Removable partial denture

REMOVABLE REMOVABLE PARTIAL DENTUREPARTIAL DENTURE

RPDs are components of RPDs are components of prosthodontics ( branch of prosthodontics ( branch of Dentistry) pertaining to the Dentistry) pertaining to the

restorations and maintenance of restorations and maintenance of oral function, comfort, appearance, oral function, comfort, appearance,

and health of the( pt) by and health of the( pt) by replacement the missing teeth and replacement the missing teeth and craniofacial tissues with artificial craniofacial tissues with artificial

substitutesubstitute..

theoptimalsmile.wix.comtheoptimalsmile.wix.com

The Basic Objectives of The Basic Objectives of prosthodontic Treatmentprosthodontic Treatment

1.1. Elimination of oral disease.Elimination of oral disease.

2.2. Preservation of the health and Preservation of the health and relationship of the teeth, and the relationship of the teeth, and the health of the oral and health of the oral and para-oral para-oral structure.structure.

3.3. Restoration of oral function Restoration of oral function (comfort, esthetic, speech).(comfort, esthetic, speech).

Consequences of Tooth Consequences 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 lips Support 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 Improve oral hygiene by preventing

stagnation of food in disused areas. stagnation of food in disused areas.

Classification Of Partially Classification Of Partially Edentulous ArchesEdentulous Arches

The most familiar classification are The most familiar classification are those proposed by Kennedy, those proposed by Kennedy, Cummer, and Bailyn, Beckett,Cummer, and Bailyn, Beckett,……

The recent classification has been The recent classification has been proposed for partial edentulism that proposed for partial edentulism that is based on diagnostic criteria.is based on diagnostic criteria.

Requirement Of an Acceptable Requirement Of an Acceptable Method Of ClassificationMethod Of Classification

1.1. It should permit immediate It should permit immediate visualization of the type of partially visualization of the type of partially edentulous arch.edentulous arch.

2.2. It should permit immediate It should permit immediate differentiation b/w tooth- supported differentiation b/w tooth- supported and the tooth and tissue-supported.and the tooth and tissue-supported.

3.3. Universally acceptable.Universally acceptable.

Kennedy ClassificationKennedy Classification

4 basic classes.4 basic classes. Edentulous areas other than those Edentulous areas other than those

determining the basic classes were determining the basic classes were designated as modification spaces.designated as modification spaces.

Class I : Bilateral edentulous areas Class I : Bilateral edentulous areas located posterior to the natural teeth.located posterior to the natural teeth.

Class II : A unilateral edentulous area Class II : A unilateral edentulous area posterior to the remaining natural posterior to the remaining natural teeth. teeth.

Kennedy ClassificationKennedy Classification

Class III: Unilateral edentulous area Class III: Unilateral edentulous area with natural teeth remaining both ant with natural teeth remaining both ant and post to it.and post to it.

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

Principal AdvantagePrincipal Advantage

It permits immediate visualization of It permits immediate visualization of the partially edentulous arch and the partially edentulous arch and allows easy distinction b\w tooth-allows easy distinction b\w tooth-supported versus tooth-tissue supported versus tooth-tissue supported prostheses.supported prostheses.

Applegate'sApplegate's Rules for Rules for Applying the Kennedy Applying the Kennedy

ClassificationClassification Rule 1 : The classification should Rule 1 : The classification should

follow, not precede extractions.follow, not precede extractions.

Rule 2 : If a 3Rule 2 : If a 3rdrd molar is missing and molar is missing and not to be replaced, it is not not to be replaced, it is not considered in the classification.considered in the classification.

Rule 3 : If a3rd molar is present and Rule 3 : If a3rd molar is present and not to be used as an abutment, it is not to be used as an abutment, it is not considered in the classification.not considered in the classification.

Applegate'sApplegate's Rules Rules

Rule 4 : If a 2Rule 4 : If a 2ndnd molar is missing and molar is missing and not to be replaced, it is not not to be replaced, it is not considered in the classification.considered in the classification.

Rule 5 : The most posterior area Rule 5 : The most posterior area always determines the classification.always determines the classification.

Rule 6 : Edentulous areas other than Rule 6 : Edentulous areas other than those determining the classification those determining the classification are referred to as modifications and are referred to as modifications and designated by their No.designated by their No.

Applegate'sApplegate's Rule Rule

Rule 7 : The extent of the Rule 7 : The extent of the modifications is not considered, only modifications is not considered, only the No. of additional edentulous the No. of additional edentulous areas.areas.

