RDP's Flashcards
What must a Kennedy Class IV Prosthesis provide for>
- Must be regarded as a Class I denture in reverse (especially if long edentulous span)
- Forces of rotation around anterior abutment teeth
- Indirect retention must be obtained posterior to the fulcrum line
What are some Advantages/Indications of Implant Assistance in RDPs?
- Distal extension support
- Reduced bone resorption
- Elimination of unesthetic retentive elements
- Decreased stress on abutments
- Improved comfort and patient satisfaction
What increases the effectiveness of Indirect Retainers?
- Needs definitive rest seat
- Distance from fulcrum line
- Major and minor connector rigidity
For an RPI, the superior edge of the proximal plate contacts _____ mm of the inferior portion of the guiding plane (junction of occlusal and middle 1/3)
1 mm
What mandibular major connectors are these?
- Labial bar
- Lingual bar
Where are forces applied to a Mucosa borne RDP?
Forces are applied to tissue only
Describe a Kennedy Class I…
Bilateral Edentulous areas located posterior to the remaining natural teeth
What are some Disadvantages of a Rotational Path RDP?
- Adjustment of rigid retentive component difficult
- Less tolerance for error
- Requires well prepared rest seats
What is the minimum space required for a lingual bar?
- 8 (7) mm from the gingival margin to the floor of the mouth
- 3 mm from free gingival margin to superior border of the bar
- The bar should at least 5 (4) mm in height
What are the 3 Biomechanical Classications for RDPs?
- Tooth borne
- Tooth-mucosa borne
- Mucosa borne
Describe the McDermott Classification…
- A modification of the Kennedy Classification
- Indicates arch configuration, and natural tooth abutment location
What do implants help do in regards to stress on abutments?
Decreases Stress on Abutments
What are some Advantages of a Swing Lock RDP?
- Relatively inexpensive method of utilizing remaining dentition
- Simple
Where surface is the Modified T-Bar placed undercut wise?
Distofacial Undercut
What is this called?
Krol
What are 4 indications for a Swing Lock RDP?
- Too few teeth for conventional RDP design
- Remaining tooth mobility
- Position not favorable for conventional design
- Maxillofacial applications
What Kennedy Classification is the altered cast technique used for?
Class I and II RDPs
Define Minor Connector…
“The connecting link between the maor connector or base of a RDP and the other units of the prosthesis, such as the clasp assembly, indirect retainers, occlusal ressts, or cingulum rests.”
What are 3 RDP Design Philosophy’s?
- Stress Equalization
- Physiologic Basing
- Broad Stress Distribution
What 2 functions must a Minor Connector provide?
- Must be rigid
- Transfer functional stress to teeth and ridge
What are some uses of a Surveyor?
- Survey of diagnostic and master casts (locate and measure undercuts for fixed and removable prostheses)
- Create measurable contours in wax patterns for fixed prostheses
- Aid in placement of precision attachments for fixed and removable prostheses
What Kennedy Classes are Twin Flex designs indicated for?
Kennedy Class 3 and 4
Describe the prep for an Occlusal Rest…
- Triangular and concave
- Rounded apex
- Shold follow the fossa outline
- Inclined towards the center of the tooth
- Should allow for minimum 1.0 mm metal thickness
What are the third 3 Indications for RDPs?
- Patient desires removable prosthesis
- High caries index
- Obturation of palatal defect
Where are mesial torqueing and axial forces directed on a RPI:Krol setup?
What is the abutment tooth braced by?
- Mesial torqueing and axial forces directed through mesial rest
- Abutment tooth is braced by the mesial adjacent tooth
What is this a picture of?
Distal Extension Support
What are 5 Advangages of using an I-Bar?
- Exact placement of retention contact
- Minimal interference with natural tooth contour
- Maximum natural cleansing action
- Passive functional movement of an extension prosthesis
- Reduced metal display, better esthetics
Pictures for Review…
Describe Kennedy Class III Edentulism…
Unilateral edentuous area with natural teeth located both anterior and posterior to it
Schneid and Mattie Classifications…
What must a Kennedy Class II Prosthesis provide for?
