RPD design Flashcards
In what order should RPD design be approached?
Saddles Support Retention Bracing/reciprocation Major connnector Minor connector
Kennedy class I
Bi-lateral free-end saddle
Kennedy class II
Uni-lateral free-end saddle
Kennedy class III
Bounded saddle
Kennedy class IV
Bounded saddle crossing midline
Craddocks class I
Tooth borne
Craddocks class II
mucosa borne
Craddocks class III
Tooth and mucosa borne
Benefits of tooth borne denture?
Allows denture to feel like normal teeth
Protects soft tissue from trauma
Transmits load via perio membrane
how far should base be placed from gingival margin?
3mm
Define Support
Resistance of a denture to occlusally directed loads
What provides support?
Rests - occlusal, cingulum, incisal
Other than support, what can rest seats help with?
Preventing over-eruption of teeth
Define Retention
Resistence of a denture to vertical displacement
What provides direct retention?
clasps - occlusally approaching or gingivally approaching
Define Indirect retention
resistance of denture to rotational displacement
When is indirect retention used?
In dentures with free end saddles
Why is indirect retention used?
Because it prevents displacement of denture around fulcrum axis (where tooth and mucosa borne dentures tend to rock)
Clasp thickness - CoCr
0.25mm
Clasp thickness - Gold
0.5mm
Clasp thickness - SS
0.75mm
How long must a CoCr clasp be?
15mm
How does should a clasp engage an undercut?
Terminal 1/3 engages undercut with only tip of clasp engaging to depth of 0.25mm
What rules are there for lingual bar?
Reqs 8mm clearance - 3mm from ginigval margin, 4mm height of bar, 1mm from floor of mouth
Should be 2mm thick
What kind of major connector is common choice for craddock class I?
Bar
What kind of connector is the choice for craddock class II?
Plate
What does an open design major connector provide?
< gingival coverage
> clearance
< gingival irritation
What does a closed major connector design provide?
> contact = > retention
> irritation to gingival tissues
Explain RPI
Stress relieving clasp system used in free-end saddle designs to prevent stress on the last abutment tooth
What is an RPI?
R - Rest - mesial on occlusal surface of tooth
P - Proximal plate - adjacent to saddle. Guide surface of 2-3mm, undercut to permit movement
I - I-bar clasp - ginigvally approaching
describe a tooth borne denture
denture is supported by the adjacent teeth by components such as occlusal rests, the force is transmitted to bone via teeth and periodontal ligaments
describe a mucosa borne denture
denture rests on the mucoperiosteum then the force is transmitted through that tissue
