RPDs Flashcards
At what stage should denture design be completed?
Before secondary impressions
What are the stages of denture design?
Outline saddles
Plan support
Direct retention
Reciprocation
Indirect retention/anti-rotation
Major connectors
Minor connectors
2 rules of RPDs
Maximum support from the underlying anatomy of teeth and alveolar bone
Minimal gingival coverage
Why its support important?
Preserve remaining periodontal tissues and remaining teeth
Where is support derived from?
Remaining teeth
Underlying alveolar bone
Factors to consider when planning tooth support
Load transmitted along the long axis of tooth
Sufficient occlusal clearance for planned space
Tooth prep required
Which factors provide direct retention?
Contact points
Soft tissue engagement of alveolar undercuts
Displacing forces
What is reciprocation and how is it achieved?
Resistance to lateral displacing forces on clasped teeth
(arm/plate) No orthodontic movement
Why do we do composite build ups lingually of lower anteriors and canines?
So forces can be applied along the long axis of the tooth
What can be used to oppose a clasp on a long clinical crown?
arm
What can be used to oppose a clasp on a short clinical crown?
plate
What can RPDs restore?
Aesthetics
Function
Self esteem
Phonetics
What is support?
Resistance towards the tissues
What is retention?
Resistance away from the tissues
What is bracing?
Resistance to lateral displacing forces
enables clasps to function by keeping them opposed to the tooth
What can denture bases be made from?
Acrylic resin
CoCr
Titanium
Vinyl resin - flexible
Pecton
Stainless steel
What is support derived from?
Occlusal rests
cingulum rests
Incisal rests
What is the saddle?
Part of the base of the partial denture which rests on or covers the edentulous ridge - spread load applied
What is the flange?
Part of the saddle that replaces missing (resorbed) buccal and lingual alveolar tissue
Flange aids retention and improves aesthetics
Why are overdentures ideal?
Because they provide the perfect support BUT need good OH
What is the purpose of rests?
Support framework against vertical load towards the tissues
Provides support by transferring the occlusal forces through the teeth and the PDL
When properly designed, transmit vertical loading through the long axis of abutment teeth
What are the purpose of clasps
Provide retention and resistance
Flexible and act by engaging undercuts
What portion of an occlusally approaching clasp should engage the undercut?
Terminal 1/3rd
Where does a gingivally approaching clasp touch the gingivae?
Contact the tooth surface only at the tip
Rest of this clasp does not touch the mucosa or the gingival margin
Length of clasp makes it more flexible than occlusally approaching clasp
Which factors affect clasp flexibility?
Alloy
Section
Length
Thickness
Curvature
How much gingival clearance should a lingual bar have?
3mm
When is a dental bar used?
Insufficient room between the gingival margin and the floor of the mouth for either a sublingual or lingual bar
Avoids damage to the periodontium
Used when there is lingual recession
When is a lingual bar used?
Placed as low as the depth of the sulcus will allow
When is a sublingual bar used?
Dimensions determined by master impression and it represent the functional depth and width of the sulcus
When might a labial bar be used?
If teeth are severely lingually inclined
What are the rules of rests if more than one tooth is missing?
rest on both adjacent teeth to saddle
Where should a rest be placed?
Mesially unless the tooth is mesially angulated
What should the functional sulcus depth be for a lingual bar?
> 8mm