- Must embody features of both Class I and Class III designs
- The dentulous side (if modification space is present) must be designed as a Class III denture
- The distal extension side must be designed as a Class I denture
What is the undercut measurement for a T-Bar?
.01 inch distal undercut
What kind of clasp is this?
Y Clasp
What are some advantages of a Twin Flex Clasp?
- Esthetic
- Adjustable
- 19 gauge wrought wire
- Soldered in 0.01 undercut
- Encirclement
What are the 3 Pillars for Design Considerations for RDPs?
- Support
- Retention
- Stability
What is a material you could use to help decide the space available for RDP Design Considerations?
Multiple Putty Matrices
Define Major Connector…
“The part of a removable partial denture that joins the components on one side of the arch to those on the opposite side”
What mandibular major connectors are these?
- Lingual plate
- Double lingual bar
Describe a Class II lever system as it relates to RDPs…
What are 5 Advantages of a Rotational Path RDP?
- Minimal # of clasps
- Anterior clasp often eliminated
- Better esthetics
- Less tooth preparation compared to a precision attachment
- May be used in absence of F/L undercut
What are first 3 indications for an RDP?
- Youth or advanced age of patient
- Great length of the edentulous span for FDP
- Excessive alveolar bone loss
Describe a Category 2 Rotational Path RDP…
- Rotational centers are located at the gingival extensions of the rigid retainers
- AP rotation replacing anterior teeth
- Lateral paths of rotation utilizing proximo-facial undercut
What are 4 different types of rests?
- Occlusal rest (proximal, channel)
- Cingulum rest
- Incisal rest
- Lingual rest (resin bonded “Ivanhoe”, dimple
Describe the shape of an Incisal Rest…
- Rounded “V” shaped notch, extends onto facial surface of tooth
What is the recomended impressions material for your RDP master impression?
Irreversible Hydrocolloid
Describe a Cingulum Rest…what shape is it?
Where is it only indicated?
- Chevron (“V”) shaped
- Must be gingival to occlusal contacts
- Only indicated on maxillary cuspids
- Bonded rests
What alternative solution can you do if for any reason you can not do the altered cast technique?
- Complete a reline
- Functional reline (Lynal)
- Selective pressure reline impressions
What are some restorative space considerations when tx planning implants/removable?
Describe Height of Contour…
“A line encircling a toth and designating its greatest circumference at a selected axial position determined by a dental surveyor”
This contour will change position as the cast is tilted on the surveying table
What is the path of insertion governed by?
Minor Connector
What is the Flexibility of Clasp affected by:
- Length
- Taper
- Diameter
- Cross-sectional form
- Material
What are some Circumferential Clasp Design Features?
- Clasp should originate from framework above the heigh of contour
- Retentive tip directed occlusally
- Terminate at line angles
- Retentive arm positioned as far apical as possible
What is an implant design consideration for a Kennedy Class IV design?
- Possible to remove the retentive arm
- Bilateral
- Anterior
When the altered cast procedure is used, the clasp design/tooth mobility…
doesn’t matter
What kind of bar clasp is this?
Modified T-Bar Clasp
What must a Clasp Design provide?
- Vertical support
- Stability (bracing)
- Encirclement
- Retention
- Reciprocation
- Passivity
What are some Implant Design Considerations for a Kennedy Class II?
- Unilateral or Bilateral
- Distal
Describe a Kennedy Class II edentulism…
Unilateral edentulous area located posterior to the remaining natural teeth
Where are forces applied to a tooth borne RDP?
Functional forces applied to remaining teeth
What is this called?
Kratochvil
What is the fourth 3 Indications for RDPs?
- Multiple edentulous areas
- Immediate Replacement of teeth
- Ease in oral hygiene
What are the 3 Dimensions of a Retentive Undercut?
- Occlusogingival
- Mesiodistal
- Buccolingual
What was the reason for utilizing the altered cast technique?
Distal extension RDPs had more movement when constructed without an altered cast procedure
Where are forces applied on a tooth-mucosa borne RDP?