Rule 8 : There are no modification in Rule 8 : There are no modification in Class IV.Class IV.

Principal Of Partial Denture Principal Of Partial Denture DesignDesign

Stresses acting on RPDs are Stresses acting on RPDs are transmitted to the teeth, and to the transmitted to the teeth, and to the tissues of the residual ridges.tissues of the residual ridges.

The stresses, which tend to move the The stresses, which tend to move the PD in different directions are:PD in different directions are:

1.1. Masticatory stress( Tissue ward Masticatory stress( Tissue ward movt).movt).

2.2. Gravity( Tissue away movt).Gravity( Tissue away movt).3.3. Sticky food pull the denture occlusaly Sticky food pull the denture occlusaly

(Tissue-away movt). (Tissue-away movt).

4. Muscles and tongue tend to displace 4. Muscles and tongue tend to displace denture from its foundation.denture from its foundation.

5. Intercuspation of the teeth may 5. Intercuspation of the teeth may tend to produce horizontal and tend to produce horizontal and rotational stresses unless occlusal is rotational stresses unless occlusal is adjusted.adjusted.

Properly Constructed PD Properly Constructed PD Must HaveMust Have::

1.1. Support: Resistance to vertical seating Support: Resistance to vertical seating forces( provided by teeth and mucosa).forces( provided by teeth and mucosa).

2.2. Retention: Resistance to vertical Retention: Resistance to vertical displacing forces.displacing forces.

3.3. Stability( bracing) resistance to Stability( bracing) resistance to horizontal and lateral displacement.horizontal and lateral displacement.

All the above should be within the All the above should be within the physiological limits of the tissue physiological limits of the tissue involved.involved.

AA

Designing SupportDesigning Support

a. Tooth support: When abutment teeth a. Tooth support: When abutment teeth available at both ends of the denture available at both ends of the denture base( bounded saddle). It most base( bounded saddle). It most commonly obtained by occlusal rests.commonly obtained by occlusal rests.

b. Mucosa support: (mucoperiosteum b. Mucosa support: (mucoperiosteum covering residual alveolar bone). It allows covering residual alveolar bone). It allows varying degree of displacement.varying degree of displacement.

The amount of displacement( tissue The amount of displacement( tissue ward movt) will depend on:ward 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 3. Area covered by the denture( the wider the area the less the wider the area the less the displacement).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 free c. Tooth-mucosa support: ( Bilateral free

end saddle).end saddle). Posterior tissue support, and anterior Posterior tissue support, and anterior

tooth support.tooth support.

Designing RetentionDesigning Retention Retention should be designed to counter Retention should be designed to counter

act dislodging forces( sticky food, muscle act dislodging forces( sticky food, muscle at periphery of the denture, at periphery of the denture, intercuspation, gravity).intercuspation, gravity).

Retention is gained by mechanical means Retention 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 atmospheric pressure, surface tension). it play a minor role RBD.tension). it play a minor role RBD.

Designing Bracing and Designing Bracing and StabilityStability

Bracing( providing resistance to Bracing( providing resistance to lateral movt.of RBD).lateral movt.of RBD).

Causes of tipping, rocking and Causes 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 Of the free end base create an axis of rotation end base create an axis of rotation around which this appliance is around which this appliance is rotated.rotated.

This axis of rotation is called a fulcrum This axis of rotation is called a fulcrum line (it is imaginary line extending line (it is imaginary line extending between the two main abutment.between the two main abutment.

How to counteract lateral How to counteract lateral shifting?shifting?

1.1. Bracing the sides of the teeth by Bracing the sides of the teeth by means of rigid clasp arms.means of rigid clasp arms.

2.2. Use of continuous bar resting on the Use of continuous bar resting on the lingual surfaces of the natural lingual surfaces of the natural standing teeth.standing 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 components Stabilizing or reciprocal components (part of clasp assembly).(part of clasp assembly).

6.6. Indirect retainers( if prosthesis has Indirect retainers( if prosthesis has distal extension).distal extension).

Major ConnectersMajor Connecters

Major connector is component of the Major connector is component of the PD which connect all parts of the PD which connect all parts of the prosthesis directly or indirectly.prosthesis directly or indirectly.

It provides the cross-arch stability to It provides the cross-arch stability to help resist displacement by help resist displacement by functional stresses.functional stresses.

