RPD Lecture 7 Flashcards
what are solutions to dealing with fulcrum and lever problems with a K class I and K class II?
- control rotation with indirect retention
- design new clasps with Mesial rest
- best saddle extension and fit to soft tissues!
why do you alter the cast?
it’s for the dual impression technique.
this promotes saddle stabilization for the DISTAL extension PRDPs!
what is the purpose of the altered cast techqnieu?
you want to EQUALIZE SUPPORT derived from the edentulous ridge and the abutment teeth;
two unequal support systems that require equalization.
what are the two support systems?
you have soft tissue and hard tissue (not displaceable)
why do you want broad coverage of the soft tissue?
the broader, the greater the distribution of the occlusal load.
this is the SNOWSHOE effect
what is the single most important factor in minimizing the abutment tooth movement?
fit of the base of the RPD
what are indications for distal extension base stabilization?
ALL MN distal extensions in Class I and II
- *some long span MX distal extension
- *some long span ANTERIOR edentulous ridges (in which the ridge has to support the PRDP)
what areas should you cover on the max and mandible?
MN -cover the retromolar bad, buccal shelf and extend fully into vestibules
MX- cover the tuberosity, extend into the pterygomaxillary notch and the buccal vestibule
describe the selected pressure technique?
the vestibule border has active tissue contact, the support area is impressed at rest.
**in the extension area, make a light cured triad tray fixed to the framework, and then extend to WITHIN 2 mm of a normal CD base
why do you receive the intaglio surface of the custom tray?
you want to provide space for the impression material; the static component of the impression
what kind of impression material should you use for the selected pressure technique?
use light or medium bodied VPS
-seat the framework and tray making sure the rests are FULLY engaged under finger pressure
should you depress the saddle area while impression material is setting?
no! it is recorded at rest! keep the pressure on the rest and clasp assemblies do allow th material to set
what are some other saddle stabilizaiton techniques?
retained, amuptated tooth (it’s not attached to the PRDP saddle- amalgam, gold, glass ionomer use dot restore the RCT access)
implant retained saddle
why might you keep multiple RCT teeth beneath the PRDP saddle?
proprioception,
bone preservation for stability + retention
Can the retaining teeth be attached to the PRDP saddle?
yes, ERA
Ball/O ring
Locator, semi precision
