TEMPOROMANDIBULAR JOINT
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CONTENTS EVOLUTION DEVELOPMENT ANATOMY PHYSIOLOGY BIOMECHANICS www.indiandentalacademy.com
BICONDYLAR GINGLIMOARTHROIDAL COMPOUND JOINT www.indiandentalacademy.com
EVOLUTION OF TMJ
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THE LIVING VERTEBRATES CLASS
EXAMPLE
Agnatha
Lampreys
Condrichthyes
Sharks
Osteichthyes
Bony fishes
Amphibia
Frogs, toads
Reptilia
Snakes, turtles, lizards
Aves
Birds www.indiandentalacademy.com
MAMMALIA Protheria
Platypus
Metatheria
Marsupials
Eutheria
Placental mammals
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SCHOOLS OF THOUGHT Morphological concept
Suspension and suction
Support for ventilation
Genetics www.indiandentalacademy.com
AGNATHA Vertebrates without jaws Gill slits- Filtering and feeding Epiceratobranchial joint in mordern sharks Oral opening
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filtering
GNATHOSOMES Ist & IInd gilled arches- Brain IIIrd & IVth gilled arches- Prehension CEPHALIZATION Skin over the edges- Teeth Simple hinge joint- Quadrate-Articular Eudiarthroidial joint- True bony fishes www.indiandentalacademy.com
JAW AND THE CRANIUM A.
Gill Slits
B.
Autostyly
D.
Modified autostyly
C.
Amphistyly
E & F. Hyostyly G. www.indiandentalacademy.com
Holostyly
AMPHIBIA Jaws – cartilagenous core with blanket of dermal bones Joints- Quadrate-Articular eudiarthroidial
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REPTILIA Increase in the dentary bone in backward direction Increase in muscle size and their mechanical advantage Dentary-Squamosal joint replaces Quadrate-Articular joint Temporalis- orgin & insertion Streptostylic suspension www.indiandentalacademy.com
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SEQUENCE OF CHANGES Availability of particular diet Variations in tooth form Replacement of the old joint Adaptation of the musculature Response of the bone Coordination activity of the joints www.indiandentalacademy.com
Why there was a need of formation of new joint Prey size Muscle force , mass and direction of muscle pull Complex pattern of muscle activity Rigid lower jaw Greater range of movements
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MAMMALIA EUTHERIA
CARNIVORE
HERBIVORE
RODENT
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HUMANS
FUNCTIONAL POWER STROKES PREHENSION
COMMUNITION CRUSHING
TEARING CARNIVORE HERBIVORE
CUTTING
GNAWING GRINDING SLICING www.indiandentalacademy.com
CARNIVORES Projecting jaws used for grabbing prey Long lower jaws with no ramus Large coronoid process and large temporalis Horizontally expanded temporal fossa Short zygomatic area www.indiandentalacademy.com
CONDYLE
Firmly fitted joint
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HERBIVORES Long jaws with long cheek teeth and no canines Cheek teeth are set well posterior Jaw joint is fitted for wide, gliding and horizontal movements Small coronoid process decreased temporal fossa Enormously lengthened masseter www.indiandentalacademy.com orgin
Lateral movements of the joint
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RODENTS Large sharp edged chisel shaped incisor teeth Long gap between incisors and cheek teeth Antero-posteriorly directed glenoid groove Less lateral movements of joint
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HOMINIDS Upright posture Bipedal locomotion-Increased manual dexterity Shrinkage and retraction of jaws Change of diet- Omnivores Increase in brain size www.indiandentalacademy.com
TMJ IN PRIMATES Unspecialized Specialized Universal
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D
THE MUSCLES
L
M
inspiratoy gills V
expiratoy www.indiandentalacademy.com
III ORDER LEVER R
F
E
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Reptile
Early mammal
Mammal www.indiandentalacademy.com
Shark
Lobe finned fish
Primitive amphibian www.indiandentalacademy.com
Primitive reptile
Primitive marsupial
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Primitive primate Man
Chimpanzee
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CONDYLAR CARTILAGE Membranous bone with periosteum Pressure on the condyle Localized ischemic changes Undifferentiated mesenchymal cells Chondroblasts proliferation Cartilage formation www.indiandentalacademy.com
INTERARTICULAR DISK No separate cartilage Enlargement of the dentary Muscle from the pterygoid region
Attachment to the new joint
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EVOLUTION & MOLECULAR BIOLOGY Homeobox genes (HOX) Neural crest cells – mid brain Hox-free default in mandibular arch Myosin heavy chain (MYH)
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Neural crest cells
DEVELOPMENT OF TMJ
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MECKELS CARTILAGE Cartilage of the first arch Extent of the cartilage
