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62 Cards in this Set
- Front
- Back
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n (denture-bearing area, denture-supporting area, stress-bearing area, stress-supporting area), the portion of the oral structures available to support a denture.
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saddle area
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mesial rest, distolingual guide plate, I-bar
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RPI
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mesial rest, distolingual guide plate, Akers' clasp-style retentive arm
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RPA
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wrought wire
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RPW
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What is the X-sectional shape of these clasps
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reverse c Clasp
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Which clasp has the greatest surface area contact with enamel? Create a ranking, most to least
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Reverse c, mod rpa, mod-t, RPI,
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should we remove mandibular torus
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True
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Advantages of Co-Ni-Cr alloys
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Higher strength
Fatigue resistance Lighter weight Lower cost |
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Composition of RPD alloys
Co-Cr (Vitallium, Nobilium, Wironium) |
30% Cr, 60% Co
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Rate density of alloys
Gold, Co-Cr, Ni-Cr, and Cp-Ti |
High med med low
Low density, more casting force required; special, expensive equipment (Ti) |
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Generally, 0 degree teeth are not used in the RPD arch
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True
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axis of rotation = RPD movement around axis = potential for loose abutment teeth
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fulcrum line
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Always identified by connecting
the TWO most DISTAL rests in KI, IIs. Two most anterior rests in K IVs |
fulcrum line
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steps when making RPD
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treatment plan
study casts, design the RPD final impressions, metal framework fit the frame, correct the cast as needed, bite relation set teeth wax try-in deliver the prosthesis follow-up & maintenance |
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How to keep the RPD in the mouth and brace (protect) the abutment teeth.
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Retention and reciprocation
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The line formed by
a tangent plane moved around the surface of a tooth when the tooth is aligned with the path of insertion. |
survey line
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Area in which we design and place a clasp, connector, or rest to “brace” the abutment tooth during RPD placement and removal
This is the concept of reciprocation |
Suprabulge
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arms of RPD clasps resist unwanted lateral stresses on the abutment tooth
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Reciprocal or bracing
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A phenomenon of friction, resistance to displacement = lack of vertical movement of the prosthesis
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retention
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= frictional forces that increase RPD retention, help control stress, and define the path of insertion
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Guide planes/plates
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All occlusal forces supported by the abutment teeth
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Kennedy III, IV
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Proper, passive fit of the metal framework
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stability
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The most posterior edentulous area
(or areas) ALWAYS determines the classification |
True
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All MCs should cross midline at __________, not diagonally, for better patient adaptation (tongue acceptance) and biomechanical rigidity
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right angles
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Name the 4 Max major conectors
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Anterior/Posterior Palatal Strap Major Connector
Single Palatal Strap Major Connector Full Palate Major Connector (6 teeh remaining) Horseshoe (U-shaped) Major Connector(kenedy class 4, least rigit |
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Indicated for situations with bilateral tooth-support and posterior edentulous spaces
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(Kennedy Class I,II,III)
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with lingual bar __ mm requirement
vertically from FGM to base of bar (lingual vestibule |
7
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The ________ must have terminal occlusal rests or cingulum rests associated with the plate in Kennedy Class I, IIs designs, to prevent horizontal forces against anterior teeth.
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linguoplate
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Rests provide support
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vertical
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Height of marginal ridge should be reduced at least ______mm to allow for bulk of metal for strength & rigidity
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1.0-1.2
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Floor of rest seat should be ____apical to marginal ridge spoon-shaped, concave
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(1.5mm),
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Walls should be
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divergent
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Useful in Class IV RPDs
Primary indication is large inoperable torus, which extends posteriorly, inhibiting placement of posterior strap |
U-shaped major connector
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Angle formed by occlusal rest and mc from which it originates should be _____ than 90° so that forces can be directed down long axis of abutment tooth
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less
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If lingual slope of chosen tooth is gradual (no cingulum exists or the tooth is a MN incisor), a bonded composite resin may be used to create the anatomy to accept a “cingulum” rest or use a “Ball rest”(Haisch, LD. JPD, 2:1; 1993:70-72)
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true
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Retentive arms of cast clasp assemblies are placed in which position on the surveyed tooth?