Characteristics Of Major Characteristics Of Major ConnectorsConnectors

1.1. Made from material compatible with Made from material compatible with oral tissue.oral tissue.

2.2. It is rigid.It is rigid.

3.3. Doesn't alter the natural contour of the Doesn't alter the natural contour of the lingual surfaces of the mandibular lingual 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 in Doesn't impinge on oral tissue in (insertion, withdrawal. Or in function).(insertion, withdrawal. Or in function).

6. Cover no more tissue than is 6. Cover no more tissue than is absolutely necessary.absolutely necessary.

7. Doesn't contribute to the trapping of 7. Doesn't contribute to the trapping of food particles.food particles.

8. Has support from other elements of 8. Has support from other elements of the frame work to minimize rotation the frame work to minimize rotation in function.in function.

9. Contribute to the support of the 9. Contribute to the support of the prosthesis.prosthesis.

Mandibular Major Mandibular Major ConnectorsConnectors

1.1. Lingual bar.Lingual bar.

2.2. Linguoplate.Linguoplate.

3.3. Sublingual bar.Sublingual bar.

4.4. Lingual bar with cingulum bar Lingual bar with cingulum bar (continuous bar).(continuous bar).

5.5. Cingulum bar (continuous bar).Cingulum bar (continuous bar).

6.6. Labial bar.Labial bar. Lingual bar and Linguopslate are most Lingual bar and Linguopslate are most

common used.common used.

1.1. Mandibular lingual BarMandibular lingual Bar

Indication: Where sufficient space exist Indication: Where sufficient space exist b/w elevated alveolar lingual sulcus b/w elevated alveolar lingual sulcus and the lingual gingival tissue.and the lingual gingival tissue.

Location: Location:

1.1. Half-pear shaped, with bulkiest portion Half-pear shaped, with bulkiest portion inferiorly.inferiorly.

2.2. Superior border tapered, located at Superior border tapered, located at least 4mm inferior to gingival margin.least 4mm inferior to gingival margin.

4. Inferior border located at site of the 4. Inferior border located at site of the alveolar lingual sulcus where the ptalveolar lingual sulcus where the pt´s tongue is elevated.´s tongue is elevated.

Finishing line: Butt-type joints with Finishing line: Butt-type joints with minor connector for retention of minor connector for retention of denture base.denture base.

22 . .Mandibular Sublingual Mandibular Sublingual BarBar

It is modification of lingual bar used It is modification of lingual bar used when the existing space not allow when the existing space not allow placement of lingual bar.placement of lingual bar.

The shape remain the same but The shape remain the same but placement is inferior and posterior to placement is inferior and posterior to site of lingual bar.site of lingual bar.

Contraindication:Contraindication:

Remaining natural anterior teeth Remaining natural anterior teeth severely tilted toward the lingual.severely tilted toward the lingual.

Characteristics and location:Characteristics and location:

1.1. Half-pear shaped same like the Half-pear shaped same like the lingual bar exceptlingual bar except that the bulkiest that the bulkiest portion is located to the lingual and portion is located to the lingual and the tapered portion is toward the the tapered portion is toward the labial.labial.

2. The superior border of the bar should 2. The superior border of the bar should be at least 3mm from the free gingival be at least 3mm from the free gingival margin of the teeth.margin of the teeth.

3. The inferior border is located at 3. The inferior border is located at height of the alveolar lingual sulcus height of the alveolar lingual sulcus when the ptwhen the pt´s tongue is elevated.´s tongue is elevated.

4. Functional impression is most.4. Functional impression is most. Finishing line: Butt-type joints with Finishing line: Butt-type joints with

minor connectors for retention of minor connectors for retention of denture base.denture base.

33 . .Mandibular Mandibular LinguoplateLinguoplate

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 The residual ridge undergone a vertical resoption which offer minimal vertical resoption which offer minimal resistance to horizontal rotation.resistance to horizontal rotation.

3.3. Periodontally weakened teeth.Periodontally weakened teeth.

4.4. When future replacement of one or When future replacement of one or more incisor teeth will be facilitated.more incisor teeth will be facilitated.


1.1. Half-pear shaped with bulkiest portion Half-pear shaped with bulkiest portion located.located.

2.2. Thin metal apron extending superiorly to Thin metal apron extending superiorly to contact cingulum of ant. Teeth.contact cingulum of ant. Teeth.

3.3. Apron extended interproximally to the Apron extended interproximally to the height of contact points.height of contact points.

4.4. Inferior border at ascertained height of Inferior border at ascertained height of the alveolar lingual sulcus where the ptthe alveolar lingual sulcus where the pt´s ´s tongue is slightly elevated.tongue is slightly elevated.

