Restoration Of The Endodontically Treated Tooth

Question 1

What clinical assessment should be made of a previously RCT tooth?

Answer 1

Is tooth restorable and can it be isolated

Coronal seal

Amount of remaining tooth structure

Swelling / draining sinus

TTP

Mobility

Increased Periodontal pocketing

Question 2

What radiographic assessment should be done of the previously RCT tooth?

Answer 2

Quality and length of root filling
- voids
- missed canals

Shape of canals

patency
- fractures instruments
- perforations

Bone levels to support tooth

Crown to root ratio 1:1.5

Any associated pathology

• inadequate root fillings should be re-treated before restoration

Question 3

What is coronal microleakage and why is it significant?

Answer 3

Ingress of MO’s into the root canal system

• important cause of RCT failure
• significant in multi rooted teeth
• no restoration within 3 months of RCT, should be re-RCT

Question 4

What are the treatment options available to an anterior tooth with intact marginal ridges after RCT

Answer 4

Composite restoration

Veneer

Question 5

What are the treatment options available to an anterior tooth with intact marginal ridges + discoloured crown, after RCT

Answer 5

Bleaching and veneer

Crown

Question 6

What are the treatment options available to an anterior tooth with marginal ridges lost

Answer 6

Core build up, with crown

Post crown

Question 7

What is the purpose of a post / core

Drawbacks?

Answer 7

To gain intraradicular support for a definitive restoration

• core provides retention for crown
• post retains core

Posts do not strengthen or reinforce teeth
Prep of root canal for a post weakens tooth

Question 8

What is the ideal clinical features for a post placement?

Answer 8

Endodontic
- no sinus / swelling / abscess
- no ttp
no exposed GP

restorative
- caries free
- 2mm ferrule, 1mm thick and 3/4 diameter

Perio
- no PPD >5mm
- no mobility or furcation
- no BOP at site

occlusion
- 2mm interocclusal space after core placed
- no bruxism / clenching

Question 9

What is an ideal post to use?

Answer 9

Parallel sided
- avoids wedging
- more retentive than tapered

Non threaded
- less stress to remaining tooth as it is passive

Cement retained
- cement acts as buffer between masticatory forces and post / tooth

Question 10

What are the different classification of posts

Answer 10

Manufacture type
- preformed/prefacbircated or custom made

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

Shape
- parallel or tapered

Question 11

Pros / cons of metal post?

Answer 11

Cheap to fabricate

Poor aesthetics
Corrosion
Radiopaque

Question 12

Pros / cons of ceramic posts?

Answer 12

Alumina, zirconia

High flexural strength and fracture toughness
Favourable aesthetics

Root fracture common and difficult to retrieve post

Question 13

Pros / cons of fibre posts?

Answer 13

Glass, quartz, carbon fibre

• flexible
• similar properties to dentine
• aesthetic
• retrievable
• bond to dentine w DBA
• radiolucent

Question 14

What is a core build up?

Answer 14

Internal part of tooth built up with restorative material to replace lost tooth tissue

Core is then prepared
- provides retention and resistance for definitive restorations

Question 15

Most common core material?

Pros / cons?

Answer 15

Composite

• good aesthetics
• bonds to tooth structure
• technique sensitive and moisture sensitive
• used with fibre posts

Question 16

Para post components?

Answer 16

Provisional post

Burn out posts

Parapets drill

Impression post

Question 17

How can rotation be prevented if there is not much coronal structure to support a post crown

Answer 17

Small vertical groove placed into the canal located in bulkiest area of root

Question 18

What is the lab prescription for a post crown?

Answer 18

Please construct cast post and core
- parapost colour

Core 6 degree taper

Please leave 2mm space in occlusion for crown

See enclosed registration / opposing impression

Shade!

Question 19

What should be done in post crown try in?

Answer 19

Check post space for temp bond and clean with parapost

Irrigate with .2% chlorhexadine

Dry with paper points

Ensure post core fits around prep

Check occlusal clearance - may need adjustment

Question 20

What are the main problems w posts and cores?

Answer 20

Perforation of the RC

Core fracture

Root fracture or cracking

Post fracture

Question 21

How is post perforation treated?

Answer 21

Repair - more specialist
- internal or external periradicular surgery

Extraction - me

Question 22

What are the %’s for reasons for post failure?

Answer 22

60% restorative issues

32% periodontal issues

Only 8% due to endodontic issues

Question 23

ideal radiographic requirements for a post and core?

Answer 23

ENDO
- if prev RCT, good quality with no voids and 4mm GP apically available

Pathology
- no periapical pathology

root anatomy
- 1:1 root post ratio
- post no wider than 1/3 root width at smallest area
- minimal to no curvature of canals
- no root resorption / fractures to root

bone levels
- no / minimal bone loss
- post 4mm subcrestal

coronal
- no caries
- no crown fractures

Question 24

Disadvantages of metal posts?

Answer 24

Removal of all undercuts needed
- more removal of sound tooth tissue

Lack of flexibility
- more prone to root fracture
- often terminal
- much less retrievable than fibre posts

Question 25

Disadvantages of fibre posts

Answer 25

Failure
- due to cementation issue
- secondary caries
- chipping of overlying composite core
- ingress of moisture between resin and post

Question 26

Advantages of direct posts vs indirect posts?

Answer 26

If placed same appt, less risk of microleakage

Reduces number of visits and also chair time

Reduced lab costs