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PRIMARY JOINT 6th week- formation 8th week- supports the mandible Dorsal end is continuous with the developing ear ossicles 16th week- Ossicles undergo endochondral ossification 10 WEEKS www.indiandentalacademy.com
CONDYLE 9th week- start 10-11 weeks- chondrifies 12th week- fuses with ramus 20 weeks- completion
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9-10 WEEKS
12 WEEKS 14WEEKS weeks ONWARDS 11 12 WEEKS www.indiandentalacademy.com
22 16 ATWEEKS WEEKS BIRTH www.indiandentalacademy.com
CARTILAGES
PRIMARY SECONDARY www.indiandentalacademy.com
Differences
….koski et al 1968
CHARACTER
CONDYLAR CARTILAGE
EPIPHYSEAL CARTILAGE
GROWTH
APPOSITIONAL
INTERSTITIAL
INTERMIDIATE LAYER
UNDIFFRENTIATED
CARTILAGE CELLS
ORGANIZATION OF CELLS
RANDOM
LINEAR
MINERALIZATION
HYPERTROPHIC ZONE
DEGENERATIVE ZONE
INTRINSIC GROWTH POTENTIAL
ABSENT
PRESENT
RESPONSE TO MECH. MORE STIMULATION
LESS
SPONGIOSA
PRESENT
ABSENT www.indiandentalacademy.com
According to BAUME: Growth Center: Is a site of endochondral ossification with tissue separating force,contributing to the increase of skeletal mass. Growth Site: Regions of Periosteal or suture bone formation and modeling resorption adaptive to environmental influences.
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GROWTH OF THE CONDYLE Articular surface Proliferative zone
Cartilage
Subchondral bone www.indiandentalacademy.com
ENDOCHONDRAL GROWTH OF CONDYLE Forces are compressive in nature Direction of growth Periosteum adapts itself mainly to tensile forces Cartilage Endochondral bone tissue cortices www.indiandentalacademy.com
CLINICAL CONSIDERATIONS 7-11 weeks morphogenesis- teratogens Regional adaptive growth Arrangement of the prechondroblast cells
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HENCE Condylar cartilage is – SECONDARY IN EVOLUTION SECONDARY IN DEVELOPMENT SECONDARY IN GROWTH
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GLENOID FOSSA 7-8 weeks - Develops earlier than the condyle 10th week- ossification 22 weeks- medial and lateral walls Shape of the fossa
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ARTICULAR CAPSULE 9-11 Weeks- first appearance 17th Week- differentiation 26th Week- completion
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ARTICULAR EMINENCE 7TH month- Formation of the trabeculae 8-9 months- Completion
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SUMMARY TMJ is one of the last synovial joints to develop Develops from two blastema It has an fibro cartilage covering Condyle is a primarily a growth site
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TEMPOROMANDIBULAR JOINT
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ANATOMY OF THE TMJ
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JOINTS FIBROUS
CARTILAGENOUS
SYNOVIAL
SYNARTHROSES
SYMPHYSES
SYNDESMOSES
SYNCHONDROSES
GOMPHOSES
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SYNOVIAL JOINT Gross anatomy Hyaline cartilage Low friction Weeping lubrication
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THE CONDYLE Oval shaped structure 15-20 mm M-L & 8-10 mm A-P Poles of the condyle Long axis
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GLENOID FOSSA Squamous portion of the temporal bone 23 mm M-L & 15 mm A-P NOT a stress bearing portion RELATIONS
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ARTICULAR EMINENTIA Anatomy Slopes- Anterior & Posterior Functional area
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ARTICULAR DISK Zones of the disk Surfaces Relations & attachments Significance of fibro cartilage Functions
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RETRODISCAL TISSUE SUPERIOR
INFERIOR
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FIBROUS CAPSULE Attachments Layers of the capsule Functions
capsule
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CAPSULE fossa
capsule condyle
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LIGAMENTS EXTRINSIC
INTRINSIC Temporomandibular lig
Sphenomandibular lig
Collateral lig
Stylomandibular lig Pterygomandibular raphe
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Contra lateral TM lig
TEMPOROMANDIBULAR LIGAMENT Two layers Functions
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FUNCTION OF TM LIGAMENT
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COLLATERAL LIGAMENT
SPHENOMANDIBULAR LIGAMENT ORGIN INSERTION RELATIONS FUNCTIONS
STYLOMANDIBULAR LIGAMENT www.indiandentalacademy.com
BLOOD SUPPLY
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NERVE SUPPLY
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HISTOLOGY
MACROSCOPIC
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ARTICULAR EMINENCE GLENOID FOSSA
MICROROSOPIC
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CONDYLE