Transmit forces equitably to mucosa and remaining teeth
Define Indirect Retainer…
“The component of a RDP that assists the direct retainer in preventing displacement of the distal extension denture base by functioning through lever action on the opposite side of the fulcrum line when the denture base moves away from the tissues in pure rotation around the fulcrum line”
Indirect Retention: “Reduces the tendency for a denture base to move in an occlusal direction or rotate around the fulcrum line”
Describe Physiologic Basing as a RDP deisgn philosophy…
- Equalization of forces is achieved by displacing or depressing the ridge mucosa during impression making
- tissue recorded in functional rather than anatomic form will allow the denture base to more radily adapt to the depressed tissue under function and withstand the forces generated
What are the elements of a T-Bar clasp?
- Distal Rest (with distal guiding plane)
- T Bar
Observe the reatainer above or below the survey line on the lingual surface…
Above!
What is the difference between Ticonium and Vitallium?
- Ticonium: nickel-chromium
- Contains beryllium to lower melting range
- Nickel sensitivity/allergic response
- Vitallium: cobalt-chromium
What are the second 3 Indications for RDPs?
- Reduced periodontal support of remaining teeth
- Need for cross-arch stabilization
- No posterior abutment tooth
What are 4 requirements for Major Connectors?
- Rigidity***
- Avoid impingement of the free gingival margin
- Avoid creating food traps
- Patient comfort
What are some different types of Bar Clasps?
- T-Bar Clasp
- I-Bar Clasp
- Modified T-Bar Clasp
- Y Clasp
“TIMY”
Why is Polyvinylsiloxane recomended for a master impression for RDP?
- Easily manipulated
- Dimensionally stable
- Minimal distortion
- Expensive
What must a Kennedy Class I prosthesis provide for?
- Adequate support for the distal extension denture base
- Flexible direct retention
- Indirect retention
What is the Major Advantage of an Implant Supported RDP in this case?
Esthetics!
Deeper retentive undercuts are indicated for what 2 materials?
- Gold alloy
- Wrought wire
What are the 2 types of Direct Retainers?
- Extracoronal
- Intracoronal
What are the undercut measurements for the following materials, Chromium Alloy, Titanium, Gold, Wrought Wire?
Describe Stress Equalization as an RDP design philosophy…
- Advocates the placement of a mechanical stressbraker attachment between the direct retainer and the base (in distal extensions)
- Equalizes stress where a combination of tooth and soft tissue support exists
which way does the Retentive Clasp in a Modified T-Bar design move under function?
Inferiorly and Mesially
Define Reciprocation…
The mechanism by which lateral forces generated by a retentive clasp passing over a height of contour are counterbalanced by a reciprocal clasp passing along a reciprocal guiding plane
Can you name all these parts of a Direct Retainer?
- Rest
- Body
- Shoulder (above contour line)
- Reciprocal arm (above)
- Retentive arm (above)
- Retentive terminal (below)
- Minor Connector
- Approach arm
What are 5 allow alternative for RDP frameworks?
- Type IV Gold
- Cobalt-chromium (Vitallium)
- Titanium
- Cobalt-chromium-nickel
- Nickel-chromium (Ticonium)
Describe a Class 3 lever as it relates to RDPs…
What are some different kinds of Circumferential Clasps (Aker’s Clasps)?
- Simple circlet (can be a reverse and multiple circlet)
- Combination clasp
- Embrasure clasp
- Ring clasp
- Hairpin clasp
- Onlay clasp
Are multiple edentulous areas good for tx planning a Rotational Path RDP?
No!
What type of edentulous span does a Rotational Path RDP favor..
Long Edentulous Spans
Where would you consider placing implants in a Kennedy Class I?
- Implant Location
- Bilateral/Distal
How far do you place an Incisal Rest from the proximal-incisal angle?
- 1.5 - 2.0 mm
- Place at mesial cusp ridge for bar clasps
- Distal cusp ridge for circumferential clasps
What are some design chracteristics of a Swing Lock RDP?
- Labial bar with I or T vertical projections
- Lingual plating: with rests adjacent to edentulous areas - located above survey line
- Locking mechanism located for patient convenience
If undercuts are not present after survey, what would you consider doing?
