.

Occlusion of crown and bridge

and clinical important in prognosis of treatment

Prepared by DR .shahen arif khdir HIGH DEGREE DIPLOMA STUDENT 2013

**************************************************

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 and

the 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 to conform

to an occlusal pattern.

Occlusion(introduction)

Static Occlusion

Static occlusion: stationary position of

upper and lower jaw (or upper & lower

teeth) in relation to each other, that’s why

it’s call static because it’s not moving, it’s

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

Significance of centric occlusion

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

axis of the teeth. As we know, it’s the most favorable

position. It is the most histological direction of forces that

will be accommodate by dental tissues & surrounding

structures.

2. At this position, it’s an End point of chewing cycle. This

position where patient end their chewing cycle. Patient

move their jaw laterally and all around when they’re

chewing and the end point of the chewing is static

position

.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 Occlusion

Dynamic occlusion: describe occlusal contacts

when the mandible is moving relative to the maxilla

When you move laterally , or protrusive , all this contact

are part of dynamic occlusion. Which is very important

because its the chewing action. Guidance from the teeth:

Determined by the shapes of teeth and TMJ

Canine guidance vs. group function

Protrusive guidance

Posterior and Anterior Determinants

Anterior Guidance :The influence of the contact

relationship between the labial surface of the mand.

incisors and the lingual surface of the max incisors on

mandibular Movement

Purpose Disclude posterior teeth in excursions Determined by

horizontal/vertical overlap ↑horizontal overlap

↓ A.G. ↑vertical overlap ↑ A.G.

Recorded by custom anterior guide table

Anterior determinants of occlusion. Different incisor relationships with differing horizontal and vertical overlaps (HO and VO) produce different anterior guidance angles (AGA). A, Class 1. B, Class 11, Division 2 (increased VC; steep AGA). C, Class 11, Division 1 (increased HO; flat AGA

The posterior determinants

shape 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).

Posterior determinants of occlusion. A, Angle of the articular eminence (condylar guidance angle). 1, Flat; 2, average; 3, steep. B, Anatomy of the medial walls of the mandibular fosse. 1, Greater than average; 2, average; 3, minimal side shift

UNILATERALLY BALANCED ARTICULATION(GROUP FUNCTION)

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 reached

centric relation. Thus , in this occlusal

arrangement the load is distributed among the

periodontal support of all posterior teeth on the

working side.

Group function or unilaterally balanced occlusion During

lateral excursions, there are no contacts between teeth on

the mediotrusive (nonworking) side, but even excursive

contacts occur on the laterotrusive (working side)

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.

Canine-guided or mutually protected occlusion. During

lateral excursions, there are no contacts on the mediotrusive

(nonworking) side; all contacts are between the laterotrusive

(working side) canines

Significance of Guidance Teeth

1. Non-axial loading

Heavily restored teeth at risk of fracture or decementation:

contact of dynamic occlusion, when you move laterally or protrusive you’re 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 teeth usually because they’re subjected to oblique forces, they’re usually subjected to higher risk of being decementation.

other manifestations: ↑ wear, mobility, fracture, migration, 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 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 of teeth. 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 excursive positions: We provide clearance during preparation in excursive movement, we have to provide adequate occlusal reduction clearance to accommodate the material of the crowns4..Select appropriate material to restore the guidance tooth: we want to restore it with strong enough and doesn’t 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

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 mandible

creating a freeway space or Intero cclusal distance of 2–4 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 condyles are in the 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 condaylarPosition (teeth to teeth relation) It can be taken when there are enough occlusal stops after preparation for a crown or bridge.

Functional contacts

Contacts during

Speech

Swallowing

Mastication:((teeth should not be together during

talking or chewing)

Contacts are:

Infrequent(short duration)

Glancing

Low intensity

Contacts other than functional

Clenching

Grinding

Biting on foreign objects

Fingernails

Pipes

Nails.

Parafunctional Contacts

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 for

teeth and restoration

The occlusal disharmony caused by improper fixed prothodontics work can cause The following adverse results:

1.Pulpitis2 .bruxing3.Premature occlusal wear and restoration perforation.4.Accelerated periodontal breakdown and teeth mobility.5.TMJ disturbances caused by high spots and excessive lateral forces.6.Dislodgment of fracture of facing s caused by excessive contents of anterior teeth in protrusion and excessive lateral forces on fixed restoration.

PATHOGENIC OCCLUSION

A 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 SYMPTOMS

There are many indications that a pathogenic occlusion

may be present. Diagnosis is often complicated

because patients almost always have a combination of

symptoms.

the following symptoms can help confirm this diagnosis.

Teeth. The teeth may exhibit hyper mobility, open

contacts, or abnormal wear. caused By excessive

occlusal force. This may be due to premature contact in

centric relation or during excursive movements. Open

proximal contacts may be the result of tooth migration

because of an unstable occlusion and should prompt

further investigation . 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 contact an often associated with tooth mobility Similarly ,isolated or circumferential periodontal defects are often associated with occlusal trauma. .

.

Widened periodontal ligament space and increased mobility of mandibular molars .Occlusal premature contacts were noted in lateral and protrusive movements.

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.

Temporomandibular Joints. Pain, clicking, or popping 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. 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 a displaced 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 translatory movement of the condoyle..

Myofascial Pain Dysfunction.

The mayo facial pain 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, but over time the functional problem

may lead to organic changes in the joint.

Criteria for Ideal Occlusion1. Simultaneous and uniform contact of as many teeth as

possible 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 long axis 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 working side during lateral excursions.

5. No posterior teeth should contact during protrusive excursions.

Occlusal design1. Distribute forces proportionate to the

ability of the teeth to resist 2. Distribute forces to as many teeth as

possible.3. Direct forces most favorably relative

to the supporting tissues.4. Avoid heavy force application in

unbraced jaw positions

OCCLUSAL TREATMENT

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 teeth

4. 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)

ASSESSMENT OF THEOCCLUSION

The diagnostic process begins with. careful history

taking .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.•Mandibular movement – painful, deviated, abnormal or restricted. *Intra-oral features: 1. Intercuspal position, retruded contact position, lateral and anterior 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

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

2 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

1Articulating paper ( marking contact

High Tech Occlusal Detection

3.T –Scan 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.

T –Scan systemComputerized occlusal analysisDetects contact

PresenceLocationIntensityTiming

High Tech Occlusal Detection

references

1. Restorative dentistry book(A.J. MCCULLOCK)

Dent Update 2003; 30: 150-1572 . contemporary fixed prothodontic

book(3rd edition)By STEPHEN F. ROSENSTIEL, BDS, MSD andMARTIN F. LAND DDS, MSDJUNHEI FUJIMOTO, DDS, MSD, DDS c3 .internet research

Thank you