RPD lecture Flashcards
(45 cards)
What is an RPD?
A removable appliance which replaces one or more missing teeth but not the entire arch
No 2 RPD’s are the same
What is a mucosa borne RPD?
Made primarily from acrylic Metal components may be included for strength or clasping Relatively cheap Can be easily modified or added to Transitional denture
What is a tooth borne RPD?
Metal framework
CoCr
Teeth attached with acrylic or composite
What is a tooth and mucosa borne RPD?
Metal framework
Acrylic forms the fitting surface and provides support in the saddle area
Where is support gained on tooth borne RPD’s?
From occlusal, cingulum or incisal rests
What are the only tooth borne dentures?
Bounded saddles
What are the properties of a tooth borne denture?
Strong and transmit load well
Complex, expensive, provided where OH is good and stable
What are tooth and mucosa borne RPD’s made from?
CoCr
What is support gained from in tooth and mucosa borne RPD’s
occlusal, incisal or cingulum rests and from the mucosa
What are the properties of tooth and mucosa borne RPD’s
Complex
Expensive
Provided with good OH
What are the requirements of an RPD?
Aesthetics Mastication Comfort Distribute occlusal forces to appropriate structures Retentive Space maintenance OVD maintenance
What are the advantages of an RPD?
Aesthetics
Function - speech and mastication
Tooth movement prevention
maintenance of OVD
What are the disadvantages of an RPD?
Tooth loss is greater with RPD rather than other methods of tooth replacement
Increased plaque accumulation
Caries, gingivitis, periodontal
Tooth movement
Design dependant?
Damage to tooth tissue
Forces on teeth may impact on supporting structures
What needs to be check in the dental history before can provide an RPD
Is the pt suitable
Does the pt want and need an RPD
Is the RPD likely to be destructive
Is there clinical need to make provision for future treatment
When providing an RPD what is the study model used for?
Edentulous areas: size and position
Undercut: for retention (POD, POI and clasping)
Occlusion - may need to mount on an articulator, so need registration rims producing
What needs to be incorporated when designing an RPD?
Saddles - number and extent
Support - tooth or tissue borne, extent of connectors and saddle for mucosa borne. Tooth rests for tooth borne
Retention - Physical muscular and mechanical forces need to be considered, survey the model for undercuts that may be used relative to path of displacement, path of insertion different to path of displacement, design options
Reciprocation for each clasp
Bracing - resistance to lateral movements
Connectors - design criteria and options for connectors
Indirect retention for free end saddles
When designing saddles what needs to be considered?
Which teeth needs to be replaced
Can I reduce occlusal table by using fewer or narrower teeth
What is the support?
What are the different ways of gaining support?
Resistance of vertical forces directed towards the mucosa
Mucosa borne
Tooth borne
Tooth/mucosa borne
How do you gain support in a mucosa borne denture?
Make the footprint of the denture large to spread the load over a large area
The hard palate provides adequate support for mucosa borne dentures to be used
Extend the denture base to the maximum denture bearing area even if only a few teeth being replaced
How can you gain support in a tooth borne denture?
Bounded saddles
Position occlusal rests on both sides of the saddle areas
Keep them as close to the saddle area as possible
This ensures the load is transmitted from the saddle area to the tooth efficiently
Metal framework is rigid
What do occlusal, cingulum and incisal rests need?
Rest seats:
Direct load down the long axis of the tooth
Overdenture, prep tooth
Where should the occlusal rests be positioned in a tooth and mucosa borne denture?
Why?
Distant to the saddle areas
- this ensures the load is transmitted down the long axis of the tooth when the denture rotates
- Also ensures that clasps disengage from the undercut under load when the denture moves
Which retentive forces are the same as complete dentures?
Physical and muscular
What are the mechanical forces needed in RPD?
Path of insertion- needs to be different to path of displacement and clasping - need enough undercut to engage
