level of competence
without an understanding of how the teeth
relate to the rest of the masticatory system
including the TMJs
• It is impossible to comprehend the fine points
of occlusion without the depth of awareness
of the anatomy, physiology and biomechanics
of the tempromandibular joint

Temporomandibular Joint
• The temporomandibular joint (TMJ) is a
diarthrodial joint that connects the condyle
of the mandible (lower jaw) to the temporal
bone at the side of a skull. As a modified
hinge joint,
• TMJ enable the jaw to rotate open and
closed, it also enables the jaw to translate
forward and backward. The condyle can
also move laterally and medially.

TEMPOROMANDIBULAR JOINT
(articular disk)
(inferior
joint
cavity)
(superi
or
joint
cavity)
(lateral
disk
ligamen
t)
(capsul
ar
ligamen
t)
(medial
disk
ligament)
(capsular
ligament)
•Ginglymoarthroidal
(Hinging and
gliding).
•Condyle fits into
fossa.
•Articular disc
separates.
•Compound joint.

Articulation
• The condyle articulates with the
temporal bone in the glenoid
fossa. The glenoid fossa is a
concave depression in the
squamous portion of the
temporal bone.
• However, these two bones are
actually separated by an
articular disc, a concept of
structure unknown throughout
the rest of the body.

Components
There are six main components of
the TMJ.
• Mandibular condyles
• Articular surface of the temporal
bone
• Capsule
• Articular disc
• Ligaments
• Lateral pterygoid

Mandibuar fossa
• Oval or oblong depression in the
temporal bone just ant to auditory
cannal
• Shape of the fossa conform some
extend to posterior and superior
surface of the condylar process

9
Mandibular Fossa
• Dense cortical bony surface of
temporal bone Posterior to
articular eminence
• Posterior nonarticular fossa is
formed by tempanic plate
• Thin at the roof of the fossa
and tympanic plate

Classification of articular
eminence shapes:
• Articular eminence morphology
was classified
• into four types, according to
the criteria set by Kurita
• et al.13 (2000):
• (A) box,
• (B) sigmoid,
• (C) flattened,
• (D) deformed
A
B
C D

Mandibular Condyle
• Convex on all bearing surfaces
• Knoblike form is wider lateromedially than
anterioposteriorly
• Condyle is perpendicular to ascending ramus
of the mandible
• The long axis are in lateral plane

Mandibular Condyle
• Modified barrel shape approx.
20 x 10 mm (ML x AP)
• Dense cortical bone covered
with dense fibrous connective
tissue with irregular cartilage
like cell

Capsule
• The capsule is a fibrous membrane that
surrounds the joint and incorporates the
articular eminance. It attaches to the articular
eminance, the articular disc and the neck of
the mandibular condyle.

Articular Capsule
• Ligamentous capsule surrounds the joint
• Attached to the neck of the condyle and around the
border of the articular surface of the temporal bone
• anterolateral aspect of the capsule may thicken form
the Temporomandibular ligament function as stabilising
structure
• The TMJ capsule does not entirely encase the joint. It is
incomplete in the anterior aspect, allowing for condylar
motion in an anterior direction during wider opening
movement and excursive motion

17
Synovial tissue
• Synovial cell and connective tissue
covering the lower and upper-joint spaces
• Synovial fluid, a proteoglycan-hyaluronic
acid complex acts as a lubricant and may
participated in nutritional and metabolic
interchange for central part.

synovial fluid
• Synovial fluid - dialysate of
plasma secreted by synovial
membrane (specialised
connective tissue)
watery lubricant - viscous,
elastic, maintains articular
cartilage cells
few cells - mainly immune
system pH buffer
• Leakage prevented by fibrous
capsule which forms a cuff

19
Articular Disk (Meniscus)
• Biconcave oval structure
interposed between the
condyle and the temporal bone
• 1 mm in the middle and 2-3
mm at periphery
• Dense collagenous connective
tissue
• Centre area is avascular, and
devoid of nerve

Articular Disk (Meniscus)
• Fuse to a strong ligament at
lateral side connect to the neck
of the condyle
• The other borders are attached
to capsule ligaments or synovial
membranes separate between
two joint spaces.

Articular disc
• The anterior portion of the disc splits
coincident with the insertion of the superior
head of the lateral pterygoid.
• The posterior portion also splits and the area
between the split continues posteriorly and is
referred to as the retrodiscal tissue.
• this piece of connective tissue is vascular
and innervated, and in some cases of
anterior disc displacement, the pain felt
during movement of the mandible is due to
the condyle pressing on this area.

Functions as a nonossified bone.
Bulk is dense fibrous tissue.
Three sections:
A. ANTERIOR - thick
B. CENTRAL (intermediate zone) - thin
C. POSTERIOR - thickest
Shape determined by morphology of condyle & fossa.
ARTICULAR
DISC
(Articular Disc)

35
anterior
anterior
capsular
capsular
ligament
ligament
articular
articular
surface
surface
superior
superior
joint
joint
cavity
cavity
superior
superior
retrodiscal
retrodiscal
lamina
lamina
inferior
inferior
joint
joint
cavity
cavity
retrodiscal
retrodiscal
tissue
tissue
inferior
inferior
retrodiscal
retrodiscal
lamina
lamina
anterior
anterior
capsular
capsular
ligament
ligament
inferior
inferior
lateral
lateral
pterygoid
pterygoid
muscles
muscles
superior
superior
lateral
lateral
pterygoid
pterygoid
muscle
muscle
ATTACHMENTS
OF THE
ARTICULAR
DISC
Posterior - retrodiscal tissue
Superior retrodiscal lamina
Inferior retrodiscal lamina
Venous plexus
Capsular ligaments - superior & inferior
Superior lateral pterygoid muscle

TWO CAVITIES:
A. UPPER IS BOUNDED BY MANDIBULAR
FOSSA & DISC.
B. LOWER IS BOUNDED BY CONDYLE &
DISC.
LUBRICATED BY SYNNOVIAL FLUID.
A. BOUNDARY LUBRICATION
B. WEEPING LUBRICATION
ARTICULAR DISC (continued)
TMJ (continued)

Classification of disc
configuration:
• In order to assess disc
configuration,
• the criterion of Murakami et
al.18 (1993)
• (A) biconcave,
• (B)biplanar,
• (C) biconvex,
• (D) hemiconvex,
• (E) folded.
A
B
C
D
E

