Removable partial denture

REMOVABLEREMOVABLE
PARTIAL DENTUREPARTIAL DENTURE
RPDs are components ofRPDs are components of
prosthodontics ( branch of Dentistry)prosthodontics ( branch of Dentistry)
pertaining to the restorations andpertaining to the restorations and
maintenance of oral function, comfort,maintenance of oral function, comfort,
appearance, and health of the( pt) byappearance, and health of the( pt) by
replacement the missing teeth andreplacement the missing teeth and
craniofacial tissues with artificialcraniofacial tissues with artificial
substitutesubstitute..
theoptimalsmile.wix.comtheoptimalsmile.wix.com

The Basic Objectives ofThe Basic Objectives of
prosthodontic Treatmentprosthodontic Treatment
1.1. Elimination of oral disease.Elimination of oral disease.
2.2. Preservation of the health andPreservation of the health and
relationship of the teeth, and the healthrelationship of the teeth, and the health
of the oral andof the oral and para-oral structure.para-oral structure.
3.3. Restoration of oral function (comfort,Restoration of oral function (comfort,
esthetic, speech).esthetic, speech).

Consequences of ToothConsequences of Tooth
LossLoss
1.1. AestheticsAesthetics
2.2. Speech.Speech.
3.3. Drifting, tilting, over-eruption.Drifting, tilting, over-eruption.
4.4. Loss of masticatory efficiency.Loss of masticatory efficiency.
5.5. Loss of vertical dimension.Loss of vertical dimension.
6.6. Deviation of mandible.Deviation of mandible.
7.7. Loss of alveolar bone.Loss of alveolar bone.

 P.D may:P.D may:
1.1. Give support to periodontally diseased teeth.Give support to periodontally diseased teeth.
2.2. Restore vertical facial dimension.Restore vertical facial dimension.
3.3. Prevent T.M.J problems.Prevent T.M.J problems.
4.4. Prevent tooth drifting or over eruption.Prevent tooth drifting or over eruption.
5.5. Stimulate non-used tissues.Stimulate non-used tissues.
6.6. Support collapsed structure (muscles of lipsSupport collapsed structure (muscles of lips
and cheeks).and cheeks).
7.7. Prevent attrition of remaining teeth.Prevent attrition of remaining teeth.
8.8. Improve oral hygiene by preventing stagnationImprove oral hygiene by preventing stagnation
of food in disused areas.of food in disused areas.

Classification Of PartiallyClassification Of Partially
Edentulous ArchesEdentulous Arches
 The most familiar classification are thoseThe most familiar classification are those
proposed by Kennedy, Cummer, andproposed by Kennedy, Cummer, and
Bailyn, Beckett,Bailyn, Beckett,……
 The recent classification has beenThe recent classification has been
proposed for partial edentulism that isproposed for partial edentulism that is
based on diagnostic criteria.based on diagnostic criteria.

Requirement Of an AcceptableRequirement Of an Acceptable
Method Of ClassificationMethod Of Classification
1.1. It should permit immediate visualizationIt should permit immediate visualization
of the type of partially edentulous arch.of the type of partially edentulous arch.
2.2. It should permit immediateIt should permit immediate
differentiation b/w tooth- supported anddifferentiation b/w tooth- supported and
the tooth and tissue-supported.the tooth and tissue-supported.
3.3. Universally acceptable.Universally acceptable.

Kennedy ClassificationKennedy Classification
 4 basic classes.4 basic classes.
 Edentulous areas other than thoseEdentulous areas other than those
determining the basic classes weredetermining the basic classes were
designated as modification spaces.designated as modification spaces.
Class I : Bilateral edentulous areas locatedClass I : Bilateral edentulous areas located
posterior to the natural teeth.posterior to the natural teeth.
Class II : A unilateral edentulous areaClass II : A unilateral edentulous area
posterior to the remaining natural teeth.posterior to the remaining natural teeth.

Kennedy ClassificationKennedy Classification
Class III: Unilateral edentulous area withClass III: Unilateral edentulous area with
natural teeth remaining both ant and postnatural teeth remaining both ant and post
to it.to it.
Class IV : A single, but bilateral (crossingClass IV : A single, but bilateral (crossing
the midline), edentulous area locatedthe midline), edentulous area located
anterior to the remaining natural teeth.anterior to the remaining natural teeth.

