Restoration of the Endodontically Restored Tooth

Question 1

What are you looking for in a tooth that potentially needs to be endodontically treated?

Answer 1

• caries
• how much tooth structure is left
• able to be isolated?
• swelling/sinus
• ttp
• buccal sulcus tender to palpation?
• mobility
• increased pocketing

Question 2

When assessing a radiograph of an endodontically restored tooth, what are you looking for?

Answer 2

• root filling voids/quality of obturation
• unfilled/missed canals
• patency (fractured instruments/posts/sclerosis)
• bone support
• crown to root ratio
• pathology

Question 3

What are some problems of restoring RCT teeth?

Answer 3

• lack of remaining tooth structure
• fractured endo instruments
• perforations

Question 4

What is coronal microleakage?

Answer 4

Ingress of micro-organisms into the root canal system
- important cause of RCT failure

Question 5

What is the choice of restoration for a RCT anterior tooth with intact marginal ridges?

Answer 5

composite restoration veneer

Question 6

What is the choice of restoration for a RCT anterior tooth with intact marginal ridges + discoloured crown?

Answer 6

bleaching or veneer (crown)

Question 7

What is the choice of restoration for a RCT anterior tooth with destroyed marginal ridges?

Answer 7

• core build-up with crown
• post crown

Question 8

what is a post/core?

Answer 8

• Core provides retention for crown
• Post retains the core

Question 9

Do posts strengthen/reinforce teeth?

Answer 9

NO
- they simply retain the core
- preparation of root canal for a post weakens the tooth

Question 10

Where is a post located?

Answer 10

Post placed in the root canal

Question 11

What is a core? (RCT reference)

Answer 11

The core is what the prosthesis is cemented to

Question 12

Should posts be placed in incisors or canines?

Answer 12

post unnecessary if sufficient coronal dentine is present

Question 13

In which teeth should post placement be avoided?

Answer 13

Mandibular incisors due to thin/tapering/narrow mesiodistal roots

Question 14

Why should you avoid placing a post in a curved canal?

Answer 14

Can cause perforation

Question 15

What is the guideline root filling length for placement of a post?

Answer 15

4-5mm root filling apically

Question 16

Why is coronal seal during RCT important?

Answer 16

good coronal seal will lead to healthier apical periodontal health as it prevents microbial leakage into the canals

Question 17

What is the guidelines for post width in RCT teeth?

Answer 17

No more than 1/3rd of root width at narrowest point and 1mm of remaining circumferential coronal dentine

Question 18

How much alveolar bone support is required for placement of a post?

Answer 18

At least half of post length into the root

Question 19

what are examples of posts

Answer 19

Fiberglass
carbon fibre posts

Question 20

What is the guidelines for post placement in terms of ferrule size?

Answer 20

at least 1.5mm height and width of remaining coronal dentine

Question 21

What is a ferrule?

Answer 21

A dentine collar!
- encirclement of 1-2mm of vertical axial tooth structure within walls of a crown
- prevents tooth fracture

Question 22

Crown margin has not been placed onto solid tooth, what is likely to occur?

Answer 22

root fracture significantly increased

Question 23

What can be done to a tooth to achieve a ferrule before placement of a crown?

Answer 23

orthodontic extrusion or crown lengthening

Question 24

What are the aspects of ‘the ideal post’?

Answer 24

• parallel sided
• non-threaded (passive, all posts are slightly threaded)
• cement retained

Question 25

Why is it important that a post is parallel sided?

Answer 25

- avoids ‘wedging’ - more retentive than tapered

Question 26

Why is it important that a post is non-threaded (passive)?

Answer 26

Smooth surface incorporates less stress to reminding tooth than threaded (active)

Question 27

Why is it important that a post is cement retained?

Answer 27

Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/tooth

Question 28

How can posts be manufactured?

Answer 28

- pre-formed - prefabricated - custom made

Question 29

What materials can posts be made of?

Answer 29

- cast metal - steel - zirconia - carbon/glass fibre

Question 30

What shape can posts be?

Answer 30

parallel sided or tapered

Question 31

What are the benefits of prefabricated posts?

Answer 31

- only 1 visit required - no impressions and lab visit required - immediate prep of core - large selections of designs and materials

Question 32

How are custom posts made?

Answer 32

- cast from direct pattern fabricated in patients mouth (duralay) - 2 visits required = impressions and fit

Question 33

What is the minimal standard restoration for a posterior endodontically treated tooth?

Answer 33

cuspal protection restoration (minimal standard restoration for a posterior endodontically treated tooth) - prevent microbial ingress - prevent catastrophic fracture (eg tooth splitting through furcation or buccal wall coming off tooth and taking cementum with it)

Question 34

What is a core build up?

Answer 34

Internal part of tooth is built-up with restorative material to replace the lost tooth tissue - can provide retention and resistance for permanent restorations

Question 35

Where should you try not to place a post in the mouth?

Answer 35

Posterior tooth - difficult access - likely to cause perforation

Question 36

What core materials are used?

Answer 36

1. Composite = best option! 2. Amalgam 3. Glass ionomer

Question 37

What is involved in placement of a Nayyar core?

Answer 37

- root treatment is removed from the root canals - amalgam is packed into the root canals and tooth build up (provides retention for the amalgam) - cannot be prepared for 24hrs until amalgam sets (PROBLEM) - difficult process

Question 38

What are the problems associated with posts?

Answer 38

- perforation - core fracture - root fracture or crack - post fracture

Question 39

How is a tooth managed that has had post perforation?

Answer 39

- repair = internal or external periradicular surgery - extraction

Question 40

What can be used to remove a post from a tooth?

Answer 40

- ultrasonics - Masseran kit - eggless - miskito forceps

Question 41

What are the reasons for post failure?

Answer 41

- 60% due to restorative reasons - 32% due to periodontal problems - 8% due to endodontic reasons

Question 42

Do all cores need a post?

Answer 42

NO

Question 43

What are the benefits and cons of using composite as a core material?

Answer 43

Benefits = - tooth coloured (good aesthetics) - bonds to tooth structure Cons = - technique sensitive - moisture control required

Question 44

What are the cons of using amalgam as a core material?

Answer 44

- poor aesthetics - core cannot be prepped straight away as amalgam needs 24 hrs to set

Question 45

What are the cons of using glas ionomer as a core material?

Answer 45

absorbs water so core expands in size

Question 46

What should apply to the design of a core?

Answer 46

- 6º taper - 10mm length

Question 47

What would be included on the lab prescription for a post and core?

Answer 47

- please contrast cast post and core - para post (colour) - core 6º taper - please leave 2mm space in occlusion for crown enclosed registration/opposing impression

Question 48

What are the steps of a post try-in?

Answer 48

- check post space for temp bond - irrigate chlorhexidine (0.2%) - dry with paper points - ensure fits around prep - do you have enough occlusal clearance

Question 49

What are the essential techniques of fitting a post-crown?

Answer 49

- be careful not to fill post space with cement - use firm apical pressure - get rid of excess - make sure no excess around when taking crown impression/fitting MCC

Question 50

What may be the signs of vertical root fracture?

Answer 50

- Long single pocket - Repeated debonding of post/core