Recontour/restore teeth
What are some different types of Implant Attachments for RDPs?
- Locators
- ERA
- Dal-Ro
- O-Ring
- EDS
What are the elements of a Modified T-Bar?
- Modified T-Bar
- Distal Rest
- Distal Proximal Plate
Describe Rules 7 and 8 of Applegate’s 8 Rules…
- The extent of the modification is not considered, only the number of additional edentulous areas
- There can be no modification areas in Class IV arches. Any edentulous area lying posterior to the single bilateral area determines the classification
What are the 5 functions of a rest?
- Directs forces (vertical and lateral) along long axis of tooth
- Vertical stop
- Can function as an indirect retainer in distal extension areas
- Prevents tooth extrusion, food impaction
- Correction of occlusal plane (occlusal rest)
Describe the First 2 of Applegate’s 8 Rules…
- Classification should follow rather than precede extractions that might alter the original classification
- If a thrid molar is missing and not to be replaced, it is not considered in the classification
Do Implant Supported RDPs aid with oral hygiene?
Yes!
Oral hygiene made easier with removable option
What are some advantages of using Wrought Wire Clasps?
- Omnidirectional flexing
- Easily adjusted and repaired
- Smaller surface contact with tooth
- Flexibility of 18 ga. WW = 19 ga cast round *
- Clasp can be easily distorted
What do Indirect Retainers help counteract, increase, precent, and stabilize?
- Counteract lifting forces
- Increase stability and support
- Prevent mucosa impingment by lingual bar
- Stabilize the framework during relining
What are 3 Classifications for partially edentulous ridges?
- Kennedy
- McDermott
- Schneid and Mattie
Describe a Guide Plane…
- Flat surface
- 2-4 mm in occlusogingival height
- Curved buccolingually
- Parallel to the path of placement
When you have extensive ridge defects, can implants help?
Yes!
What are Rules 3 and 4 of Applegate’s 8 Rules?
- If a third molar is present and is to be used as an abutment, it is considered in the classification
- If a second molar is missing and is not to be replaced, it is not considered in the classification
What is the Path of Insertion?
- The direction in which the prosthesis is inserted and removed from the abutment teeth
- Most prostheses have two or more insertion paths
- Too much tilt creates ineffective tooth contours
- Design for dislodging forces
What are rules 5 and 6 of Applegate’s 8 Rules?
- The most posterior edentulous area or areas always determines the classification
- Edentulous areas other than those determining the classification are referred to as modification spaces and are deisgnated by their number
During function, where does the retentive calsp move in a T-bar setup?
Inferiorly and Mesially
Describe a Class I lever system as it applies to RDPs…
For an RPI, the gingival portion of the proximal plate is relieved with _____ ga wax
30 ga
What does an RPI enhance?
Enhances the reciprocation from the proixmal plate and increases the gingival exposure between the approach arm and the denture base
Where does Rotation occur in an RPI:Krol?
Occurs in area of mesial rest
Describe Broad Stress Distribution as a RDP design Philosophy…
- Distributing the forces of occlusion to as many teeth and as much of the available soft tissue as possible - excessive trauma to the remaiing teeth and residual ridge can be prevented
- Accomplished by the use of additional rests, indirect retainers, claps, and braod coverage denture bases
What are 2 factors that make a Rotational Path RDP not favorable?
- Lingual tilted teeth
- Mucosa supported
What are 2 Disadvantages of a Swing Lock RDP?
- Poor esthetics
- Dexterity required
Beading depth and width…
0.5 - 1.0 mm
Describe Suprabulge and Infrabulge as it relates to the Height of Contour…
- Infrabulge: that portion of the crown apical to the survey line
- Suprabulge: converges toward the occlusal surface
What are 4 reasons why you would bead the maxillary framework?
- Beading depth and width of 0.5 - 1.0 mm
- Fades out 6 mm from free gingival margin
- Prevents collecting of food under major connector
- Allows thinning of metal at borders
For an RPI, where is the I-bar placed?