SYNOVIAL MEMBRANE Vascular connective tissue Retrodiscal tissues Type A cells- macrophages Type-B cells- synovial fluid (80%) LUBRICATION NUTRITION www.indiandentalacademy.com
RADIOGRAPHIC ANATOMY TRANSCRANIAL PANORAMIC
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ARTHROGRAPHY
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CT IMAGING
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MRI IMAGING
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PHYSIOLOGY OF TMJ
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NEUROANATOMY REFLEXES OF THE JOINT PSYCHOLOGICAL ASPECTS
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NEUROANATOMY SENSORY INERVATION Main nerve supply- Auriculotemporal nerve- Posterior & lateral parts of the capsule It has the richest innervations Massetric & Deep temporal – medial parts of the capsule Center of the disk and the articulating surfaces are not innervated
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RECEPTOR INNERVATION OF TMJ FOUR TYPES RUFFINI GOLGI-TENDON VATER PACINI CORPUSCLES FREE NERVE ENDINGS www.indiandentalacademy.com
ANATOMICAL DESIGNATION
FUNCTIONAL DESIGNATION
REFLEX ROLE
LOCATION
RUFFINI ENDING
Static mechanoreceptor
Posture
Post & posterioro -lateral aspects of capsule
VATER-PACINI CORPUSCLE
Dynamic mechanoreceptor
Movement accelerator
TM ligament
GOLGI TENDON
Static mechanoreceptor
Protection of the ligament
TM ligament
FREE NERVE ENDING
Pain receptor
Protection of the joint
Distributed throughout the capsule
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CENTRAL PROJECTION
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MOTOR INNERVATION REFLEXES OF TMJ ORGIN
Mandibular Inhibition in masserteric closing discharge TONUS facilitation
Opening of mandible
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JAW CLOSING REFLEX The stretch reflex of jaw closers When the jaw is tapped muscle spindles of elevators are excited The A.P generated travel to the mesencephalic nucleus Travels to motor nucleus Extra fusal fibers of the elevator muscle www.indiandentalacademy.com
FUNCTION- Maintenance of the jaw against gravity and the inertial loading
MONOSYNAPTIC
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JAW OPENING REFLEX The flexor reflex of the jaw closers Reflex is activated biting into hard objects A.P is carried to the spinal nucleus Interneurons synapse with motor nucleus Excitation of the depressors www.indiandentalacademy.com
FUNCTION- protection of the hard and soft tissues POLYSYNAPTIC
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JAW UNLOADING REFLEX Sudden breakage of the food item Sudden closing of the jaw Spindles are unloaded Elevators are inhibited Occlusion is prevented www.indiandentalacademy.com
REFLEXES PROTECTING THE TMJ These reflexes ONLY operate to restrict EXTREME opening movements Maximal opening could be increased with anesthesia Attenuation of discharge on the contralateral muscles TMJ has no receptors that can monitor loading of the joint
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REFLEXES PROTECTING THE TEETH Normal postion of the mandible Balancing interference Position of the mandible Position of the mandible
Balancing interference
Normal closing Mandibular deviation Mandibular deviation
Mandibular deviation www.indiandentalacademy.com
TMJ AND THE TONGUE 0 DEG- no change in genioglossus muscle 21 < DEG- increased activity is seen Infiltration of the anesthetic abolished the reflex Associated with the receptors monitoring the adequeacy of the ventilation
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PSYCHOLOGICAL ASPECTS OF THE INERVATIONS MANDIBULAR POSITION SENSE Duplication of the mandibular movement SIZE THRESHOLD- .01 MM of objects
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SUMMARY Auriculotemporal nerve- lateral & posteriorly Jaw muscle activity probably affects the sensitivity of receptors Its sensitivity is increased by inflammation and elevated pressures Receptors cannot protect against excessive loading Crucial mass is more important than Crucial mix
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BIOMECHANICS
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MUSCLES Microscopic features Arrangement of the muscle fibers
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TYPES OF MUSCLE FIBERS SLOW MUSCLE FIBERS- TYPE I MASSETER & MEDIAL PTERYGOID POST FIBERS OF THE TEMPORALIS LATERAL PTERYGOID
FAST MUSCLE FIBERS- TYPE II POST FIBERS OF MASSETER AND MEDIAL PTERYGOID TEMPORALIS SUPERFICIAL 50%
MUSCLES OF THE MASTICATION INTERMDIATE FIBERS TYPE II C
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MUSCLES OF MASTICATION
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MASSETER
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FEATURES
SUPERFICIAL
DEEP
ORGIN
Zygomatic process
Anterior two thirds of zygomatic arch
INSERTION
Angle and lower portion of mandible
