Partial Dentures Flashcards
What are some unwanted extra-oral effects of losing teeth?
Obtuse naso-labial angle
Loss of facial height
TMJ problems
Alveolar compensation
Loss of lip support
Difficulty in function- speech and mastication
What are some unwanted intra-oral effects of losing teeth?
Alveolar resorption
Tooth movement- tilting and drifting
Over-eruption of teeth
Toothwear
What is the definition of support?
Resistance of the denture to occlusal directed load.
Outline the Craddock Classification.
Class 1- tooth borne
Class 2- mucosa borne
Class 3- tooth and mucosa borne
What is the advantage of a Craddock class 1 denture?
Load of the denture is transferred down the PDL.
Makes the denture base feel more like the natural dentition.
More comfortable.
What teeth are best for providing support?
The teeth with the longest root area depending on the health of the PDL
- Molars, then canines, then upper centrals, upper laterals and lastly lower incisors.
What denture component provides support?
Rests
- occlusal, cingulum or incisal.
What is the disadvantage of having a Craddock Class 2 denture?
More movement in the denture because it rests on soft tissue.
Denture will need to be bigger for retention.
What is a Kennedy class I?
Bilateral free end saddle.
What is a Kennedy class II?
Unilateral free end saddle.
What is a Kennedy class III?
Bounded saddle.
What is a Kennedy class IV?
Bounded saddle that crosses the midline.
What is the definition of retention?
Resistance of the denture to vertical displacement.
What components of the denture are used for retention?
Clasps
- occlusal approaching or gingival approaching.
Guide planes.
Shape of the denture
Coverage of the mucosa
Soft tissue undercuts
Adhesion from saliva
Path of insertion
Precision attachments
What is a disadvantage of having to cut a rest seat?
Potential exposed dentine.
Loss of occlusal stop when denture is not worn.
Destruction of tooth surface.
For a free end saddle, where is the rest placed?
Mesial on the abutment tooth.
Where should you not place a rest?
On an occlusal centric stop.
For a bounded saddle, where should the rest be placed?
Closest to the saddle area- distal.
What is the purpose of a rest?
Prevents movement of the RPD towards the mucosa.
Assists in distribution of occlusal load.
Prevent over-eruption of unopposed teeth.
Retention and indirect retention.
What is a major connector?
Portion of the RPD that connects all the components together.
What is a minor connector?
Connects the major connector to other components.
What is the use of impression compound in primary impressions?
Used in free end saddles to stabilise the tray and supports the alginate material.
- more accurate impression.
What is the purpose of a primary impression?
To produce a special tray to take master impressions.
To make a study cast which is used to survey.
Why do you need to place the alginate impressions in a bag with a damp cloth?
Syneresis of the alginate occurs- releases water in dry situations.
This can cause the material to distort.
Why must you already have the design before you take master impressions?
Need to know whether you need to cut rest seats, determine guide planes, make undercuts and do this before you take the masters.
What type of dental stone is used to cast primary impressions for cobalt chrome?
100% dental stone.
What is the purpose of a master impression?
To make record blocks
What measurements do you take at the jaw registration stage?
Jaw reg
Shade
Mould
What is the purpose of surveying primary casts?
Identify and mark the maximum contours of the tooth and tissue surfaces to fabricate an RPD.
Establish a suitable path of insertion.
How long does a stainless steel occlusal approaching circumferential clasp need to be to engage a 0.25mm undercut?
15mm.
How much of the clasp engages an undercut?
terminal 1/3.
What are the seven aspects of denture design?
- Saddle(s)
- Support
- Retention
- Indirect retention
- Bracing/reciprocation
- Connectors
- Review and simplify
What is indirect retention?
Resistance to rotational displacement.
What type of clasp should be placed on a canine or premolar?
Gingival approaching clasp