Design principles of RPDs

Question 1

Why do clinicians design the denture

Answer 1

We have seen the patient

• tooth condition
• periodontal condition
• motivation
• cost

Question 2

What are alternative treatments instead of RPDs

Answer 2

• no active treatment
• fixed prostheses (conventional/ resin bonded)
• implants (rarely mix with RPDs as they have no movement)

Question 3

What is montgomery consent

Answer 3

need patients consent - they need to know their options even if you can’t offer it (i.e. alternative treatments to RPDs)

Question 4

What are the different aspects of design

Answer 4

1. Saddle (s)
2. Support
3. Retention
4. Indirect retention
5. Bracing
6. Connectors
7. Review and simplify

Question 5

Kennedy classification for bilateral free end saddle

Answer 5

class 1

Question 6

Kennedy classification for unilateral free end saddle

Answer 6

class 2

Question 7

Kennedy classification for bounded saddle

Answer 7

class 3

Question 8

Kennedy classification for anterior bounded saddle crossing midline

Answer 8

class 4

Question 9

kennedy classification rules

Answer 9

• always go for lowest classification possible

- can have modifications if more saddles

Question 10

What are saddles

Answer 10

the teeth being replaced

Question 11

what is support

Answer 11

the resistance of the denture to occlusally directed load

Question 12

Craddocks classifcation 1

Answer 12

tooth borne

Question 13

Craddocks classifcation 2

Answer 13

mucosa borne

Question 14

Craddocks classifcation 3

Answer 14

tooth and mucosa borne

Question 15

what is retention

Answer 15

resistance of the denture to vertical displacement (lifting away from the tissues)

Question 16

How can you achieve retention

Answer 16

• clasps (tell technician what undercut you want to go for)
• soft tissue undercuts
• adhesion (maxillary plates)
• friction
• path of insertion
• precision attachments/implants

Question 17

What is indirect retention

Answer 17

resistance to rotational displacement

Question 18

What is bracing

Answer 18

prevents a clasp arm moving the clasped tooth

Question 19

what does the major connector do

Answer 19

connects all the components

Question 20

what does the minor connector do

Answer 20

connects rests, clasps and bracing arms

Question 21

Advantages and disadvantages of flanged saddle design

Answer 21

Advantages: good retention, stops food trapping, appearance will stay constant over time
Disadvantages: ?

Question 22

Advantages and disadvantages of gum fitted/open face saddle design

Answer 22

Advantages:?
Disadvantages: no retention, looks good initially but as resorption occurs you will see a gap (but if patient likes them don’t change)

Question 23

Where should the support be

Answer 23

• as close as we can to saddles
• consider tooth prep
• depends on mucosa/tooth support

Question 24

What should you consider when deciding between craddock classifications

Answer 24

• periodontal condition of abutments
• size and position of supporting mucosa
• occlusion/ chewing capability
• aesthetics

Question 25

What are the options to achieve direct retention

Answer 25

• clasps
• engaging soft-tissue undercuts
• hydrostatic pressure
• path of insertion
• muscle control

Question 26

how do you work out whether you need indirect retention

Answer 26

look at retention and look for rotation - see if support negates this

Question 27

The final stage is ‘review’, what does this mean

Answer 27

can you make the design:

• simpler
• less fussy
• with less components