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44 . .Mandibular Lingual Bar Mandibular Lingual Bar with Continuous with Continuous

Bar( Cingulum BarBar( Cingulum Bar)) Indication for use:Indication for use:

1.1. When Linguoplate is indicated but When Linguoplate is indicated but the axial alignment of ant. Teeth the axial alignment of ant. Teeth prevent .prevent .

2.2. When wide diastema b/w When wide diastema b/w mandibular ant. Teeth.mandibular ant. Teeth.


1.1. Shaped and located same as lingual Shaped and located same as lingual bar.bar.

2.2. Thin, narrow(3mm) metal strap located Thin, narrow(3mm) metal strap located on a cingula of anterior teeth. Scalloped on a cingula of anterior teeth. Scalloped to follow interproximal embrasures.to follow interproximal embrasures.

3.3. Originated bilaterally from incisal, Originated bilaterally from incisal, lingual, or occlusal rests of adjacent lingual, or occlusal rests of adjacent principal abutment.principal abutment.

55 . .Mandibular Labial BarMandibular Labial Bar


1.1. When a lingual inclination of When a lingual inclination of remaining MPM and incisors teeth remaining MPM and incisors teeth cannot be corrected.cannot be corrected.

2.2. Severe lingual tori cannot be Severe lingual tori cannot be removed.removed.

3.3. Severe tissue undercut.Severe tissue undercut.

Characteristics and location:Characteristics and location:1.1. Half Half ––pear shaped with bulkiest portion pear shaped with bulkiest portion

inferiorly locatedinferiorly located on the labial and on the labial and buccal aspect of the mandible.buccal 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 Superior border located at least 4mm

inferior to labial and buccal gingival inferior to labial and buccal gingival margins and more if possible.margins and more if possible.

4.4. Inferior border located in the labial Inferior border located in the labial buccal vestibule.buccal vestibule.

Maxillary Major Maxillary Major ConnectorsConnectors

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 Ant. Border follow the valleys b/w rugae

at right angle to median suture line.at right angle to median suture line.3.3. Posterior border at right angle to median Posterior 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 Confined with in an area bounded by the

four principal rests.four principal rests.

B. B. Single Broad Palatal Major Single 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 Anterior border following valleys of rugae and at right angle to median rugae and at right angle to median suture line and extending anterior suture line and extending anterior to occlusal rests or in direct to occlusal rests or in direct retainer.retainer.

3. Posterior border located at junction 3. Posterior border located at junction of hard and soft palate. And of hard and soft palate. And extended to pterygomaxillary extended to pterygomaxillary notches.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 Long edentulous span class II MOD 1 arches.1 arches.

3.3. Class IV.Class IV.

4.4. Palatal tori.Palatal tori.


1.1. Parallelogram shaped and open in Parallelogram shaped and open in center portion.center portion.

2.2. Relatively broad(8-10mm) ant. And Relatively broad(8-10mm) ant. And post. Palatal strap.post. Palatal strap.

3.3. Lateral palatal strap (7-9mm) Lateral palatal strap (7-9mm) parallel to curve of arch. 6mm from parallel to curve of arch. 6mm from gingiva of remaining teeth.gingiva of remaining teeth.

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

D. D. Complete Palatal CoverageComplete Palatal Coverage


1.1. Situation in which only some or ant Situation in which only some or ant teeth remains.teeth remains.

2.2. Class II arch with large posterior Class II arch with large posterior modification space and some modification space and some missing anterior teeth.missing anterior teeth.

3. Class I arch with 1-4 PM and some 3. Class I arch with 1-4 PM and some or all ant teeth remaining, abutment or all ant teeth remaining, abutment support is poor, residual ridge support is poor, residual ridge extremely resorbed, direct retention extremely resorbed, direct retention is difficult to obtainedis difficult to obtained

4. No tori.4. No tori.

Characteristics and location:Characteristics and location:1.1. Anatomic replica form supported Anatomic replica form supported

anteriority by rests seats.anteriority by rests seats.2.2. Palatal Linguoplate supported anteriorly Palatal Linguoplate supported anteriorly

and designed for the attachment of and designed for the attachment of acrylic resin extension posteriorly.acrylic resin extension posteriorly.

3.3. Contact all of the teeth remaining in the Contact all of the teeth remaining in the arch.arch.

4.4. Posterior border, terminates at the Posterior border, terminates at the junction of the hard and soft palate, junction of the hard and soft palate, extended to hasmular notch areas.extended to hasmular notch areas.