I-bar is placed mesial to the greatest prominence of the abutment tooth
Describe the Schneid & Mattie Classification…
- A modification of the Kennedy Classification
- Indicates arch configuration, and implant location
What does the Occlusal, Middle, and Gingival third of a Direct Retainer provide?
- Support
- Stabilization
- Retention
Describe a Category 1 Rotational Path RDP…
- Rotational centers are located at the termini of the extended rests of the rigid retainers
- AP/PA rotation replacing posterior teeth
- Lateral paths of insertion utilizing proximo-lingual undercuts
Distance beading fades from free gignival margin…
6 mm
What does RPI stand for regarding Krol?
- Rest (mesial rest)
- Proximal plate (on a short guiding plane)
- I-bar direct retainer
What are some examples of Maxillary Major Connectors?
- Posterior palatal bar
- Anteroposterior palatal bar: bar = half pear shape 5.0 mm +
- Palatal strap: strap = 8.0 mm
- Anteroposterior palatal strap: closed horseshoe
- Horseshoe
- Complete palate: metal/acrylic resin
For an RPI, what is the length of the distal guide plane both occlusogingivally and in the occlusal one third faciolingually?
- Distal guiding plane is 2-3 mm occlusogingivally
- In the occlusal one third and 3-4 faciolingually
What must a Kennedy Class III Prosthesis provide for?
- Does not have the same design requirements as Class I or II because:
- Supported at both ends
- Does not move during function
- Indirect retention may be needed if direct retention is not obtained on one or more teeth
Regarding RPI Mechanics, what happens to the I-bar and Proximal Plate during function?
They disengage
What are some contraindications for RPI?
- Soft tissue undercut below the abutment tooth
- Teeth with severe lingual tilt, no facial undercut
- Teeth with severe facial tilt
- Mouth with high lingual floor in which linguoplating is indicated
Why is Irreversible Hydrocolloid recomended for RDP master impression?
- Permits use of stock or custom tray
- Adequate reproduction
- Low tear strength in undercuts
- Viscosity may be adjusted
- Setting time can be adjusted
- Simple and inexpensive
What makes a Combination Clasp Design Unique?
- WW retentive arm
- Distal rest
- Cast reciprocating arm
- Distal guide plan
Define Direct Retainer…
“That component of a RDP used to retain and prevent dislodgement, consisting of a clasp assembly or precision attachment”
Describe the I-Bar Design: Kartochvil…
- Bar must cross the tooth-tissue junction at right angles, parallel to long axis of tooth
- Retention in 0.01 inches, oval-shaped contact
- Tip of I-bar kept below the survey line
- Origin of approach arm located between the denture teeth
- “Push” type of retention
What are 3 Advantages of an RPI?
- Minimal toooth coverage
- Minimal gingival coverage
- Good stress control
Describe Kennedy Class IV edentulism…
A single bilateral edentulous area located anterior to the remaining natural teeth
What are some implant placement considerations for a Kennedy Class III?
- Possible to remove retentive arm
- Unilateral or bilateral
What can Implants help with in regards to bone/RDPs?
Reduces Bone Resorption
Loaded Implants Preserve Bone
When do you use altered cast technique?
- When a RDP must gain support, stability, and retention from the residual ridge
- Indicated for Class I and Class I RDPs
How do you determine Tissue Relief for a Lingual Bar?
- Amount depends on tissue anatomy and the degree of prosthesis displacement
- Undercut areas require maximum relief
- Kennedy Class I needs more relief than a Class III (less prosthesis movement)
Why would you use a mandibular lingual plate versus a lingual bar?
- Inadequate space for bar
- Can splint periodontally compromised teeth
- Easy to add to if anticipate tooth loss later
- More comfortable than lingual bar
Describe the I-Bar Design: Kratochvil…
- Mesial rest, distal rest in adjacent tooth
- Proximal plate on long distal guiding plane, from marginal ridge to the tooth-tissue junction and 2 mm onto attached tissue
- I-bar placed at greatest prominence of facial surface of abutment tooth
- Must physiologically adjust metal-tissue contact area with chloroform/rouge
