RPD Cram Flashcards
SDA occlusal units
3-5 provide satisfactory function
RPD design components
Saddles
Support
Retention
Reciprocation/bracing
Major connector
Indirect retention
How is support achieved?
Rests
How is retention achieved?
Clasps
Define the Kennedy Classifications
I - bilateral free end saddle
II - unilateral free end saddle
III - Unilateral bounded posterior
IV - Anterior bounded
Define the Craddock Classifications
Tooth borne
- Resistance to occlusal load Via PDL
Mucosa borne
- Resistance to occlusal load via mucosal coverage
Tooth + mucosa
- Combo
- In free end saddles
Define support
Resistance to vertical movement towards the mucosa
Define retention
Resistance to vertical displacement forces away from the mucosa
Define Stability
Resistance to horizontal movement
Define indirect retention
Resistance to rotational displacement of denture
Define reciprocation
Each clasp unit has an opposing element to retentive clasp arm to prevent pressure from clasp acting on the tooth
Function of rests
Resistance of movement towards mucosa
Distribute load
Prevents OE of unopposed
Advantages of an every denture design
Less harmful mucosa borne
Doesn’t cover gingival margins
Cocr/gold/SS mm
0.25mm
0.5mm
0.75
Where are clasps placed?
Below the bulbous part of the tooth - undercut
Identified with surveyor
What is the minimum clasp length for CoCr
15mm
Define the RPI system
Stress relieving system in free end saddles to prevent stress on last abutment tooth
R - mesial
P - proximal plate
I - gingivally approaching
Mechanism of an RPI system
Rotation of denture at mesial rest
I bar clasp rotate down + mesially to disengage and prevent torque
Examples of maxillary connectors
AP strap
AP ring
Mid palatal strap
Horseshoe
Examples of mandibular connectors
Lingual bar
Lingual plate
Dental bar
List advantages + disadvantages of Lingual bar
ADV
- Perio compromised teeth
- Free from gingival margin
DISADV
- Can’t add teeth
- Less comfortable
- Less rigid
- Not for tori
List advantages + disadvantages of lingual plate
ADV
- Can add teeth
- Good indirect retention
DISADV
- Covers gingival margin
- Bad for perio/caries
List advantages + disadvantages of AP ring
ADV
- Good for tori
- Little coverage
- Wide relief of gingival margin
- Rigid
- Palate sensation
DISADV
- Less support to free end saddles across HP
- Uncomfortable
- Greater cross sectional thickness
List advantages + disadvantages of plate
ADV
- Rigid
- Wide relief
- Support across HP to free end saddles
- Thinner cross section
DISADV
- Mucosal tissue covered
- No sensation/speech
RPD clinical stages
Primary imps + ask for preliminary record block if required
Master imps
FW trial +/- jaw reg
Tooth trial
Delivery
Review
Complete denture stages
Primary imps
Master imps
Jaw regi
Tooth trial
Delivery
Review
When do you need a preliminary record block
If you can’t hand articulate the casts because there are free end saddles
This will allow the occlusion to be recorded and lab can mount casts to this registration
Materials to take RPD master imp in
Medium bodied PVS - Extrude
Polyether - Impregum
Alginate
Lab card info for primary imps
Please pour up primary imps in 50:50 plaster + stone and construct light cured acrylic special tray w spacer and with E/O handle
IF NON HAND ARTICULATED
Please also provide preliminary record block on light cured base for registration
What must be completed before visit 2?
Survey
Decide rest seats + design
Lad card info for master imps
COCR
Please pour up master imps in improved stone and construct chrome FW per design
ACRYLIC
Please pour up master imps in 100% dental stone and provide record block shellac base for jaw registration
Lad card info for FW trial
Please construct wax record blocks on FW
Lab card info for jaw reg
Please articulate casts to regi provided on average value articulator
Please set teeth for tooth trial shade + mould
Lab card info for delivery
Please take to finish in acrylic
How do we do a retrial?
Remove teeth + re-record occlusion
When occlusion discrepancy too great/bite propped open
What to check on delivery
Pin on table
Occlusion
Extensions
In mouth
Retention extension stability occlusion adjusted with acrylic bur
Advantages of CoCr
Increased:
Strength
Comfort (thinner + greater temp conductivity)
Retention
Accuracy (metal prevents warping during processing)
OH - less porous
Disadvantages of CoCr
Difficult to make additions
Difficult to repair
Cost
Allergy to Ni Chromium
Advantages of Acrylic RPD
Cost
Good for perio
Easier to modify + add teeth
Easier to repair
Disadvantages of Acrylic RPD
Decreased:
Strength
Comfort (thicker to compensate for lower impact strength, more palatal coverage for support)
Accuracy
OH - more porous
