Support, design and occlusal considerations for distal extension base partial

denture

Arjun Dhiman

Content Introduction

SupportFactors affecting support for distal extension

partial denture

Design for distal extension base

Occlusion for distal extension base

Introduction Class I: bilateral edentulous areas

located posterior to the natural teeth

Class II: a unilateral edentulous area located posterior to the remaining natural teeth

Class III: A unilateral edentulous area with natural teeth remaining both anterior and posterior to it

Class IV: A single, but bilateral (crossing the midline), edentulous area located anterior to the remaining natural teeth

Tooth supported

Class III

Class IV

Class VI

How a distal extension base differs from tooth borne partial denture?

Support

Method of impression registration

Need for indirect retention

Need for relining

SUPPORT Resistance to the vertical

components of masticatory force which prevents the partial denture from being displaced toward the soft tissue

Provided by the occlusal rest and residual ridge

Support for distal extension base

TOOTH-TISSUE SUPPORTED.

Tooth support: occlusal rest on the abutment tooth. The tooth should be engaged in such a

manner that prosthesis framework promotes axial loading since teeth provides most effective resistance when stressed along the long axis.

In distal extension the denture becomes increasingly tissue supported as the distance from the abutment increases.

Closer to abutment , more of the occlusal load is transmitted to the abutment tooth by means of rest.

Factors influencing the support of a distal extension base

Contour and

quality of

residual ridge

Extent of residual

ridge coverage by the denture

base

Type and accuracy

of the impressi

on registrati

on

Accuracy of fit of the

denture base

Design of rpd

framework

Total occlusal load applie

d

1) Contour And Quality Of Residual Ridge

Ideal ridge:Cortical bone covering dense cancellous bone

withBroad rounded crestHigh vertical slopesCovered by firm, dense, fibrous CT

Easily displaceable tissue will not adequately support a denture base, and tissue that is interposed b/w sharp, bony residual ridge and denture base will not remain in healthy state.

Nature and positional relation of bone to the direction of forces both are important for optimum support.

Lining mucosa restricts

both lingual and buccal

mucosa adjacent to

teeth in mandible

Loss of firm mucosa

overlying RR

following tooth

extraction in posterior mandible

Pressure placed over

crest results in

irritation of tissue and

chronic inflammatio

n

Therefore crest

cant be primary

sress bearing

area,

Buccal shelf

area is better

suited for support

MandibleCREST CANCELLOUS

Buccal shelf region

Bounded by :External oblique ridgeCrest of ridge

Better suited for primary stress bearing area:Relatively firm, dense, fibrous

CT supported by cortical bone.Bears more of a horizontal

relationship to vertical forces

Maxilla

Oral tissues – firm , dense nature (similar to mucosa of hard palate)

Topography of a partially edentulous area poses restriction on selection of primary stress bearing area

Crestal area- primary stress bearing area

Some resistance is provided by buccal and lingual slopes of the ridge.

Palatal tissue– dispaceable – cant be primary stress bearing area.

CREST CANCELLOUS

2) Extent of residual ridge coverage by the denture base

Time-honored Principle: base should cover as wide as area as the limiting structures will permit & that the patient can comfortably tolerate

Supported by the Snow Shoe Principle : broader coverage furnishes the best support with the least load per unit area

Kaires stated ‘max coverage of denture bearing area with large , wide denture bases is of utmost importance in withstanding both horizontal and vertical stresses

Maxillary distal extensionFull coverage base extending to cover the

tuberosity & hamular notches Posterior border: taper towards tissues; beveledTermination on tissues that are resilient but not

movableTissue surface should be lightly beaded if in

metal & post - dammed if in acrylicMetal finished lines- sharp straight junction with

no overlapping of acrylicBuccal flange should extend into vestibular

fornix Anterior border of labial flange taper

posteriorly; beveled

2mm in thickness, rounded and smooth

Labial flange properly contoured; festooning

Extension of mandibular distal extension base

T.Fischer and W.D. Sweeney – total area of maxilla capable of support 1.6 times mandible

Should extent to cover retromolar pads distally and laterally to include the buccal shelf

Lingual flange : vertically downwards into alveolingual sulcus.

Distolingual flange extended laterally into retromylohyoid space; beveled.

Concave to allow adequate tongue space

Height : anatomy of mylohyoid ridge.

Labial and buccal extensions : mucosal reflections.