LIGAMENTS OF
THE TMJ:
1. PROTECT THE STRUCTURES.
2. DO NOT STRETCH.
3. ARE NOT ACTIVE IN JOINT
FUNCTION.
4. LIMIT & RESTRICT BORDER
MOVEMENTS.
FUNCTIONAL LIGAMENTS:
COLLATERAL
CAPSULAR
TM LIGAMANT
ACCESSARY LIGAMENTS:
SPHENOMANDIBULAR
STYLOMANDIBULAR

• There are three ligaments associated with the TMJ: one
major and two minor ligaments.
• The major ligament, the temporomandibular ligament, is
really the thickened lateral portion of the capsule, and it
has two parts: an outer oblique portion (OOP) and an
inner horizontal portion (IHP).
• The minor ligaments, the stylomandibular and
sphenomandibular ligaments are accesory and are not
directly attached to any part of the joint.
– The stylomandibular ligament separates the infratemporal
region (anterior) from the parotid region (posterior), and runs
from the styloid process to the angle of the mandible.
– The sphenomandibular ligament runs from the spine of the
sphenoid bone to the lingula of the mandible.
IHP
OOP

The nerves of the temporomandibular
joint are derived from the
auriculotemporal and masseteric
branches of V3
 INNERVATED BY TRIGEMINAL
NERVE (CN V).
TMJ (continued)

TMJ (continued)
VASCULARIZED BY
Its arterial blood supply is from the
superficial temporal branch of the external
carotid artery
MAJOR:
SUPERFICIAL TEMPORAL
ART.
MIDDLE MENINGEAL ART.
INTERNAL MAXILLARY ART.
MINOR:
DEEP AURICULAR ART.
ANTERIOR TYMPANIC ART.
ASCENDING PHARYNGEAL
ART.

ORIGIN
Upper head: infratemporal surface of sphenoid
bone. Lower head: lateral surface of lateral
pterygoid plate
INSERTION
Pterygoid fovea below condyloid process of
mandible and intra-articular cartilage of
temporomandibular joint
ACTION
Depresses and protracts mandible to open
mouth. Pulls forward cartilage of joint during
opening of mouth. Aids in chewing.
NERVE
Nerves to lateral pterygoid (anterior division of
mandibular nerve (V))
LATERAL PTERYGOID

ORIGIN
Temporal fossa between inferior temporal
line and infratemporal crest
INSERTION
Medial and anterior aspect of coronoid
process of mandible
ACTION
Elevates mandible and posterior fibers
retract
NERVE
Deep temporal branches from anterior
division of mandibular nerve (V)
TEMPORALIS

ORIGIN
Deep head medial side of lateral pterygoid plate
and fossa between medial and lateral plates .
Superficial head : Tuberosity of maxilla and
pyramidal process of palatine bone
INSERTION
Medial aspect of angle of mandible
ACTION
Elevates the mandible and assist in closing the
jaw. Assists the lateral pterygoids in moving the
jaw side-to-side.
NERVE
Nerve to medial pterygoid (main trunk of
mandibular nerve (V))
MEDIAL PTERYGOID

ORIGIN
Anterior two thirds of zygomatic arch and
zygomatic process of maxilla
INSERTION
Lateral surface of angle and lower ramus
of mandible
ACTION
Elevates mandible (enables forced
closure of mouth)
NERVE
Anterior division of mandibular nerve (V)
MASSETER

ORIGIN
Anterior belly: digatric fossa on posterior
surface of symphysis menti. posterior belly:
base of medial aspect of mastoid process
INSERTION
Fibrous loop to lesser cornu of hyoid bone
ACTION
Elevates hyoid bone. Aids swallowing and
depresses mandible
NERVE
Anterior belly: mylohyoid nerve (V). posterior
belly: facial nerve (VII)
DIGASTRIC

ORIGIN
Anterior belly: digastric fossa on posterior
surface of symphysis menti. posterior belly :
base of medial aspect of mastoid process
INSERTION
Fibrous loop to lesser cornu of hyoid bone
ACTION
Elevates hyoid bone: Aids swallowing and
depresses mandible
NERVE
Anterior belly: mylohyoid nerve (V). posterior
belly: facial nerve (VII)
DIGASTRIC (ANTERIOR VIEW))

Non Masticatory Muscle
• Digastric muscle
• Mylohyoid muscle
• Geniohyoid muscle
• Orbicularis Oris

• Articulation and jaw movement
• Mastication, speech, deglutition
• Disc:
1. Stabilization
2. Destabilization
3. Lubrication
4. Nutrition
5. Load dissipation

Understanding condyle-disk alignment
Medial lateral ligaments
Posterior ligament
Superior elastic stratum
Superior lat.pterygoid muscles

How muscle controls disk alignment

Articular disc divides the TMJ
into two distinct compartments.
The inferior compartment allows
for pure rotation of the condylar
head, which corresponds to the
first 20 mm or so of the opening
of the mouth. After the mouth is
open to this extent, the mouth
can no longer open without the
superior compartment of the
TMJ becoming active.

MANDIBULAR FUNCTION
MOVEMENT PATTERN
• Purpose:
• To identify incoordination of craniomandibular
function.
• To determine weakness/inhibition of the
depressors of the mandible.
• To determine if lateral pterygoids, masseters,
temporalis or medial pterygoids are overactive.
• To screen for functional pathology related to
activity limitations with chewing, swallowing,
speaking, respiration, and emotional expression

Centric relation
• The jaw to jaw relationship in which the condyles
articulate with the thinnest avascular portion of their
respective discs with the complex in the anterior superior
position against the slopes of the articular eminences,
regardless of any tooth to tooth relationship.
• This position is clinically discernable when the mandible
is directed superiorly and anteriorly and restricted to a
purely rotary movement about a transverse horizontal
axis.
• In centric relation, the condyle-disc assemblies are
braced medially. Thus, centric relation is also the
midmost position of the mandible.
• If a healthy joint is correctly positioned and aligned in
centric relation, it can resist maximum loading in function
with no sign of tension or tenderness. GPT

• The definition of CR has evolved over the past
half-century from being a posterior and superior
position of the condyle in relation to the glenoid
fossa to an anterior-superior position. Before 1987,
CR was considered a retruded (posterior-superior)
condylar position. The latest edition of the
Glossary of Prosthodontic Terms (GPT) defines
CR as "a maxillomandibular relationship in which
the condyles articulate with the thinnest avascular
portion of their respective disks with the complex
in the anterior-superior position against the slopes
of the articular eminences.”

