Prosthodontics: RPD Flashcards
Kennedy Class I
Bilateral Distal Extension
Kennedy Class II
Unilateral Distal Extension
Kennedy Class III
Unilateral Bounded Edentulous Space (BES)
Kennedy Class IV
Bilateral BES (Crosses Midline)
Applegate’s Rules
- Classify after All extractions
- Do not consider Missing 3rd molars
- Consider Abutment 3rd molars
- Do Not Consider Missing 2nd Molars
- Most posterior edentulous area determines classification
- Other edentulous areas=modifications
- extent of modification doesn’ t matter, only number
- Class IV can NOT have any modifications
Major Connector
central component of metal framework
* connects all components
Provides rigidity
Not placed on movable tissue (Only on palate or lingual aspect of alveolar ridge)
Maxillary Major Connectors: Types
Should cross midline at 90 degrees
Types:
* complete palatal plate
* Horseshoe
* Palatal Strap
Complete Palatal Plate
Most Rigid Maxillary Major Connector
When is a complete palatal plate for maxillay major connector indicated?
- all posterior teeth are missing bilaterally (Class 1)
- shallow palatal vault
- periodontally compromised teeth
- small mouth
- flat or flabby alveolar ridges
Horse Shoe major connector
Least Rigid Maxillary Major Connector
When is a horse shoe major connector indicated to use?
Large palatal torus
Palatal Strap
Maxillary Major Connector
* metal strap that goes from L to R
Beading
Only for Maxillary Major Connectors
0.5 mm round groove in the cast at the borders of the major connector
* Adds Strength
* maintains tissue contact=prevent food impaction
What are the different types of mandibular major connectors?
Lingual Bar
Lingual Plate
Labial Bar (Aka Swinglock)
Lingual Bar
Mandibular Major Connector
* Lingual vestibule depth >/= 7mm
* simplest
* most common
Lingual Plate
Mandibular Major Connector
Indications
* Lingual vestibule depth < 7 mm
* anticipate more tooth loss
* Lingual Tori
* Bilateral Missing Posterior Teeth(Class 1)
Labial Bar
mandibular Major connector
* aka Swinglock
Indicated when:
* missing canine
* unfavorable soft tissue contour
* questionable perio prognosis
Minor Connectors
connect major connectors to rests, indirect retainers, and clasps
Rest
Rigid extension of RPD framework
* contacts occlusal, lingual, or incisal surface of abutment tooth
Provides Support
* directs forces down long axis
Rest Seat
Prepped into occlusal, lingual or incisal surface of abutment tooth
* receive and support rest
Occlusal Rest
Spoon Shaped
* rounded, semicircular outline form
1/3 MD width
1/2 intercuspal width (B/L)
1.5 mm depth
Floor inclines apically toward center
* < 90 degrees w/vertical minor connector
Cingulum Rest
Inverted V or U Shape
2.5-3 mm MD Length
2 mm B/L Width (ledge)
1.5 mm Deep
What are the benefits of a cingulum rest?
Distribute occlusal load (good)
esthetics
strength–due to how close they are to major connector (Dont need minor connector)
When are cingulum rests contraindicated?
Mandibular Incisors
Incisal Rests
Rounded notch at incisal angle
* used as indirect retainer
* less favorable leverage than lingual rest
* not esthetic
2.5 mm MD Length
1.5 mm Depth
Proximal Plate
Metal plate that contacts proximal surface of abutment tooth
Guide Planes
path of insertion and removal
1/3 Buccolingual width
extends 2-3 mm down from marginal ridge
Indirect Retainer
Indirect retainer
* perpendicular and anterior to fulcrum line (Axis of rotation)
* fulcrum line=line through most distal rests
* anti-rotation of distal extension area
What does a Direct Retainer consist of?
Aka Clasp Assembly
Consists of:
Rest: Support
Minor Connector: Stability
Clasp Arms
* Retentive Clasp Arm: Retention
* Reciprocal Clasp Arm: Stability
Direct Retainer: Extracoronal Retainer vs Intracoronal Retainer
Extracoronal Retainer:
* more common
* conventional clasp design
* encircles tooth at least 180 degrees
Intracoronal Retainer:
* precision attachment
* key and keyway pattern
* most esthetic bc no clasps
Retentive Clasp
Originates from minor connector & rest
Contacts tooth below HOC/Survey Line
* Retention
Reciprocal Clasp
Aka Stabilizing Clasp
* Stability
Contacts tooth Above HOC/Survey Line
* not torqued by retentive clasp
Suprabulge vs Infrabulge Clasps
Suprabulge: Originate above survey line/HOC
Infrabulge: Orginate below survey line
What are some examples of suprabulge clasps?
- circumferential (Akers)
- Ring
- Combination
- Embrasure
What are some examples of infrabulge clasps?
- I Bar
- T Bar
- Bar Type
- Y Type
Circumferential Clasp
Aka Akers Clasp
* Most commonly used
* rest seats adjacent to edentulous space
Ring Clasp
Suprabulge
undercut=adjacent to BES
* molars and MF undercut
Embrassure Clasp
Suprabulge
Rests on both teeth
* so clasps don’t wedge teeth apart
T-Bar
Infrabulge
* T-Bar
* Modified T-Bar (R Bar)
I-Bar
Infrabulge
- needs enough vestibular depth
- No Soft Tissue undercut
RPI
Type of Direct Retainer
* Rest, Proximal Plate, I bar
* M Rest
RPA
Aka RPC
Type of Direct Retainer
* Rest, Proximal Plate, Akers/Circumferential
Clasp Selection: General Rules
* BES vs Distal Extensions
BES:
* use Akers clasps
* rest seats adjacent to edentulous space
Distal Extensions: (order of preference)
1. RPI
2. RPA
3. Wrought Wire
Wrought Wire Indications
Periodontally Compromised tooth
Endo-Treated tooth
More Flexible
seperately positioned and sauntered onto framework
Less torque on teeth
Cobalt Chromium
Framework material
2.3% shrinkage
* causes irregularities & porosity
Cold-working (aka plastic deformation or work hardening)
* manipulate metal at ambient temp
* Main reason why clasps break