3) Need for special impression techniques

Support derived – tooth + residual ridge

Two forms of residual ridge – anatomic & functional

Difference in stress bearing capacity of different areas of residual ridge

Difference in resiliency

Anatomic Functional

Record teeth in anatomic form & residual ridge in functional form

Dual impression technique

Situations indicated for Dual impression

Displacement of soft tissue covering the ridge is more – mandibular foundation

Limited denture bearing area requiring proper recording of the peripheral extension –mandibular distal extension

Long span anterior edentulous ridge (normally including six anterior) – some portion of support must be derived from the ridge

Objectives of dual impression

To distribute the support b/w ridge and the abutment

To minimize the movement of the denture base thereby reducing leverage on the abutment

To obtain a corrected or an altered master cast

Types of Dual impression techniques

Physiologic or functional

Selective tissue placement impression techniques

Records the ridge by placing occlusal load on impression tray

McLean’s & Hindel’s

Functional relining

Fluid wax technique

Not only equalizes support but has an added advantage of directing forces to areas most capable of withstanding the force

Providing relief in selective areas of the impression tray

4) Accuracy of fit of denture base

Support enhanced by intimate contact basal seat area

Tissue surface must represent the true negative of basal seat of master cast.

6) Total occlusal load applied

Determine amount of support required

Denture base opposed by full complement of natural teeth or if edentulous span is long increase support is required.

We can narrow the occlusal table

To increase the masticatory efficiency supplemental groove and sluiceways can be made less force will be transmitted to the ridge

orient the food bolus over natural teeth rather than prosthetic teeth, because:

More stable nature of natural dentition

Proprioceptive feedback they provide for chewing

Nociceptive feedback from the supporting mucosa.

5)Design of the removable partial denture

Movements of distal extension base

The requirements for movement control are generally functions of whether the prosthesis will be tooth supported or tooth-tissue supported.

For tooth supported prosthesis the movement potential is less because teeth provide resistance to functional loading.

For tooth – tissue supported removable partial denture , the residual ridge presents a quite variable potential for support.

Systematically developed and outlined on diagnostic cast:

From where prosthesis is supported?

How the support is connected?

How the prosthesis is retained?

How retention and support are connected?

How the edentulous base is connected?

I ) Support for Prosthesis

Distal extension tooth-tissue supported

Consider abutment tooth condition:Pdl health

Crown-to-root ratio

Crown and root morphologies

Bone index area

Location of tooth in the arch

Relation of tooth to other support units opposing dentition.

If tooth and tissue supported.

Also Consider Residual ridge condition: 6 factors

Denture base area adjacent to abutment teeth are primarily tooth supported , as we proceed farther away it becomes tissue supported.

it is necessary to incorporate characteristics in the partial denture that will distribute the functional load equitably b/w the abutment teeth and supporting tissue of the edentulous ridge.

II) Connect the support

These connection is facilitated by designing and locating major and minor connectors in compliance with the basic principles and concepts.

Major connector• connection• Retention of denture

by means of extensive tissue coverage

Minor connector• Join rests and clasp

to saddles• Bracing and

reciprocation in case of RPI concept

III) Determine how the partial denture is to be retained.

Select clasp design that will 1. Avoid direct transmission of tipping &

torquing forces to the abutment2. Accommodate the basic principles of clasp

design by definitive location of components parts correctly positioned on abutment tooth surfaces.

3. Provide retention against reasonable dislodging forces.

4. Be compatible with undercut locations, tissue contour, and esthetic desires of the patient.

IV) Connect retention and support

Through major and minor connector

V) Connect edentulous baseOutline and join the edentulous area to already

established design components.

Components of partial design

3 Essentials of design:Support

Connectors

Retainers

In addition, in distal extension base, provision should be made for:

Impression technique:

Method of direct retention : should be such that it transfers the load directly along the long axis of abutment teeth.

Indirect retainer

Support : resistance to vertical force.

During function , force is transmitted through saddles of partial denture and is ultimately resisted by the bone.

On the abutment teeth force is transmitted to bone via teeth and pdl, while in area of tissue support forces are transmitted to bone via mucosa.

Rest and rest seatsRest: A rigid extension of fixed or

removable partial denture which contacts a remaining tooth to dissipate horizontal or vertical forces

Rest seat: That portion of a natural tooth or cast restoration of a tooth selected or prepared to receive an occlusal, incisal, or lingual rest

The primary purpose of rest is to provide vertical support for the partial denture.