Understanding Centric relation
• Centric relation is the relationship of the mandible to
the maxilla when the properly aligned condyle-disk
assemblies are in the most superior position against
the eminentaie irrespective of vertical dimension or
tooth position
• At the most superior position,the condyle-disk
assemblies are braced medially,thus centric relation
is also the midmost position
• A properly aligned condyle-disk assembly in centric
relation can resist maximum loading by the elevator
muscles with no sign of discomfort

• To short through the confusion, let’s
dissect the definition of centric relation
and look at it bit by bit in light of what is
known about the anatomy and
biomechanics of mandibular function

The relationship of the mandible to the maxilla
• The casts mounted in centric relation
enable the dentist to accurately determine
the what must be done to bring the teeth
into harmony with correct max-mandi
relationship
• The goal is to achieve maximum
intercuspation without requiring
displacement of the TMJs.With the condylar
axis recorded, all treatment options can be
explored including occlusal
equilibration,orhodontics,restoration,or
surgery

Properly aligned condyle-disk assemblies
• If the disk is not aligned, the
condyle is not in centric
• When the disk and condyle are
properly aligned all the loading
force directed through the
avascular,noninnervated structure
that were designed to accept load

Against eminentiae
Contraction of elevator muscles
which are distal to posterior teeth
and between the teeth and
TMJ,keep the condyle-disk
assemblies loaded throughout
the functional movements,
condyle will be pulled tightly
against eminentiae.

Irrespective of tooth position and vertical
dimension
Rotates on fixed point when aligned with the rotational center
of the condylar axis at the medial poles
Condyle can rotate on a
Fixed axis to an opening
of about 20mm

Most superior position
There are many important facets to this
Understanding and every one has high
clinical value
? uppermost postion
? unloading the joints
? decompress
? support

Medial pole bracing in line with
internal Pterygoid muscle
contraction establishes the
midmost position at centric relation
Midmost position
This medial pole stop also prevents the
lower posterior teeth from moving horizontally
towards the midline, an essential anatomic design
That makes a normal curve of occlusion possible.
It also explain why an immediate side shit is not
possible from the fully seated position of the condyles
in centric relation

Internal pterygoid muscle contraction
establishs the medial position at
centric relation
The axial alignment of all posterior
teeth is nearly parallel with strong
inward pull of the internal pterygoid
muscles.

• The purpose of the lateral pterygoids is to work
together to pull the mandible forward
("advance" it), and to translate the condyles (open
the mouth).
(Although one lateral pterygoid can contract without
the other, the result is a swinging of the mandible to
the opposite side, and serves no functional purpose.)
• The lateral pterygoid muscles are always involved in
any deviation from centric relation
Mao et al found that a significient proportion of
fibres within the lat.pterygoid are predominatly
anarobic and are fast acting and fatigue-
susceptable.The fatigue-susceptible
characteristics of these fibres involve
in muscle discomfort from burxing and clenching
The inferior lat. Pterygoid muscle was implicated
in the development of isometric horizontal forces
toward the end of the intercuspal phase of chewing
cycle

The medial poles of the condyles are the only rotation
points that would permit a fixed axis of rotation because
the condyles are not parallel to the horizontal axis.
Rotation around fixed angle is probable because
the angulation of the condyle in relation to the
horizontal axis 90º angulation with plane of the
ramus that place their alignment at an abtuse
angle each other. Medial pole is the only logical
common rotation point that permit a true rotation
to occur on a fixed axis
The extremly important signifigantce of TMJ socket
Design
The term centric is an adjective that mean centered
The medial poles are centered in the middle of the
Medial third of the fossae which stops condyles
Upward movement on heavily buttressed bony point
FIXED AXIS

The purpose of lateral pole translation during
Condylar rotation is to provide a sort of
windshield wiper effect spreading synovial fluid
back and forth over the entire surface
Irregularites in the surface of the condyle aid
the flow of synovial Fluid by providing
indentation for the fluid to travel in

MANDIBULAR POSTURAL REST
POSITION (MPRP)
• The normal MPRP is in equilibrium between the
downward pull of gravity and the myotatic reflex
contraction of the mandibular elevators. MPRP
depends on muscle tonus of the anterior and
posterior cervical muscles, head posture, and the
inherent elasticity of muscles.
• Significance of MPRP is that, under normal
conditions, it is a time for rest and repair of the
TMJ system.

Review of TMJ Normal Function.
A) The movement of the condyle and disc occurs together.
B) The unfolding of the the Retrodiscal lamina.
C) At maximum opening the position of the condyle to the
eminence.
A B C

Major function of the
Masticatary system
1. Mastication
2. Swallowing
3. Speech
Secondary function
Respration & expression of emotions
Occlusion plays important role in function of
the masticatory system

Mastication
• Defined as the act of chewing foods
• It is complex function that uses the muscles,teeth,and
periodontal supportive structures, as well as the
lips,checks,tongue,plate,and salivary glands
• It is a functional activity
• During function (chewing), there is no purpose in
the attempt to translate the condyle.

• In normal chewing function, the mandible opens,
and then, while initiating closing, there is a shift
slightly to the side of the bolus, due to
the orientation of the masseter and medial
pterygoid. There is no "canine rise" during
normal chewing fucntion. Canine rise is
mechanism to combat parafunction.
(From Lindeen and Gibbs: Advances in occlusion, Boston, 1982, John Wright PSG, p.19)

The moving yellow dot in the jaw
tracing to the left shows the tracking
of the gingival margin of a lower
incisor during the left "working"
movement of chewing. The red
lines are jaw movements with the
teeth in contact (excursive grinding
to each side). The outter most line
is the envelop of maximum
movements.
(From Lindeen and Gibbs: Advances in occlusion, Boston, 1982, John Wright PSG, p.19)

The animation to the right
demonstrate how the condyle
immediately translates upon
opening during masticatory
function, due to the contraction
of the lateral pterygoid. As
closing ensues, the LPs relax,
and the elevators contract. The
tension of the posterior segment
of the temporalis "un-translates"
the condyle. During last portion
of closing, the anterior
temporalis and masseters brace
the condyles against the
eminance (seating to "CR"),
referred to as "rotation".

