Static Occlusion

7/29/2019 Static Occlusion

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Occlusion of crown and bridge

and clinical important in prognosis of treatment

Prepared by

DR .shahen arif khdir

HIGH DEGREE DIPLOMA STUDENT

Occlusion(introduction)


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The way in which the upper and lower teeth relate to each

other or in most of these, the maxillary and mandibuler

teeth contact simultaneously when the condylar

processes are fully seated in the mandibular fosse andthe teeth do not interfere with harmonious movement of

the mandible during function.

Clinical Relevance: Occlusion is of fundamental importance in

restorative dentistry, as all restorations placed in the

mouth can have a profound effect on it. From Intra

coronal direct placement restorations to complex crown

and bridgework, the restoration must be planned toconform to an occlusal pattern.

*Static OcclusionStatic occlusion: stationary position of upper and lower jaw (or

upper & lower teeth) in relation to each other, thats why

its call static because its not moving, its a postural

position, close position where the patient not moving his

mandible against his maxilla.

Centric occlusion (CO

the occlusion the patient makes when they fit their teeth

together in maximum inter cuspation CO is also called

Inter- cuspal position (ICP)

Bite of convenience Habitual bite


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*Significance centric occlusion

1. At this position occlusal force is directed along the long

axis of the teeth. As we know, its the most favorable

position. It is the most histological direction of forces thatwill be accommodate by dental tissues & surrounding

structures.

2. At this position, its an End point of chewing cycle. These

positions where patient end their chewing cycle. Patient

move their jaw laterally and all around when theyre

chewing and the end point of the chewing is staticposition.

.3.The position in which simple restoration are made. Usually

we made our restoration in this position. Because it is

reproducible, easy, simple, safe to do.

Dynamic OcclusionDynamic occlusion: describe occlusal contacts when the

mandible is moving relative to the maxilla When you

move laterally, o r protrusive , all this contact are part

of dynamic occlusion. Which is very important

because its the chewing action. Usually dynamic

occlusion is dictated or determined or guided by the

shapes teeth and the TMJ.

Guidance from the teeth: Determined by the shapes of teeth and TMJ Canine guidance vs. group function Protrusive guidance


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Posterior and Anterior DeterminantsAnterior Guidance: The influence of the contact relationship

between the labial surfaces of the mand. Incisors and thelingual surface of the max incisors on mandibular

Movement

Purpose

Disclude posterior teeth in excursions Determined byhorizontal/vertical overlap

horizontal overlap A.G.

vertical overlap A.G.Recorded by custom anterior guide table

The posterior determinantsshape of the articular eminences, anatomy of the medial

walls of the mandibular fossae , configuration of the

mandibular condylar processes-cannot be controlled , nor

is it possible to influence the neuromuscular responses of

the patient, unless it is done by indirect means (e.g.,

through changes in the configuration of the contacting

teeth or by the provision of an occlusal appliance).

UNILATERALLY BALANCED ARTICULATION(GROUPFUNCTION)


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In a unilaterally balanced articulation, excursive contact occurs

between all opposing posterior teeth on the latero trusive

(working) side only. On the medio trusive (nonworking)

side, no contact occurs until the mandible has reachedcentric relation. Thus, in this occlusal arrangement the

load is distributed among the periodontal support of all

posterior teeth on the working side. This can be

advantageous if, for instance, the periodontal support of

the canine is compromised.

MUTUALLY PROTECTED OCCLUSION(Canine-guided)Canine protected occlusion : The contact between maxillary

and mandibular canine in lateral movement lead to no

contact of posterior teeth on either working or balancing

(non working)sides.

Significance of Guidance Teeth.

1. Non-axial loading

Usually contact of dynamic occlusion, when you move laterallyor protrusive youre loading the teeth in contact in a non-

axial direction, in an oblique direction, those forces are

destructive by nature and they need more adaptation.

That would make heavily restored teeth or crown teeth at

a higher risk of fracture and crown seated on this tooth

usually because theyre subjected to oblique forces;

theyre usually subjected to higher risk of beingdecementation.

Other manifestation: increase wear, when you check older age

patient for example most of the canine had been worn

due to its role as guidance for long time. With aging


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usually the occlusion change, from canine guidance to

group function (because of wear). Because the canine

already become short. Cusp worn. So the guidance will

be shared by another cusp of teeth, adjacent cusp ofteeth. We have mobility, fracture, migration, TMJ

dysfunction (possibility to have).

2. Identify guidance teeth before preparation If guidance

tooth is satisfactory, I mean good, sound, strong, we

should re-establish the same guidance pattern in the new

restoration #If guidance tooth is weak, transfer guidance

contacts to the adjacent stronger teeth.