Upper portion of the lateral aspect of ramus
ORIENTATION
Oblique downwards
Vertically downwards
FUNCTIONS
Protruding of mandible
Stabilizing condyle against the articular eminence
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TEMPORALIS Fan shaped muscle ORIGIN- Temporal fossa & the lateral surface of the skull INSERTION- Forms a tendon inserts into coronoid process and the anterior border of the ramus
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DIVISIONSANTERIOR MIDDLE POSTERIOR -
Directed vertically Oblique orientation Horizontally
More concerned with moving and stabilizing the mandible
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MEDIAL PTERYGOID ORIGIN- Medial portion of the lateral pterygoid plate - maxillary tuberosity INSERTION- medial portion of the angle of mandible FUNCTIONS- Elevating and protrusion of the mandible -Unilateral contraction mediotrusive movement
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LATERAL PTERYGOID Two divisions- INFERIOR LATERAL PTERYGOID SUPERIOR LATERAL PTERYGOID INFERIOR HEADORIGIN- outer surface of the lateral pterygoid plate INSERTION- neck of the condyle FUNCTIONS- Protrusion when contracts simultaneously - Mediotrusive motion when contracts unilaterally
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SUPERIOR HEADORIGIN- Infratemporal surface of of the greater wing of the sphenoid INSERTION- FOUR TYPES
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I
Insertion into the condyle by merging into the central tendon
II Insert directly into pterygoid fovea(60 â&#x20AC;&#x201C; 70 %) III Blend with the fibers of the capsule IV Insert directly into the medial portion of the disk (30 %)
FUNCTIONSActive during the closing especially during the power stroke www.indiandentalacademy.com
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DIGASTRICS POSTERIOR BELLY – Origin- Mastoid notch Fibers- Downwards forwards and inwards Attachment- Hyoid bone ANTERIOR BELLYOrigin- Fossa of the lingual surface of the mandible Fibers- Downward and backward FUNCTION – Depression of the mandible www.indiandentalacademy.com
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TYPES OF MOVEMENT ROTATIONAL MOVEMENT HORIZONTAL AXIS FRONTAL AXIS SAGITTAL AXIS
TRANSLATIONAL MOVEMENT SINGLE PLANE BORDER MOVEMENTS www.indiandentalacademy.com
HORIZONTAL AXIS
HINGE AXIS
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FRONTAL AXIS
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SAGITTAL AXIS
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TRANSLATION MOVEMENT Definition Occurs in the superior joint cavity Both hinge and the translation occurs simultaneously
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SAGITTAL PLANE BORDER MOVEMENTS FOUR COMPONENTS
Posterior Anterior Superior Functional
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HORIZONTAL BORDER MOVEMENTS
L
R
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FRONTAL BORDER MOVEMENTS
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ENVELOPE OF MOTION
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BENNETT MOVEMENT & ANGLE
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ARTICULAR DISK
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ELEVATION
SUMMARY
TEMPORALIS
RETRACTION
MASSETER & MEDIAL PTERYGOID
PROTRACTION
DIAGASTRIC & GENIOHYOID
LATERAL PTERYGOID
DEPRESSION www.indiandentalacademy.com
ARTHROSCOPY OF TMJ Kenji Takagi Japan first introduced this technique Insertion of an rigid endoscope into the joint compartment for observation and therapeutic purpose Arthrography is mandatory before this procedure- Joint space
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INSTRUMENTATION TV camera and video Scopes - 2.4, 1.9, 1.7 mm Sheath - 2.7, 2.4 , 2 mm Light source â&#x20AC;&#x201C; xenon arc illuminator
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TECHNIQUE
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NORMAL JOINT
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REFERENCES LASKIN- Temporomandibular joint CARLSSON, SESSLE, MOHL,ZARB- Temporomandibular And masticatory muscle disorders BERKOVITZ- Oral anatomy J.P OKESON- Temporomandibular disorders
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IDE NAKAZAWA –Anatomical atlas of TMJ TENCATE – Oral histogy Koski et al , 1968 AJO-DO MAJOR M ASH-Wheelers dental anatomy, Physiology and occlussion
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T.M GRABER ,T RAKOSI, A G PETROVIC- Dentofacial orthopedics with functional appliances
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ď Ž
Ct fig
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MRI fig
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Thank you www.indiandentalacademy.com Leader in continuing dental education
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