Swallowing
• Swallowing is series of coordinated muscular contraction that moves
a bolus of food from the oral cavity through the esophagus to the
stomach
• In normal adult swallow the mandible is stabilized by tooth
contacts.the swallowing last for 683sec.
• The force applied during swallowing appx.66.5pounds that is
7.8pounds more than force applied during mastication
• The mandible is braced,it thought to a somewhat posterior or retruded
position

Speech
• It occurs when volume of air is
forced from the lungs by the
diaphragm through the larynx
and oral cavity

Normal unilateral activity and effect
of a Lateral Pterygoid muscle
• Although Lateral Pterygoids are
intended to work together to depress
the mandible, a voluntary unilateral
activity results in an excursive
movement to the contralateral side.
• In the example to the right, the
contraction of the left inferior belly of
the LP advances/translates its
condyle and then pulls it still further
medially. Following the cessation of
its contraction, the reciprocal activity
of the temporalis' then elevate the
mandible (the superior belly of the
LP contracts simultaneously with the
temporalis, thought to thereby
stabilize the disc assembly).

Parafunctional Clenching Potential
of the Temporalis
• Following the translation(s) of the
condyle(s), the temporalis' role is to
elevate the mandible, with the intent
of grasping/biting the object/food
that has been positioned between
the teeth. The occluding of the
teeth is the LPs signal to re-open
the mandible. However, in the
event the temporalis contraction(s)
persist, re-opening may not be
possible, depending on the intensity
of the continuing temporalis
activity.

Coordinated muscle function
at maximum intercuspation
Disharmony between the
Occlusion and the TMJs
Incoordinated muscle
function
during jaw opening
during jaw closing

This is the scenario that always present in
Occluso-muscle pain …
the most common type of TMD

Occlusal interferences that require displacement of the
TMJs to achieve maximum intercuspation of the teeth
can cause in coordination of all the masticatory
Neuromusclature.
This called occluso-muscle pain, so called TMJ pain

Fulcrum:The pressure point of support
on which lever rotates
Force: exertion of power that starts
or stops movement
Loading: the pressure structure bears
from a compressive force
Tension: a pulling force against resistance
Distortion: Distortion or change of shape
as a result of compressive or tensive force
Important terms to understand as they relate to muscle

Normal function versus
Parafunction
• Normal reciprocal functioning of the Lateral Pterygoids and
Masseters/Med.Pteygoids/Temporalis'.
• The Lateral Pterygoids advance the condyles, thereby opening
the mouth (depressing the mandible), with the assistance of the
Digastric
• The oblique orientation of the Masseters and Medial Pterygoids
create a sling. The non-working side Medial Pterygoid contacts
simultaneously with the opposide side working Masseter.
• This oblique orientation of the Med.Pterygoids and Masseters that
create the functional "shift" of the mandible, not an unilateral
contraction of a Lateral Pterygoid.

• The degree of frequency, duration
and intensity of the contractions of
a Lateral Pterygoid is a function of
the resistance provided by the
parafunction ipsilateral and/or
contralateral Temporalis. For
example, in the animation to the
left, as a Lateral Pterygoid
attempts to translate its condyle, it
is met with resistance provided by
the contralateral Temporalis,
thereby causing the Lateral
Pterygoid to pull its condyle in a
medial direction toward the
contralateral contact.
Protusive Clenching"
depicting the progression of bruxism

IMPORTANCE OF OCCLUSAL HARMONY
• THE CLOSING MUSCLES PULL THE CONDYLE disk
assembly up until it is stopped by bone at the medial pole.
• The lateral pterygoid muscles are capable of holding the
condyles during protrusive function but in the presence of an
occusal interference they can never be relived of this function.
• The mechanoreceptor system is designed like a glove of
periodontal receptors capable of evaluating the direction and
intensity of stresses on the teeth and designed to program the
lateral ptergoid muscles to position the jaw so that the
elevator muscles can close directly into maximum occlusal
contact.
• The lateral pterygoid muscles are always involved in any
deviation from centric relation.
• The muscles can not relax the protective bracing contraction
as long as the occusal interference is present.

Disorder of the muscles of
mastication, the TMJ and
associated structures

The TMJ Controversies
Burt Reynolds‘ illustrates the two kinds of
controversy surrounding TMJ:
its symptoms can be confused with a lot of other
illnesses, and its cure is far from agreed upon. The
reason for the difficulty diagnosing TMJ disorders
is that pain in one part of your body can be
referred to other parts through the connecting
nerves and muscles.
The reason why the treatment of TMJ disorders is
controversial is that the causes are still not fully
understood.

• Temporomandibular disorders (TMD) is a
collective term embracing all the problems
relating to the TMJ and related musculoskeletal
structures
• Internal Derangement(ID) / OA(osteoarthritis) is
considered to be the most common cause of
serious TMJ pain and dysfunction and therefore
the most likely to be treated surgically.

• In dysfunctional joints, non-symmetrical
movement or loss of range of motion may be
displayed due muscular imbalance or to a
derangement of one or both discs. If the disc
has become displaced anteriorly or torsioned
on the condyle, the patient may experience a
popping or clicking sound or jerking or
zigzag movement when opening or closing.
Range of motion may be reduce significantly
and pain may or may not accompany the
symptoms. The disc may also be completely
or partially destroyed or the condylar head
may be eroded by osteoarthritis.

Causative Factors of TMJ
Dysfunction
• Some of the most common factors include:
• ❑ Intra joint dysfunction - adhesions, scarring, displacement
• or destruction of disc(s), arthrosis, deposition of calcium
• ❑ Musculoskeletal - hypertonic muscles, referred pain from
• trigger points, postural distortions, skeletal misalignments
• ❑ Occlusal factors - loss of vertical dimension, premature
• contacts, other malocclusal conditions
• ❑ Psychological - stress load, emotional distress, depression,
• neurosis
• ❑ Biochemical - hormonal, neurostimulants, allergies/food
• sensitivities (both known and hidden), chemical exposures,
• drugs (prescription, recreational), mineral and
• vitamin deficiencies, biochemical imbalances or toxicity

TMD pain or Dysfunction can be
separated into three broad categories
I. Masticatory muscles disorders
II. Structural intercapsular
disorders
III. Condition that mimic TMDs

Occluso-muscle disorder
• Discomfort or dysfunction resulting from
hyperactive, incordinated muscle function
that is triggered by deflective occlusal
interferences to physiologic jaw
movements and noxious habits.

