Talking the talk partial dentures Flashcards
Define support in terms of dentures
Support is resistance to vertical force directed towards the mucosa
Give examples of structures in the mouth that can support a denture
- Tooth
- Mucosa
- Tooth and mucosa
What do we call a denture supported by teeth?
Tooth borne
What do we call a denture supported by mucosa?
Mucosa borne
What do we call a denture supported by tooth and mucosa?
Tooth and mucosa borne
How can tooth support for dentures be achieved?
1, Adding occlusal rests
- Adding cingulum rests
- Adding incised rests and onlays
Name some mucosal borne dentures
- Every denture
- Spoon denture
- Transitional/colleted denture (gum stripper)
What is another name for the transitional denture?
Gum stripper (BUT DONT USE THIS NAME ON CLINIC)
What is a major disadvantage of transitional dentures?
They can trap plaque underneath the denture against the adjacent teeth
Define saddle
An edentulous region of the alveolar ridge
Give examples of some different types of saddles
- Bounded saddle
2. Free end saddle
Define bounded saddle
A saddle which has a tooth at each end
Define free end saddle
An edentulous area with teeth at one end
Define retention
It is the resistance to a vertical force directed away from the mucosa
How can retention be gained on a denture
By the use of clasps
How do claps work
They ‘engage undercut’ to gain retention
What can cause a denture to be loose?
- Lacks support
- Lacks retention
- Lacks resistance to lateral movement
Name the different types of clasps
- Retentive clasp
2. Reciprocated clasp
How does a retentive claps work?
As the denture moves up, the claps is forced to expand
The resistance to the claps to expansionists holds the denture in place
What is an undercut?
The area below the survey line (Line of maximum bulbosity) on a tooth
What is the survey line on a tooth?
The line of maximum bulbosity
Which direction can clasps approach the undercut from?
Can approach:
- Gingivally
- Occlusally
What is bracing in terms of dentures
Bracing is resistance to a horizontal force
Define reciprocation
It is the resistance to the specific horizontal forces generated by retentive clasps
Give an example of reciprocation
A bracing element which is in contact with the side of the tooth opposite the retentive clasps
What must retentive clasps always be to make a denture successful?
Must ALWAYS be reciprocated
Where is the reciprocated clasps found on a tooth?
On the side opposite to the retentive clasp
What is indirect retention
Resistance to rotational displacement in a tooth and mucosal borne denture
What is rotational displacement and what can it lead to
When a denture rotates around the claps usually due to sticky food pulling the denture away from the mucosa
Can lead to the denture becoming loose
How is indirect retention usually achieved?
By placing a rest on a tooth anterior to the clasp
What is a sulcus
A space that has been produced between tongue/lips/cheeks and the residual alveolar ridge
What does the functional depth of sulcus describe
The minimum depth of the sulcus when the muscles are contracting
Define flanges
Parts of the denture which extend into the sulcus
Where should flanges extend to?
Normally extend to the functional depth of the sulcus
What is it called when flanges extend beyond the functional depth of the sulcus
they are over extended
What are the problems associated with over extended flanges
They can cause the denture to be unstable in function
What is it called when flanges DO NOT extend to the functional depth of the sulcus
They are under extended
What are the problems associated with under extended flanges
They may lead to loss of suction under the denture (so loss of retention)
What is occlusion?
Occlusion is the precise way in which teeth in the upper arch meet the teeth in the lower arch
What is denture occlusal instability
When teeth meet incorrectly and make the denture unstable
What is denture occlusal instability usually die to?
A premature contact point
Name some components of a partial denture
- Occlusal rests
- Cingulum rest
- Clasps
- RPI clasping system
- Connectors
Where are occlusal rests found
They extend upto 1/3rd across the occlusal surface of the tooth
They are usually directly down the long axis of the tooth
Describe the shape of an occlusal rest
They are saucer shaped in profile
They should not interfere with occlusion
What is the purpose of an occlusal rest?
- Give support to denture
2. Keep clasps in the correct position
Where are cingulum rests found?
Down the long axis of the tooth on the cingulum
They are clear of occlusion
What is the purpose of a cingulum rest?
To keep clasps in position
What can happen if a cingulum rest isn’t postponed correctly?
It can start acting like an orthodontic appliance and move the tooth
Which material is best suited to providing the framework for partial dentures
Cobalt chrome
What is a problem with using cobalt chrome to make partial dentures?
It is quite stiff and inflexible
How much horizontal depth of undercut do we need to engage for a cobalt chrome denture?
0.25mm
How big do clasps on dentures need to be do be able to ho in and out of undercuts without distorting itself?
15mm long (1.5cm)
What can happen if a clasp is stretch ed beyond its elastic limit
The clasp will break
OR
sit away from the tooth not providing retention
Which clap type engages with the undercut
ONLY retentive as reciprocating clasp arms sit above the survey line
What are guide planes
They are flat surfaces cut into enamel of teeth which are parallel to the path of insertion of a denture
Other than cutting enamel how else can guide planes be made?
By adding composite to the tooth surface and cutting away the composite
What does the RPI in RPI clasping system stand for
Rest
Plane
I bar
Where is the rest found in the RPI clasping system
Mesial rest
Where is the plane found in the RPI clasping system
Distal guide plane
Where is the I bar found in the RPI clasping system
Retentive I bar clasp
When are RPI clasping system used
Designed for lower free end saddles
Why is an RPI clasp system good?
Gives good support, retention and reciprocation
What are connectors?
Rigid components of a denture which hold all other components together
Name the 2 types of connectors
Major and minor
What are major connectors
They usually connect from left and right sides of a denture
Define over extended flanges
Flanges that extend beyond the functional depth of the sulcus
Define under extended flanges
Flanges that DO NOT extend to the functional depth of the sulcus
What are minor connectors
A branch from the major connector to the various components eg claps, occlusal rests, saddles etc
Name the classification we use to classify dentures
Kennedy classification
Name the different classes found in the Kennedy classification
Class I
Class II
Class III
Class IV
What is a Kennedy class I denture?
A bilateral free end saddle
Found on both sides of the mouth and one side of each denture is edentulous
What is a Kennedy class II denture?
A unilateral free end saddle
Found on both sides of the mouth but only one denture has an edentulous side
What is a Kennedy class III denture?
A bounded saddle denture (Found on both sides of the mouth and each denture has a tooth on both sides)
What is a Kennedy class Iv denture?
The saddle anterior to the abutments
Denture for anterior teeth
