RPD design and dental laboratory prescription.pdf

Question 1

Important considerations

Answer 1

• RPD design is not a right or wrong affair: there may be different solutions to the same problem
• More than one solution may be perfectly acceptable by the same patient
• It is important to identify the patient’s specific needs and try to address those first
• A lot of the design decisions are determined by clinical information

Question 2

How to make this work?
A proven method for success:

Answer 2

1. Formulate the theoretically ideal design for the specific case
2. Adapt to the patient’s needs
3. Adjust according to the clinical presentation
4. Revise and finalise the design
5. Demonstrate and explain the design to the patient
6. Revise again if needed
7. Communicate the design to the dental technician
8. Ensure the execution is correct

Question 3

Prerequisites for formulating the ideal design

Answer 3

1. Thorough clinical examination & special tests (e.g. radiographs of abutment teeth)
2. Having listened to the patient and identified their needs
3. Good quality primary casts, articulated
4. Assessed the occlusion & prosthetic space for replacing teeth and RPD components
5. Surveyed the primary casts & selected a path of insertion
6. Good understanding of the biomechanics & component parts of RPDs!

Question 4

Aims of RPD design:

Answer 4

• Ensure the RPD can resist movement in 6 directions: towards the tissues, away from the tissues, forwards, backwards, left and right
• Don’t forget rotational movements!
• Satisfy aesthetic demands to the degree possible
• Ensure the RPD can be placed and removed by the patient!
• Come up with a design as hygienic as possible

Question 5

RPD design step by step

Answer 5

1. Select path of insertion and survey cast
2. Mark teeth to be replaced
3. Indicate positions and depth of undercuts
4. Plan support (rests / saddles)
5. Plan retention (direct retainers)
6. Plan stability (bracing arms)
7. Join all components with the simplest major connector possible
8. Assess the design for indirect retention
9. Verify undercuts and modify the direct retainers if needed
10. Review overall design and modify if needed

Question 6

1. Select path of insertion (POI) and survey cast

Answer 6

• In the anterior region, the POI is dictated by aesthetics
• In most cases, the POI will be parallel to the distal surface of the last abutment tooth
• If missing anterior teeth: POI usually parallel to mesial surfaces of the abutment teeth
• Posteriorly, the POI is dictated by proximal undercuts
  The POI will be parallel to the distal surface of the most distal abutment tooth if there is a free end saddle, or aim to engage an undercut area in bounded saddles
• Surveying the cast will indicate the relative undercuts for the selected path of insertion Never forget: these must also be present at the horizontal position!

Question 7

2. Mark teeth to be replaced

Answer 7

Question 8

3. Indicate positions and depth of undercuts

Answer 8

Question 9

4. Plan support (saddles)

Answer 9

Question 10

4. Plan support (rests)

Answer 10

Question 11

5. Plan retention (direct retainers)

Answer 11

Question 12

6. Plan stability (bracing arms)

Answer 12

Question 13

7. Join all components with the simplest major connector possible

Answer 13

Question 14

8. Assess the design for indirect retention – tip:
   check for all possible directions of rotational movement!

Answer 14

Question 15

9. Verify undercuts and modify the direct retainers if needed

Answer 15

Question 16

10. Review overall design and modify if needed

Answer 16

Question 17

Communication with the dental technician