• Determine the healthy TMJs
• Occluso-muscle pain relationship
• Occlusal contact-condyle position

Muscles
Deformation at weakest link(s)
Muscles
Signs
•Reduced ROM
•Deviation POM
•Tender to palpation
•Hypertrophy
•incoordination
Sympt
oms
•Pain
•hyperactivity
•Headaches
Signs
•Disk derangement
•Click
•Structural deformation
Symp
toms
•Pain
•Discomfort
Signs
•Occlusaldisease
•Hypermobility
•Excessive wear
•Tooth migration
•Abfraction
•Cusp fracture
Sympt
oms
•Hypersensitivity
•Pain on biting
Joints
Bite/ teeth
Tension
compression
Centric relation mechanoreception
CNS

How to determine healthy TMJs
• Screening history
• Load test
• Range and path of movement tests
• Dopller analysis
• Radiography / imaging
• Anterior bite place for muscle
deprogramming

MASTICATORY MUSCLE RESPONSE
Internal pterygoid
• It has a direct correlation with the direction of displacement of the
same side condyle
Masseter muscle
• Tenderness and restricted inopening in the morning are almost
certain indications of nighttime bruxing
Temporalis muscle
• A source of sharp pain behind the eye
• Temporal headache,pain
Inferior lat. Pterygoid
• Any deflective occlusal incline that requires displacement of the
condyle to achieve maximum intercuspation is a direct causative
factor in lateral pterygoid hyperactivity and tenderness
Superior lat.Pterygoid
• This is the muscle responsible for keeping the disk aligned during
function
• A reciprocal click is indicative of hyperactivity spasm of this muscle.

• Hyoid area
• SCM(sternocleiodomastoid
muscle)
• Occipital area
• Trapezius muscle

Nocturnal parafunctional activities
• These occur at night when the patient is sleeping and
seem to occur as single episodes (clenching) and
rhythmic contractions (bruxing).
• Bruxism seems to occur during the transition from
lighter to deeper sleep.
• The individual seems to exert as much as 60% of his
maximum biting force during these bruxing events and
this is a significant amount of force.
• Also, the forces, which occur during functional activity,
are parallel to the long axis of the teeth, which are well
tolerated, but the forces applied during non-functional
movement are in horizontal directions which are
deleterious to the periodontium.

• Bruxism can not be casually described as "hyperactivity of the
lateral pterygoid". Each of the graphics below displays identical
degreess of LP "hyperactivity":
• Only the graphic to the far left can be considered to NOT be
bruxism, although there IS hyperactivity of the LPs. The
definitive component of bruxism is the degree of parafunctional
elevation, that is, the clenching component. An accurated
definition of bruxism is: Jaw clenching, with or without
forcible excursive movements, where the intensity of the
clenching dictates the severity (or lack of) grinding (neither
the graphic at the far left or the far right would display tooth
wear, yet the graphic at the far right is the most extreme form of
bruxism).

• Functional forces occur near the centric position,
which is musculoskeletal stable position whereas
parafunctional activity occurs at eccentric positions,
which place more strain on the masticatory system.
• Parafunctional activities cause sustained contraction
of the muscle, which inhibits normal blood flow and
ischemia, fatigue and pain in the muscle.
• Protective reflexes, which are present during
functional activities, seem to be absent during
parafunctional activities.
• Therefore, this is more likely to cause breakdown of
the masticatory system and TMDs than functional
activities.

Cause of bruxing events
• It was earlier believed that occlusal
interferences were the main cause of bruxism
but new studies, show that this is not so.
• Instead, the factor that seems to have definite
effect of bruxism seems to be emotional
stress. It has been observed that in people
who encounter a stressful event, the
nocturnal masseter activity increases.

Boyd Classification of Parafunction
Primary Clenching
Unilateral Post. Resistance
Contralateral joint strain/load
Unilateral Post. Resistance
Ipsilateraljoint strain/load

Boyd Classification of Parafunction
Unilateral Canine Clenching/Resistance
Contralateral joint strain/load
Protrusive IncisalResistance

Masticatory muscle hyperactivity in
temporomandibular disorders: is it an extrapyramidally
expressed disorder?
• Masticatory muscle hyperactivity appears to have an
important role in temporomandibular disorders. A
pathophysiological model for masticatory muscle
hyperactivity is proposed that is centrally mediated, yet
maintains support for present peripheral causes and
therapies.
• In this hypothesis, masticatory muscle hyperactivity
represents a mild extrapyramidal disorder distantly
related to orofacial dyskinesias.
• Experimental evidence suggests a neurotransmitter
imbalance in the basal ganglia, involving dopaminergic
preponderance, or cholinergic and GABA-nergic
hypofunction as the underlying cause.

STAGES OF INTERCAPSULAR DISORDER
• Alignment of the disk
• Cause of derangement
• Condition of the disk and its attachments
• Condition of bony structures
• Level of discomfort and dysfunction
• Potential for further pathosis and its
consequences
• Potential for correction of the problem
through adaptive changes

• The seven structural elements are
• Disk alignment
• Disk shape
• Ligament
• Joint shape
• Muscle
• Bone surfaces
• Pain

• Neither the joint nor the occlusion is correctly
related, so both must be reoriented to achieve the
necessary harmony in the system.
• The stages of disk derangement usually occur in a
fairly consistent sequence that starts with a
beginning partial derangement at the lateral
pole.
• From this stage it is progressive and the degree
of damage in the joint is related to time and the
intensive of load that the deranged joint must bear
because of incoordinated muscle
hypercontraction.

• The disk becomes misaligned in stages, the
stages result from forces that progressively stretch
or tear the ligaments that binds the disk to the
condyle.
• In coordinated muscle maintains the contacted
force against the joint for prolonged periods of
time through clenching or bruxing.
• Prolonged loading that caused the adaptive
changes to occur in both the hard and soft tissue
• most derangements start at the lateral pole.

In a deformed TMJ the type and degree of adaption must be
determined before addressing the relationship between the
occlusion and the TMJ
ACP Is the manageably stable relationship of the mandible
to the maxilla that is achived when deformed
TMJs have adopted to a degree that can comfortably
Accept firm loading when completely
seated at most superior position against the eminentiae
ADAPTED CENTRIC POSTURE

Intercapsular disorders of the TMJs
• Any disease,deformation
or disorder that involves
the tissues within the
capsule of the TMJ
One of the three things must occur to allow the disk
displacement:
1. Stretched
2. Torn
3. migrate

BEGINNING OF LATERAL POLE
DEARANGEMENT
The earliest stage of disk derangement starts with
slight anterior derangement of the lateral part of the
disk
A lateral blow to the mandible can traumatize the
lateral pole on the opposite side injuring.

