Post and Cores

Question 1

What radiographic endodontic status would indicate a post placement?

Answer 1

Previously root treated
Good apical/coronal seal
Obturation within 2mm of apex
Well condensed
Periapical status

Question 2

What aspects of root anatomy may indicate a post crown?

Answer 2

Wide roots
Minimum 1:1 root to crown ratio
Minimal or no curvature
No evidence of root resorption

Question 3

What is the minimum length that a post must be able to extend to sub-crestal on a tooth?

Answer 3

At least 4mm sub-crestal.

Question 4

What clinical endodontic signs may indicate a post crown?

Answer 4

No sinus
No abscess
Not TTP
No exposed GP

Question 5

What are the restorative indications for a crown?

Answer 5

Caries free

Minimum 2mm ferrule extending at least around 3/4 of tooth

Minimum 2mm free occlusal space after core placement to allow for crown to be fabricated.

In group function.

Question 6

What are the periodontal indications for placing a post crown?

Answer 6

No bleeding pockets >4mm
No pockets >5mm
No pus
BOP <15%
Tooth not mobile
No furcation involvement

Question 7

List the advantages and disadvantages of a direct post.

Answer 7

ADV- Same day post placement, and lower cost.

DIS- Less accurate fit, not suitable for wider canals, no suitable if less than ideal ferrule remains.

Question 8

List the advantages and disadvantages of an indirect post.

Answer 8

ADV- More accurate fit, suitable for wider canals, and impaired ferrules

DIS- Requires more appointments and costs more.

Question 9

What types of materials can posts be made of?

Answer 9

Metal (Cast gold, SS, brass, titanium)

Ceramic (Zirconia, alumina)

Fibre (Glass, quarts, carbon)

Question 10

Outline the advantages and disadvantages of a cast metal post?

Answer 10

ADV- Radiopaque, easy to retrieve, better fir to overlaying metal crown.

DIS- Poor aesthetics, risk of root fracture from transferred force, corrosion risk.

Question 11

Outline the advantages and disadvantages of a ceramic post?

Answer 11

ADV - High flexural strength, greater aesthetics.

DIS - Difficult to retrieve, technique sensitive, difficult to spread silane coupling agent, requires a dry field.

Question 12

Outline the advantages and disadvantages of a fibre post.

Answer 12

ADV- Allows light cure through post, mimics roots elasticity modulus.

DIS- Difficult to retrieve, technique sensitive, less radiopaque.

Question 13

What is the benefit of a parallel post over a tapered one?

Answer 13

Less stress on root
Greater retention

Question 14

What is the benefit of a tapered post over a parallel one?

Answer 14

More conservative.

Question 15

What is the benefit of a smooth post over a serrated one?

Answer 15

Passive fit, less stress on root upon insertion, risk of root fracture.

Question 16

What is the benefit of a serrated post over a smooth one?

Answer 16

More retentive.

Question 17

What are the ideal post characteristics?

Answer 17

Parallel sided (more retentive)
Non-threaded (imparts less stress onto tooth)
Cement retained (acts as a buffer between forces)

Question 18

What extra-oral landmarks do you look for when assessing for a post crown?

Answer 18

• Smile line
• Symmetry
• Incisal show
• Speech
• Skeletal pattern
• FWS
• TMJ

Question 19

What intra-oral features would help you assess whether to place a post crown?

Answer 19

• Occlusion
• Excursions
• Guidance
• Periodontal status
• Caries status
• Overeruption
• Shade and shape
• Interocclusal space
• Ferrule placement

Question 20

What are the risks of placing a post?

Answer 20

Perforation
Root fracture
Post fracture
Infection requiring re-RCT

All of which could then indicate XLA
Note that the risk are increased in bruxists, Class IId2, and Class III edge to edge malocclusions.

Question 21

What are the ideal post lengths and widths for a post crown?

Answer 21

4mm sub-crestal post
At least same height of the crown
Ideally 2/3 root length, whilst maintaining apical 4mm
Width not greater than 1/3 root diameter

Question 22

What are the preparation requirements for a post?

Answer 22

2mm high ferrule
4mm preserved apical GP to maintain seal
Width not greater than 1/3 root diameter

Question 23

Outline the procedure for prepping a tooth for a direct post?

Answer 23

Assessment/consent/MH/Shade

Check occlusion and guidance points

Give LA and place dam

Remove previous restorations/caries

Refine crown margins

Calculate working length of desired post

Use GG 3/4 to prep 2mm of GP from canal

Use post system to create post space

Adjust prep to include ferrule, and other retentive factors

Question 24

Outline the procedure for cementing a fibre post.

Answer 24

Irrigate post space with hypochlorite

Try in the post to assess prep

PA can be used to check

Use cement based on manufacturers instructions

Load the post space with cement, seat to prep margins

Remove excess cement

Prepare and redefine margins for crown prep

Take impressions for crown prep and provisional restoration.

Question 25

Outline the procedure for taking the impression for an indirect post.

Answer 25

Complete prep
Wash prep with hypochlorite
Select tray
Insert impression post, blunt coronal for retention
Retract gingiva
Carefully wash and dry
One stage impression - light body around prep and post
Medium body over top
Take a bite reg and opposing arch alginate
Place temporary post inside prep
Complete composite core build up
Construct provisional restoration