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DSRP 6602/6603DISP 7212/7213
Lecture 2
Components, Tooth
modifications
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RPD Components
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RPD Components
Major Connectors
Minor ConnectorsProximal Plates
Rests
Direct RetainersIndirect Retainers
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Major Connectors
Connect parts of the prosthesis on one
side of the arch to those on the opposite
side
All other parts are directly or indirectly
attached to this component
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Major Connectors
Rigidity is necessary to
Control the relationship of remaining teeth to eachother, minimizing movement of the RPD
Control direction of force and torque against allremaining support structures & opposing occlusion
Provide greatest potential to control functional loadingby utilizing and uniting all remaining structures of thearch
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Maxillary
Major Connectors
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Maxillary Major Connectors
Considerations
Gingival tissue requires unrestricted superficial bloodsupply borders of MC should be minimum 6mm
away & parallel to gingival margins
The posterior limit for all maxillary MC shouldterminate just anterior to the vibrating line
All MC should cross midline at right angles, notdiagonally, for better tongue acceptance
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Maxillary Major Connectors
Types (4)
Full Palate Major Connector
Single Palatal Strap Major Connector
Anterior/Posterior Palatal Strap Major Connector
Horseshoe (U-shaped) Major Connector
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Full Palate Major Connector
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Full Palate Major Connector
Uniformly thin, broad, contoured plate followingcontours of/covering the (majority of the) palate
Indicated in situations where remainingabutment tooth on either side is canine or 1stpremolar, esp. in cases with severe vertical ridgeresorption, complete denture scenario
It is thought to be more readily accepted byunderlying tissues and tongue because of closeadaptation to palate, thinness, & thermalconductivity
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Anterior/Posterior Strap
Major Connector
What does this remind you of?
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Anterior/Posterior Strap
Major Connector
Very stable & rigid MC- strength from A/P straps
linked by struts forming square frame, all
components brace others against possible
torque & flexureMX torus may be encircled by this MC
Can be used with any Kennedy Class
Posterior strap should be flat, at least 8mm wide,and located as far posteriorly as possible
anterior to vibrating line
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Single Palatal Strap
Major Connector
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Single Palatal Strap
Major Connector
Indicated for situations with bilateral tooth-support and posterior edentulous spaces(Kennedy Class III)
Sufficient rigidity = minimum 8mm width
Not indicated to connect anterior edentulousspace with distal extension bases, for thesecases use A-P strap
Preferred by patients over an A-P strap
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U-Shaped Major Connector
Horseshoe
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U-Shaped Major Connector
Least desirable of MC designs, should never be usedarbitrarily
Lacks rigidity, allows lateral flexure under occlusal loads,
leading to torquing to abutment teeth
Useful in Class IV RPDs
Primary indication is large inoperable torus, whichextends posteriorly, inhibiting placement of posteriorstrap
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Mandibular
Major Connectors
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Mandibular Major Connectors
Types (2)
Lingual Bar Major Connector
Linguoplate Major Connector
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Lingual Bar Major Connector
Located above moving tissue (floor of themouth) and as far as possible below gingivaltissue margins
Superior border = 4mm below free gingivalmargin
Inferior aspect has half-pear contour for greatest
bulk & rigidity
Preferred by patients over a linguoplate
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Lingual Bar Major Connector
Note: 8 mm requirement
vertically from FGM
to base of bar. Boards
require 7 mm minimum,
(3 gingiva, 4 bar).