Principal AdvantagePrincipal Advantage
 It permits immediate visualization of theIt permits immediate visualization of the
partially edentulous arch and allows easypartially edentulous arch and allows easy
distinction bw tooth-supported versusdistinction bw tooth-supported versus
tooth-tissue supported prostheses.tooth-tissue supported prostheses.

Applegate'sApplegate's Rules forRules for
Applying the KennedyApplying the Kennedy
ClassificationClassification
Rule 1 : The classification should follow, notRule 1 : The classification should follow, not
precede extractions.precede extractions.
Rule 2 : If a 3Rule 2 : If a 3rdrd
molar is missing and not tomolar is missing and not to
be replaced, it is not considered in thebe replaced, it is not considered in the
classification.classification.
Rule 3 : If a3rd molar is present and not toRule 3 : If a3rd molar is present and not to
be used as an abutment, it is notbe used as an abutment, it is not
considered in the classification.considered in the classification.

Applegate'sApplegate's RulesRules
Rule 4 : If a 2Rule 4 : If a 2ndnd
molar is missing and not tomolar is missing and not to
be replaced, it is not considered in thebe replaced, it is not considered in the
classification.classification.
Rule 5 : The most posterior area alwaysRule 5 : The most posterior area always
determines the classification.determines the classification.
Rule 6 : Edentulous areas other than thoseRule 6 : Edentulous areas other than those
determining the classification are referreddetermining the classification are referred
to as modifications and designated byto as modifications and designated by
their No.their No.

Applegate'sApplegate's RuleRule
Rule 7 : The extent of the modifications isRule 7 : The extent of the modifications is
not considered, only the No. of additionalnot considered, only the No. of additional
edentulous areas.edentulous areas.
Rule 8 : There are no modification in ClassRule 8 : There are no modification in Class
IV.IV.

Principal Of Partial DenturePrincipal Of Partial Denture
DesignDesign
 Stresses acting on RPDs are transmittedStresses acting on RPDs are transmitted
to the teeth, and to the tissues of theto the teeth, and to the tissues of the
residual ridges.residual ridges.
 The stresses, which tend to move the PDThe stresses, which tend to move the PD
in different directions are:in different directions are:
1.1. Masticatory stress( Tissue ward movt).Masticatory stress( Tissue ward movt).
2.2. Gravity( Tissue away movt).Gravity( Tissue away movt).
3.3. Sticky food pull the denture occlusalySticky food pull the denture occlusaly
(Tissue-away movt).(Tissue-away movt).

4. Muscles and tongue tend to displace4. Muscles and tongue tend to displace
denture from its foundation.denture from its foundation.
5. Intercuspation of the teeth may tend to5. Intercuspation of the teeth may tend to
produce horizontal and rotationalproduce horizontal and rotational
stresses unless occlusal is adjusted.stresses unless occlusal is adjusted.

Properly Constructed PDProperly Constructed PD
Must HaveMust Have::
1.1. Support: Resistance to vertical seatingSupport: Resistance to vertical seating
forces( provided by teeth and mucosa).forces( provided by teeth and mucosa).
2.2. Retention: Resistance to verticalRetention: Resistance to vertical
displacing forces.displacing forces.
3.3. Stability( bracing) resistance toStability( bracing) resistance to
horizontal and lateral displacement.horizontal and lateral displacement.
 All the above should be within theAll the above should be within the
physiological limits of the tissue involved.physiological limits of the tissue involved.
AA

Designing SupportDesigning Support
a. Tooth support: When abutment teeth availablea. Tooth support: When abutment teeth available
at both ends of the denture base( boundedat both ends of the denture base( bounded
saddle). It most commonly obtained bysaddle). It most commonly obtained by
occlusal rests.occlusal rests.
b. Mucosa support: (mucoperiosteum coveringb. Mucosa support: (mucoperiosteum covering
residual alveolar bone). It allows varyingresidual alveolar bone). It allows varying
degree of displacement.degree of displacement.
 The amount of displacement( tissue wardThe amount of displacement( tissue ward
movt) will depend on:movt) will depend on:
1.1. The amount of pressure applied.The amount of pressure applied.
2.2. The nature of the mucosa (thickness).The nature of the mucosa (thickness).

