Planning Crowns

Question 1

Indications for crowns?

Answer 1

Broken down teeth
Heavily restored teeth
Tooth wear
Hypoplastic condition
Alter occlusion
Restore missing function
Appearance 
Trauma 

WHO R FAB

Question 2

Contraindications for crowns?

Answer 2

More conservation option available
Poor OH
Very broken down e.g caries subgingival
Periodontal - not enough bone support

Question 3

What is an ideal crown margin?

Answer 3

Sound tooth structure
Need 2mm biological width above bone
If invade biological width - inflammation and bone loss

Question 4

3 stages of planning a crown?

Answer 4

Hx and examination
Critical thinking and decision making
Detailed planning of crown - perform clinical/ lab stages

Question 5

What should be considered in hx and examination?

Answer 5

1. Pt factors
2. Mouth condition
3. Tooth in question

Question 6

What should be considered in pt factors during hx/examination?

Answer 6

Attitudes and expectations
Co-operation - crown complex w/ few appts
Age - older pt have brittle teeth, younger have larger pulp chambers

Question 7

6 basic points of aesthetics?

Answer 7

1. Colour
2. Contour
3. Outline
4. Symmetry
5. Proportion
6. Soft tissue harmony

Question 8

Why should pulp status be checked prior tx?

Answer 8

Legal aspect - take PA
15-20% teeth become non-vital
Assess size/depth current restoration - increased risk loss vitality
Easier undertake endo prior’s

Question 9

What periodontal factors should you consider?

Answer 9

Assess inflammatory defects
Assess soft tissue contour
Gingival recession
Ridge defect
Gingival asymmetry
Loss papilla = black triangle

Question 10

What is Tarnow rule?

Answer 10

5mm rule
If distance from bone to contact point less 5mm - complete fill of gingival embrasures
If distance bone to contact point +5mm - more likely to have black triangles (make sure contact within 5mm of bone)

Question 11

What to consider in critical thinking and decision making?

Answer 11

Tooth worth being kept
If suitable - any restorations more suitable
Is enough tooth structure for crown - will need restoration first?
If pre-crown tx needed? - orthodontic, bleaching, RCT

Question 12

What to consider in detailed planning phase?

Answer 12

Conformative vs reorganisation approach
Diagnostic wax-up - use Protemp intra-orally to see result
Determine best material

Question 13

What is conformative vs reorganisation approach?

Answer 13

Conformative

• Anterior teeth crowned - no change posterior occlusion
• No altered occlusion

Reorganisation

• If no stable occlusion
• Occlusion reorganised

Question 14

Different types of crowns?

Answer 14

Full coverage
Partial coverage
Post-core crowns

Question 15

What types of materials can be used?

Answer 15

Gold/ metal
Metal ceramic -PFM (good bruxism case)
Ceramic - dentine bonded (good hypo plastic condition)
High strength ceramic - increased prep
Composite crown - long term temp.