Restoration of endodontically treated tooth - posts

Question 1

What are the measurements for post placement? (width and length)

Answer 1

Post needs to be longer than the clinical crown
Need 4-5mm root-filling apically
Post width - has to be no more than 1/3 root width at narrowest point. Will seriously weaken the tooth if not enough dentine either side of the post.

Question 2

What is a post/ core?

Answer 2

Gains intra-radicular support for a definitive restoration.
CORE provides retention for crown
POST retains the core

Question 3

What does a post do to strength of tooth?

Answer 3

Post does not strengthen or re-enforce teeth
Preparation of root canal for a post WEAKENS TOOTH

Question 4

What is a ferrule?

Answer 4

A ferrule is 360 degree collar of circumferential dentine extending 2-3mm above the gingival margin.

Question 5

What is the primary factor that indicates if an RCT will fail or not?

Answer 5

Having a good coronal seal

Question 6

What are the 3 factors that make an ideal post?

Answer 6

parallel-sided
Non-threaded (passive) - smooth surface incorporates less stress to remaining tooth
Cement-retained

Question 7

What is a direct and indirect post?

Answer 7

Direct - comes in a kit and place directly into tooth
Indirect - made in a lab

Question 8

What are the advantages of a ceramic post?

Answer 8

High flexural strength and fracture toughness, favourable aesthetics

Question 9

What is a core build-up?

Answer 9

Internal part of tooth is built-up with restorative material to replace the lost tooth tissue.
Core prepared and provides retention.

Question 10

What is the most commonly used core material?

Answer 10

Composite

Question 11

Benefits and disadvantages of composite as a core build-up material?

Answer 11

Advantages - Tooth coloured = good aesthetics, bonds to tooth structure

Disadvantages - technique sensitive so moisture control required

Question 12

Disadvantages of GI as core material?

Answer 12

Absorbs water and core expands in size
Less stable than composite

Question 13

What problems can occur with post crowns?

Answer 13

Perforation
Core fracture
Root fracture or crack
Post fracture

Question 14

What is a good prognosis for an endodontically treated tooth?

Answer 14

10 years

Question 15

When would a post be required?

Answer 15

Insufficient tooth structure to restore without - no walls remaining or if there has been a loss of 3 walls.

Question 16

What are the appointment stages for a direct post?

Answer 16

1. Endo treatment and temporise
2. Obturation and temporise
3. Para-post kit to drill out GP to size of post you want. Cement post and prepare core. Take impression of cemented post and core to make crown.
4. Get final crown made and fit.

Question 17

What are some stresses that may cause root fracture?

Answer 17

Functional lever forces
Lateral forces exerted during post insertion
Wedging effect of tapered posts

Question 18

Give 3 potential reasons why a post-core may de-bond?

Answer 18

Secondary caries
Poor moisture control during cementation - poor operator technique
Root fracture

Question 19

Give 4 reasons why a fracture at the junction of the post and core may occur?

Answer 19

Weakest point - more likely to fracture here
Lack of sufficient ferrule
Trauma
Bio-corrosion

Question 20

Name 3 ways of receiving a fractured post?

Answer 20

Ultrasonic tip
Moskito forceps
Eggler forceps - specifically for removing posts

Question 21

Are cast or fibre posts more likely to fracture the root?

Answer 21

Cast posts

Question 22

Are cast or fibre posts more likely to de-bond coronally (leading to recurrent caries)?

Answer 22

Fibre-posts

Question 23

Whats advantages of cast metal posts?

Answer 23

Custom made - follows canal shape
Useful in flared canals
Conserve tooth tissue which reduces risk of perforation compared to parallel-sided fibre posts

Question 24

What are advantages of fibre posts?

Answer 24

Can be placed immediately
Tooth coloured - enhanced aesthetics
Compatible with current adhesive systems
Low elastic modulus similar to dentine - post absorbs/ dissipates stress

Question 25

What teeth should not have posts placed and why?

Answer 25

Lower incisors - too thin roots would end up hollowing out whole tooth for post prep
Molar teeth

Question 26

What are some disadvantages of fibre-posts?

Answer 26

Difficult to remove upon re-treatment

Question 27

What are some disadvantages of cast metal posts?

Answer 27

Direct/ indirect techniques - impression required - lab and extra clinical stages
More room for error
Unfavourable aesthetics if shine through

Question 28

What are some advantages of tapered posts?

Answer 28

Follows root form ensuring maximal remaining root dentine apically
Less likely to perforate
Stress concentration coronally
Better for small tapered roots

Question 29

What are some advantages of parallel posts?

Answer 29

Uniform stress distribution along the length
Do not generate as much stress in root canal because wedging effect is less, therefore lower risk of root fracture

Question 30

What are the disadvantages of parallel posts?

Answer 30

More tooth structure removal - higher risk for perforation
Stress concentrated more apically

Question 31

What are some disadvantages of tapered posts?

Answer 31

Induce more stress into the root increasing the risk of root fracture

Question 32

What are disadvantages of a ceramic post?

Answer 32

Difficult retrievability and root fracture common