3. Area covered by the denture( the wider3. Area covered by the denture( the wider
the area the less the displacement).the area the less the displacement).
4. Fit of the denture base.4. Fit of the denture base.
5. Type of impression( anatomical,5. Type of impression( anatomical,
functional, or selective pressure).functional, or selective pressure).
c. Tooth-mucosa support: ( Bilateral freec. Tooth-mucosa support: ( Bilateral free
end saddle).end saddle).
 Posterior tissue support, and anteriorPosterior tissue support, and anterior
tooth support.tooth support.

Designing RetentionDesigning Retention
 Retention should be designed to counter actRetention should be designed to counter act
dislodging forces( sticky food, muscle atdislodging forces( sticky food, muscle at
periphery of the denture, intercuspation, gravity).periphery of the denture, intercuspation, gravity).
 Retention is gained by mechanical meansRetention is gained by mechanical means
1. direct retainers:1. direct retainers:
a. Intercoronal( clasps).a. Intercoronal( clasps).
b. intracronal(percision attachment).b. intracronal(percision attachment).
2. Indirect retainers.2. Indirect retainers.

 Physical factors( cohesion, adhesion,Physical factors( cohesion, adhesion,
atmospheric pressure, surface tension). itatmospheric pressure, surface tension). it
play a minor role RBD.play a minor role RBD.

Designing Bracing and StabilityDesigning Bracing and Stability
 Bracing( providing resistance to lateralBracing( providing resistance to lateral
movt.of RBD).movt.of RBD).
 Causes of tipping, rocking andCauses of tipping, rocking and
rotation of P.D.rotation of P.D.
1.1. Quality of supporting structure.Quality of supporting structure.

2. The tissue-ward movt.2. The tissue-ward movt. Of the free endOf the free end
base create an axis of rotation aroundbase create an axis of rotation around
which this appliance is rotated.which this appliance is rotated.
This axis of rotation is called a fulcrum lineThis axis of rotation is called a fulcrum line
(it is imaginary line extending between(it is imaginary line extending between
the two main abutment.the two main abutment.

How to counteract lateral shifting?How to counteract lateral shifting?
1.1. Bracing the sides of the teeth by meansBracing the sides of the teeth by means
of rigid clasp arms.of rigid clasp arms.
2.2. Use of continuous bar resting on theUse of continuous bar resting on the
lingual surfaces of the natural standinglingual surfaces of the natural standing
teeth.teeth.

Components Of RPDsComponents Of RPDs
1.1. Major connectors.Major connectors.
2.2. Minor connectors.Minor connectors.
3.3. Rests.Rests.
4.4. Direct retainers.Direct retainers.
5.5. Stabilizing or reciprocal componentsStabilizing or reciprocal components
(part of clasp assembly).(part of clasp assembly).
6.6. Indirect retainers( if prosthesis has distalIndirect retainers( if prosthesis has distal
extension).extension).

Major ConnectersMajor Connecters
 Major connector is component of the PDMajor connector is component of the PD
which connect all parts of the prosthesiswhich connect all parts of the prosthesis
directly or indirectly.directly or indirectly.
 It provides the cross-arch stability to helpIt provides the cross-arch stability to help
resist displacement by functional stresses.resist displacement by functional stresses.

Characteristics Of MajorCharacteristics Of Major
ConnectorsConnectors
1.1. Made from material compatible with oralMade from material compatible with oral
tissue.tissue.
2.2. It is rigid.It is rigid.
3.3. Doesn't alter the natural contour of theDoesn't alter the natural contour of the
lingual surfaces of the mandibularlingual surfaces of the mandibular
alveolar ridge or of the palatal vault.alveolar ridge or of the palatal vault.
4.4. Doesn't impinge on oral tissue inDoesn't impinge on oral tissue in
(insertion, withdrawal. Or in function).(insertion, withdrawal. Or in function).

6. Cover no more tissue than is absolutely6. Cover no more tissue than is absolutely
necessary.necessary.
7. Doesn't contribute to the trapping of food7. Doesn't contribute to the trapping of food
particles.particles.
8. Has support from other elements of the8. Has support from other elements of the
frame work to minimize rotation inframe work to minimize rotation in
function.function.
9. Contribute to the support of the9. Contribute to the support of the
prosthesis.prosthesis.