LATERAL POLE DEARANGEMENT cont,
Passible casues
1. Muscle incoordination
2. Distalization of the working side condyle in lat excursions
3. Distalization of the condyle during max.intercuspation
4. Trauma
5. Heavy bruxing or clenching
signs and symptoms
1. Loud,staccato click or pop when chewing
2. Muscle pain
3. Tooth wear instability or sensivity
4. lat pole displacement can’t occur without help from incoordinated
muscles contraction

Complete anterior disc displacement
• Disc completely displaced forward of the
condyle
Cause
• Progressive stage of derangement
• Sudden accidental injury
• Suddenly by yawn or routine dental
procedure
• Reduce resistance to muscle hyper
contraction
• Hormonal imbalance, emotional stress,
allergies and reaction to drugs or chemicals

Medial pole displacement
Disc displaced medially on medial pole
Cause
Reciprocal click
click,creptius on rotation and translation
If the disk displaces medially there is an
increased potential for avascluar necrosis,

Posterior disc displacement
Posterior disc displacement of the TMJ is rare but
has probably been overlooked in the past because of
a lack of well-defined imaging characteristics
Usually no noise
- Can't close fully
- Teeth don't meet in posterior
- May "lock" half open
- Painful to open and close fully

Classification of Intercapsular
Disorders
PIPER’S CLASSIFICATION

CLASSIFICATION IF INTRACAPSULAR
DISORDER
• Stage I – structurally intact TMJ
• DIAGNOSIS
• History of click negative
• Load testing negative
• Doppler negative
• Imaging Normal
• Range and path of motion Normal
• MUSCLE PALPATION:- THE MEDIAL
PTERYGOID muscle will almost always be tender
to some degree when palpated if the same side
condyle has to displace from centric relation in
order to achieve maximum intercuspation
• DISTINGUISHING CHARACTERISTICS OF
STAGE 1. No laxity of ligaments and no
alteration of bone surfaces therefore the disk
can not displace so in patients who do not have
retrodiskal edema form trauma the treatment is
focused on eliminating the causes of
masticatory muscle of any deflective inclines
that can activate the lateral pterygoid muscle.

STAGE ii – INTERMITTEN CLICK
• This stage is characterized by
beginning laxity of the lateral diskal
ligament in combination with lateral
pterygoid muscle hyperactivity . disk
replacement is reversible if muscle
coordination is re-established
• DIAGNOSIS
• History of click intermitten
• Load testing negative
• Doppler possible mild crepitus
on translation only
• Imaging Normal
• Range and path of motion Variable
• Pain Source Muscle

STAGE III a – LATERAL POLE CLICK
• DIAGNOSIS
• History of click Yes (reciprocal)
• Load testing negative if muscle contraction is
released,
• Doppler quite on rotation click crepitus on
translation
• Imaging (transcranial) Normal
• Range and path of motion Variable
• Pain Source Muscle
• A sure sign of muscle tension in the disk and elongation
of the posterior ligament at the lateral pole.Occlusal
correction usually effecting in stopping the click in most
III a disk derangements. Since there are patients often
have also other sign and symptoms including muscle
pain and/or sign of tooth wear instability or sensitivity a
careful examination of all masticatory. System
structures is in order. While some of these patients may
go for years without progressive damage of the TMJ
.many go on to closed locks and an escalation of
symptoms.

STAGE III b – LATERAL-POLE LOCK
DIAGNOSIS
• History of click had a click that disappear
• Load testing negative when condyles are
completely seated
• Doppler quite on rotation click and
crepitus on translation
• Imaging (transcranial) Normal
• MRI Disk displaced off lateral pole
only
• Range and path of motion may vary from normal to
abnormal of opening
• Pain Source Mostly Muscle,some retrodiskal
compression Possible
IMPLICATION
• Occlusal muscle pain can still be treated successfully.this is
the last stage of disk dearangement that is treatable with
fairly predictable long term stability of the TMJs. If the
occlusion is perfected while the disk still covers the medial
pole and adapted centric posture can be verified, we have
seen almost no progression to stage IV . at this stage
surgery(including arthoscopy) is not needed.

STAGE IV a – Medial pole clik
DIAGNOSIS
• History of click Reciprocal Clik
• Load testing Pain if not reduced,if reduced, can
accept loading
• Doppler Click, crepitus on rotation and
translation
• Imaging (transcranial) Normal if disk is reduced,space
closed if disk displaced
• Range and path of motion Variable from normal to restricted
and deviated
Pain Source compression of retrodiskal tissue,
muscle pain
IMPLICATIONS
• This stage is almost always progressive if not treated. Since
the disk is still reducible on the medial pole, occlusal correction
is sometimes all that is needed to prevent incoordinated muscle
contraction(superior lateral pterygoid) from displacing the disk .
if the shape of the disk is not too badly deformed yet, an
acceptable result can often be achieve.
• The key to conservative treatment hinges on whether adapted
centric posture can be determined and then maintained . a full
occlusal splint, permissive to ACP, may be effective.
• MRI may be justified as a diagnostic step for this stage of
intracapsular deformation.

STAGE IV b – MEDIAL-POLE LOCK
DIAGNOSIS
• History of click Had click that disappeared
• Noise may be none present
• Load testing Tender to gentle loading in early stages
• Doppler crepitus on all movements
• Imaging (transcranial) space closed above and behind condyle
• MRI disk displaced off both poles
• Pain Source compression of retrodiskal tissue, muscle pain
IMPLICATIONS
• At this stage,it is very doubtful that the disk can be re captured and maintained
on the medial pole. Progression is a certainty that typically leads to painful
loading of the retrodiskal tissue , perforation, osseous changes – loss of condyle
height – excessive posterior tooth wear. If the disk displaces medially there ia an
increased potential for avascluar necrosis, thus an MRI analysis and surgical
consultation are indicated.conservative splint therapy may lead to pseudodisk
formation and improvement of symptoms, but care in diagnosis is particularly
important at this stage.

