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DESCRIPTION
under Dr. MACCAY
Citation preview
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
“Being excited about being wrong because that means you’ve discovered something new”
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