Maintains components in their planned positions

Maintains established occlusal relationships by preventing settling of the denture

Prevents impingement of soft tissue

Directs and distributes occlusal loads to abutment teeth

Basic guidelines for design:

Floor of rest seat preparation must be less than 90 degrees with long axis of tooth as this design grasps the tooth to prevent its migration

Preparation should be saucer shaped without any sharp angles and ledges.

Rest should be free to move within the rest seat to release the stresses which would otherwise transmit to the tooth

More the no. of teeth that bear rest seats, the less will be the stress places on each individual tooth.

Connectors

1) Connectors: major and minor connector

Major connector

•Component of partial denture that connects the parts of prosthesis located on one side of the arch with those on the other side.•It provides cross arch stabilization

Minor connector

•Arise from the major connector and join it with other parts of the denture

Major connector Location:

MC should be free of movable tissue

Impingement of gingival tissue should be avoided

Bony and soft tissue prominences should be avoided during placement and removal.

Relief should be provided beneath a major connector to prevent its settling into areas of possible interference, such as inoperable tori or elevated median palatal sutures.

MC should be located and or relieved to prevent impingement of tissue because the distal extension denture rotates in function.

The part of the framework adjoining the tooth surface should be hidden in embrasures to avoid discomfort

Design considerations of major connectors:

Intentional relief: maxillary-6mmmandibular-3mm

Borders should be parallel to gingival margins

Metal framework should cross the gingival margin at right angle only

Design procedures for maxillary major connector (Blatterfien 1953)

Step 1: primary stress bearing areas that are to be covered by denture base are marked

Step 2: relief areas are marked

Step 3: connector areas are outlined to designate areas that are available to place components of major connector

Step 4: selection of connector type

Step 5: unification

Design of mandibular major connectors:

Step 1: outline the basal seat areas

Step 2: Outline the inferior border of the major connector

Step 3: superior border

Step 4: connect the basal seat area to borders , and add minor connectors

Criteria of selection.

1. Requirement for indirect retention

2. horizontal stability and stress distribution.lingual plate and double lingual bar

3. Anatomic considerations:lingual tori,lingual frenum, interproximal spaces

4. Esthetics

5. Phonetics considerations

6. Patient preference factor.

Minor connector

Minor connector should be rigid for distribution of forces

Should not be bulky

When minor connector is present between two teeth,

it should be triangular and occupy minimum space

Junction of major and minor connector should be rounded

Metal surface towards tongue should be beveled.

contacts the guiding plane surfaces of the abutment teeth ,

An open lattice or ladder type of design is preferable and is conveniently made by using preformed 12 guage round wax strips.

MiC for mandibular distal extension base should extend posteriorly about 2/3rd length of the edentulous ridge and have elements on both lingual and buccal surface.

Add strength and minimize distortion of cured base It should not interfere with the arrangement of artificial teeth.

Form and location:

It should be located in embrasure where it will be least noticeable to the tongue

It should be thickest towards the the lingual surface, tapering towards the contact area

Retainers Direct retainer

Indirect retainer

Direct retainersA direct retainer is any unit of a removable

partial denture that engages on abutment tooth in such a manner as to resist displacement of the prosthesis away from basal seat tissues

Direct retainers for distal extension cases:

To retain prosthesis against reasonable dislodging forces without damage to abutment teeth

To aid in resisting any tendency of the denture to be displaced in horizontal plane

Must also be able to flex or disengage when denture base moves tissue ward under function. Thus the retainer may act as a stress breaker

Round, tapered clasp forms or combination circumferential clasp or a bar clasp can be used.

Tripod configuration

Used primarily for class 2 arches.

One clasp on the Dentulous side of the arch should be positioned as far posterior, and the other, as far anterior as factors such as interocclusal space, retentive undercut, and esthetics considerations will permit.

Bilateral configuration

Used in class 1 cases. In this configuration the

clasps exert little neutralizing effect on the leverage induced stresses generated be the denture base. These stresses must be controlled by other means.

The terminal abutment tooth on the each side of the arch must be clasped regardless of where it is positioned.

Quadrilateral configuration

Is indicated in class 3 arches particularly when modification space exists on the opposite side.

A retentive clasp is positioned on each abutment tooth adjacent to the edentulous spaces.

In this design leverage is effectively neutralized.

Forces acting on abutment teeth

A typical design of a distal extension base ( DEB)

- distoocclusal rest

- clasp arm in mesiobuccal undercut

Vertical component of occlusal load distal to long axis of tooth - distal tilting.