Mandibular Major ConnectorsMandibular Major Connectors
1.1. Lingual bar.Lingual bar.
2.2. Linguoplate.Linguoplate.
3.3. Sublingual bar.Sublingual bar.
4.4. Lingual bar with cingulum bar (continuous bar).Lingual bar with cingulum bar (continuous bar).
5.5. Cingulum bar (continuous bar).Cingulum bar (continuous bar).
6.6. Labial bar.Labial bar.
 Lingual bar and Linguopslate are mostLingual bar and Linguopslate are most
common used.common used.

1.1. Mandibular lingual BarMandibular lingual Bar
 Indication: Where sufficient space existIndication: Where sufficient space exist
b/w elevated alveolar lingual sulcus andb/w elevated alveolar lingual sulcus and
the lingual gingival tissue.the lingual gingival tissue.
 Location:Location:
1.1. Half-pear shaped, with bulkiest portionHalf-pear shaped, with bulkiest portion
inferiorly.inferiorly.
2.2. Superior border tapered, located at leastSuperior border tapered, located at least
4mm inferior to gingival margin.4mm inferior to gingival margin.

4. Inferior border located at site of the4. Inferior border located at site of the
alveolar lingual sulcus where the ptalveolar lingual sulcus where the pt´s´s
tongue is elevated.tongue is elevated.
 Finishing line: Butt-type joints with minorFinishing line: Butt-type joints with minor
connector for retention of denture base.connector for retention of denture base.

22..Mandibular Sublingual BarMandibular Sublingual Bar
 It is modification of lingual bar used whenIt is modification of lingual bar used when
the existing space not allow placement ofthe existing space not allow placement of
lingual bar.lingual bar.
 The shape remain the same butThe shape remain the same but
placement is inferior and posterior to siteplacement is inferior and posterior to site
of lingual bar.of lingual bar.

 Contraindication:Contraindication:
Remaining natural anterior teeth severelyRemaining natural anterior teeth severely
tilted toward the lingual.tilted toward the lingual.
 Characteristics and location:Characteristics and location:
1.1. Half-pear shaped same like the lingualHalf-pear shaped same like the lingual
bar exceptbar except that the bulkiest portion isthat the bulkiest portion is
located to the lingual and the taperedlocated to the lingual and the tapered
portion is toward the labial.portion is toward the labial.

2. The superior border of the bar should be2. The superior border of the bar should be
at least 3mm from the free gingival marginat least 3mm from the free gingival margin
of the teeth.of the teeth.
3. The inferior border is located at height of3. The inferior border is located at height of
the alveolar lingual sulcus when the ptthe alveolar lingual sulcus when the pt´s´s
tongue is elevated.tongue is elevated.
4. Functional impression is most.4. Functional impression is most.
 Finishing line: Butt-type joints with minorFinishing line: Butt-type joints with minor
connectors for retention of denture base.connectors for retention of denture base.

33..Mandibular LinguoplateMandibular Linguoplate
 Indication for use:Indication for use:
1.1. No sufficient space for lingual bar.No sufficient space for lingual bar.
2.2. The residual ridge undergone a verticalThe residual ridge undergone a vertical
resoption which offer minimal resistanceresoption which offer minimal resistance
to horizontal rotation.to horizontal rotation.
3.3. Periodontally weakened teeth.Periodontally weakened teeth.
4.4. When future replacement of one or moreWhen future replacement of one or more
incisor teeth will be facilitated.incisor teeth will be facilitated.

1.1. Half-pear shaped with bulkiest portion located.Half-pear shaped with bulkiest portion located.
2.2. Thin metal apron extending superiorly toThin metal apron extending superiorly to
contact cingulum of ant. Teeth.contact cingulum of ant. Teeth.
3.3. Apron extended interproximally to the height ofApron extended interproximally to the height of
contact points.contact points.
4.4. Inferior border at ascertained height of theInferior border at ascertained height of the
alveolar lingual sulcus where the ptalveolar lingual sulcus where the pt´s tongue is´s tongue is
slightly elevated.slightly elevated.

