REMOVABLE PARTIAL

DENTURE

CHATCHAI KUNAVISARUT

CHANITA SUPA-AMORNKUL

DIAGNOSIS, TREATMENT PLANNING,

DESIGN, TREATMENT SEQUENCING

AND MOUTH PREPARATION

! Study cast surveyor

! Diagnosis

! Guiding and verify the appropriate tooth preparation

! Mouth preparation goal

! Support

! Stabilization

! Retention

! Harmonious occlusion

DIAGNOSIS, TREATMENT PLANNING,

DESIGN, TREATMENT SEQUENCING

AND MOUTH PREPARATION

! Mouth preparation sequence

! Proximal tooth surfaces! Parallel to guiding plane

! Occlusal rest seats! Direct occlusal force along the long axis

! Spoon shape

! Retentive area! Resist dislodging force

! Reciprocal area

DIAGNOSIS, TREATMENT PLANNING,

DESIGN, TREATMENT SEQUENCING

AND MOUTH PREPARATION

! Take impression with alginate for ascertain the

contour of abutment

! Take another impression for master cast

! Master cast

! Survey

! Draw RPD framework design

! Tripoding

CLASSIFICATION OF

PARTIALLY EDENTULOUS

ARCHES

KENNEDY’S CLASSIFICATION

APPLEGATE’S RULE APPLYING THE

KENNEDY CLASSIFICATION

COMPONENT OF PARTIAL

DENTURE DESIGN

MAJOR CONNECTOR

MAJOR CONNECTOR

! Join the components on one side of the arch with

those on the other side

! Rigidity " Distribution force

! Not impingement subgingival

BORDER OF MAJOR CONNECTOR

! Design

! Symmetrical

! Cross midline at right angle

! Avoid torus

! Smooth and round contour

! Self cleansing

MAXILLARY MAJOR CONNECTOR

! Palatal bar

! Palatal strap

! Anteroposterior palatal bar

! Horseshoe

! Anteroposterior palatal strap

! Complete palate

PALATAL BAR

Narrow half oval with thickest point at the middle

Interim application

Uncomfortable

Little vertical support

All support derive from remaining teeth

Short span class III

Should not place anterior to second molar

PALATAL STRAP

Wide – thin band of metal

At least 8 mm. wide

Little interfere tongue

Patient accept

Resistance to bending and twisting force

Distribute stress

Patient may complain of palatal coverage

ANTEROPOSTERIOR PALATAL BAR

Anterior bar = Palatal strap Posterior bar = Palatal bar

Join two bar with flat longitudinal element

Rigidity

Minimized soft tissue coverage

Uncomfortable

Little support from palate

Not the first choice

Support is not major consideration

Widely separate abutment

HORSESHOE CONNECTOR

Thin metal band running along the lingual surface of remaining teeth and extending (6-8 mm.) on to the palatal tissue

Symmetry

Replaced several anterior teeth

Prominent median palatal suture line

Inoperable torus

Tendency to flex or deform

Not good for cross arch stabilization

More rigid connector cannot be used

ANTEROPOSTERIOR PALATAL STRAP

Indicated when replace numerous teeth or present of palatine torus

Extensive length of border may irritation to tongue

Open area in palatal region at least 20x15 mm.