Accentuated by clasp arm in mesial undercut – “ bottle opener principle”.

Distal extension base

Moreover the proximity of the rest to the denture base results in base rotating around a small radius with fulcrum away from COR of the abutment – Steffel.

Mesial occlusal rest produces a more favorable fulcrum point closer to the COR and rotation around a larger radius.

Nally (1963) Thompson, Kratochvil and Caputo (1977) evaluted stress patterns and concluded:1. Clasp with mesial rest, buccal I-bar/ wrought wire

and cast lingual arm : most favourable stress distribution.

2. Distal rests tilts abutments distally and roots mesially : horizontal forces in bone.

3. Mesial rests transmit forces in a more vertical direction.

4. Distal rests : > horizontal forces on abutment.

- So, combination circumferential clasp or a bar clasp can be used.

Box & Synge -PDL is better able to withstand vertical forces directed along the long axis of abutment tooth than the horizontal forces as > PDL fibers are activated in resisting vertical forces than the off-vertical forces

RPI CONCEPT

Rest, Proximal Plate & I bar concept

Kratochvil developed a concept for an innovative clasp assembly in the early 1960’s

They are

An occlusal rest arising from a minor connector on the side of abutment away from edentulous space

An I-shaped bar clasp retaining arm placed midbuccally on the abutment

A vertical plate contacting the distal and distolingual surfaces of the abutment adjacent to the development space

PurposeThis clasp configuration was designed to allow

extension base removable partial denture some degree of tissue ward rotational freedom without torque to the clasped teeth

Krol made certain modifications in the design of the proximal plate and supplied a name:

RPI bar clasp design

Thus a new system of bar clasp for removable partial denture came into being

Indirect retainers The component of removable partial denture that assists

the direct retainer in preventing displacement of the distal extension denture base by functioning through lever action on the opposite side of the fulcrum line when the denture base moves away from the tissues in pure rotation around the fulcrum line.

Indirect retainer also contributes to a lesser degree, to the support and stability of the denture.

Imaginary Axis of rotation =fulcrum line

Formed at terminal abutment axis (line joining 2 posterior most rests)

The primary fulcrum line on distal extension partial dentures, is an imaginary line passing through the most distal rest seat (of a tooth) on each side of the arch.

If the denture base extends mesially, the primary fulcrum line passes through the most mesial rest seat on each side of the arch.

Class 1.

It must always be used and positioned as far anteriorly as possible.

Class 2

its use is not as critical as in class 1

An abutment tooth with suitable contours for clasping should be selected as far anterior on the tooth-supported side as possible.

This rest and clasp assembly, may serve as the indirect retainer if it is located far enough anterior to the fulcrum line.

If modification space exists-

The most anterior abutment on the tooth supported side, with its rest and clasp assembly, may be located far enough anterior to the fulcrum line to serve as the indirect retainer.

A definite rest seat positioned even farther anterior ,if possible, may increase the effectiveness of the indirect retention.

Denture base

denture base should cover maximum area of the supporting tissue as possible

Denture base flanges should be as long as possible-to help stabilize against horizontal movements

Distal extension denture base should cover the retro molar area and tuberosity of maxilla as these structures better absorb stress

Overextension should be avoided as interference with functional movements of surrounding tissues will transmit stresses to the remaining teeth

Accurate adaptation of denture base leads to less tendency for movement during function

Contour of the polished surfaces also helps in reducing the stress transmitted.

Stress distribution in a distal extension case depends on:

1. good PDL support with favorable ridge : any retainer with equal distribution of load

2. good PDL support with unfavorable ridge: >stress on abutment

3. poor PDL support with favorable ridge : >stress on ridge therefore a stress releasing type of retainer

4 Poor PDL & ridge support : stress releasing type of retainer to preserve the remaining, teeth as long as possible

Strain on abutment teeth can be minimized

Functional basing

Broader coverage

Harmonious occlusion

Correct choice of direct retainers

Stressbreakers

Stress breakers

A device which relieves the abutment teeth of

all or part of the occlusal forces.” -- GPT.

Concept of stressbreakers came in existence in relation to free- end partial dentures to reduce the torque & load on abutment teeth

Designed to separate the action of retaining elements from the movement of denture base by allowing some movement b/w the two

Types of stress – directors Group I

• With movable joints b/w Direct Retainers and denture base that permit vertical movement, or hinge-type or a combination.

