Occlosion sheet # 1 -Muna Sawwan

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Occlosion sheet # 1 -Muna Sawwan

Post by Shadi Jarrar on 12/2/2011, 1:56 am

بسم الله الرحمن الرحيم


occlusion 1.docx

By the name of ALLAH
Occlusion lec. 1

Today's lec. Is an intro. To occlusion and revision for some info.

Components of the TMJ:
• mandibular fossa
• condyler process
• articular disk
• joint capsule
• mandibular ligaments and muscles
function of the TMJ:
• muscle control of disk alignment.
• Tempromandibular ligament.
• Disk.
• Arteriovenous shunt.
• Mandibular position and mandibular movement.

 There is no escape from occlusion :D
 Dentist cant move,remove or repair without knowing the proper contact during centric or eccentric movement
 Masticatory system is the functional unit of the body that is responsible for chewing, speaking and swallowing.
 Also plays a role in breathing (if nose is obstructed) and tasting (the presence of taste buds.)
 The system is made up of joint (bones) , ligaments, teeth and muscles.
 There is also neurological control ; neuronal input…. Ex. : mouth opening >>signal to brain>>muscle move>>opening of the mouth.
 So neurological system regulate and coordinate ll the structures.
 There is also skeletal components:
o Maxilla
o Mandible
o Temporal

Components of the TMJ:
♣ Condyler head >>>>mandible
♣ Condyler fossa
♣ Articular eminence
♣ Temporal bone>>>>maxilla
♣ Articular disk>>>>maxilla

All the articular surfaces of the condyle ,fossa and eminence are covered with avascular layer of dense fibrous c.t.
They should be avascular because I they were vascularised then during movement we will feel pain
The absence of the B.V is a sign that these areas are designed to receive considerable pressure.
The avascular areas are devoid of nerves as well. As it can receive great pressure with no signs of discomfort.
The movement of TMJ is a combination between hinge and gliding movements.
Hinge>> rotation>> first 20 mm of mouth opening then rotation stops,,,, why????
Which ligament is the responsible of termination of this movement???
"plz ma tt7zro 5l9 had kolloh elmfrood revision " dr.said (6b3n el7ke mwjjh l Thara2)!!
Its tempromandibular ligament,, so the mandible cont. in a translocation movement.
Gliding movement (translocation) occur in the upper part between temporal bone and condyler with the disk,,,,,,,while hinge movement occur in the lower compartment between disk and condyler head.
TMJ is unique because unlike other joints its 2 joint with one bone (that adds to the complexity of the movements) >>>movements should occur in two joints at the same time.
Mandibular fossa is an oval depression in the temporal bone (just anterior to the auditory canal. Its bounded anteriorly by condyler eminence, external middle root of the zygoma and auditory process .
Bounded posteriorly by tympanic plate of petrous part of temporal bone.
The shape of this fossa should looks like the shape of the mandible because they are going to move together.
The condyler process is part of the mandible and its (condyle) is perpendicular to the ascending ramus of the mandible.
The articualr disk is thin, oval plate between the condyle of the mandible and the mandible and the mandibular fossa.
The shape is to accommodate the shape of the condyle +mandibular fossa ,,, sooooooo its upper surface is concavo convex (ant.>>post.) ,,should looks like mandibular fossa and articular eminence..
Its lower surface is concave >> to contact with the condyle.
Circumference is connected to the articular capsule,, يعني ما بسبح لحالو
So it should be connected from medial and distal parts to the capsule ,,,anteriorly its connected to superior head of lateral ptyregoid (while inf. Head is connected to the head of condyle).
Its thicker at its periphery (especially behind) than center. نفس فكرة RBCs.
Dense collagenous c.t that is in central part is relatively avascularized so its nourished by synovial fluid,,, the fibers of which its composed are concentric (circles) following circle of the disk and it divides the joint into 2 cavities each of which is varnished with synovial membrane..
The joint capsule thin loose envelope attached above to the mand. Fossa and inferiorly to the neck of the condyler head.
Ant.lateral part of the capsule is thickened to form temptomandibular ligament (terminate hinge movement ).
Innervations to capsule is from trigeminal nerve and it contains many nerve endings.
Vascular supply is from maxillary artery (masseteric and temporal branches).
Mandibular ligaments (stabilize articular systems during jaw movements)
 Stylomandibular ligament
 Sphenomandibular ligament (attached to the lingula of the mandible)
 Otomandibular (between joint and ear,,so sometimes when the patient open or move TMJ,, the pain is referred to the ear )
 Tempromandibular
 Collateral disk ligament

