Restoration of the root filled tooth Flashcards by Rachel Sladden

Objectives of a restoration (4)

To create a mechanical system which mimics an un-restored tooth

withstands impact loads
resists wear
distributes and dissipates stresses throughout the radicular dentine and supporting periodontal structures

How well did you know this?

Not at all

Perfectly

Considerations for restoring and endodontically treated tooth? (8)

Adequacy of root filling
Preserving apical seal
Potential for coronal disassembly if necessary to re-navigate canal system
How long after RCT should I leave before restoring tooth?
Why was endo performed?
Was endo uneventful?
Is resultant root-filling technically excellent?
Is tooth asymptomatic?
Can I disassemble coronal resconstruction?

How well did you know this?

Not at all

Perfectly

Why restore a RFT? (3)

Avoid bacterial leakage
Restore coronal structure
Restore aesthetics

How well did you know this?

Not at all

Perfectly

Coronal leakage can be due to (6)

Breakdown of the temp
Delay in placing definitive coronal restoration
Fracture or crack of existing coronal restoration
Exposed dentine tubules
Presence of pre-existing or 2. caries
Contamination of pulpal space during post-hole prep and temp

How well did you know this?

Not at all

Perfectly

How many teeth contaminated along whole length after 19 or 42 days? (2)

50%, length after dependent on type of micro-organism

100% of RFT exposed to saliva became contaminated within 30 days

How well did you know this?

Not at all

Perfectly

What is the weak link in RCTs when it comes to coronal leakage? (4)

GP-Dentine interface
Sealer offers limited protection
Avoid packing excess GP across floor of pulp chamber in molars
Ensure effective seal of pulp chamber with GIC or RMGIC and restore with definitive restoration

How well did you know this?

Not at all

Perfectly

Challenges in restoring RFT (7)

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

How well did you know this?

Not at all

Perfectly

Loss of proprioception in RFT (2)

May be placed under greater oclcusal loads but are less able to withstand these forces

How well did you know this?

Not at all

Perfectly

When to restore an RFT (2)

ASAP

When infection is resolved

How well did you know this?

Not at all

Perfectly

Considerations when restoring an RFT (5)

Previous pulpal/ apical history?
-elective
-non-symptomatic
-periapical abscess
-periradicular cyst
Rad history
Symptoms history
Effectiveness of RCT
Age

How well did you know this?

Not at all

Perfectly

Biomechanical principles of restoring RFT (5)

To restore structural integrity of radicular mass
To aid retention of coronal component
To restore crown with material adhesively united to radicular mass
Retain as much tooth structure as possible
Consider need for cuspal protection of posterior teeth

How well did you know this?

Not at all

Perfectly

Considering need for cuspal protection of posterior teeth (2)

Required if more than 2 surfaces lost or under large occlusal forces
Does not always mean a crown!

How well did you know this?

Not at all

Perfectly

Objectives when replacing dentine (8)

Adeqaute compressive, tensile and flexural strengths to perform under load
Matched elastic moduli
Matched coefficient of thermal expansion
Cariostatic chemistry
Potential for bonding
Radiopacity greater than dentine/ enamel
Ease of mixing, manipulation and placement
Cariostatic chemistry

How well did you know this?

Not at all

Perfectly

Materials for replacing dentine (3)

Microfilled/ hybrid composites in combination with dentine bonding system
Amalgam
GIC to be used in limited circumstances

How well did you know this?

Not at all

Perfectly

Materials used for intracoronal restorations (4)

Amalgam
Composite
Gold
Ceramics

How well did you know this?

Not at all

Perfectly

Elastic modulus, fracture strength and compressive strength of enamel (3)

85GPa
10MPa
400MPa

How well did you know this?

Not at all

Perfectly

Elastic modulus, fracture strength and compressive strength of dentine (3)

15GPa
50MPa
300MPa

How well did you know this?

Not at all

Perfectly

Elastic modulus, fracture strength and compressive strength of composite (3)

20GPa
60MPa
100MPa

How well did you know this?

Not at all

Perfectly

Elastic modulus, fracture strength and compressive strength of amalgam (3)

35GPa
100MPa
400MPa

How well did you know this?

Not at all

Perfectly

Amalgam for intracoronal restorations (4)

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

How well did you know this?

Not at all

Perfectly

Composite for intracoronal restorations (7)

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

How well did you know this?

Not at all

Perfectly

Gold intracoronal restorations (4)

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

How well did you know this?