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A. Infrabulge
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RPD Components
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Major Connectors
Minor Connectors Proximal Plates Rests Direct Retainers = clasps/others Indirect Retainers |
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Direct retainers do not keep the RPD seated in the mouth
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False, it does keep the RPD in mouth
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Areas ________ to the height of contour are used for placement of flexible (terminal third), retentive clasp components
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apical
This is called retention |
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Areas coronal to the height of contour are used for the placement of stabilizing, (non-retentive)
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reciprocating clasp components
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- resistance to the horizontal components of masticatory forces
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Bracing
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In adequated encirlement More than 180° should be engaged by the clasp assembly. Why?
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prevents horizontal tooth movement away from the confines of the clasp assembly; assists in bracing
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(located in gingival 1/3 of abutment tooth in a predetermined undercut of 0.01”)
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Retentive arm
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(mc, plate) (located in the occlusal 1/3 of abutment tooth)
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Reciprocating arm
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Flexibility is _______…key concept… …...rigid clasps cannot _______
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crucial and seat
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“C” clasp is half round in X-section
this is the classic suprabulge clasp. Why |
(low flexibility);, the retentive clasp has flexible (1/3 portion) as it is removed and inserted in the mouth. Suprabulge deals with horizontal movements
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Infrabulge clasp- approaches the coronal portion of the tooth from an apical position and does not cross the height of contour when the RPD is fully seated (DeVan). The survey line is crossed only during insertion & removal.
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True
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In infrabulge (I-bar clasp) retentive clasp ALWAYS on facial?
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True
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Fulcrum line is the axis of rotation
and passes through the two most distal rests (anterior rests in KIVs) |
True
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Occlusal or cingulum rests anterior to and __________ to the fulcrum line function as indirect retainers
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perpendicular
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Kennedy Class I or II arches: distal extension saddle
First choice is the |
Infrabulge Bar Clasp:
Ex. RPI (I-bar), modified T-bar |
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an abutment tooth with 0.01” undercut in cervical 1/3 that can be accessed from the gingival aspect
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Bar Clasp
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What are contraindications whne using Bar Clasp?
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Severe buccal/lingual tilt
B: Soft tissue undercuts within 3 mm of the free gingival margin (cannot insert/remove with a metal loop in tissue undercut, irritating to tongue/cheek and acts as trap for food debris) : Shallow buccal vestibule (minimum 3-4 mm needed) Prominent buccal frenum |
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0.01” Mid-Facial undercut in the gingival 1/3 or 1/2 of the abutment tooth
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RPI )I-bar)
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Directs center of rotation (of clasp) mesiogingivally, disengaging the tooth during functional loading
provides vertcal suppport |
mesial rest
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Provide horizontal stability
Reunite & stabilize the arch retention due to parallelism Provide reciprocation & encirclement |
proximal plates
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T Or F I-Bar Should not be placed in a distobuccal undercut (will not disengage under function).
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true
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0.01” Disto-Buccal undercut in the gingival 1/3 or 1/2 of the abutment tooth
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mod- T bar
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If cannot use infrabulge why use a suprabulge
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There exist bony/soft tissue undercuts or frena apical to the free gingival margin in the first 3 mm of tissue
Shallow vestibule Patient factors: medical/physical conditions (OA, CVA, Parkinsons), poor eyesight |
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distal extension
0.01” or more Mesio-Facial undercut in the gingival half of the abutment tooth |
Cast round wire (modified) RPA; RPW (wrought wire
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Engage an 0.02” undercut
The most flexible |
RPW
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0.01” Disto-Facial undercut in the gingival half of the abutment tooth
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Reverse “C” clasp
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