occlusion of crown bridge
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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 2013
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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 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
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