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BDS3 Endo > Posts and Cores > Flashcards

Posts and Cores Flashcards

1
Q

Before restoring an endodontically treated tooth with indirect restoration, what should be done?

A

Assessment of RCT tooth:
-clinically
-radiographically
-check existing restoration coronal seal and microleakagae

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2
Q

In clinical assessment of an RCT’d tooth, what are you looking at?

A

-coronal seal/caries etc
-amount of tooth structure remaining - ferrule
-restorable? - can you isolate it with rubber dam
-swelling
-sinus
-TTP
-buccal sulcus/apical area tender to palpation
-mobility
-increased pockeing - perio disease and root fractures

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3
Q

In clinical assessment of an RCT’d tooth, what are you looking at?

A

-coronal seal/caries etc
-amount of tooth structure remaining - ferrule
-restorable? - can you isolate it with rubber dam
-swelling
-sinus
-TTP
-buccal sulcus/apical area tender to palpation
-mobility
-increased pockeing - perio disease and root fractures

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4
Q

In radiographic assessment of RCT’d tooth, what are you looking at before deciding to restore?

A

-root filling - length, quality of obturation
-shape of canal
-patency (fractured instruments etc)
-bone support
-crown to root ratio
-any pathology

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5
Q

Why do you need to assess a previous RCT before placing an indirect restoration?

A

Inadequate root fillings should be re-treated before any definitive indirect restorations are placed

If have had coronal leakage etc. the root canal will be infected. Want to start fresh and if you didn’t do the previous RCT then you don’t know what conditions it was carried out under.

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6
Q

What is coronal microleakage and why is it important?

A

-ingress of oral micro-organisms into the root canal system
-IMPORTANT cause of RCT failure
-is significant in multi-rooted teeth

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7
Q

What can be done to try and prevent the impact of any coronal microleakage?

A

-when doing RCT trum the GP to the ACJ and place RMGI over the pulp floor and root canal openings to seal it (lining - not too thick so rest of pulp chamver can be used for retention)

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8
Q

Root canal treated teeth that have been left unrestored for how long should be re-RCT’d?

A

3 months

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9
Q

What are some restorative problems after RCT?

A

-lack or no ferrule
-wide post holed (re-RCT)
-endo complications - # instruments, perfs, short/long root fillings

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10
Q

What are the choices of restoration for a RCT’d tooth?

A

-direct restoration (composite)
-indirect - crown or post-crown, veneer

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11
Q

Options for anterior RCT’d tooth? When would you choose each option?

A

Direct composite = intact marginal ridges
Direct composite + veneer/crown (+possible bleaching) = anterior with intact marginal ridges +/- discoloured crown
Core build-up w/ crown (post crown) = marginal ridges destoryed

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12
Q

Describe a post/core/why its used/how it works.

A

-used when not enough tooth structure
-gains intraradicular support for a definitive restoration
-core provides retention for crown
-post retains the core

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13
Q

Why are posts required for anterior teeth but not as much for posterior teeth?

A

-Multi-rooted teeth (molars) have large pulp chambers which can retain a core and therefore the overlying crown
-anterior teeth have much smaller pulp chambers and are therefore not retentitve enough so require a post (anterior teeth are subject to lateral forces whereas posterior are subject to vertical forces)

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14
Q

How much root filling should there be apically for post placement?

A

4-5mm of root filling apically

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15
Q

What should the width of a post be?

A

-no more than 1/4rd of the root width at narrowest point and 1mm of remianing circumferential coronal dentine

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16
Q

For sufficient alveolar bone support with posts, how much alveolar bone should there be?

A

At least half of post length into the root

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17
Q

For sufficient alveolar bone support with posts, how much alveolar bone should there be?

A

At least half of post length into the root

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18
Q

What should the post length/crown length ratio be?

A

minimum 1:1

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18
Q

What should the post length/crown length ratio be?

A

minimum 1:1

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19
Q

What is the minimum ferrule mesurement you should have for post placement?

A

At least 1.5mm height and width

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20
Q

Define a ferrule. Why is it important?

A

have at least 1.5-2mm collar of dentine supra-gingivally 360degrees around the circumference of the tooth

so you can place your crown margins on solid tooth rather than restorative material. This is important as it will give the core and crown resistant to rotatational displacement and gives a coronal seal (ferrule effect) - prevents tooth fracture

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21
Q

If the crown margin is not placed on sound tooth tissue, what is significatnly increased?

A

The risk of root fracture

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22
Q

If the crown margin is not placed on sound tooth tissue, what is significatnly increased?

A

The risk of root fracture

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23
Q

If you do not have a significant enough ferrule, apart from XLA, what are the other options? What do you need to consider for these tx options?

A

Orthodotnic extrusions or surgical crown lengthening to give a ferrule

NEed to consider the root length

24
Q

What are the properties of an ideal post?

A

-parallel sided
-non-threaded (passive and less stress to remaining tooth)
-cement retained

25
Q

Why do you want you post to be parallel-sided and cement retained?

A

Parallel-sided = avoids ‘wedging’ that you get with tapered post and is more retentive than tapered post

Cement retained = less retentive than threaded posts but cement acts as a buffer between masticatory forces and post/tooth

26
Q

What are the different types of posts you can get (classification)?

A

-Manufacture method: pre-formed or custom made
-Material: cast metal, steel, zirconia, carbon/glass fibre
-Shape: parallel sided or tapered

27
Q

What are the different types of posts you can get (classification)?

A

-Manufacture method: pre-formed or custom made
-Material: cast metal, steel, zirconia, carbon/glass fibre
-Shape: parallel sided or tapered

28
Q

Do all cores need a post?