Not at all

Perfectly

Ceramic intracoronal restorations (5)

Adhesive cementation
Same adhesive limitations as composite
High elastic modulus - brittle
Higher incidence of tooth fracture
Small intracoronal OK

Extra-coronal restorations: there is a need for (5)

Intra-radicular retention
Dentine core replacement
Enamel replacement
Requirements of each component
Assembly of components

Challenges of total crown replacement (4)

Restoration needs to be retained by root Must allow stress distribution Must not cause root fracture Must be durable

Principles in crown retention (3)

Retain as much dentine mass as possible Restore dentine mass with suitable material if necessary Use intra-radicular post in combination with the above only if retention is compromised

Core materials (4)

Amalgam Core composite Glass ionomers Compomers

Core build-up with amalgam: factors (4)

Strong Reliable Successful Adhesion?

Core build-up with composite: factors (4)

Strong Adhesive Predictable? Mismatch in thermal expansion

Core build-up with glass ionomers: factors (6)

``` Low tensile strength - brittle Unreliable Poor adhesion Excellent thermal match to tooth Dimensionally stable Reserve for patches only ```

Intra-radicular posts function (2)

Retain and support core and coronal restoration | Aid in transferring functional loads to as wide an area as possible

Do intra-radicular posts increase tooth fracture strength? (1)

Ideal material for intra-radicular posts (4)

Ideally a rigid material or elastic with a Ferrule Appropriate dimensions (width and length) Prefabricated or cast Integrated with an appropriate core material

Intra-radicular posts - considerations (8)

``` Parallel sided or tapered Surface configuration Active or passive fit Length, width Ferrule Anti-rotation Cast or prefabricated Choice of material ```

Why should intra-radicular posts be parallel sided? (1)

Force down axial direction of tooth (resistance to axial forces)

Intra-radicular posts: how is surface consideration achieved? (5)

``` Casting roughness Sandblasted Etched Grooved Fluted ```

Post retention: active vs passive system (4)

Active -thread cuts into post-hole wall to aid post retention -introduces great stresses into system Passive -post retained in hole by means of adhesive lute -surface of post may be configures to aid adhesion

Depth of intra-radicular posts (4)

Deeper post holes distribute stress better Deeper post holes increase retention BUT Deeper post holes disturb apical seals Deeper post holes destroy tooth substance

Post design length (3)

3-4mm short of apex 2/3 of total root length 1/2 greater than crown height

Crown / root ratio in post design (2)

The greater the ratio the poorer the prognosis | Large building on small foundation is not safe place to live

Post design: width (2)

Strength more dependent upon outer perimeter of root | Post should be as narrow as possible but within strength limits of material

Post design: diameter (3)

Narrow posts are conservative of tooth substance BUT Narrow posts are weak Narrow posts are easily rotated

Dentine Ferrule (3)

Retention of >1.5mm of vertical sound tooth structure between crown margin and dentine-core interface that wraps 360 degrees around tooth

Anti-rotation (1)

In most clinical cases, the irregular shape of access cavity will provide the required anti-rotation

Prefabricated post designs (3)

Circular post holes Divergent roots Narrow post holes (SS)

Cast post design (4)

Non-circular root-canals Direct or indirect Choice of alloy Path of withdrawal and insertion

Choice of post material: two choices for elasticity (2)

Iso-elastic - same elasticity as dentine | Gradient of elasticity - increasing gradient from low dentine outside to a stiff (post) core inside

Metal alloys for intra-radicular posts (3)

Strong, corrosion resistant Prefabricated: SS, TiVal CastL gold alloys, nickel-chrome

Other precrabricated materials for intra-radicular posts (3)

Resin-reinforced carbon-fibre Ceramics Composite fibre

Rigid post systems (4)

SS Gold alloys Ni-Cr alloys Zirconium ceramics

Zirconia post system properties (2)

High modulus of elasticity --> extreme stiffness | Acceptable strength

The Parapost system (6)

``` Complete integrated system Parallel posts Matching instruments and posts Anti-rotational pins Multiple clinical techniques Multiple materials and combinations ```

Extra-coronal restoration materials (3)

Gold Ceramic Porcelain fused to metal

Full-veneer gold crown (3)

Provides strong protective veneer over underlying structure Margin of safety is greater than for ceramic or composite materials Durable but unaesthetic

Aesthetic crowns types (2)

All ceramic | Ceramic bonded to metal

Biological fracture types (3)

Periapical abscess Periodontal disease Recurrent caries

Mechanical failure types (4)

Inappropriate coronal retention Unfavourable displacing forces Loss of structural integrity of tooth Inappropriate use of materials and techniques