INDEX

introduction

The establishment of satisfactory occlusion for RPD

Desirable occlusal contact relationship for removable partial denture

Method for establishing occlusal relationship

Why to record jaw relation ?

General consideration in occlusion for RPD

conclusion

Definition of Occlusion

Occlusion, means simply the contact

between teeth. More technically, it is the

relationship between the maxillary

(upper) and mandibular (lower) teeth

when they approach each other, as

occurs during chewing or at rest.

Centric relation

It is the relation of the mandible to maxilla

when the mandible in the most retruded

unstrained position and the condyle articulate

with the thinnest avascular portion of the

articular disc.

Eccentric relation

Any relation other than centric, like

protrusion and lateral movement

Protrusion movement

During protrusive movement the posterior

guidance system of the mandible is provided

by the temporomandibular joints.

Anterior guidance is provided by whichever

teeth touch during eccentric movements of

the mandible. It can be the incisors or

premolar in case of anterior open bite.

Lateral movement

Working side: Toward which the mandible

moves.

Balancing or non working side: away from

which the mandible moves

Lateral Movement

Balanced Occlusion:

Where there is simultaneous contact between the upper and lower teeth, anterior and posterior, left and right, during centric and eccentric movement.

Non balanced occlusion:

Where the contact between the upper and lower teeth is only during centric movement.

Occlusal Relationship for RPD

The fourth phase in the treatment of patients with RPD is the establishment of functional and harmonious occlusion.

Occlusal harmony between a removable partial denture and remaining natural teeth is a major factor in preservation of the health of their surrounding structures.

Failure to provide and maintain

adequate occlusion on RPD is result

of:

1. Lack of support for denture base,

2. The fallacy of establishing occlusion to a single

static jaw relation record,

3. An unacceptable occlusal plane .

The establishment of satisfactory occlusion of

RPD patients should include the following:

1) Analysis of the existing occlusion

2) Correction of the existing occlusal disharmony.

3) The recording of centric relation or an adjusted

centric occlusion.

4) Recording of eccentric relation or eccentric

occlusion.

5) Correction of occlusal discrepancies created by the

fit of the framework or during processing of the

denture.

Desirable occlusal contact

relationship for RPDs

The following occlusal arrangements are

recommended to develop a harmonious

occlusal relationship of RPD and to enhance

stability of RPD:-

Desirable occlusal contact

relationship for RPDs

Simultaneous bilateral occlusal contact of

opposing posterior teeth should be present

when the patient in centric occlusion

Desirable occlusal contact

relationship for RPDs

Occlusion for tooth supported

RPD(Kennedy Class??) may be arranged

similar to the occlusion seen in natural teeth,

since stability results from the direct

retainers at both ends of the denture

Desirable occlusal contact

relationship for RPDs

For lower PD opposed by upper CD,

bilateral balanced occlusion should be

formulated in both centric and eccentric

positions to promote stability of the CD.

Desirable occlusal contact

relationship for RPDS

5.In Class I mandibular opposed by class I

maxillary bilateral balance occlusion is

needed.

Balanced contact of opposing posterior teeth in

a protrusive or lateral positions is desired

only when an opposing CD or bilateral distal

extension maxillary RPD is placed.

Desirable occlusal contact

relationship for RPDS Class I mandibular PD opposed by upper

natural dentition:

In working side there must be contact to distribute the stresses over the greatest possible area in order to improve the masticatory function.

In balancing side and in protrusion there must be no contact to achieve stability of the PD.

Desirable occusal contact

relationship for RPDS

For class II (maxillary or mandibular)

opposed by natural dentition, unbalanced

occlusion is needed.

In working side there must be contact

Balancing side contact will not enhance

stability since it is entirely tooth supported by

the framework.

Desirable occusal contact

relationship for RPDS

In class III mandibular PD opposed by class

III maxillary PD:

Working side contacts are required.

Balancing and protrusive contacts are not

required since it is tooth borne PD.

Desirable occusal contact

relationship for RPDS In class IV RPD opposed by natural teeth:

Contact is required in centric position between anterior teeth to prevent over-eruption of the natural teeth.

Avoid anterior contact during eccentric position to eliminate the unfavourable forces to the opposing ridge, and to enhance the stability of the RPD.

Methods for establishing occlusal

relationships

Occlusal relationship may be established

by use of the most appropriate of the

following methods to fit a particular

partially edentulous situation:-

Direct apposition of casts

The first method is used when there are sufficient opposing teeth remain in contact to make the existing jaw relationship obvious .

In this method, opposing casts may be occluded by hand.

The occluded casts should be held in apposition with rigid supports attached with sticky wax to the bases of casts until they are securely mounted in the articulator.