Good support from palate

Resistance to flexure

Uncomfortable

COMPLETE PALATE

Ultimate rigidity and support

Posterior border extend to hard and soft palate junction

Anterior border cover cingular of anterior teeth

Greatest amount of tissue coverage

Replaced all posterior teeth

Periodontal compromised

Distribution force to remaining teeth and tissue

Stabilization

Extensive tissue coverage

INDICATION OF MAXILLARY MAJOR

CONNECTOR

Condition Major connector

Weak periodontal support of

remaining teeth

-Wide palatal strap

-Complete palate

Adequate periodontal support of

remaining teeth

-Palatal strap

-Ant.-post. palatal bar

Long span distal extension -Ant.-post. palatal strap

-Complete palate

Replaced anterior teeth -Ant.-post. palatal strap

-Complete palate

-Horseshoe

Condition Major connector

Torus present -Ant.-post. Palatal strap

-Ant. -post. Palatal bar

-Horseshoe

•Very sparing use horseshoe connector•Palatal bar is rarely indicated

MANDIBULAR MAJOR CONNECTOR

! Lingual bar

! Lingual plate

! Double lingual bar

! Labial bar

LINGUAL BAR

Indicate for all tooth support unless insufficient space

At least 8 mm. between gin. margin and floor of mouth

Minimum contact with teeth and soft tissue

Half pear shape

Simplicity

Decrease plaque accumulate

Need extreme care for design and construction

LINGUAL PLATE

Half pear shape and thin piece of metal

Scallop appearance

Always support by rests

Insufficient vertical space for lingual bar

Splinting

Existing of mandibular tori

Exceptional rigidity

More comfortable than lingual bar

Extensive coverage

DOUBLE LINGUAL BAR

Characteristics of both lingual bar and plate

Join 2 bars with rigid minor connector

Contact with remaining anterior teeth indicated

Marginal gingival receives natural stimulation

Horizontal stabilization

Tendency to trap debris

Not comfortable

LABIAL BAR

Run across the mucosa on facial surface

Indicated in the presence of a gross uncorrectable interference

Half pear shape

Swing-lock

Tipped remaining mandibular teeth

Poor patient acceptance

Distort lower lip

Discomfort

MANDIBULAR MAJOR CONNECTOR

Condition Mandibular major connector

Tooth support Lingual bar

-Insufficient space

-Inoperative torus

-High lingual frenum attachment

Lingual plate

-Reduced periodontal support in

anterior teeth

-Large interproximal space

-Modified lingual plate

(step back design)

-Double lingual bar

Condition Mandibular major connector

Replace all posterior teeth Lingual plate

• Labial bar is rarely indicatedMINOR CONNECTOR

MINOR CONNECTOR

! Join the remaining component of RPD to the

major connector

! Distribute force to supporting teeth and oral

tissues

! Rigidity

TYPE OF MINOR CONNECTOR

! Join clasp to major connector

! Join direct retainers or auxiliary rest to major

connector

! Join denture base to major connector

! Serve as approach arms for bar- type clasp

JOIN CLASP TO MAJOR CONNECTOR

Rigid

Locate on proximal surface

Broad buccolingually but thin mesiodistally

JOIN INDIRECT RETAINERS OR AUXILIARY REST

TO MAJOR CONNECTOR

Right angle with the major connector

Gently curve junction

Positioned in lingual embrassure

JOIN DENTURE BASE TO MAJOR CONNECTOR

Open construction form ladder like network

Mesh construction

Bead, wire or nail head components on metal base

OPEN CONSTRUCTION FORM LADDER LIKE NETWORK

Strong enough to anchor denture base

Distal extension

In maxillary arch, extend as far posterior as practical

In mandibular arch, extend two thirds the length of edentulous ridge

SERVE AS APPROACH ARMS FOR BAR- TYPE CLASP

Not required to be rigid

Must not cross tissue undercut

RESTS AND REST SEAT

! A rest that is part of a retentive clasp is referred

to a primary rest

! A rest that is responsible for additional support

or indirect retention is called an auxiliary rest or

secondary rest

PRIMARY REST

! Prevent vertical movement

! Transmit force to supporting tissue

! Ball and socket joints

AUXILIARY REST

! Indirect retainer in extension base

! Place anterior or posterior to the axis of rotation

MAJOR FORM OF REST

! Occlusal rest

! Lingual or cingulum rest

! Incisal rest

OCCLUSAL REST

Triangular

1/3 – 1/2 of mesiodistal diameter

Approximate 1/2 of bucco lingual width

OCCLUSAL REST

Floor of rest seat slightly inclined toward the center of the teeth

Deepest portion located near the center

At least 0.5 mm. thick at thinnest point

1.0-1.5 mm. thick at the marginal ridge

LINGUAL AND CINGULUM REST

Primarily used on maxillary canine

V shape

Ball and socket assembly

INCISAL REST

Frequently used in mandibular canine

Small V shaped notch

Located approximately 1.5 to 2.0 mm. from the proximal incisal angle

DIRECT RETAINER

DIRECT RETAINER

! Engage abutment and resist dislodging forces

! Two type

! Intracoronal direct retainer! Precision attachment

! Semiprecision attachment

! Extracoronal direct retainer! Retentive clasp

! Suprabulge

! Infrabulge

! Attachment

RETENTIVE CLASP ASSEMBLIES

! Structure of clasp assembly

! Rest

! Retentive arm

! Reciprocal element

! Minor connector

RETENTION

! The quality of clasp that resists forces acting to

dislodge component from supporting tissue

! Depend on

! Type of clasp

! Flexibility

! Undercut

CLASP ARM FLEXIBILITY

! Depend on

! Length " increase

! Cross-sectional diameter "circular

! Longitudinal taper

! Clasp curvature " single plane

! Metallurgical properties of alloy "gold , wrought

wire

RECIPROCATION

The quality of clasp that counteracts lateral displacement of an abutment when retentive clasp terminate