44..Mandibular Lingual Bar withMandibular Lingual Bar with
Continuous Bar( CingulumContinuous Bar( Cingulum
BarBar((
1.1. When Linguoplate is indicated but theWhen Linguoplate is indicated but the
axial alignment of ant. Teeth prevent .axial alignment of ant. Teeth prevent .
2.2. When wide diastema b/w mandibularWhen wide diastema b/w mandibular
ant. Teeth.ant. Teeth.

1.1. Shaped and located same as lingual bar.Shaped and located same as lingual bar.
2.2. Thin, narrow(3mm) metal strap locatedThin, narrow(3mm) metal strap located
on a cingula of anterior teeth. Scallopedon a cingula of anterior teeth. Scalloped
to follow interproximal embrasures.to follow interproximal embrasures.
3.3. Originated bilaterally from incisal, lingual,Originated bilaterally from incisal, lingual,
or occlusal rests of adjacent principalor occlusal rests of adjacent principal
abutment.abutment.

55..Mandibular Labial BarMandibular Labial Bar
1.1. When a lingual inclination of remainingWhen a lingual inclination of remaining
MPM and incisors teeth cannot beMPM and incisors teeth cannot be
corrected.corrected.
2.2. Severe lingual tori cannot be removed.Severe lingual tori cannot be removed.
3.3. Severe tissue undercut.Severe tissue undercut.

1.1. HalfHalf ––pear shaped with bulkiest portionpear shaped with bulkiest portion
inferiorly locatedinferiorly located on the labial and buccalon the labial and buccal
aspect of the mandible.aspect of the mandible.
2.2. Superior border tapered to soft tissue.Superior border tapered to soft tissue.
3.3. Superior border located at least 4mm inferiorSuperior border located at least 4mm inferior
to labial and buccal gingival margins and moreto labial and buccal gingival margins and more
if possible.if possible.
4.4. Inferior border located in the labial buccalInferior border located in the labial buccal
vestibule.vestibule.

Maxillary Major ConnectorsMaxillary Major Connectors
A. Single palatal strapA. Single palatal strap
 Characteristics and Location:Characteristics and Location:
1.1. Anatomic replica form.Anatomic replica form.
2.2. Ant. Border follow the valleys b/w rugae atAnt. Border follow the valleys b/w rugae at
right angle to median suture line.right angle to median suture line.
3.3. Posterior border at right angle to medianPosterior border at right angle to median
suture line.suture line.
4.4. Strap should be 8mm wide.Strap should be 8mm wide.
5.5. Confined with in an area bounded by the fourConfined with in an area bounded by the four
principal rests.principal rests.

B.B. Single Broad Palatal MajorSingle Broad Palatal Major
ConnectorConnector
 Indication:Indication:
1.1. Class I.Class I.
2.2. V or U shaped palate.V or U shaped palate.
3.3. Strong abutments.Strong abutments.
4.4. 6 remaining ant teeth.6 remaining ant teeth.
5.5. No interfering tori.No interfering tori.

1.1. Anatomic replica form.Anatomic replica form.
2.2. Anterior border following valleys of rugaeAnterior border following valleys of rugae
and at right angle to median suture lineand at right angle to median suture line
and extending anterior to occlusal restsand extending anterior to occlusal rests
or in direct retainer.or in direct retainer.

3. Posterior border located at junction of3. Posterior border located at junction of
hard and soft palate. And extended tohard and soft palate. And extended to
pterygomaxillary notches.pterygomaxillary notches.

C.C. Anterior-posterior StrapAnterior-posterior Strap
 IndicationIndication::
1.1. Class I and II.Class I and II.
2.2. Long edentulous span class II MOD 1Long edentulous span class II MOD 1
arches.arches.
3.3. Class IV.Class IV.
4.4. Palatal tori.Palatal tori.

1.1. Parallelogram shaped and open inParallelogram shaped and open in
center portion.center portion.
2.2. Relatively broad(8-10mm) ant. And post.Relatively broad(8-10mm) ant. And post.
Palatal strap.Palatal strap.
3.3. Lateral palatal strap (7-9mm) parallel toLateral palatal strap (7-9mm) parallel to
curve of arch. 6mm from gingiva ofcurve of arch. 6mm from gingiva of
remaining teeth.remaining teeth.

