Restoration of a root filled tooth 1

Question 1

What is the objective of restorative dentistry?

Answer 1

Create a mechanical system which mimics an unrestored tooth

• withstands impact loads
• Resists wear
• Distributes and dissipates stresses throughout the radicular dentine and the supporting periodontal structures

Question 2

What to consider with endo?

Answer 2

Adequacy of root filling
Preserve apical seal
Potential for coronal disassembly if it’s necessary to re-navigate the canal system
After root filling, how long should I leave the tooth before restoring it?
Is the tooth asymp?

Question 3

Why restore a root filled tooth?

Answer 3

To avoid bac leakage
To restore coronal structure
To restore aesthetics

Question 4

What is coronal leakage due to?

Answer 4

Breakdown of the - visit temp restoration
A delay in placing the definitive coronal restoration
Fracture or cracks of the existing coronal restoration
Exposed dentine tubules
Presence of pre-existing or 2ndry caries
Contamination of the pulpal space during post-hole preparation and temporisation

Question 5

Coronal leakage features?

Answer 5

Qual of coronal restoration is very important, more so than the quality of RCT
50% of teeth were contaminated
100% of root canals of root filled teeth exposed to saliva become contaminated within 30 days

Question 6

Why is coronal leakage common?

Answer 6

The GP-dentine interface is weak
Sealer offers limited protection
Avoid packing excess GP across the floor of the pulp chamber in molars
Ensure an effective seal of the pulp chamber with a GIC or RMGIC and restore and definitive restoration

Question 7

What makes a root filled tooth different?

Answer 7

Compromised architecture
Changes in physical properties
Changes in loading

Question 8

Challenges of the tooth after being root filled?

Answer 8

Severe or total coronal damage
Compromised mechanical integrity of remaining tooth
Reduced capability for stress distribution
Greater potential for bac leakage
Possible damage to periodontal supporting structures
Possible change in physical properties of dentine
Loss of proprioception from the pulp

Question 9

What does a loss of proprioception mean for the tooth?

Answer 9

Root filled teeth may be placed under greater occlusal loads than vital teeth, but are less able to withstand these forces

Question 10

When should you place a definitive restoration after completing a root canal?

Answer 10

When evidence of healing of the periapical tissues
ASAP
When combined evidence from the operative outcome, history, presenting symptoms, clinical findings and radiographic findings point to a resolution of infection

Consider:
- Previous pulpal/apical history - elective, non-symptomatic, periapical abscess, periradicular cyst

Look at radiographic history (RAD CHANGES AFTER 9-12 MONTHS), symptoms history, effectiveness of RCT procedure, age

Question 11

Why restore a root filled tooth?

Answer 11

Restore structural integrity of the radicular mass
Aid retention of the coronal component
Restore crown with a material adhesively united to the radicular mass
Retain as much tooth structure as possible
Consider need for cuspal protection of posterior teeth

Question 12

When to consider the need for cuspal protection of posterior teeth?

Answer 12

If more than 2 surfaces or large occlusal forces

Does NOT always mean a crown - crown prep will remove remaining cusps and weaken the tooth irreversibly

Question 13

Objectives for dentine replacement?

Answer 13

1. Adequate compressive, tensile and flexural strengths to perform under load
2. Matched elastic moduli
3. Matched coefficient of thermal expansion
4. Cariostatic chemistry
5. Potential for bonding
6. Radiopacity greater than dentine/enamel
7. Ease of mixing, manipulation and placement
8. Cariostatic chemistry

Question 14

Materials for replacing dentine?

Answer 14

Composites with dentine bonding systems
Amalgam
Materials used in limited circumstances - glass ionomer

Question 15

Elastic modulus, fracture strength and compressive strength of enamel and dentine?

Answer 15

Elastic modulus:
Enamel 85GPa
Dentine 15GPa

Fracture strength:
Enamel 10MPa
Dentine 50MPa

Compressive strength:
Enamel 400MPa
Dentine 300MPa

Question 16

Intracoronal restorations with amalgam features?

Answer 16

Requires cuspal coverage
Substantial removal of tooth needed
Unaesthetic
Amalgam may be bonded in posterior restorations

Question 17

Intracoronal restorations with composite features?

Answer 17

Adhesive
Unpredictable bond strength to dentine
Subject to chemical degradation
Highly effective for simple access closure of anterior teeth
Adequate for small access cavities
Requires effective placement techniques
Large posterior restorations may benefit from cuspal protection

Question 18

Intracoronal restorations with gold features?

Answer 18

Requires cuspal coverage
Provides cuspal bracing
Technically and clinically challenging
Can be cemented adhesively

Question 19

Intracoronal restorations with ceramic features?

Answer 19

Adhesive cementation
Same adhesive limitiations as composite 
High elastic modulus - brittle
Higher incidence of tooth fracture
Ok for small intra-coronal restorations