CLASP RETAINED
REMOVABLE PARTIAL
DENTURES
COMPONENT PARTS OF A
REMOVABLE PARTIAL DENTURE
• Retentive Arm
• Bracing or Reciprocal
Arm or Plate
• Rest
• Minor Connector
• Major Connector
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Grid Retention Areas
Tissue Stop
Indirect Retainer
Denture Base
Denture Teeth
Cast RPD Framework
Components
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Major Connector
Minor Connectors
Clasp Assembly
Retention for Replacement Teeth
Cast RPD Framework
Components
• MAJOR CONNECTOR
• A major connector is the part of a RPD
that connects the components on one side of
the arch to the components on the opposite
of the arch.
Major Connector Requirements
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Rigidity
Should be contoured
Should avoid circumjacent structures
Minimum bulk
Maxillary Major Connectors
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Palatal Strap
Anterior Posterior (A-P) Palatal Strap
Palatal Plate
Palatal Bar
U-Shaped (Horseshoe) Palatal Connector
Palatal Strap
Palatal Strap
A-P Bar
• Palatal bar is defined as being 8mm or less
in width.
• A palatal strap is greater than 8mm in width
• OBVIOUSLY,THIS IS NOT
BRAIN SURGERY
Palatal Plate
Strap or Bar ?
Anterior edge should
follow contour of rugae
A-P Strap or Bars ????
Maxillary framework should be
6mm from free marginal
gingiva, if this is not possible
than the framework should end
on teeth.
Maxillary Major Connectors
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Palatal Strap
Anterior Posterior (A-P) Palatal Strap
Anterior Posterior (A-P) Palatal Bar
Palatal Plate
Palatal Bar
U-Shaped (Horseshoe) Palatal Connector
Mandibular Major Connectors
Mandibular Major Connectors
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Lingual Bar
Lingual Plate
Double Ling Bar (Kennedy Bar)
Labial Bar
Swinglock
Mandibular Major Connectors
Lingual Plate
Lingual Bar
• The superior border of a lingual bar should
be at LEAST 4 mm below the free marginal
gingiva.
Lingual Bar
and
Lingual Plate
Indications For Use Of A Lingual
Plate
• For stabilization of periodontally involved teeth.
• In Class I situations in which residual ridges have
undergone excessive vertical resorption.
• When the lingual frenum is high or the space available
between the gingival margin and the floor of the mouth is
<8 mm.
• Lingual bar approximately 4mm + 4mm clearance from
free marginal gingiva = 8mm and want no impingement of
lingual frenum.
Indications for use of a Lingual
Plate, continued
• When the patient has found a lingual bar
objectionable in the past
• When the future replacement of one or more
incisor teeth will be facilitated by the
addition to the lingual plate.
Lingual plates must always
terminate in a prepared rest seat
and never on an inclined surface.
Labial Bar
Double Lingual
Bar
or
Kennedy Bar
Palatal torus
U Shaped
Swing Lock
Major Connector
Or
Clasp???
Mandibular Major Connectors
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Lingual Bar
Lingual Plate
Double Ling Bar (Kennedy Bar)
Labial Bar
Swinglock
Cast RPD Framework
Components
• MAJOR CONNECTOR
• MINOR CONNECTORS
• Minor connectors are those components
that serve as the connecting link between
the major connector and the other
components.
• Many times a minor connector will be
continuous with a lingual or palatal plate
rather than a distinct element.
Reciprocal Arm
Retentive Arm
APPLICATION OF CLASP
ASSEMBLY TO TOOTH
• Minor connectors may play a critical role
by serving as a connector for indirect
retainers that minimize the rotation of free
end saddles.
• An indirect retainer is that part of an RPD
that assists the direct retainer in preventing
displacement of distal extension denture
bases by resisting lever action from the
opposite side of the fulcrum line. It is the
rest within the rest seat that prevents the
displacement.
Indirect retention
• The ideal position for an indirect retainer is
at a right angle to the fulcrum and located
on the strongest tooth.
Cast RPD Framework
Components
• MAJOR CONNECTOR
• MINOR CONNECTORS
Cast RPD Framework
Components
• Major Connector
• Minor Connectors
• Clasp Assembly
• A clasp assembly is the part of a RPD that
acts as a direct retainer and/or stabilizer for
a prosthesis by partially encompassing or
contacting an abutment tooth.
• Clasps are made up of a retentive arm, a
reciprocal or bracing arm, and a rest.
CLASP ASSEMBLY
Clasp
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Retentive Arm
Bracing or Reciprocal Arm or Plate
Rest
Minor Connector
Clasps
• Retentive Arm (Direct Retainer)-that
component of an RPD used to retain or
prevent dislodgement. The terminal third of
which is the ONLY portion of the casting
that touches the tooth BELOW the height
of contour therefore, it must move over the
height of contour for the RPD to go to
place. It must flex or the tooth move.
Clasps
• Reciprocal Arm-stabilizes the tooth by
being in contact with the opposing side of
the tooth during the entire period of the
retentive arm deformation. (Its movement
over the height of contour during insertion
and removal.)
BRACING
2o Bracing:
– Cross arch bracing
• location of retentive
arms on the same side
of the teeth on opposite
sides of the arch.
RETENTION (pp84-93)
• Angle of convergence-THE UNDERCUT
Size and Distance
• Length of the clasp arm
• Diameter of the clasp arm
• Cross sectional form of clasp arm
• Material used for clasp arm-CrCo vs Gold
• Uniformity of retention-across the arch
Dental Retainers
•Clasps
–Cast
•Suprabulge
•Infrabulge
–Wrought wire
•Attachments
•Intracoronal
•Extracoronal
Stress breaking
• Aim - reduce torquing force on distal
abutment teeth
Stress breaking
Mesial Rest - Wrought Wire
RPI
REST
PLATE
I-BAR
• Don’t get hung up on
names of clasps; learn the
principles, the names will
change.
MADDEN CLASP
Failure to
cover the
retromolar
pad