4. Anterior palatal strap; ant border not4. Anterior palatal strap; ant border not
placed further interiorly than ant rests andplaced further interiorly than ant rests and
never closer than 6mm to lingual gingivalnever closer than 6mm to lingual gingival
cervices.cervices.

D.D. Complete Palatal CoverageComplete Palatal Coverage
Indication for use:Indication for use:
1.1. Situation in which only some or ant teethSituation in which only some or ant teeth
remains.remains.
2.2. Class II arch with large posteriorClass II arch with large posterior
modification space and some missingmodification space and some missing
anterior teeth.anterior teeth.

3. Class I arch with 1-4 PM and some or all3. Class I arch with 1-4 PM and some or all
ant teeth remaining, abutment support isant teeth remaining, abutment support is
poor, residual ridge extremely resorbed,poor, residual ridge extremely resorbed,
direct retention is difficult to obtaineddirect retention is difficult to obtained
4. No tori.4. No tori.

1.1. Anatomic replica form supported anteriority byAnatomic replica form supported anteriority by
rests seats.rests seats.
2.2. Palatal Linguoplate supported anteriorly andPalatal Linguoplate supported anteriorly and
designed for the attachment of acrylic resindesigned for the attachment of acrylic resin
extension posteriorly.extension posteriorly.
3.3. Contact all of the teeth remaining in the arch.Contact all of the teeth remaining in the arch.
4.4. Posterior border, terminates at the junction ofPosterior border, terminates at the junction of
the hard and soft palate, extended to hasmularthe hard and soft palate, extended to hasmular
notch areas.notch areas.

D.D. U-shaped Palatal Major ConnectorU-shaped Palatal Major Connector
 Is used only in which inoperable toriIs used only in which inoperable tori
extended to the posterior limit of the hardextended to the posterior limit of the hard
palate.palate.
 It is the least favorable design of all palatalIt is the least favorable design of all palatal
major connector( lack rigidity).major connector( lack rigidity).

Rests and Rest seatsRests and Rest seats
 Vertical support provided by restsVertical support provided by rests
(occlusal, incisal, or cingulum).(occlusal, incisal, or cingulum).
 Rests located on properly prepared toothRests located on properly prepared tooth
surface .surface .
 The prepared surface of an abutment toThe prepared surface of an abutment to
receive the rest is called the rest seat.receive the rest is called the rest seat.

 The primary purpose of the rest is to provideThe primary purpose of the rest is to provide
vertical support for PD. It also does thevertical support for PD. It also does the
following:following:
1.1. Maintain components in planned position.Maintain components in planned position.
2.2. Maintained established occlusal relationship.Maintained established occlusal relationship.
3.3. Prevent impingement of soft tissue.Prevent impingement of soft tissue.
4.4. Direct and distribute occlusal loads toDirect and distribute occlusal loads to
abutment teeth.abutment teeth.

Form Of Occlusal Rest and RestForm Of Occlusal Rest and Rest
SeatsSeats
1.1. The outline form of the occlusal restThe outline form of the occlusal rest
should be rounded, triangular shapedshould be rounded, triangular shaped
with the apex toward the center ofwith the apex toward the center of
occlusal surfaces.occlusal surfaces.
2.2. It should be as long as it is wide. TheIt should be as long as it is wide. The
base is 2.5mm for M and PM.base is 2.5mm for M and PM.
3.3. Reduction in marginal ridge is 1.5mm.Reduction in marginal ridge is 1.5mm.

4. It should be concave and spoon shaped4. It should be concave and spoon shaped
(no sharp edges or line angle).(no sharp edges or line angle).
5. The angle formed by the occlusal rest and5. The angle formed by the occlusal rest and
the vertical minor connector from whichthe vertical minor connector from which
its originate should be less than 90its originate should be less than 90*.*.

Extended Occlusal RestExtended Occlusal Rest
 In mesially inclined abutmentIn mesially inclined abutment the restthe rest
extend more than one half of the mesio-extend more than one half of the mesio-
distal width.distal width.
 In severely tilted abutment the extendedIn severely tilted abutment the extended
occlusal rest may take the form of an onlyocclusal rest may take the form of an only
to restore the occlusal plane.to restore the occlusal plane.

