RPDs Flashcards
What is Kennedy class 1?
Bilateral free end saddles
What is Kennedy class 2?
Unilateral free end saddles
What is Kennedy class 3?
Bounded saddle that doesn’t cross the mid line
What is Kennedy class 4?
Bounded saddle that crosses the mid line
What is a mod in Kennedy classification?
A bounded saddle, in addition to the saddle that indicates the classification.
NB: there is no such thing as a class 4 mod 1
What is an abutment?
A tooth that serves as support to the denture
What is a Pontic?
suspended component on a fixed partial denture that replaces the missing natural tooth
What is the residual ridge?
portion of alveolar bone and its soft tissue covering that remains after tooth loss/ extraction
What type of impression tray is preferable?
perforated
aids retention when tray is being removed
What is dental plaster?
- has large irregular particles
- heated in an open vessel with air readily available
What is gypsum?
- used for making dental casts
What is dental stone?
- small, regular particles
- heated in an autoclave
What is improved dental stone?
- compact smooth particles
- heated with added chemicals (calcium and magnesium)
What is a wax wafer?
- thin piece of wax a patient bites on to demonstrate the occlusion
What is an ARCON articulator?
- articulated condyle articulator
- anatomically similar to the TMJ
What is a non-ARCON articulator?
- doesn’t replicate the movement of the TMJ
- simple hinge movement
- can still show the occlusal relationship, but not how the teeth come together naturally
What is the design process order?
- saddles (yellow)
- support (red)
- retention (green)
- indirect retention (purple)
- reciprocation (blue)
- connectors (black)
- review
What is Craddock class 1?
- tooth borne support
- abutment teeth on both sides of the saddle
- no more than three teeth wide
What is Craddock class 2?
- mucosa borne support
- edentulous patients
What is Craddock class 3?
- mixed support
- free end saddles
- large saddles
What makes an ideal abutment tooth?
- suitable undercut
- space for a rest ie no heavy occlusal contacts
What is a gingivally approaching clasp?
- approaches undercut from the gingival margin
- does not cross the maximum bulbosity of the tooth
- used primarily on narrower teeth ie anteriors
What is a occlusal approaching clasp?
- approaches undercut from the occlusal surface
- crosses the maximum bulbosity of the tooth
- used primarily on molars
What is a ring clasp?
- self reciprocating occlusally approaching clasp
What is the recommended pattern of retention?
-triangular
Do rests work better on metal or acrylic bases?
metal as they are an integral part of the framework whereas on acrylic bases they need to be added and have potential to weaken base
What is the default position for a rest?
- abutment teeth, on the nearest surface to saddle
What is an RPI?
- a stress relieving clasp
- rest system used in free end saddles
- rests are placed on the mesial surface of the abutment tooth to reduce torque
- a post is used as reciprocation
- a gingivally approaching clasp is used
Why should rests extend to the midline of the tooth?
- to ensure force is transferred down the long axis of the tooth
What risks are associated with rest seats?
- dentine exposure
- sensitivity
- destruction of sound tooth tissue
- loss of occlusal stop when denture not in place
What benefits are associated with occlusal rests?
- prevent movement of RPD towards mucosa
- prevent over eruption of unopposed teeth
- distribute occlusal load
- indirect retention
- determines axis of rotation
What is indirect retention?
- resistance to rotational displacement
- key in free end saddles
- eg rests, connectors, saddles
What is retention?
- resistance to vertical displacement
What is reciprocation?
- prevents the forces from the clasp moving the tooth
What is bracing?
- resistance to lateral movement
What is key to ensuring good oral hygiene with a denture?
- clear margins where possible
- reduce the dark triangles by altering path of displacement
- OR ensuring gaps are big enough to allow salivary flow
When is a plate connector preferable?
- less tooth borne support
- Craddock class 2 or 3
What is the default mandibular connector?
- lingual bar
What are the disadvantages of a plate connector?
- more mucosal coverage
- may cover gingival margins
What are the disadvantages of a bar connector?
- thicker so patients may not tolerate well
What is closed saddle design?
- no space between saddle and abutment tooth
- better retention
- more mucosal coverage which may irritate