Occlusal analysis and the correction of any

existing occlusal disharmony should

preceded the acceptance of such jaw

relation record.

Interocclusal records with

posterior teeth remaining

Second method, which is modification of

the first , is used when sufficient natural

teeth remain to support RPD (Kennedy

class III or IV), but the relation of

opposing natural teeth does not permit

the occluding of casts by hand. In such

situations, jaw relations must be

established by use some type of

interocclusal record.

Technique:

Place softened wax wafer between teeth & patient is guided to close in centric relation( correct closure must be examined before wax placement)

Wax removed, chilled in water & examined

Layer of ZnO impression paste/ quick setting applied over wax record, to correct occlusal record

Record is placed between upper & lower casts.

Occlusal relations using

occlusion rims on record bases

A third method is used when:

one or more distal extension areas are ,

present .

when a tooth –supported edentulous

space is large.

or when opposing teeth do not meet. In

these instances, occlusion rim on

accurate jaw relation bases must be

used.

Technique:

Necessitates accurately adapted record bases to help support occlusal record

Base may be shellac, acrylic resin, metallic framework

Softened wax occlusion rim is used, which is made out of contact but keeping a stop to maintain vertical dimension

An interocclusal record material (ZnO eugenol, self cure acrylic resin or quick setting plaster) is used to record occlusal relationship

Jaw relation records made

entirely on occlusion rims

The fourth method is used when there is no contact between remaining natural teeth e.g;

maxillary CD opposed by mandibular PD

Maxillary Class I denture opposed by lower anterior natural teeth

Or when remaining natural teeth are few & do not occlude

Jaw relation records in these cases are the same as for CD

Functional generating path

method (dynamic occlusion)

This technique produces an occlusion

that is in functional harmony with facial

skeleton, the musculature, the TMJ &

the remaining natural teeth

Each tooth opposed to the edentulous

space makes all the functional

movements of the mandible

Construct an acrylic denture base attached to metallic framework

Occlusion rim wax must have enough height & width to record all extremes of mandibular movement

There must be positive occlusal contacts with opposing dentition in order to avoid loss in vertical dimension

Patient wears occlusion rim constantly for 24 hrs, including night except removal at meals, to curve wax by opposing teeth

Why to Record the Jaw Relations ?

The goal in developing an occlusal scheme

for a removable partial denture is to establish

and maintain a harmonious relationship with

all oral structures, and to provide a

masticatory apparatus that is efficient and

esthetically acceptable.

Why to Record the Jaw Relations ?

To ensure that all the effects of occlusal

loading be distributed as evenly as possible to

all supporting structures capable of receiving

the force.

To best control the undesirable effects of

rotational or torquing forces on the

prosthesis.

Why to Record the Jaw Relations ?

To prevent any deflective contacts of the

teeth during centric or eccentric closures as

these can produce pathological changes in

the supportive structures or in the

neuromuscular mechanism that controls

mandibular movement.

MATERIAL FOR ARTIFICIAL

POSTERIOR TEETH: •Mostly acrylic resin teeth are generally preferred to porcelain teeth

because, they are nearly resemble enamel in their abrasion potential against opposing teeth

• Improved acrylic teeth with gold occlusal surface are mostly preferred to opposition of natural teeth restored with gold occlusal surfaces.

• Porcelain teeth are generally used in opposition to other porcelain teeth.

• Acrylic resin tooth surface become impregnated with abrasive particles, so act as abrasive surface itself so resin teeth some time capable of wearing opposing gold surface.

• There should be reduced buccolingual width of posterior teeth. • A acrylic resin teeth are easily modified and easily lend themselves to construction of cast gold surface on their occlusal gold surface.

General considerations in occlusion of

RPD

Avoid placing artificial teeth over

retromolar pad area to avoid shunting of

the denture anteriorly

General considerations in occlusion of

RPD

In mandibular distal extension buccal cusps

should be positioned on the buccal turn of

the crest of the ridge to direct the stresses

toward the buccal shelf of bone which is the

primary stress bearing area.

General considerations in occlusion

of RPD

Positioning of the maxillary buccal cusps

slightly buccal to the ridge, which is an

unfavourable condition, but it will be

counteracted by the direct retainer on the

other side of the PD.

General considerations in occlusion

of RPD

Using of narrow artificial teeth

buccolingually, or small teeth in order to

minimize the forces transmitted to the

underlying tissue.

CONCLUSION

The balanced occlusion is the most important factor for the retention

of the prosthesis.

The occlusion must be evaluate before the prosthesis fabrication start.

Proper method to be used for the record of correct occlusion.

Imbalanced occlusion is the main cause of retention loss of the prosthesis.

McCracken’s removable partial prosthodontics

Stewart’s Cinical Removable Partial Prosthodontics

Thank you