Interim Restorations for Teeth Undergoing Endo Therapy Flashcards
Endo tx aim?
Eliminate bac from the tooth
Tooth maintained in disinfected state by preventing any further ingress of bac during and after tx
Steps to successful endo?
- Diagnose and remove the cause of disease
- Use an antiseptic technique
- Mechanically instrument the canals to enlarge them
- Irrigate the canals with one or more antibac soln
- Medicate the canals with an antibac agent
- Temporarily restore the tooth to avoid bac ingress during and after tx
- Fill the root canal system once disinfected
- Restore the tooth to normal function
What can occur if you do not follow these steps?
Risk the potential for:
- Bac already in the tooth to survive and proliferate
- New organisms to enter the tooth and establish colonies
= Continuation of apical periodontitis or the development of a new apical periodontitis lesion
Define interim restoration
A restoration which has been placed in the tooth after the previous restoration, caries, cracks etc have been removed at the commencement of endo tx
This restoration will remain in place whilst the endo tx is being performed and after the RC filling is complete until the definitive coronal restoration is placed
Define temporary restoration
Restoration placed in an endo access cavity
Likely to have been cut through an interim restoration in most cases
What are the most common pathways of bac entry?
Caries
Cracks
Exposed dentine
Broken down restoration margins
When should endo tx never be performed?
Through a failing or poor quality restoration
Or through a temporary restoration
What advantages does an interim restoration prior to endo tx provide?
Structural integrity of tooth
Support for weakened cusps
Coronal seal
Rubber dam will be easy to apply, with appropriate structure for the clamp to grip
No ideal access cavity can be cut
No risk of leakage through the coronal restoration when using irrigants
A temp restoration will be retained better
A well restored tooth will be more comfortable and functional for pt
When may an interim restoration not be required?
If the tooth is unrestored or has only a small intracoronal restoration (not compromised) (large or medium restorations should be replaced)
List the appropriate materials for interim restorations
Composite
RMGIC
Amalgam
What materials are NOT suitable for interim restorations?
IRM
GIC
What may be needed for large restorations or cracked teeth?
Support by metal bands
- An ortho bad
- Copper rings
OR
Reduce occlusal surface and rebuild the tooth using composite or amalgam (RMGIC not suitable)
What will a metal band provide?
Support of weakened tooth structure, esp cusps
Prevent progression of cracks
What principles should be applied when using a metal band?
Ensure band is correct size for tooth
GIC or RMGIC should be used when luting the band
Provide good margins = good hygiene
Ensure restoration harmonises with the occlusion
How to manage teeth with full coverage crowns? Why?
Removed prior to endo tx
Allows assessment of underlying tooth structure
Identification of hidden pathology
Better orientation when undertaking endo tx
Better coronal seal
When should crowns be left prior to endo tx?
If it’s certain that there is no chance of coronal leakage or pathology hidden under the crown
How to remove crowns?
Take a sectional putty impression of the tooth prior to removing the crown = stent to make temp restoration
Make a groove through the crown to tooth tissue and twist instrument into the groove
If unsuccessful, continue the groove occlusally, if still unsuccessful, lingually
How to make a provisional crown?
Protemp/quicktemp or trim/snap in the putty stent
Ensure crown is fitting well, good margins
Can cement with zinc phosphate rather than tempbond
Can seal dentinal tubules with a dentine bonding agent
OR construct a provisional crown using a pre-formed metal crown
How to manage provisional restorations during endo tx?
Should be removed prior to undertaking endo tx and replaced between appts and at end of tx
Access cavity filled with IRM/GIC - crown falls off = tooth is sealed
RCT complete - provisional - definitive crown asap
How to manage teeth with post crowns?
Temp can be very challenging
No temporary and restore the access with an adhesive restoration e.g. GIC
OR
Temporary partial overdenture and seal the access
RCT temporary restoration desirable properties?
Durable and effective coronal seal
Cheap
Easy to remove
Obvious difference between tooth tissue/interim restoration to ensure no more tooth tissue is removed upon removal
Examples of temporary restoration materials?
Zinc phosphate or Calcium sulphate based materials e.g. cavit/cortisol GIC RMGIC IRM Composite
Top layer - gic, irm etc
2nd layer - sponge or soft temp material (cavit/cortisol)
Then calcium hydroxide paste in the canal
Criteria for temporary restorations?
3mm in depth to provide adequate seal
Cotton wool wicks saliva and bac through the restoration
Foam pellets do not do this and are compressed under the temp restoration allowing easier removal
Cavit/cortisol - excellent double seal but more difficult to remove
Pt return if temp comes off to minimise bac contam
What to do upon completion of endo tx/how to place a temp restoration?
Cut GP points back to ADJ
Place GIC in access cavity but leave at least 3mm more coronally
Restore coronal aspect with amalgam/GIC
Indirect restoration - immediately or following a period of monitoring
Why do posterior teeth undergoing endo tx need protection?
Reduced tooth structure Loss of marginal ridge Access cavity Axial forces can flex cusps Non-axial forces are even more damaging
How does occlusion impact the protection of posterior teeth?
ICP - directs forces axially down posterior teeth
Lateral guidance can either be group function or canine guided
Canine guided = protects posterior teeth
Group function = damaging to posterior teeth, premolars more at risk, premolars weaker due to more tooth tissue loss
Non-working side interferences are damaging for root treated teeth
Forces on posteriors can lead to cusp fracture
When does the risk of posterior tooth fracture increase?
When more heavily restored = weakened tooth
Occlusal
Occlusal plus 1 marginal ridge loss
Occlusal, both MR loss
Occlusal, both MR, MOD
Occlusal, both MR, MOD, palatal/buccal restoration
How to protect posterior teeth with weakened tooth structures?
Interrim measures
- Occlusal adjustments to decrease loading
- Cuspal reduction with overlay restoration
- Cemented ortho band
- Interim crown
Definitive measures
- Cusp reduction and overlay restoration
- Full crown
- Onlay/overlay indirect restoration
How to make occlusal adjustments to decrease loading?
Articulating paper - 1 colour records ICP, another records lateral excursions
Remove lateral excursions with rugby bur
Why be careful with adjusting the occlusion?
Can introduce interfering contacts
Loss of ICP contacts
Transfer guidance to other teeth
How to reduce the cusp and provide an overlay restoration?
Reduce cusps by 2-3mm with a bur
Build up tooth with composite/amalgam
Restore ICP contacts
Keep excursive contacts to a minimum
Onlay/overlay indirect restoration?
Conservative compared to full crown
Strong
Can be cemented
Gold/high strength porcelain/composite
Full crown protection?
Full coverage = good seal
Destructive - v thin dentine walls remaining