3 .Provide clearance during preparation in excursivepositions: We provide clearance during preparation in

excursive movement; we have to provide adequate

occlusal reduction clearance to accommodate the

material of the crowns, PFM or all ceramic for example.Usually for ceramic we have to reduce huge incisal edge,

it will be about /2mm, so we will have adequate bulk of

material , or the metal under porcelain where the metal

provide enough strength under loading and for the

porcelain not to be fracture,. We should check the

clearance in all movement as well, you ask your patient to

move his jaw from side to side, and check if there anyenough clearance in lateral movement or not. Sometimes

you might have adequate clearance in CO position but not

when lateral movement. This is not enough because the

patient does not only occluding in static position, in


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chewing cycle the patient will start moving in lateral

movement. So we have to check the clearance in all

movement.

4..Select appropriate material to restore the guidance tooth

If this tooth is the guidance tooth we want to restore it with

strong enough and doesnt distort because it is subjective to un

favorably pattern direction of forces, and subjective to excessive

wear ,and again its come in contact with opposing teeth more

frequently than other teeth, so it might damage the adjacent, to

the opposing tooth as well, so we need to get material that are

strong enough for the opposing dentition

*Vertical Dimension

The vertical dimension of occlusion: (VDO) is the vertical

height of the face when the teeth are in maximum inter

cuspation teeth are held apart in the rest position by the

muscles of mastication acting on the mandiblecreating a freeway space or Intero cclusal distance of 24 mm

*Resting vertical dimension :a measured distance between the

upper and lower jaws when all forces upon the mandible

are in equilibrium and the patient is in an upright position

*Occlusal vertical dimension:

A measured distance between the upper and lower jaws when

the teeth are in full intercuspation.

*Centric relation:

The relation of the mandible to the maxilla when the

condylesare in the


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Most superior anterior position in the glenoid fossa ,from which

unstrained lateral movements can be made at the occluding

vertical dimension normal for the patient(Arch to Arch relation

ship).Centric occlusion(co):

The centered contact position of the occlusal surfaces of the

mandibular teeth against those of the maxillary teeth,

irrespectives of condaylar

Position (teeth to teeth relation) It can be taken when there

are enough occlusal stops after preparation for a crown or

bridge.

Functional contactsContacts during:

Speech

Swallowing

Mastication

Contacts are: Infrequent Glancing Low intensity

Parafunctional Contacts Contacts other than functional

Clenching Grinding Biting on foreign objects


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FingernailsPipesNails.

Significance of Parafunction Increased force

Intensity Frequency Duration Adverse loading Non axial Un braced mandible

Clinical findings Mobility Tooth /restoration fracture Restoration displacement Muscle pain/dysfunction TMJ pain/dysfunction Aggressive wear

The occlusal disharmony caused by improper fixed

prothodontics work can cause The following adverse results:

1.Pulpitis

2 .bruxing


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3. Premature occlusal wear and restoration perforation.

4. Accelerated periodontal breakdown and teeth mobility.

5.TMJ disturbances caused by high spots and excessive lateralforces.

6. Dislodgment of fracture of facing s caused by excessive

contents of anterior teeth in protrusion and excessive lateral

forces on fixed restoration.

PATHOGENIC OCCLUSIONA pathogenic occlusion is defined as an occlusal relationship

capable of producing pathologic changes in the stoma to

gnathic system. In such occlusions sufficient disharmony

exists between the teeth and the TMJs to result in

symptoms that require intervention

SIGNS AND SYMPTOMSThere are many indications that a pathogenic occlusion may

be present. Diagnosis is often complicated because

patients almost always have a combination of symptoms.

Teeth. The teeth may exhibit hyper mobility, open contacts, or

abnormal wear. Hyper mobility of an individual tooth or

opposing pair of teeth is often an indication of excessive

occlusal force. This may be due to premature contact in

centric relation or during excursive movements. Such

contacts frequently can be detected by placing the tip of

the index finger on the crown portion of the mobile tooth


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and asking the patient to repeatedly tap the teeth

together .Small amounts of movement that otherwise

might not be readily seen often can be felt this way. Open

proximal contacts may be the result of tooth migrationbecause of an unstable occlusion and should prompt

further investigation .Diagnostic casts made during

previous treatment will help assess any changes in the

stability of the occlusion. Abnormal tooth wear, cusp

fracture, or chipping of incisal edges may be signs of

parafunction activity.

Periodontium.:

There is no convincing evidence that chronic periodontal

disease is caused directly by occlusal overload. However, a

widened periodontal ligament space(detected radio

graphically)may indicate premature occlusal

contactan often associated with tooth mobility

Similarly ,isolated or circumferential periodontal defects

are often associated with occlusal trauma. Inpatients with

advanced periodontal disease who have extensive bone

loss, rapid tooth migration may occur with even minor

occlusal

Musculature. Acute or chronic muscular pain on palpation

can indicate habits associated with tension such as

bruxing or clenching. Chronic muscle fatigue can lead to

muscle spasm and pain.