• Devices with hinges, sleeves, cylinders or ball and socket joint.

Group II

• Articulated Partial Dentures – flexible connection b/w the Direct Retainers and denture base is provided.

- Wrought wire connectors

- Divided or split major connectors

- Movable joints b/w two major connectors.

Advantages of stress directors Minimizes horizontal forces to the abutment teeth Intermittent pressure of the denture bases provides physical

stimulation to the underlying tissues Allows splinting of the weak teeth

Disadvantages of stress directors More stresses to the residual ridges Reduced effectiveness of the indirect

retention and cross arch stabilization. Entrapment of the food particles Distortion of the flexible connectors that places more stress on the

abutment teeth Relining frequently needed repair and maintenance costly

Occlusal harmony b/w rpd and the remaining natural teeth is a major factor in the preservation of the health of their surrounding structures.

Harmonious occlusion: Occlusion whereby the masticating mechanisms can carry out its physiologic functions while factors of occlusion remain in state of good health. Factors of occlusion:

TMJNeuromuscular mech.TeethSupporting structures.

Occlusal consideration for distal extension base

The establishment of satisfactory occlusion for the removable partial denture should include the following :Analysis of existing occlusionCorrection of existing occlusal disharmony Recording of centric relation or an adjusted centric

occlusion Recording of eccentric jaw relations or functional

eccentric occlusion Correction of occlusal discrepancies created by the

fit of the framework and in processing the rpd.

EDEC principle for the fabrication of prosthesis is:E- examine pre-existing occlusionD – design the prosthesisE – execute the prosthesis C- check the occlusion at the completion.

Occlusal forms of the teeth of rpd must be made to conform to an already established occlusal pattern.

The only exception are thosein which an opposing complete denture can be made to function harmoniously with the rpd

or in which only anterior teeth remain in both the arches and the incisal relationship can be made so that tooth contacts do not disturb denture stability or retention.

All other types of rpd the remaining teeth dictate the occlusion

Dentist should strive for planned contacts in centric occlusion and no interferences in lateral excursions

Approaches for the establishment of occlusion

Conformative

Reorganized Conformative; occlusion conforms to the

constraints of patients present occlusion scheme.Reorganized approach: occlusion is reorganized to

more ideal occlusionFor the correction of overclosure Gross discrepancy b/w centric relation and maximum

intercuspation position.

Materials for artificial teeth

Posterior teeth may be made of porcelain or resin.

Acrylic resin teeth are generally preferred to porcelain teeth , because they are more easily modified .

Improved acrylic resin teeth with gold occlusal surfaces are preferably used in opposition to natural teeth.

The best combination of opposing occlusal surfaces to maintain the established occlusion and to prevent deleterious abrasion are porcelain to porcelain surfaces gold surfaces to natural or restored natural teeth and gold surfaces to gold surfaces.

Posterior teeth formObjective in rpd occlusion is harmony b/w natural

and artificial dentition .

In cd patient teeth is selected and articulated acc., to dentist of what constitutes the most favourable cd occlusion, whereas rpd denture occlusion must be made to harmonize with an existing occlusal pattern.

Teeth should be narrower b-l and m-d

Artificial Teeth morphologyMonoplane

Semianatomic

AnatomicFor balanced occlusion as in denture opposing

complete denture : anatomic teeth preferred

Methods of establishing occlusion

Functionally generated pathway technique

Articulator or static techniqueSteps:

Analysis of existing occlusionCorrection on existing occlusion disharmony Recording of the functional dynamic occlusion

Functionally generated pathway techniqueProcedure

Pathways of the natural tooth against edentulous span are recorded using occlusal rim by making all functional movements of the mandible

Pathways so generated are poured in improved stone. Each ridge or groove in resulting stone cast represents path of cusp

Setting the teeth in contact with the paths results in functional and harmonious occlusion

Procedure :directly under supervision of dentistAt home, movements performed and evaluated by

dentist after 24 hours

Setting of the artificial teethAt increased vd (1mm)Occlusal adjustments by selective grinding

Advantages: Easy approach Eliminates recording of interocclusal relationship &

transferring to articulators No use of face bow

Disadvantages: Occlusion in one arch must be formulated before other Movement of distal extension base results in inaccurate

recording Verification of pathway is difficult

Static / articulator technique

Determination of vd

Determination of horizontal jaw relationships

Centric relation & intercuspal position coincides with no evidence of occlusal pathology