Symptom Condition
Headaches Sinusitis
Temporal arteritis
Tension, migraine, and cluster headaches
Pain Postherpetic neuralgia
Reflex sympathetic dystrophy or traumatic
neuroma after head or neck surgery
Toothache
Trigeminal neuralgia
Pain accompanied by hearing problems Obstruction of the ear canals or eustachian
tube
Otitis media
Pain in the head, neck, and other areas of the
body
Pain, numbness
Fibromyalgia
Generalized myofascial pain
Intracranial aneurysm
Metastatic tumors
Pain that radiates to the temporomandibular joint
region
Whiplash injuries affecting muscle or
cervical spine
Pain that worsens when the patient swallows or
turns the head
Cervical spine or muscle disorders
Eagle syndrome (calcified styloid process)
Glossopharyngeal neuralgia
Subacute thyroiditis
Trismus Depressed fracture of the zygomatic arch
Infection
Osteochondroma of the coronoid process
Pericoronitis

Predisposing factors for TMD
• Gender
• Age
• Posture
• Occlusion
• Sleeping disorders

Major Categories of TMDS
• Muscle Disorders
• Muscle pain
• Protective muscle splinting (trismus, bracing,
guarding)
• Myospasm
• Myositis
• Myofascial pain (trigger point activity)
• Contracture
• Hypertrophy
• Dyskinesia (muscle incoordination)
• Dstonia
• Bruxism

Temporomandibular joint disorders
• Disc displacement or internal derangement
• Arthralgia
• Capsulitis or synovitis
• Arthritis disease (systemic)
• Degenerative disease (osteoarthritis)
• Traumatic articular disease (sprain or strain, fracture)
• Disc displacement without reduction (closed lock)
• Disc displacement with reduction
• Subluxation of the condyle
• Dislocation of the condyle

• Inflammatory disorders
• Continuous pain that is increased with
function

• Disorders of mandibular mobility
(hyper- or hypo-mobility)
• Hypermobility
• Adhesion
• Ankylosis
• Coronoid process elongation
• Fibrosis of muscle (contracture)

• Growth disorders
• Hypoplasias
• Hyperplasias
• Neoplasias

TM CLINICAL EXAMINATION
1. History
2. ROM
3. Mandibular tracking
4. Auscultation
5. Palpation
6. Provocations (joint/muscle
challenges)

A large majority of the population report joint
sounds in the TMJ; however, it is of greater
concern when it is symptomatic or painful.
Temporomandibular joint tenderness is
evaluated by palpation of the pre-auricular
and intra-auricular spaces

• After TMJ evaluation, the muscles of
mastication and associated cervical
muscles are examined for tenderness
Extraoral examination of the temporalis
muscle.
Intra-orally, the temporalis insertion,
masseter origin, lateral and medial
pterygoids are evaluated bilaterally. In
order to palpate the temporalis insertion,
the patient opens the mouth and a
finger is placed on the anterior border of
the ramus of the mandible (just lateral
and distal to the third molar area). The
finger is then moved superiorly until the
most superior portion of the anterior
border of the ramus is palpated. This is
the coronoid process where the
temporalis muscle insertion exists.

Extraoral examination of the masseter muscle
In addition, the masseter origin can be
palpated by next moving the finger from the
lateral pterygoid position in an anterior and
superior direction. The masseter originates
as a thick tendon from the zygomatic process
of the maxilla and from the inferior border of
the zygomatic arch.

• Immediately after palpating the temporalis insertion with
the finger in the same location, the patient is asked to
move the mandible to the ipsilateral side. After the
patient moves the mandible laterally, the finger is moved
just lateral and superior-distally, and the lateral pterygoid
muscle can be palpated

• The medial pterygoid muscle is
palpated by having the patient open
the mouth, and the examiner places
finger pressure in the posterior, floor
of the mouth (lateral to the tongue and
medial to the mandibular posterior
teeth). Intra-oral palpation of the
lateral and medial pterygoid muscles
is difficult due to limited access.
Tenderness elicited with these two
specific muscle groups should be
interpreted with caution, as an
unacceptable rate of false positives
can occur.

• TMJ Doppler
• Doppler auscultation is a valuable adjunct
to clinical and radiographic assessment of
TMJ disorders in our office. Listening
carefully to the joint sounds provided by
the DOPPLER yields highly reliable
information about the status of the
condyle-disc assembly (jaw joint).

Different modalities for TMJ disorder
evaluation
• Magnetic resonance imaging (MRI)
• TMJ arthroscopy
• In panoramic imaging
• Tomography
• computed tomography (CT)
• Cone Beam Computed Tomography (CBCT).

PANORAMIC RADIOGRAPHY
(OPG)
• Used to detect gross osseous abnormalities and
dental disease.
• Limited value for diagnosis of specific conditions
causing temporomandibular joint dysfunction
• because mild degenerative disease is seen
equally in symptomatic and asymptomatic people.
• Not recommended as a routine investigation in all
patients who present with TMJ symptoms.
• Only patients with clinical evidence of significant
TMJ disease or a lack of response to
• conservative management should have an OPG.

MAGNETIC RESONANCE
IMAGING
• Largely replaced orthography as the imaging modality used to
assess the location and morphology of the intra-articular disc.
• Superior to radiography and computed tomography for soft tissue
definition, and considered the modality of choice for assessing both
soft and hard tissues of the TMJ.
• MRI can detect anterior displacement of the intra-articular disc with
a sensitivity and specificity of 86% and 63% respectively. For
sideways and rotational disc displacement the sensitivity and
specificity is 81% and 87% respectively
• Most studies are limited because surgery is not optimal as a gold
standard due to the small surgical incision, and difficulties in
observing medial and lateral disc displacement. A study of the
accuracy of MRI for TMJ autopsy specimens revealed an accuracy
of 95% for disc morphology and position, and 93% for osseous
conditions.

COMPUTED TOMOGRAPHY
• Limited accuracy to detect intra-articular disc
morphology and position, however studies using multi-
detector CT have not been published.
• For anterior displacement of the intra-articular disc CT
has a sensitivity and specificity of 66% and 68%
respectively. For sideways and rotational disc
displacement the sensitivity and specificity is 64% and
83% respectively.
• Not recommended as a first line investigation for TMJ
disorders.
• Good accuracy for diagnosing osseous abnormalities,
including advanced degenerative joint disease and
ankylosis.

