Week 1- Cr-Co RPD's Flashcards
What is required before surveying for RPD?
- Check teeth
- Take radiogrpahs
- Take good primary impressions in alginate
- Have model poured in yellow stone
- Then, survey the denture, design it and fabricate special tray.
Why do you need to survey the cast?
Everything below the survey line is an undercut so retention will come from clasp placement in the undercut zone.
What is Kennedy Class II?
Unilateral edentulous area located posterior to the remaining teeth.
What is Kennedy Class I?
Bilateral edentulous areas
What are the classifications of RPD’s on support?
- Tooth
- Tissue
- Tooth and tissue
What is Kennedy Class III?
Unilateral edentulous area with natural teeth anterior and posterior to it
What is Kennedy Class IV?
Single edentulous area located anterior to remaining teeth
What problems arise from Kennedy Class I?
Absence of abutment teeth distally created problems of support and retention.
What is the support for Kennedy Class II?
Both tooth and tissue supported
What is the support for Kennedy Class III?
Can be entirely tooth supported
What are the following Kennedy classes?
- A. Class I
- B. Class II
- C. Class III
- D. Class IV
- E. Class II Mod I
- F. Class II Mod I
- G. Class II Mod II
- H. Class III Mod II
What undercut measurement is suitable for Co-Cr clasps?
0.25mm
What undercut measurement is suitable for gold alloy clasps?
0.56mm
What undercut measurement is suitable for wrought wire clasps?
0.75mm
What is a potential issue with the following case?
Large undercut indicated by high survey line. Would result in unaesthetic clasp placement. Also cannot be used for Co-Cr partial.
What is the issue for making a Co-Cr denture in the following study model?
Lingual tilt of premolar prevents lower frame to be made
What are the clinical steps in making an RPD?
- Take alginate impressions for study models
- Survey and check undercut depths
- Design RPD
- Give pt estimation of cost
- Fabricate special tray
- Prepare rest seats etc. Then take secondary impressions
- Send to lab and request wax rim attached
- Jaw relation and shade selection
- Try in wax up then send for processing
- Insert RPD and recall in 7 days
What material should be used when taking secondary impressions for co-cr dentures?
PVS or Polyether (impregum)
What should be checked when trying in the RPD?
Engagement of clasps
Seating of occlusal rests
Check occlusion with articulating paper
What are the components of a co-cr denture?
- Major connector
- Minor connector
- Occlusal rest seats
- Retainers or clasps
- Reciprocation
What happens if a co-cr clasp engages less than 0.25mm undercut?
Retention is unpredictable
What happens if a co-cr clasp engages more than 0.25mm undercut?
Likely that its proportional limit will be exceeded when the denture is seated or removed. Clasp would become permanently deformed and non-retentive
Where should the occlusally approaching clasp run?
From the side of the tooth with the least undercut to the side with the greatest undercut.
How long should a retentive clasp be in co-cr?
At least 15mm
What teeth should co-cr occlusally approaching clasps be used on?
Molar teeth