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Temporomandibular Joints. Pain, clicking, orpopping in the

TMJs can indicate TM disorders .Clicking and popping may

be present without the patient's awareness. A

stethoscope is a useful diagnostic aid; a recent studyfound joint sounds are generally reliable indicators of

temporo mandibular disorders. The patient may

complain of TMJ pain that is actually of muscular origin

and is referred to the joint Clicking may also be associated

with internal derangements of the joint. A patient with

unilateral clicking when opening and closing (reciprocal

click)in conjunction with a midline deviation may have adisplaced disk. The midline deviation will typically occur

toward the side of the affected joint because the displaced

disk can prevent (or slowdown) the normal anterior

translator movement of the condoyle..

Discrepancies. Tooth movement may make it difficult for these

patients to institute proper oral hygiene measures, and

the result may be a recurrence of periodontal disease

.Myofascial Pain Dysfunction.The mayo facialpain dysfunction (MPD)syndrome presents as

diffuse unilateral pain in the pre auricular area, with

muscle tenderness, clicking, or popping noises in the

contra lateral TMJ and limitation of jaw function. Often

the muscles, and not the TMJ, are the primary site, butover time the functional problem may lead to organic

changes in the joint

*Criteria for Ideal Occlusion


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1. Simultaneous and uniform contact of as many teeth aspossible in centric occlusion. Anterior teeth may touch,

but the intensity should be slightly less than the posterior

teeth as the forces of occlusion are at an angle to the long

axis for anterior teeth. This criterion provides for the

optimum distribution of forces.

2.The forces of the occlusion are directed down the longaxis of the teeth. Axial forces have been shown to be

more favorably received by the attachment apparatus

than horizontal or oblique forces.3.Anterior tooth contacts compatible with functional

movements. A deep vertical overlap of the anterior teeth

may allow for taller/sharper posterior cusps

4.No posterior teeth should contact on the non workingside during lateral excursions.

5.No posterior teeth should contact during protrusiveexcursions.

Occlusal design

1.Distribute forces proportionate to the ability of theteeth to resist

2.Distribute forces to as many teeth as possible.3.Direct forces most favorably relative to the supporting

tissues.

OCCLUSAL TREATMENTWhen a patient exhibits signs and symptoms that appear

correlated to occlusal interferences ,occlusal treatment


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should be considered .Such treatment can include tooth

movement through orthodontics, elimination of deflective

occlusal contacts through selective reshaping of the

occlusal surfaces of teeth, or the restoration andreplacement of missing teeth resulting in more favorable

distribution of occlusal force

The objectives of occlusal treatment are as follows:

1. To direct the occlusal forces along the long axes of the teeth

2. To attain simultaneous contact of all teeth in centric relation

3. To eliminate any occlusal contact on inclined planes to

enhance the positional stability of the teeth4. To have centric relation coincide with the maximum

intercuspation position

5. To arrive at the occlusal scheme selected for the patient

(e.g., unilateral balanced versus mutually protected)

ASSESSMEN of the OCCLUSION.The diagnostic process begins with careful history taking and

clinical examination. Signs an symptoms of clicking or

locking of the temporo mandibular joints, muscle spasm,

excessive or uneven occlusal wear and pain on chewing

must be recorded. Further investigations including

radiographs, vitality tests and articulated study casts will

provide additional information.The examination should include

*.Extra-oral components

Temporo mandibular joints, muscle hypertrophy/spasm.


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Mandibular movement painful, deviated, abnormal orrestricted.

*Intra-oral features:

1. Intercuspal position, retruded contact position, lateral andanterior guidance.

2. Location and extent of occlusal face tin

.

3. Ease of movement between mandibular positions.

4. Extent of posterior support.

5. Over-erupted, tilted or mobile teeth.

DETECTING OCCLUSALCONTACt

Articulating paper is used to mark or indicate the position of

occlusal

Contacts. Articulating paper

Marking Contacts Teeth must be dry!!!! Use fresh paper for best results Apply Vaseline film to paper

Helps transfer ink Sandblast metal / porcelain

Helps with ink transfer Also Articulated study casts ,mounted on a semi-adjustable

articulator using a face bow record, provide more detailed

information that cannot be readily assessed in the mouth.


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High Tech Occlusal DetectionTScan system

Computerized occlusal analysisDetects Presence of contacts Intensity of contacts Timing of contacts

Similar to digital radiology, sensor between teeth and can

detect certain things.

references1,Restorative dentistry book(A.J. MCCULLOCK)

Dent Update 2003; 30: 150-157

2 . contemporary fixed prothodontic book(3rd

edition)

By STEPHEN F. ROSENSTIEL, BDS, MSD and

MARTIN F. LAND DDS, MSD

JUNHEI FUJIMOTO, DDS, MSD, DDS c

3 .internet research

Documents

Static Occlusion