Current Thoughts on TMJ and Its Relationship
to Grinding and Clenching of the Teeth
• TMJ Disorder is a complex abnormality
involving disk displacement and deformity,
inflammation, alteration of the synovial fluid,
degenerative changes in the articular
surfaces, and arthritis.
• Sleeping abnormalities such as clenching
and grinding of the teeth results in adverse
escessive loading of the TMJ causing
breakdown of the lubrication system resulting
in degenerative changes in the articular
surfaces and disk displacement.

General Signs & Symptoms of
TMD
• Pain on opening
• Trismus (limitation of mouth
opening) or deviated jaw
mobility
• Joint noises (clicking, popping,
grinding)
• Pain on chewing
• Tenderness or pain felt in the
jaw joint or muscles, or both
• Pain felt in the area of the ear,
temples, or cheeks

General Signs & Symptoms of TMD,
con’t
• Ear “fullness”
• Subjective hearing loss
• Change in occlusion
• Abnormal wear of the teeth
• Headache (most common
presentation are frontotemporal &
suboccipital)
• Muscle hypertonicity
• Hypertrophy of the jaw muscles

General Signs & Symptoms of TMD,
con’t
• Tinnitis
• Dizziness
• Neck pain
• Upper trapezial pain
• Upper extremity pain & paresthesia
• Difficulty swallowing

Treatment of TMD
•Bruxing guard
•Bite adjusted (deprogrammed) bruxing guard
•Prosthetic solution (crowns and bridges)
•Orthodontic solution (braces)
•The use of drugs in TMJ
•The all natural cures
•The treatment of severe TMJ and internal joint
deterioration
•Arthroscopy
•Open surgical procedures
•Implants and joint replacement
•Images showing results of whole joint replacement
surgery

• Reassurance
• Once the specialist has explained the nature of the condition and the
symptoms usually resolve after a period of time, many patients do not
seek further treatment.
• Soft diet and limitation of mouth opening
• This allows the muscles to recover from their period of overactivity.
• Jaw exercises
• These are designed to reprogramme the chewing muscles.
• Bite raising appliances
• These are similar to sports mouthguards. They are worn over the
teeth to provide a cushion which in turn reduces muscle activity and
muscle spasm. It can also help to move a displaced disc back into
position.

Occlusal Splints
Types of Occlusal Splints:
Permissive occlusal splints
Directive Occlusal splints

Permissive occlusal splints
• Have smooth surface on one side that
allows the muscles to move the mandible
without interference from deflective tools
inclines so the condyle can slide back and
up the eminance to complete seating in
CR

Directive Occlusal splints
• Direct the lower arch into a specific
occlusal relationship that in turn directs the
condyle to predetermined position.
• Very limited use only for specific condition
involving intercapsular TMDs

B (Bruxism) Splints
• The B Splint is useful for rapid
harmonization of occluso-muscle
disorders. Its effectiveness is due to
decreased muscle activity of the Lateral
Pterygoids, Medial Pterygoids, Masseters,
and Temporalis muscles created by
malocclusion and/or parafunction
(bruxism). Clinical EMG studies
consistently show up to an 80% reduction
in elevator muscle activity due to clenching

Anterior deprogramming splints

The basic principle behind the
NTI-tss
When considering an abnormal Trigeminal system
where the Sensory Nucleus is hypersensitive, it is not
unusual for the Motor Division to be also hyperactive.
A hyperactive Trigeminal Motor Root results in
excessive jaw muscle contraction, during certain
stages of sleep, resulting in intense jaw clenching
and/or vigorous teeth grinding.
These two activities produce a significant
bombardment of noxious input (nociception) to the
Sensory Nucleus, while also being the known cause of
"TMD" (temporomandibular disorders), thereby
becoming a self-perpetuation of chronic headache
and/or migraine

• "NTI" refers to the nocturnal inhibition of trigeminal
nociception.
In order for jaw clenching and teeth grinding to achieve
pathologic intensity, the molars and/or canine teeth must be
touching each other, or another object (like a traditional
mouthpiece).
By keeping the molars and canines from touching anything
during sleep, Nociception to the Trigeminal is Inhibited.
Minimizing jaw muscle intensity (that is, Trigeminal Motor
Hyperactvity and the resultant nociception) therefore requires
providing for incisor (front teeth) contact only during sleep.

• The most distinguishing characteristic of the NTI
device is the discluding element, or "DE", which
creates the exclusive contact between the
incisors. In addition to preventing any molar or
canine contact during sleep, the practitioner must
also ensure that the device's design does not
overly "open" the patient's mouth. Excessive
opening while the patient is clenching on an object
can create a strain of the TMJ (jaw joint), which
would result in another noxious sensory input,
thereby defeating the purpose of the NTI device.

• Medication
• These are many and varied and may help symptoms
by providing pain relief and muscle Relaxation
• Physiotherapy
• Ultrasound and deep heat treatments may relieve
symptoms.
• Surgery
• Although rarely necessary for TMJ dysfunction, a
closer and more detailed look at the joint using an
arthroscope (camera put into the joint) may be
necessary. If all else fails open surgery of the joint
may be indicated.

• Jaw Exercises
• There are two main
exercises which may be
useful.
• a.Range of Movement,
• b.Progressive Resisted
Range of Motion
• It is important to warm up
your facial muscles for a
few minutes with a hot
water bottle before
starting your exercises.
Opening Lateral Deviation
Protrusion / Retrusion
Lateral Deviation

Summary
• Remember!
• TMJ dysfunction is not a disease, but a temporary
malfunction of the jaw joint and its muscles.
• Many patients get better without medical treatment.
• Almost all remaining patients get better with simple
non-surgical methods of treatment.
• It is common for patients to present to their family
dentist with facial pain that requires evaluation for a
possible TMD. It is important for dentist to have
current knowledge of temporomandibular disorders
and be able to perform a basic assessment of
patients presenting with possible TMD for proper
treatment and / or referral.

Reference
• Temporomandibular disorder – a practioner guide ;Anni
kaisberg
• Management of Tempromandibular dysfunction and
Occlusion – Jeffrey P Okeson
• Functional Occlusion From TMJ
• To Smile design – Peter E.Dawson,DDS
• Ash and Ramfjord. Occlusion 4th edition. W.B. Saunders
Company, 1995
• Mohl, Zarb, Carlsson and Rugh. A textbook of Occlusion.
Quintessence Publishing Co., 1998
• Sicher and DuBrul. Oral Anatomy 6th edition. The C.V.
Mosby company, 1975
• Kraus, Jordan and Abrams. Dental anatomy and
Occlusion. The Williams and Wilkins company, 1969

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