RECIPROCATION ELEMENT

! Cast clasp

! Lingual plate

! Combination of mesial and distal minor

connector

! Prepared parallel to path of insertion

ENCIRCLEMENT

! The characteristic of clasp that prevent

movement of abutment away from associated

clasp assembly

! Contact over at least 180°

PASSIVITY

! Quality of clasp that prevent the transmission of

the adverse forces to the associated abutment

LOCATION OF RETENTIVE CLASP

TERMINUS

! Mesial or distal line angle

! Facial surface better than lingual surface

! Length " Flexibility

! Contraindicated in premolar

SIMPLE CIRCLET DESIGN (Aker’s clasp)

Widely used

Tooth support RPD

Engage undercut remote from edentulous area

Half round cross sectional

Disadvantages- Increase circumference clinical crown- Increase tooth coverage

REVERSE AKER DESIGN

Undercut located adjacent to edentulous area

Infrabulge clasp is contraindicated

Kennedy class I ,II

Disadvantage - Reduced strength- Lack of rest adjacent to edentulous area- Poor esthetic

MULTIPLE CIRCLET DESIGN

2 simple circlet clasp joined at the terminal aspect of their reciprocal elements

Principle abutment is periodontal compromised

Disadvantage- The same as simple circlet and reverse circlet

EMBRASURE CLASP

2 simple circlet joined at bodies

Used on no edentulous area side

Insufficient tooth preparation results in

Inadequate cross sectional dimension

Compromised clasp strength

RING CLASP DESIGN

Indicated on tipped mandibular molar

Engage mesiolingual or mesiobuccal undercut

Auxiliary bracing arm

Distal and mesial –occlusal rest

Disadvantage- Tooth coverage- Difficult correction

Contraindication- Limit vestibular depth- Soft tissue undercut

BuccalLingual

C-CLASP DESIGN (Back action clasp)

“Fishhook” or “Hairpin” clasp

Simple circlet clasp with loop back retentive arm

Sufficient crown height

Disadvantage- Insufficient flexibility- Tooth coverage- Esthetic compromised

WROUGHT WIRE CIRCUMFERENTIAL CLASP

Combination clasp- Occlusal rest- Cast metal reciprocal arm- Wrought wire retentive arm

Circular cross sectional

Kennedy class I and II

Mesiobuccal undercut

Minimal tooth coverage

Disadvantage-Breakage-Minimal stabilizing

COMBINATION CLASP IN INFRABULGE CLASP

! Bar type

! Flexibility

! Length

! Taper

! More esthetics

! T-clasp, modified T clasp, Y clasp and I bar

! Disadvantage

! Food accumulate

! Flexibility ! " Horizontal stability "

DESIGN RULES

! Approach arm

! must not impinge soft tissue

! cross perpendicular to free gingival margin

! Uniformly tapered " Flexibility

! Terminate clasp positioned " Apically on the abutment

! Rigid minor connector " Bracing and Stabilization

T-CLASP DESIGN

Kennedy class I and II

Undercut locate adjacent edentulous area

O.01’’ undercut

Contraindication- Severe soft tissue undercut- High of contour locate near occlusal surface

A = Approach armB= Vertical projection of approach arm

C= Location where B cross perpendicular to free gingivalD=Point of first tooth contact

E=Terminus of the retentive claspF= Encirclement portion

I-CLASP OR I BAR

Contact area

2-3 mm. in height

1.5-2 mm. in width

Mesial rest

Kennedy class I and II

RPI- Mesial rest- Proximal plate- I bar

MODIFIED T-CLASP

No retentive horizontal projection

Kennedy class I and II

Undercut locate near adjacent edentulous area

Canine and premolar

Advantage- Improve esthetic compare with conventional T clasp

Y-CLASP DESIGN

Equivalent to T-clasp

Mesial and distal projection terminate near occlusal surface

INDIRECT RETAINER

INDIRECT RETAINER

! Framework component that resists rotational

displacement of an extension base from the

supporting tissue

! Require for Kennedy class I, II and IV

EFFECT OF ROTATIONAL

MOVEMENT

! Occlusal dislodging forces

! Denture base move away from supporting tissue

! Anterior segment of major connector impinge upon

underlining tissue

FACTOR DETERMINE INDIRECT

RETAINER

! Position on the opposite site of fulcrum line

! Perpendicular and far from fulcrum line

! Canine and premolar

! Rest at each end of lingual plate

FORM OF INDIRECT RETAINER

! Auxiliary occlusal rest

! Cingulum rest

! Incisal rest

Distal Extension RPD

! Direct retainer design

81

83

Indirect retainer

84

SUPPORT FOR DISTAL

EXTENSION DENTURE BASE

! Maximum border extension

! Accurate border detail

! Primary supporting area

! Form of the ridge under function

Impression technique

! Final impression with custom tray and

elastomeric impression material

! Altered-cast technique

86

Miscellaneous

! Retentive arms should be on the same side

! Dimpling

! Treatment denture

! RPD drawing

- in paper

- on the cast

87

THANK YOU

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