Posterior teeth missing in both arches so fabrication in centric relation

Face bow transfer allows accurate mounting of upper cast wrt condylar axis, similar to one relation which exists b/w maxilla & hinge axis

Indication: when multiple posterior teeth are missing in one or both arches face bow transfer eliminates error in establishing occlusion

Methods for establishing occlusal relationships

Direct opposition of casts. Interocclusal records with posterior teeth remainingOcclusal relations using occlusal rims on record

bases Jaw relations records made entirely on occlusion

rims

Direct opposition of casts.Advantages:

Less clinical appointmentsBetter than recording of inaccurate wax record

Limitations:Exaggerates existing Occlusal disharmony

Interocclusal records with posterior teeth remaining

Most common

Least accurate

Interocclusal wax record errors- during or after removal from mouth,

chances of distortion a wax contacts mucosal surfaces can distort soft

tissues resulting in inaccurate seating over stone cast

Wax record should be corrected with bite registration paste- final recording medium

Occlusal relations using occlusal rims on record bases

Record bases- stable & accurate

Material : vlc., self cure acrylic, cast metal, compression

moulded/ processed acrylic

Record made with Soften wax occlusion rimsQuick setting impression plasterBite registration pasteAuto polymerizing resin

Jaw relations records made entirely on occlusion rims

Indication:No opposite natural tooth contacts e.g.. Maxillary

complete denture opposite mandibular distal extension bases.

No interocclusal material is added.

Arrangement of posterior teeth

Simultaneous bilateral contacts of opposing posterior teeth must occur in centric occlusion.

Maxillary Complete Denture Opposes The Removable Partial Denture.

Bilateral balanced occlusion in eccentric positions

However simultaneous contacts in a protrusive relationship do not receive priority over appearance , phonetics, and or a favourable occlusal plane.

Mandibular Distal Extension Denture

Working side contacts.

These contacts should occur simultaneously with working side contacts of the natural teeth to distribute the stress over the greatest possible area

Maxillary Bilateral Distal Extension

Rpd opposing mandibular distal extension base or natural teeth Simultaneous working and balancing

contacts should be formulated for the whenever possible.

The Maxillary Or Mandibular Unilateral Distal Extension Rpd Only working contacts need to be formulated for

either. Balancing side contacts won’t enhance stability of the denture ‘coz it is entirely tooth supported by the framework on balancing side.

Balanced contact of opposing posterior teeth in a straightforward protrusive relationship and functional excursive positions is desired only when an opposing complete denture or bilateral distal extension maxillary rpd is placed.

Artificial teeth should not be arranged farther distally than the beginning of a sharp upward incline of the mandibular residual ridge or over the retromolar pad.

Design Principles for distal extension cases

For Class I

1. Clasps

2 clasps on each terminal tooth are sufficient.

For distobuccal undercut a vertical projection clasp is indicated

For mesiobuccal undercut wrought wire clasp.

Reciprocal arm should be rigid. Can also be replaced with lingual plate.

Summary

For Class II

1. Clasps

Usually 3 clasps are designed.

The distal extension side can be designed similar to Class I

The tooth supported, or modification side should have two retentive clasps:

For Class I and II

2. Rests

For maximum possible support.

Designed for direction of stress in a direction along the long axis of the tooth.

Should always be placed on the tooth adjacent to the edentulous area.

For Class I and II3. Indirect Retention

Location: as far anterior to the fulcrum line

2 indirect retainers for Class I situation, and 1 on the on the opposite side as the edentulous area in Class II is sufficient.

Lingual plate with rest seats is an efficient retainer.

For Class I and II

4. Major Connector

Must be rigid and not impinge on soft tissue.

Maxillary: support from hard palate whenever possible.

Mandibular: lingual plate for increased rigidity, indirect retention and elimination of areas of food impaction.

5. Minor Connector

Rigid

Positioned to enhance comfort, cleanliness, and placement of artificial teeth

6. Occlusion

Centric relation and occlusion should coincide.

Artificial teeth should be positioned to reduce stress.

Positioned to enhance comfort, direction of stress along long axis, and efficiency of mastication.

7. Denture Base

Broad coverage for equal stress distribution.

Borders should not interfere with the functional movements of the tissues.

Selective pressure technique is indicated for edentulous space

References McCrackens Removable Partial Denture – Alan

B. Carr, Glen P. McGivney

Clinical Removable Partial prosthodontics – Stewart , Rudd,Kuebker