Indirect retainers Flashcards
The component of a RPD 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 retainer
❑Prevents movement of the distal extension base away from the residual ridge
❑Converts Class I lever to Class II lever
Indirect retainer
Function of \_\_\_\_\_\_\_: imit RPD vertical dislodgement ❑Reduce leverage on abutments ❑Reduce tissue impingement by mandibular major connectors ❑Increase RPD stability & support ❑Stabilize the framework during relining
Indirect Retainer
❑Usually a rest located on the opposite side of the fulcrum line that assist the direct retainer in resisting movement of the RPD in an occlusal direction-like when eating sticky food
Indirect retainer
❑Usually in the form of an auxiliary rest
❑Ideal position is perpendicular to fulcrum line
❑Place as far forward of fulcrum line as possible
Indirect retainer
The ______ the distance between the fulcrum line and the indirect retainer, the more effective the direct retainer will be.
greater
Is lingual plating enough for an indirect retainer?
No
If a lingual plate major connector is used, what must be added to achieve the functionality of an indirect retainer?
Rests at each end
What 2 Kennedy classes are indirect retainers required?
1 and 2
How many indirect retainers are needed in a class 1?
2 indirect retainers
How many indirect retainers are needed in a class 2?
1 indirect retainer
The indirect retainer is placed on the ____ side of the fulcrum line from direct retainers so the denture base doesn’t move away from tissues in pure rotation
Opposite
❑_______ occurs around most distal rests
❑Resisted by rests and denture base
Rotation
______-supported RPD denture base:
- Support prosthetic teeth
- Esthetics: replace missing tissue
- Horizontal stability
Tooth supported
______-supported RPD denture base:
- Support prosthetic teeth
- Esthetics: replace missing tissue
- Horizontal stability
- Vertical support
- Secondary retention: interfacial surface tension between base & underlying mucosa
Tooth-tissue supported
More surface area of coverage by denture base leads to _____ stress
Less stress
If the tissue of the the residual ridge is more displaceable, there is ____ support
Less support
_____ bone has better support than cancellous
Cortical
What are the 4 factors affecting denture base support of distal extension RPD?
Quality of Soft Tissue over ridge
Type of BOne
Amount of denture base coverage
Accuracy of fit of the denture base
Requirements of an Ideal ________
- Accurate & dimensionally stable
- Tissue compatibility
- Thermal conductivity
- Low specific gravity: light weight
- Sufficient strength: resist fracture
- Esthetic
- Potential for future reline
Denture Base Material
\_\_\_\_\_\_\_ denture base material: l❑Difficult to adjust ❑Poor esthetics ❑Part of cast framework ❑Good thermal conductivity ❑Can be kept thin: ❑Advantage where inadequate inter-arch space
❑Metal
\_\_\_\_\_\_\_ denture base material: ❑Most common ❑Easily adjusted & relined ❑Good esthetics ❑Attachment to framework by lattice or mesh
❑Polymethylmethacrylate (PMMA)/Acrylic resin
Denture base retention on mandibular arch extends how to what point
2/3 distance to retromolar pad
Denture base retention on maxillary arch extends how to what point
2/3 distance to hamular notch
______ denture base retention:
❑Two struts of metal
❑Extend longitudinally along residual ridge
❑Positioned buccal & lingual to ridge crest
❑Avoid longitudinal strut along ridge crest
❑Interferes with tooth placement
❑Cleavage action occurs within denture base
❑Strongest attachment
❑Easiest to reline
❑Preferred retention
Lattice retention
______ denture base retention:
❑Thin sheet of metal with multiple holes
❑Extension over ridge similar to lattice
❑Inferior attachment strength
Mesh retention
A ______ is essential to prevent displacement or deformation of the metal framework during resin-packing procedures.
❑Projects from the tissue surface of the minor connector to contact the dental cast.
cast stop
All internal finish line angle between acrylic resin and metal components should be ______ degrees
90 degrees
All internal angles of external finish line should be ______ degrees
Less than 90 degrees
\_\_\_\_\_ teeth: ❑Most common ❑Easily adjusted ❑Not wear opposing natural dentition ❑Chemical bond with denture base
❑Acrylic
\_\_\_\_\_\_ teeth: ❑Fracture easily ❑Wear opposing dentition ❑Difficult to adjust ❑Mechanical retention only to denture base
❑Porcelain
_____ teeth:
❑Denture tooth with drilled channel
❑Secured to metal post
❑Used with metal base: inadequate interarch space
❑Tube teeth
_________
❑Composite resin polymerized around projections of metal from denture base
❑Anterior teeth only
❑Inadequate interarch space
❑Reinforced acrylic pontics(RAPs)
\_\_\_\_\_\_ teeth ❑Used with severely inadequate interarch space ❑Poor esthetics ❑Used only in posterior ❑Difficult to adjust
Metal teeth