D. D. U-shaped Palatal Major U-shaped Palatal Major ConnectorConnector

Is used only in which inoperable tori Is used only in which inoperable tori extended to the posterior limit of the extended to the posterior limit of the hard palate.hard palate.

It is the least favorable design of all It is the least favorable design of all palatal major connector( lack palatal major connector( lack rigidity).rigidity).

Rests and Rest seatsRests and Rest seats

Vertical support provided by rests Vertical support provided by rests (occlusal, incisal, or cingulum).(occlusal, incisal, or cingulum).

Rests located on properly prepared Rests located on properly prepared tooth surface .tooth surface .

The prepared surface of an abutment The prepared surface of an abutment to receive the rest is called the rest to receive the rest is called the rest seat.seat.

The primary purpose of the rest is to The primary purpose of the rest is to provide vertical support for PD. It also provide vertical support for PD. It also does the following:does the following:

1.1. Maintain components in planned position.Maintain components in planned position.

2.2. Maintained established occlusal Maintained established occlusal relationship.relationship.

3.3. Prevent impingement of soft tissue.Prevent impingement of soft tissue.

4.4. Direct and distribute occlusal loads to Direct and distribute occlusal loads to abutment teeth.abutment teeth.

Form Of Occlusal Rest and Rest Form Of Occlusal Rest and Rest SeatsSeats

1.1. The outline form of the occlusal rest The outline form of the occlusal rest should be rounded, triangular should be rounded, triangular shaped with the apex toward the shaped with the apex toward the center of occlusal surfaces.center of occlusal surfaces.

2.2. It should be as long as it is wide. It should be as long as it is wide. The base is 2.5mm for M and PM.The base is 2.5mm for M and PM.

3.3. Reduction in marginal ridge is Reduction in marginal ridge is 1.5mm.1.5mm.

4. It should be concave and spoon 4. It should be concave and spoon shaped (no sharp edges or line shaped (no sharp edges or line angle).angle).

5. The angle formed by the occlusal 5. The angle formed by the occlusal rest and the vertical minor rest and the vertical minor connector from which its originate connector from which its originate should be less than 90should be less than 90*.*.

Extended Occlusal RestExtended Occlusal Rest

In mesially inclined abutmentIn mesially inclined abutment the the rest extend more than one half of the rest extend more than one half of the mesio-distal width.mesio-distal width.

In severely tilted abutment the In severely tilted abutment the extended occlusal rest may take the extended occlusal rest may take the form of an only to restore the form of an only to restore the occlusal plane.occlusal plane.

Interproximal Occlusal rests.Interproximal Occlusal rests. Intra-coronal Rest: It is used for both Intra-coronal Rest: It is used for both

occlusal support and horizontal occlusal support and horizontal stabilization. Horizontal stabilization is stabilization. Horizontal stabilization is derived from the near vertical walls of this derived from the near vertical walls of this type of rest seat.type of rest seat.

The form of the rest should be parallel to The form of the rest should be parallel to path of placement, slightly tapered path of placement, slightly tapered occlusaly, and slightly dove-tailed to occlusaly, and slightly dove-tailed to preve3nt dislodgement proximally.preve3nt dislodgement proximally.

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

Direct RetainerDirect Retainer

It is a clasp or attachments applied to an It is a clasp or attachments applied to an abutment tooth for the purpose of holding abutment tooth for the purpose of holding RPD in position.RPD in position.

ClassificationClassification::

1.1. Extracronal direct retainerExtracronal direct retainer) ) casted clasp, casted clasp, wrought wire clasp).wrought wire clasp).

a/ Occlusaly approaching clasp a/ Occlusaly approaching clasp (circumferential) .(circumferential) .

b/ Gingivally approaching clasps (Bar b/ Gingivally approaching clasps (Bar clasps)clasps)

2. Intracronal direct 2. Intracronal direct retainer( attachments):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 arm3. Reciprocal arm 4. Occlusal rest3. Reciprocal arm 4. Occlusal rest5. Shoulder 6. Body 7. Minor connector5. Shoulder 6. Body 7. Minor connector

Height of contour: is greatest Height of contour: is greatest convexity of tooth.convexity of tooth.

The basic principle of clasp design The basic principle of clasp design is encirclement to obtain more than is encirclement to obtain more than 180180* of continuous contact.* of continuous contact.

