W1 - Cr-Co Dentures - Abbott Flashcards
Overview of RPD components
Requirements of major connectors
- Rigidity
- Provide cross-arch stability and force-distribution
- No interference with tongue or disruption of anatomy (md or palate)
- No food trapping
- Cover no more tissue than absolutely necessary
Design guidelines of Major connectors
- Free from movable tissue
- Avoids impingement of gingival tissue
- Bony and soft tissue prominences to be avoided (if impossible, provide relief)
- Borders should run parallel to the gingival margins of remaining teeth
- If gingival margins of teeth must be crossed, should be crossed at right angles
How far should the border of a maxillary major connector be from the free gingival margin
How far should the border of a mandibular major connector be from the free gingival margin
2 most commonly used mandibular major connectors
Lingual bar
Lingual plate
When to use lingual bar vs lingual plate
Lingual bar - ideal, more comfortable, hygienic, go-to option
Lingual plate - if incisors are perio involved, if space btw gingival tissue and lingual sulcus is less than 8mm, frenum or tori
What can be done to lingual plate if pt has diastemas
Use interrupted lingual plate
6 Types of maxillary major connectors
- Palatal strap
- Anterior-posterior palatal strap
- Palatal plate
- U-shaped / horse-shoe
- Palatal bar
- Anterior-posterior bar
2 Types of Saddles / retentive framework
2 Functions of rests
- Provide a vertical stop
- Transfer force onto teeth and tissue
Primary rest vs secondary / auxillary rest
Primary - rest that is part of retentive clasp assembly
Secondary - responsible for additional support or indirect retention
3 types of rest design
Occlusal
Lingual/cingulum
Incisal
Supra-bulge vs Infra-bulge clasps
Supra- occlusal approach (circumferential clasps)
Infra- gingival approach (bar types)
List some examples of suprabulge clasps
How do the reciprocal and retentive arms differ in suprabulge clasps?
⅓ of retentive arm engages undercut
Reciprocal arm never goes below surveyed line
Contraindications of infra-bulge clasps
Deep cervical tooth undercut
Severe tissue undercut
Shallow vestibule (4mm)
When survey line is close to the occlusal surface
Where should indirect retainers be placed?
Perpendicularly from the fulcrum line as far forward as practical
kennedy class 3
kennedy class 4
Undercuts greater than ______ cannot be used for Co-Cr
0.25
suggest acrylic denture
Clinical steps of making RPD
- Take alginate imps for study models
- Survey study model
- Design RPD - pencil sketch
- Give pt estimate $$$
- Make special tray
- Prepare dentition (ex- occlusal rests)
- Take secondary impression (PVS or polyether)
- Send imp to lab and ask for framework to be returned with wax rim attached
- Check framework is seating properly (now is the time to reject)
- Jaw relation and shade selection
- Try in wax up, send for processing if happy
- Insertion of RPD
- Recall in 7 days
Where should the tip end in an I-bar clasp?
Tip should end at the most prominent part of the bucccal surface of the abutment tooth
Where should the clasps be placed in a kennedy class 2 pt?
One clasp as close to saddle as possible
Other clasp as far posteriorly as possible on opposite arch
How should be the bur be held when preparing cingulum rest sites?
parallel to long axis of tooth
Why can’t composite be used to build up a rest site instead of drilling into tooth structure?
Dimensions of occlusal rest seat preparation
1.5mm deep
2mm wide
Spoon-shaped