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Lingual Bar Major Connector
Note: 4+ mm rule
National boards: 3+ mm rule
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Linguoplate Major Connector
Superiorly should follow natural curvature
of tooth contour above cingula, not
extending above middle 1/3 of teeth
The linguoplate itself is NOT considered
an adequate indirect retainer. Must have
terminal rests or cingulum rests beneath
the plate in Kennedy Class I, IIs
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Linguoplate Major Connector
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Linguoplate Major Connector
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Linguoplate Major Connector
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Linguoplate Major Connector
Indications
Stabilization of periodontally mobile teeth by
splinting
Provision for future anticipated loss of teeth
which may be added to the plate
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RPD Components
Major Connectors
Minor ConnectorsProximal Plates
Rests
Direct RetainersIndirect Retainers
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Minor Connectors
Connecting link from MC or denture baseto all other RPD components
Transfer stresses to abutment teeth and/orunderlying supporting tissues
Supports the clasp and rest assembly
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Minor Connectors
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Minor Connectors Retaining
Denture Bases
Ladder
Lattice Meshwork
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Minor Connectors
Open lattice or ladder design preferable
Should not interfere with setting of teeth
Mandibular distal extension should extend at
least 2/3 length of edentulous span
20 gauge wax relief between framework & basal
seat
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Guide Plane
A flat area on a tooth surface created tofollow the contour of the tooth and definethe path of insertion
Location: on the mesial &/or distal ofabutment teeth facing an edentulousspace
Size: 2-3 x 2-3 mm depending upon thetooth
Guide plate: the framework metal thatengages the guide plane
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Minor Connector: Proximal Plate
Proximal guide plate
in metal
Guide plane
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Minor Connectors:
proximal Guide Plates
Helps to maintain arch integrity by
anterior-posteriorbracing action
(resistance to horizontal forces)
Acts as a retainer (secondary) due to
frictional contact with parallel guiding
surfaces
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Guide Platesstability, support,
retention
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Minor Connectors: Rests are cast
to fit rest seats
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Rests & Rest Seats
Rests provide vertical support
Prevent impingement of soft tissues by
resisting tissue-ward movement
Direct & distribute occlusal loads tosupporting abutment teeth
Preserve established occlusal relationships
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Occlusal Rests & Rest Seats
Outline of rest seat should resemble rounded ,
with apex pointing toward center of tooth
Should be as long as it wide
At marginal ridge, base of should be at least
2.5mm for molars and premolars
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Occlusal Rests & Rest Seats
Height of marginal ridge should be
reduced at least 1.0-1.5 mm to allow for
bulk of metal for strength & rigidity
Floor of rest seat should be apical to
marginal ridge, spoon-shaped, concave
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Occlusal Rest Seats
Deepest part
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Rests & Rest Seats
Angle formed by occlusal rest and mC
from which it originates should be less
than 90 so that forces can be directed
down long axis of abutment tooth
If angle >90, slippage could occur and
orthodontic tooth movement may result
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Occlusal Rests & Rest Seats
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Embrasure Rests
& Rest Seats
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Rest Seats
May be placed within sound enamel Enamel not at increased risk for caries given
appropriate oral hygiene
May be placed on any restorative materialscientifically proven to be fracture and distortionresistant
Important to inform pt ahead of time of thechance of perforation through existingrestoration, potentially necessitatingreplacement or repair (esp. crowns)
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Cingulum Rests & Rest Seats
Canine preferred over incisors
If lingual slope of chosen tooth is gradual
rather than perpendicular, bondedcomposite rest seat preferred
Cingulum rest preferred over incisal rest(less tendency to tip tooth and estheticallysuperior)
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Cingulum Rest Seats
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Incisal Rests & Rest Seats
Placed at incisal angles of anterior teeth
Least desirable placement of rest seat,
possible esthetic issue, may causeorthodontic movement due to unfavorableleverage
Rounded notch at incisal angle, withdeepest portion apical to incisal edge
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Single Incisal Rest
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Tooth Modifications for
RPD Designs
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Tooth modifications
Guide planes
Create an area of retention
Change of survey line (height of contour)
Rests
Survey crown
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Guide planes
Prepared on the mesial and/or distal ofabutment teeth aligned with the crest ofthe edentulous ridge
Extend from marginal ridge to junction ofmiddle and gingival thirds, dependingupon the contour of the tooth
NOT a meat cleaver slice, rather a gentlere-shaping of enamel which follows thecontour of the tooth, curved planes
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Distal guide plane #21
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Create an area of retention
This may be accomplished by
enameloplasty or composite resin bonding
Enameloplasty does not change the height
of contour when creating retention belowthe survey line
Composite resin bonding effectively
moves the survey line occlusally orincisally
#13: survey line too gingival,
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#13: survey line too gingival,
composite resin bonding indicated
facially to move retention occlusally
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Change in survey line
This may be accomplished by
enameloplasty or
composite resin bonding orsurvey crown
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Change in survey line
Raising the survey line occlusally
increases retention below the line
Lowering the survey line gingivally
decreases retention below the line
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Change in survey line
Remove interferences when seating the
retentive and reciprocal clasp arms or
guide planes (lowering the survey line)
NOTE: reciprocal arm must be in suprabulge
Enhance esthetics of clasp placement
(lowering the survey line)
Lowering survey line on disto
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Lowering survey line on disto-
facial of #21 for clasp placement
Remove interferences on mesial
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Remove interferences on mesial
of #25 & #29
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Rests
In enamel, NOT dentin (recurrent caries)
In existing amalgams, composite resins
In created composite resins
In survey crowns
In pre-existing crowns and FPDs, be
certain to obtain informed consent.why?
Occlusal rests mesial of
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Occlusal rests mesial of
#21(enamel) & #29(gold)
Composite resin cingulum rests
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Composite resin cingulum rests
to be bonded to #22, 27
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Survey crown
Why? When all else fails or the tooth would
be an excellent candidate for full coverage
in its own right
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FGSC #29 (the survey line is lousy)
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Occlusal view of survey crown #29
Recommended