Occlusion Pt2 (review slides)

Rotation

The process of moving around an

axis

rotation

In the masticatory system,

__ occurs when the mouth

opens and closes.

condyles

Teeth can be separated and then

occluded with no positional

change of the __.

Translation

Movement in which every point of

the moving object has

simultaneously the same velocity

and direction

Translation

In the masticatory system, __

occurs when the mandible

moves forward as in protrusion

same

The teeth, condyles and rami, all

move in the __ direction and

to the __ degree

Mandibular Movements

We trace or record these

movements (tooth or condylar

movements) from three spatial

planes: (Sagittal, frontal and horizontal)

Maximum intercuspation

The complete intercuspation of the opposing teeth, independent of the condylar position. (The best fit of the teeth together independent of the condylar position)

posterior

MI is Habitual position for dentate patient, requires __

teeth.

posterior

MI means that the maxillary lingual and mandibular

buccal cusps of the __ teeth are evenly distributed

and in stable contact with the opposing occlusal fossae

and /or marginal ridge

Centric relation

Maxillo-mandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disc within the TMJ complex in their anterior superior positions against the slope of the

articular eminence

MI

CR Rarely coincides with __ in dentate patients (independent of tooth contact)

CR

The most orthopedically sound position

CR

A position that we use for:

• Complete dentures

• When MI does not exist

• Full mouth rehabilitation

CR

Usually need to manipulate the mandible into this position

Retrusive

Backward movement of the mandible from

MI back to CR

1-2

Retrusive: In 90% people there is a discrepancy

between MI and CR about __ mm

protrusive

Forward moment of mandible with the teeth

together

• Usually guided by the incisors.

Working Side

Left and right lateral excursions: Side towards which mandible moves

Non-Working side

Left and right lateral excursions: opposite side towards which

mandible moves. Also called balancing side

Working side

the side toward which

the mandible moves in a lateral

excursion; syn, LATEROTRUSION

laterotrusive contacts

Contacts of

teeth made on the side of the occlusion

toward which the mandible has been

moved. (In this image left side contacts)

Bennet angle

the angle that is formed by the non-working condyle and the sagittal plane during lateral movement

Bennet movement

The side shift of the mandible is also know as the Bennett movement

Non working side

that side of the mandible that

moves toward the medial line in a lateral excursion

(the opposite side toward which the mandible

moves in a lateral excursion; syn, MEDIOTRUSION

Mediotrusive contacts

Contact of the teeth on the side opposite to the

direction of laterotrusion of the mandible.

• Most common mediotrusive contact is the palatal cusp of

maxillary second molar

the mandible

Undesirable contacts

(In this image right side

contacts. (very desruptive if present)

Review

MI

Red dots

Protrusion

Black arrows

Mediotrusion

Green arrows

Laterotrusion

Blue arrows

Left and right lateral excursions

• Canine guidance (only the canines contact on that side)

• All anterior teeth

• Group function (multiple teeth contact on that side)

• Combination

working

Ideally contact should only be on the __ side

Occlusal interference

Contact between teeth in one of the

excursions/movements of the mandible

when free sliding movement of the mandible

is interrupted

• Example, when there is contact on the non-

working side during lateral translation

Occlusal harmony

• Absence of occlusal interference

• Allows free movement of teeth in all excursions

without damage to teeth or restorations

vertical dimension of occlusion

Relationship between the mandible and

the maxilla with the teeth in MI

Optimal Functional Occlusion

The optimum orthopedic relationship that will prevent, minimize or eliminate any break down or trauma

Optimal Functional Occlusion

When the mouth closes, condyles in most superior

anterior position (Musculo skeletally stable) resting

on posterior slope of articular eminence, with

articular disc properly interposed. Even,

simultaneous bilateral contact of all posterior teeth.

Slight clearance of anterior teeth.

posterior

All __ tooth contact provide axial loading of

occlusal force.

PDL

The fibers of the __ are aligned such that

vertically directed forces through the long axis

(axial loading) can be well accepted and

dissipated.

Non-axial

loading

•When the force is not directed through its long

axis but rather a horizontal component (__) is incorporated that tends to cause

tipping and other problems.

Vertical forces

__- well accepted by the PDL

Horizontal forces

__ - cannot be effectively dissipated

Cusp tips contact flat surfaces

the resultant force is directed vertically through the long axes of the teeth (arrows). This type of force is accepted well by the periodontal ligament.

Opposing teeth contact on inclines

the direction of force is not through the long axes of the teeth. Instead tipping forces are created (arrows) that tend to cause compression of certain areas of the PDL. The forces are not effectively dissapated to the bone

Can cause mobility and/or tooth sensitivity

guiding

Because these non-axial forces are so damaging to the posterior teeth, we need specific __ systems to make sure the posterior teeth separate the instant the mandible starts to move off- center.

canine guidance

When the mandible moves a right or left laterotrusive excursion, the maxillary and mandibular canines are the appropriate teeth to contact and dissipate the horizontal forces while disoccluding or disarticulating the posterior teeth. When this condition exists, the patient is said to have __.

horizontal

Canines are best suited to accept __ forces that occur during eccentric movements in addition to disarticulating the posterior teeth.

lateral

• canines have Longest and largest roots that are surrounded by dense compact bone which tolerates __ forces better than the medullary bone found around posterior teeth

muscles

Fewer __ are active when canines contact during eccentric movements than when posterior teeth contact lower level of muscular activity would decrease forces to the dental and joint structures.

group function

If canine guidance is not possible, the acceptable alternative is __.

Group function

Multiple contact relations between the maxillary and mandibular teeth in lateral movements on the working side whereby simultaneous contact of several teeth acts as a group to distribute occlusal forces.

posterior

In group function Any laterotrusive contacts more __ than the mesial portion of the first molar are not desirable because of the increased amount of force that

can be created as the contact gets closer to the fulcrum (TMJ).

canines and the premolars

In group function The contacts are on the __

disocclude

The laterotrusive contacts (either canine guidance

or group function) need to provide adequate

guidance to __ the teeth on the opposite

side of the arch (mediotrusive or nonworking

side).

Mediotrusive

__ contacts (interferences) can be

destructive because of the amount and

direction of the forces

anterior guidance

During protrusive movement the anterior teeth can best receive and dissipate the forces. Unlike posterior teeth, anterior teeth are in proper position to accept

the forces of eccentric mandibular movements. Therefore during protrusion, the anterior and not the posterior teeth should contact. The anterior teeth should provide adequate contact or guidance to disarticulate the posteriors,

which is called __

Posterior teeth:

Static loading and vertical forces

Anterior teeth:

__ dynamic loading and horizontal forces

Posterior teeth:

Function effectively in forces applied during closure of the mouth, primarily

because their position in the arch is such that the force can be directed through their long axes and thus dissipated efficiently.

Anterior teeth:

Unlike posterior teeth, anterior teeth are in proper position to accept the

forces of eccentric mandibular movements

Bilateral occlusion

The ability of ornithopods to chew on both sides of the mouth at the same time is referred to as: