Interim restoration and protection of teeth Flashcards by Clelia Serra

What does endodontic treatment aim to do?

How do you maintain them in the disinfected state?

Eliminate bacteria from the tooth

Maintained by preventing further ingress of bacteria during and after treatment or the treatment will fail

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What would happen if you fail to keep the tooth sealed between appointments/

Will undo all of the disinfection undertaken in previous appointments

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What are the 8 steps to successful endo?

Diagnose and remove the cause of the disease
Use aseptic technique
Mechanically instrument the root canals to enlarge them
Irrigate the canals with one or more antibacterial solution
Medicate the canals with an antibacterial agent
Temporarily restore the tooth to avoid bacterial ingress during and after treatment
Fill the root canal system once disinfected
Restore the tooth to normal funciton

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What happens if you fail to comply to the 8 steps of successful endo?

Risk potential for bacterial already in the tooth to survive and proliferate or new organisms to enter the tooth and establish colonies

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What is the result of bacterial already in the tooth surviving or new organisms entering?

Continuation of apical periodontitis which was already present or the development of a new apical periodontitis lesion

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What is an interim restoration - prior to RCT?

A restoration already placed on the tooth after the previous restoration/caries/cracks have been removed
Such restoration will remain in place whilst the endodontic treatment is being performed and after the root canal filling has been completed until definitive coronal restoration is placed

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What is a temporary restoration?

A restoration placed in an endodontic access

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What is the main cause of pulp and periapical disease?

the presence of bacteria within the tooth
Need to consider how the bacteria entered the tooth initially - need to remove the path of entry to prevent further bacterial ingress

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What are the most common paths of entry for bacteria?

Caries
Cracks
Exposed dentine
Broken down restoration margins

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What do you do to be sure that the portals of entry for bacteria have been removed?
What does this allow investigation of?

The existing restoration should be replaced with a good quality, well-sealed restoration
Investigation of the tooth to assess restorability and overall prognosis

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What should endo treatment never be preformed under?

failing or poor quality restorations or through temp restorations

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What are the advantages of restoring with an interim restoration prior to endo treatment

Structural integrity
Support for weakend cusps
Coronal seal
RD easier for clamp to grip
An ideal access cavity will be cut
No risk of leakage through coronal restoration whenw using irrigant
A temp restoration will be retained better
A well restored tooth will be more comfortable and functional to the patient
The restoration can be used as core restoration if an indirect is required after

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When may an interim restoration not be required?

If the tooth is unrestored or has a small intra-coronal restoration

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What are the appropriate restorations for interims?

Composite
RMGIC
Amalgam

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What materials shouldnt be used for interims?

IRM and GIC

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What may large restorations or teeth with cracks need to be supported with?``

Metal band - orthodontic band or copper rings

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What advantages does a metal band provide?

Support of weakened tooth structure, especially cusps

Prevention of progression of cracks

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What principles should be applied when selecting a band to put on a tooth?

Ensure the band is the correct size for the tooth
A chemically curing cement should be used when luting the band (GIC or RMGIC)
Provide food margins to allow adequate OH
Ensure restoration harmonises with occlusion

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What can be done instead of using a band to keep the heavily restored tooth intact?

Reduce the occlusal surface and rebuild the tooth using strong restorative material
Distrupt ICP forces so more evenly distributed
Options include amalgam or composite

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What should ideally be done to teeth with crowns on before starting endo treatment?

Full coverage crowns should be removed prior to commencing endo treatment

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If have good margins, can leave the crown on the tooth, what are the advantages of this?

Thorough assessment of underlying tooth structure
Identification of hidden pathology
Better orientation when undertaking endodontic treatment - follows anatomy better
Better coronal seal

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When should crowns be left in situ?

If it is certain that there is no chance of coronal leakage or pathology hidden under the crown

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How do you remove the crowns?

Take sectional putty impression of the tooth prior to removing the crown to use as stent to make temp rerstoration
Make a groove through the crown - through to tooth tissue/core material and twist an instrument into the groove
Porcelain need gauze ready as shatters

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How do you make a provisional crown?

Use temporary crown compostie material e.g. Protemp or QuickTemp or cold cure acrylic in the putty stent
Ensure the crown is well fitting with excellent margins
Consider cementing with zinc phosphate not tempbond if retention not good
Consider sealing the dentinal tubules with dentine bonding agent
Alternatively - construct with a pre-formed metal crown adapted to fit with provisional crown material

If have a provisional crown what should also be provided?

The access cavity should be restored with a temp restoration and not left open - so if the temp falls off the tooth will still be sealed

How do you temporise teeth with post-crowns?

Prior to cementing a temp post-crown may be prudent to place cavit at the base of the crown - improves the seal Best solution is to provide a temp post-crown and restor access with an adhesive restoration: GIC Or a temp overdenture can be provided and access sealed with cavit

What is the problem with temporising a tooth with post crown?

Can have as much contamination as teeth with no restoration in situ

What does the temporary material do

Occupy the access cavity between appointments

What is the main requirement of the temp material?

Provide effective and duable coronal seal

What are the other properties of the temp material?

Ease of removal at next appointment Obvious difference between the tooth tissue or interim restoration to allow removal without risking damage to tooth tissue inexpensive

What are potential temp materials

Zinc-oxide/calcium based materials e.g. cavit, coltisol Zinc-oxide based reinforced intermediate restorative materials e.g. IRM GIC RMGIC Reinforced GIC e.g. Ketac Fil, Ketac Silver Composite

How do you temporise the tooth between appointments?

Intermediate or provisional filling material e.g IRM or GIC Then sponge or soft temp material e.g. cavit or soltosol Then Calcium hydroxide paste in the canal

how deep must the temporary material be in order to provide seal?

3mm in depth

Why should cotton wool not be used under the temp restoration?

it wicks saliva and bacteria through the restoration

What is the advantage and disadvantage of cavit?

Provides a better seal but can be difficult to remove

What should be done on completion of treatment to stop contamination

Cut the GP back to the ADJ Place GIC in the access cavity but leaving at least 3mm more coronally Restore the coronal aspect with composite or amalgam if an indirect restoration is required decide if it is to be undertaken immediately or following a period of monitoring

Why do posterior teeth that have undergone endodontic therapy require protection?

``` Reduced tooth structure Access cavity Loss of marginal ridges Axial forces can flex cusps non-axial forces are more damaging ```

Where does ICP direct forces?

Axially down posterior teeth

What is lateral guidance in relation to root filled molars?

The teeth will either be involved in guiding lateral excursions - either canine or group guided

Why is canine guidance preferred over group function?

Canine protects the posterior teeth | Group is damaging to posterior teeth especially if been root treated

Why are premolars most at risk?

They are more commonly involved in group function compared to molars Also weaker due to comparatively more tooth tissue loss

What other forces are also extremely damaging for root treated teeth?

Non-working side interferences are

What increases the risk of fracture?

As the tooth becomes more heavily restored

Which is most at risk of fracture?

Occlusal access and both marginal ridges and MOD restoration and buccal/palatal restoration

What do you need if have increasingly weakened tooth structures?

Cuspal coverage protection

What are the 2 options for protecting posterior teeth with weakened structure?

Interim measures and definitive measures

What are the different interim measures for protecting posterior teeth with weakened structure

``` Occlusal adjustment to reduce loading Cusp reduction and overlay restoration long-term Cemented orthodontic band Interim crown (metal/composite/acrylic) ```

What are the different definitive measures for protecting posterior teeth with weakened structure

Cusp reduction and overlay restoration Onlay/Overlay indirect restorations Full crown

How do you carry out occlusal adjustment to reduce occlusal loading?

Use occlusal marking foil to highlight contacts in ICP Use a different colour for marking foil to highlight contacts in lateral excursion Then use diamond bur to keep ICP contacts - with opposing tooth and remove the lateral excursive contacts - reduces risk of cust fracture, when change guidance transfer to another tooth

Why do you have to be careful when adjusting occlusal contacts?

Every change can have a knock on effect for other teeth; transfer of guidance to other teeth, introduction of interfering contacts, accidental loss of ICP contacts

What should the occlusal adjustments be ideally fist be undertaken on?

study casts mounted on semi-adjustable articulator mouted with a facebow

How do you go about cusp reduction and making an indirect restoration?

``` Reduce cusps by 2-3mm with a bur Use composite or amalgam to build tooth up Ensure ICP contacts are restored Keep excursive contacts to a minimum Onlay/overlay indirect restoration ```

Why do cusp reduction and overlay restoration?

Provides strong, indirect restorative option whilst conserving tooth tissue compared to full coverage crown

What are the onlay's made from?

traditionally gold, but can also be constructed from high-strength porcelain or composite

What can the onlays be cemented with?

Adhesive cement

What is the advantage and disadvantages of using a crown for the posterior definitive restoration after being root filled?

Provides full coverage therefore, good seal Remove more tooth tissue Tooth will have an access restoration and full coverage prep - leaves very thin walls of dentine remaining

Evidence for using crowns over direct restorations on root-treated teeth?

10 year survival of crowns (81%) compared to direct restorations (63%) on root-treated teeth Koidis 2007

Evidence for how much more likely no indirect restorations likely to fail over crowns?

Root treated teeth without an indirect restoration 6x more likely to fail than crowns Aquilino, Caplan 2002

Evidence for root treated with no crown failing in anterior teeth, premolars, molars

Anterior teeth - 4.8x higher Premolars 5.8x higher Molars 6.2x higher compared to teeth with crowns - Salehrabi Rotstein 2004