RPD Classification

Question 1

Describe the responsibility of the dentist in the design of RPDs

Answer 1

• Provide design prescription to the dental technician
• Dentist is the only person who has a clear view about the biological field and function findings which will affect treatment for that patient

Question 2

Describe 3 ways a prescription can be done for an RPD

Answer 2

1. Written
2. Drawn
3. Marked on cast

Question 3

Describe the design sequence for RPDs

Answer 3

1. Articulate and survey study casts
2. Classification
3. Path of Insertion
4. Saddles
5. Support
6. Connector
7. Direct and indirect retention
8. Bracing and reciprocation

Question 4

Name 2 classifications used to describe RPDs

Answer 4

1. Kennedy

2. Craddock

Question 5

What does the Kennedy Classification of RPDs describe?

Answer 5

Designed to describe the unrestored natural dentition but commonly used to describe the intended denture

Question 6

Describe Class I - Class IV of the Kennedy Classification

Answer 6

Class I - Edentulous areas bilateral and posterior to standing teeth
Class II - Edentulous areas unilateral and posterior to standing teeth
Class III - Edentulous area unilateral and has standing teeth anterior and posterior
Class IV - Single edentulous area anterior to standing teeth that crosses the midline

Question 7

Describe how the Kennedy Classification works if there are 2 or more saddles present

Answer 7

• Additional saddles are indicated as modifications i.e 2 additional saddles is 2 modifications
• Most posterior saddle is given priority in classifying

Question 8

Describe Class I - Class III of the Craddock Classification

Answer 8

Class I - Denture entirely supported on abutment teeth
Class II - Denture entirely supported on mucosa
Class III - Denture dually supported by the abutment teeth and mucosa

Question 9

What is the path of insertion?

Answer 9

The path followed by denture from first contact with teeth until fully seated

Question 10

Describe the relationship of the PoI with the PoW and PoD

Answer 10

PoW - Always coincides with PoI

PoD - May or may not coincide with PoI (PoD is assumed to be at right angles to occlusal plane)

Question 11

How may a single PoI be created if a denture has multiple paths?

Answer 11

Natural or prepared guide planes

Question 12

What is the optimum and most commonly used PoI?

Answer 12

Vertical

Question 13

Name 3 reasons RPDs may not use vertical PoI

Answer 13

1. Improve aesthetics
2. Improve retention
3. Avoid interferences from large undercuts

Question 14

Describe how changing PoI may improve aesthetics of an RPD

Answer 14

Anterior path of insertion is based on a posterior tilt which leads to a closed design in the anterior portion of the mouth and can eliminate black triangles between denture and teeth

Question 15

Describe how changing PoI may improve retention of an RPD

Answer 15

Improved retention using guide planes to engage undercuts so that PoI differs from PoD

Question 15

Name 6 advantages of guide planes

Answer 15

1. Provides definite PoI
2. Increases retention due to resistance to movement in PoD
3. Displacement limited to PoI
4. Provides bracing and reciprocation
5. Protects tooth tissue by preventing food impaction
6. Helps distribute occlusal force throughout the arch

Question 16

How may guide planes be prepared if there are no natural ones present?

Answer 16

Straight bur used at maximum bulbosity of two teeth to prepare vertical parallel surfaces

Question 17

What is a key point to remember when changing PoI?

Answer 17

New survey line needs to be drawn as there will be additional undercut areas present