TMJ function
Articular disk divides the joint into 2 parts (upper and lower)
Hinge movement occur in the lower part while translocation occur in the upper part
Disk is firmly attached medially and laterally to the capsule.
In normal condition the disk is always position so that the pressure from condyle is directed to the central part. To avoid it going laterally so to avoid lever function.
يعني عشان نخلي القوة دايما centrally.
(positioning of the disk occur by the elastic fibers attached to the back of the head which is kept under tension against the superior lateral ptyregoid muscle).
 We said that the disk is attached anteriorly to a muscle ,, so it must be attached posteriorly to keep it away from dislodgment ,, so its attached to a ligament.
 Condyler dislodgement:
• Collateral ligament
• Posterior ligament
• Medial and lateral disk ligaments
• Superior elastic stratum
• Superior lateral ptyregoid muscle
All these keep condyle in position (either the condyle is above or above and forward).
>>> collateral diskal ligament >> attached the medial and distal borders of the articular disk to the poles of the condyle (like saddle on the hourse) ,,,, these ligaments are composed of collagenous c.t fibers that don’t stretch….. they are responsible for the hinge movement of TMJ ,,,, they are innervated and they provide information about joint position and movement (they must be innervated to give info. To the brain.)

Muscle control of disk alignment

During hinge movement :
Disk is attached to superior head/ inferior head of lateral ptyregoid and posterior stratum.
Now,, during hinge movement disk should move downward and forward so,, inferior head pulls it down,,, but then after that disk must go back slightly and then upward soooo,,, superior head is now relaxed to allow the posterior stratum to pull the disk slightly backward and upward….. now the disk is on the top of the condyler eminence .

Sooooo,,,,, in max. opening when the condyle reach the crest of the eminence, the elastic fibers rotated the disk back because the superior lat.ptyregoid is released .
during closing>> reverse ,,,, y3ne : inferior head relaxes to allow andible to go backward,, whie superior head tighten to assume more front position. (if superior head ma shad,, then btesm3oo 9ot l2enno be9eer fe lock ll joint).

Tempromandibular ligament on lateral part of the capsule function when the jaw open 20 mm or more…. Its attachment to the superior surface of the neck of the head of the condyle stops the rotational movement and force the translocation one.
(we don’t feel this movement “20 mm hinge then translocation”)
Arterio-Venous shunt
All this area “avascular” except behind the disk and behind the condyle we have an area that is rich in blood supply …..now while opening your mouth disk of condyle moves forward forcing the blood into the vessels ( and the vessels widen).
But during closing the condyle goes backward and the blood supply decrease.
Sometimes when disk is displaced, patient feel pain,, bcoz this area “when b.v widen” will be under pressure so patient feel pain.
All load bearing structures are built to accept compressive loading forces , as long as the disk and condyle are in proper alignment , for the forces to be directed through the loading bearing zones ,,, these areas also are free of nerve endings and blood vessels
“loading forces are directed through the condyler fulcrum during functional jaw movement”
Revision (l m3loomatkom el3ammeh )
Basic jaw position:
• Centric occlusion: max. intercuspation between the teeth.
• Centric relation: opening and closing without translocation of the condyle :when its in the most retruded physiological position.
• Inter cuspal position =centric occlusion
• Retruded contact position = centric relation
• Rest position
Note: centric relation is reproducible “doesn’t change as long as every thing is healthy”
 Hinge axis movement :is the movement of both condyles in rotational axis.
 Centric occlusion is ant. To centric relation by 1 mm “if more: something wrong”
 10 % of population have their centric occlusion coincidence with their centric relation
 Rest position when u r setting ( o saned 9’hrak )
 And ur head is in upright position>>> lips are in contact with each other but ur teeth are not.
Mandibular movement :
Bennet shift and bennet angle:
Bennet movement occur during lateral movement ( on the non-working side)>>>>translocation movement
(on working side>>>> rotation with a slight side shift)
Soooo as the condyle (on non-working side) moves downward and inward >>separation occur between the teeth also in non working side..the angle between the vertival and line of condyle movement is called bennet angle .

Envelope of mandibular movement

Mouth opening could be from centric occlusion area or centric relation
RCP >> ICP : hinge movement 20 mm
ICP >> E : translocation
Jaw also is capable to do forward movement so from centric occlusion u can move ur teeth forward
Lower teeth first go downward against palatal surfaces of upper ant. Till reaching edge to edge then upward against labila sur. Of upper then forward.Also opening can be done from max. protrusion.
These movements (functional and para-functional “like biting ur lips or nails “) occur in this envelope.
Max. opening 50-60 ,,,, lower limit is 40
We need to know these movements to examine patients (muscle spasm\ limitations)
Max protrusion>> 8-10 cm
Retrusion 1 cm ,, max. 2 cm “ ymkn mn cent. Occlusion !!! “
Dr. said that she will give us ana article an dhard copy for the chapter..
The End
Done by : Muna Jamal Sawwan

Shadi Jarrar
مشرف عام

عدد المساهمات : 997
النشاط : 12
تاريخ التسجيل : 2009-08-28
العمر : 27
الموقع : Amman-Jordan


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