Types of cast Circumferential clasps:Types of cast Circumferential clasps:1.1. Simple circlet clasp: widely used, Simple circlet clasp: widely used,

tooth supported PD, approach the tooth supported PD, approach the undercut from edentulous space. undercut from edentulous space. Not used for distal extension.Not used for distal extension.

22. Reverse clasp.. Reverse clasp.3. Multiple circlet clasp( combination of 3. Multiple circlet clasp( combination of

two circlet clasps).two circlet clasps).4. Embrasure clasp4. Embrasure clasp5. Ring clasp; no buccal undercut. 5. Ring clasp; no buccal undercut.

Isolated abutment, lingually tipped Isolated abutment, lingually tipped molar, from disto- buccal to disto-molar, from disto- buccal to disto-lingual undercut.lingual undercut.

6. Hairpin clasp. when undercut is near 6. Hairpin clasp. when undercut is near to edentulous space. to edentulous space.

77. Combination clasp.. Combination clasp.

Bar clasp: Composed of two parts Bar clasp: Composed of two parts ( Gingivally approaching and ( Gingivally approaching and retentive tip)retentive tip)

1.1. Approach arm: It is a minor Approach arm: It is a minor connector. Semi circular in cross connector. Semi circular in cross section, cross the gingival margin at section, cross the gingival margin at right angle.right angle.

2.2. Retentive terminal : it should end Retentive terminal : it should end below undercut.below undercut.

Advantages:Advantages:1.1. Easy to insert and difficult to Easy to insert and difficult to

remove.remove.

2.2. More aesthetic, cover less tooth More 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 direct Apart of RPD which assists the direct retainers in preventing displacement retainers in preventing displacement of distal extension denture base by of distal extension denture base by functioning through lever action on functioning through lever action on the opposite side of the fulcrum line.the opposite side of the fulcrum line.

Types of indirect retainer:Types of indirect retainer:

1.1. Auxiliary occlusal rest, most Auxiliary occlusal rest, most frequently used, located far as frequently used, located far as possible from distal extension base, possible from distal extension base, placed perpendicular to the mid placed perpendicular to the mid point of the fulcrum line. If this point of the fulcrum line. If this perpendicular line ends on the perpendicular line ends on the incisal area it is a voided, instead it incisal area it is a voided, instead it transfers to PM in both sides.transfers to PM in both sides.

2. Canine extension from occlusal rest, 2. Canine extension from occlusal rest, finger like extention(lug seat) from finger like extention(lug seat) from the PM rest is placed on the lingual the PM rest is placed on the lingual slope of adjacent canine.slope of adjacent canine.

3. Canine rest.3. Canine rest.

4. Continuous bar retainers and 4. Continuous bar retainers and Linguoplate.Linguoplate.

Denture BaseDenture Base

Denture base defined as that part of a Denture base defined as that part of a denture which rests on the oral denture which rests on the oral mucosa and to which teeth are mucosa and to which teeth are attached.attached.

Ideal requirements:Ideal requirements:1.1. Accurate tissue adaptation with Accurate tissue adaptation with

minimal change in volume.minimal change in volume.2.2. Thermal conductivity.Thermal conductivity.3.3. Sufficient strength to resist fracture or Sufficient 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. AcrylicAcrylic2.2. Metal.Metal.3.3. Combination.Combination. Acrylic Resin denture base; mainly Acrylic Resin denture base; mainly

used for distal extension PD- used for distal extension PD- attached to the frame work by attached to the frame work by minor connector-with 1.5mm thick minor connector-with 1.5mm thick to have a adequate strength.to have a adequate strength.

Advantages:Advantages:

1.1. Anterior teeth can be replaced at Anterior teeth can be replaced at their original position (aesthetic their original position (aesthetic level).level).

2.2. Restore the contour of the edentulous Restore the contour of the edentulous ridge.ridge.

3.3. Brings out the normal contour of the Brings out the normal contour of the lip and cheeks.lip 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 Tend to accumulate mucous deposits and food debris.deposits and food debris.

3.3. Soft tissue irritation.Soft tissue irritation.

4.4. Allergy.Allergy.

Metal denture base: mainly used for Metal denture base: mainly used for tooth supported PD.tooth supported PD.

Advantages:Advantages:

1.1. Accurate tissue adaptaion( better Accurate tissue adaptaion( better retention).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 tissue Heat 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 Over extension can injure the soft tissue.tissue.

3.3. Poor aesthetic.Poor aesthetic.

4.4. Difficult to reline and rebase.Difficult to reline and rebase.

Education

Removable partial denture