 Interproximal Occlusal rests.Interproximal Occlusal rests.
 Intra-coronal Rest: It is used for both occlusalIntra-coronal Rest: It is used for both occlusal
support and horizontal stabilization.support and horizontal stabilization.
Horizontal stabilization is derived from the nearHorizontal stabilization is derived from the near
vertical walls of this type of rest seat.vertical walls of this type of rest seat.
 The form of the rest should be parallel to path ofThe form of the rest should be parallel to path of
placement, slightly tapered occlusaly, andplacement, slightly tapered occlusaly, and
slightly dove-tailed to preve3nt dislodgementslightly dove-tailed to preve3nt dislodgement
proximally.proximally.

 The main advantages of the internal restThe main advantages of the internal rest
are that it facilitates the elimination of theare that it facilitates the elimination of the
visible clasp arm.visible clasp arm.

Direct RetainerDirect Retainer
 It is a clasp or attachments applied to anIt is a clasp or attachments applied to an
abutment tooth for the purpose of holding RPDabutment tooth for the purpose of holding RPD
in position.in position.
 ClassificationClassification::
1.1. Extracronal direct retainerExtracronal direct retainer)) casted clasp,casted clasp,
wrought wire clasp).wrought wire clasp).
a/ Occlusaly approaching claspa/ Occlusaly approaching clasp
(circumferential) .(circumferential) .
b/ Gingivally approaching clasps (Bar clasps)b/ Gingivally approaching clasps (Bar clasps)

2. Intracronal direct retainer( attachments):2. Intracronal direct retainer( attachments):
a/ Internal attachment.a/ Internal attachment.
b/ External attachment.b/ External attachment.
c/ Special attachment.c/ Special attachment.
 Component parts of the clasp:Component parts of the clasp:
1. Retentive terminal 2. Retentive arm1. Retentive terminal 2. Retentive arm
3. Reciprocal arm 4. Occlusal rest3. Reciprocal arm 4. Occlusal rest
5. Shoulder 6. Body 7. Minor connector5. Shoulder 6. Body 7. Minor connector

 Height of contour: is greatest convexityHeight of contour: is greatest convexity
of tooth.of tooth.
 The basic principle of clasp design isThe basic principle of clasp design is
encirclement to obtain more than 180encirclement to obtain more than 180 **
of continuous contact.of continuous contact.
 Types of cast Circumferential clasps:Types of cast Circumferential clasps:
1.1. Simple circlet clasp: widely used, toothSimple circlet clasp: widely used, tooth
supported PD, approach the undercutsupported PD, approach the undercut
from edentulous space. Not used forfrom edentulous space. Not used for
distal extension.distal extension.

22. Reverse clasp.. Reverse clasp.
3. Multiple circlet clasp( combination of3. Multiple circlet clasp( combination of
two circlet clasps).two circlet clasps).
4. Embrasure clasp4. Embrasure clasp
5. Ring clasp; no buccal undercut. Isolated5. Ring clasp; no buccal undercut. Isolated
abutment, lingually tipped molar, fromabutment, lingually tipped molar, from
disto- buccal to disto-lingual undercut.disto- buccal to disto-lingual undercut.
6. Hairpin clasp. when undercut is near to6. Hairpin clasp. when undercut is near to
edentulous space.edentulous space.
77. Combination clasp.. Combination clasp.

 Bar clasp: Composed of two partsBar clasp: Composed of two parts
( Gingivally approaching and retentive( Gingivally approaching and retentive
tip)tip)
1.1. Approach arm: It is a minor connector.Approach arm: It is a minor connector.
Semi circular in cross section, cross theSemi circular in cross section, cross the
gingival margin at right angle.gingival margin at right angle.
2.2. Retentive terminal : it should end belowRetentive terminal : it should end below
undercut.undercut.

Advantages:Advantages:
1.1. Easy to insert and difficult to remove.Easy to insert and difficult to remove.
2.2. More aesthetic, cover less toothMore aesthetic, cover less tooth
structure.structure.
– Types of Bar clasps:Types of Bar clasps:
1.1. T-Bar clasp.T-Bar clasp.
2.2. Y- Bar clasp.Y- Bar clasp.
3.3. I- Bar clasp.I- Bar clasp.

