Removable Partial Denture Design - SDEO Flashcards
What is the saddle
The part of the removable denture which sits on the edentulous ridge and carries the replacement teeth
What is the Kennedy Classification for this saddle and what is its name
Kennedy Class I
Bilateral free end saddle
What is the Kennedy Classification for this saddle and what is its name
kennedy class 2
unilateral free end saddle
What is the Kennedy Classification for this saddle and what is its name
Kennedy class 3
bounded saddle
What is the Kennedy Classification for this saddle and what is its name
Kennedy Class 4
Anterior bounded saddle crossing the midline
What is the classifcation for this saddle
Kennedy Class I, mod. 1
What is the classification for this saddle
Kennedy Class II, mod. 2
What is the classification for this saddle
Kennedy Class III, mod. 1
What is support
the resistance of the denture to occlusally directed forces
What should we think of when deciding which tooth to use and where each support will be placed (if using teeth)
the crown:root ratio
What is class 1 Craddock Classification
denture is supported by remaining natural teeth
what is class 2 craddck classification
vertical biting forces applied to the denture are resisted by soft tissue only
What is class 3 craddock classification
tooth and mucosa borne
how do we achieve tooth suport
by placing rests on the teeth which directs the forces down the long axis of the tooth
how much can each healthy tooth support in addition to its own occlusal load
that of 1.5 similar teeth
What type of dentures are rests best used
As part of the cast metal alloy base but can also be incorporated into the acrylic dentures however this can weaken the acrylic base
What is essential in mucosal support
tilise a large area to provide greater support so to reduce load per area which is provided by the denture base
When may we consider mucosal support
- Inadequate teeth available to support the number of teeth being replaced
- Teeth that are available are in poor condition
- The denture is required as a transitional or immediate denture
When do we consider tooth and mucosal support
- here are inadequate teeth for tooth borne support only
- There is a free end saddle
What are the rest types
- Small
- Large
- Full coverage
- Cingulum rests
- Incisal rests
What is the issue with small rests
they apply a larger force per unit area and should be avoided
how large should large rests be
large enough to direct forces down the long axis of the tooth
what is a full coverage rest
tooth is covered with an onlay
what does a cingulum rest require
may require some preparation of the enamel at the cingulum unless a prominent cingulum is already present
what may incisal rests require
May require some preparation of the enamel at the incisal edge. These rests are very limited by aesthetic and are very rarely made
Where are rests placed in a bounded saddle
Equal distance on either side of the saddle so the load is distributed evenly between supports
How should rests be placed in a free end saddle
Should be placed on the mesial end of the abutment tooth
Otherwise abutment tooth may tilt distally - this is called distal axial torque
What is the dimensions of a cobalt chrome rest
should be at least 1mm wide and a depth of 0.5mm and should cover enough tooth tissue (ideally to midline) to direct occlusal forces down the vertical axis of the tooth
How do we ensure a rest does not interfere with occlusion
enamel of the tooth can be prepared if the space for a rest is required
position of a rest on the tooth can be changed to avoid preparing a rest seat
what is the ideal placement of a rest
either side of a bounded saddle
mesial rest for a free ended saddle
What is retention
Retention is the resitsance of the denture to vertical movements away from the tissues and can be direct or indircet
what are the different types of direct retention
- mechanical
- frictional
- muscular
- physical
What is mechanical retention
engages hard or soft tissue undercuts
What is frictional retention
uses parellel guide planes to retain the denture base
What is muscular retention
forces of the muscles keep the denture in place
What is physical retention?
Forces of adhesion and cohesion to the denture bearing surface
What does the length of the tooth have to be if it is an occlusally approaching/suprabulge clasp
length of the tooth has to be >15mm to accommodate the 15mm clasp arm
What does the length of the tooth have to be for a gingivally approaching/infrabulge clasp
length of the tooth does not have to be > 15mm to accommodate the 15mm clasp arm