Indirect RetainerIndirect Retainer
 Apart of RPD which assists the directApart of RPD which assists the direct
retainers in preventing displacement ofretainers in preventing displacement of
distal extension denture base bydistal extension denture base by
functioning through lever action on thefunctioning through lever action on the
opposite side of the fulcrum line.opposite side of the fulcrum line.

 Types of indirect retainer:Types of indirect retainer:
1.1. Auxiliary occlusal rest, most frequentlyAuxiliary occlusal rest, most frequently
used, located far as possible from distalused, located far as possible from distal
extension base, placed perpendicular toextension base, placed perpendicular to
the mid point of the fulcrum line. If thisthe mid point of the fulcrum line. If this
perpendicular line ends on the incisalperpendicular line ends on the incisal
area it is a voided, instead it transfers toarea it is a voided, instead it transfers to
PM in both sides.PM in both sides.

2. Canine extension from occlusal rest,2. Canine extension from occlusal rest,
finger like extention(lug seat) from the PMfinger like extention(lug seat) from the PM
rest is placed on the lingual slope ofrest is placed on the lingual slope of
adjacent canine.adjacent canine.
3. Canine rest.3. Canine rest.
4. Continuous bar retainers and Linguoplate.4. Continuous bar retainers and Linguoplate.

Denture BaseDenture Base
 Denture base defined as that part of aDenture base defined as that part of a
denture which rests on the oral mucosadenture which rests on the oral mucosa
and to which teeth are attached.and to which teeth are attached.
 Ideal requirements:Ideal requirements:
1.1. Accurate tissue adaptation with minimalAccurate tissue adaptation with minimal
change in volume.change in volume.
2.2. Thermal conductivity.Thermal conductivity.
3.3. Sufficient strength to resist fracture orSufficient strength to resist fracture or
distortion under function.distortion under function.

4. Cleansability.4. Cleansability.
5. Ability to be relined if necessary.5. Ability to be relined if necessary.
6 Cost effective.6 Cost effective.
7. Low specific gravity.7. Low specific gravity.
8. Ability to achieve a good finish.8. Ability to achieve a good finish.

 Types of denture base:Types of denture base:
1.1. AcrylicAcrylic
2.2. Metal.Metal.
3.3. Combination.Combination.
 Acrylic Resin denture base; mainly usedAcrylic Resin denture base; mainly used
for distal extension PD- attached to thefor distal extension PD- attached to the
frame work by minor connector-withframe work by minor connector-with
1.5mm thick to have a adequate1.5mm thick to have a adequate
strength.strength.

 Advantages:Advantages:
1.1. Anterior teeth can be replaced at theirAnterior teeth can be replaced at their
original position (aesthetic level).original position (aesthetic level).
2.2. Restore the contour of the edentulousRestore the contour of the edentulous
ridge.ridge.
3.3. Brings out the normal contour of the lipBrings out the normal contour of the lip
and cheeks.and cheeks.
4.4. Can be relined.Can be relined.

 Disadvantages:Disadvantages:
1.1. May break on usage.May break on usage.
2.2. Tend to accumulate mucous depositsTend to accumulate mucous deposits
and food debris.and food debris.
3.3. Soft tissue irritation.Soft tissue irritation.
4.4. Allergy.Allergy.

 Metal denture base: mainly used for toothMetal denture base: mainly used for tooth
supported PD.supported PD.
 Advantages:Advantages:
1.1. Accurate tissue adaptaion( better retention).Accurate tissue adaptaion( better retention).
2.2. Easy to clean.Easy to clean.
3.3. Strong even in thin section.Strong even in thin section.
4.4. Heat conductivity( physiologic tissueHeat conductivity( physiologic tissue
stimulation).stimulation).

 Disadvantage:Disadvantage:
1.1. Difficult to trim and adjust.Difficult to trim and adjust.
2.2. Over extension can injure the soft tissue.Over extension can injure the soft tissue.
3.3. Poor aesthetic.Poor aesthetic.
4.4. Difficult to reline and rebase.Difficult to reline and rebase.

Removable partial denture

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Removable partial denture