A

No - not if there is sufficient coronal dentine

29
Q

Describe prefabricated posts/adv/basic parts of procedure.

A

-only 1 visit required
-no impressions and no fit visit required
-chairside core build-up
-post and core materials are different
-immediate prep of core
-large selection of designs and materials

30
Q

Describe prefabricated posts/adv/basic parts of procedure.

A

-only 1 visit required
-no impressions and no fit visit required
-chairside core build-up
-post and core materials are different
-immediate prep of core
-large selection of designs and materials

31
Q

Describe how custom posts differ from prefabricated.

A

-take impressions and the post and core are fabricated in the lab
-the post and core are unified (made in one piece, same material)
-need 2 visits: impressions and fit (need a temp fillings and can risk contamination of root canal between visits)

32
Q

What different materials can posts be made from?

A

-Metal: cast gold, SS, brass< Ti
-Ceramics: alumina, zirconia
-Fibre: glass, quartz, carbon

33
Q

Adv and disadv of each post material type? (metal, ceramics, fibre)

A

-Metal: poor aesthetics, root fracture, corrosion, nickel sensitivity, raidopaque on radiographs
-Ceramics: high flextural strength and fracture toughness, favourable aesthetics, difficult retrieval and root fracture common
-Fibre: flexible, similar properties to dentine, aethetiv, retrievable, bond to dentine with DBAA’s, radiolucent on radiographs

34
Q

What are the disadv and adv of tapered prefab, parallel prefab, threaded and custom posts?

A
35
Q

What materials can be used for a core/what is the best?

A

-composite - most commonly used, good aesthetics, bonds to tooth, technique sensitive so moisture control required
-amalgam - tend to avoid as retention is required, poor aesthetics, need to wait to prep as amalgam takes 24hrs to prep
-GI (not really used as it absorbs water so core expands in size)

36
Q

What post material is a composite core used with?

A

-fibre posts

37
Q

What post material is a composite core used with?

A

-fibre posts

38
Q

How can an amalgam core be made more retentive?

A

Nayyar core: root treatment is removed from root canals
-amalgam packed into root canals and tooth built up
-this provides retnetion for the amalgam
-cannot be prepared for 24hrs until amalgam has set

38
Q

How can an amalgam core be made more retentive?

A

Nayyar core: root treatment is removed from root canals
-amalgam packed into root canals and tooth built up
-this provides retnetion for the amalgam
-cannot be prepared for 24hrs until amalgam has set

39
Q

Managment options for post perf?

A

-repair: internal or external (periradicular surgery)
-XLA

40
Q

What can be used to remove a post?

A

-ultra-sonics
-masseran kit
-eggler
-moskito forcepts

41
Q

Reasons for post crown failure?

A

-60% due to restorative reasons e.g. caries around crown margins
-32% due to perio problems
-8% due to endo reasons

42
Q

When building up a core/preping it, what design factors do you need to consider?

A

-6 degree taper
-lenght required - need to allow 2mm clearance for MCC

43
Q

How do you remove GP?

A

-can use dam
-soften with heat or solvent (eucalyptus oil)
-gates glidden to min size 3 (in straight part of canal only)
-leave 305mm GP in apical 3rd

44
Q

Why do you leave GP at apical 3rd when placing post and core?

A

To act as an apical plus

45
Q

How do you prep the canal for a post?

A

There are post drills (called para post - there are also posts that match the size of the drill)

46
Q

Lab prescription for post and core?

A

-please contrust cast post and core
-para post (colour)
-core 6 degree taper
-please leave 2mm space in occlusion for crown
-enclosed registration/opposing impression and shade

47
Q

Stages in cast post prep.

A

1-assessmeny
2-desgin of new restoration
3-provisional restoration
4-GP removal
5-post space prep and anti-rotation features
6-provisional construction
7-impression
8-lab prescription
9-provisional placement
10-tryin
11-fit

48
Q

Describe try-in stage.

A

-check post space for temp bond
-irrigate CHX
-dry with paper points
-ensure fits around perp
-do you have enough occlusal clearance?

49
Q

Describe fitting a post and core.

A

-be careful not to fill post space with cement
-may prevent it seating
-firm apical pressure
-ged rid of excess cement
-make sure no excess when taking crown impression
-practise the fit sequence

Note: can get post core and crown made on same impression but chance is that one will fit and the other won’t

50
Q

How do you get core retention in posterior teeth?

A

-undercuts and dentine pins or bonding agents

Note: the advs of post outweight disadvantages (narrow roots and perf/fracture more common)
Note: avoid Nayyar core in posterior teeth

51
Q

If a posterior teeth requires post then what canals/roots are usually used? Why these canals?

A

-distal roots of mandibular molars
-palatal roots of maxilalry molars

as provide large and usually straighter canal for post insertion

52
Q

If a posterior teeth requires post then what canals/roots are usually used? Why these canals?

A

-distal roots of mandibular molars
-palatal roots of maxilalry molars

as provide large and usually straighter canal for post insertion

53
Q

Minimum restoration for posterior RCT’s teeth?

A

cast restoration with occlusal coverage e.g. MOD onlay

Better coronal seal and outcomes

54
Q

Why do you want cuspal coverage/protection in posterior teeth?

A

-prevents catastrophic fracture
-maintains coronal seal
-prevents microbial ingress

55
Q

Why do you want cuspal coverage/protection in posterior teeth?

A

-prevents catastrophic fracture
-maintains coronal seal
-prevents microbial ingress

56
Q

When considering restoration of premolars, what should you be thinking?

A

-cuspal coverage as first option
-posts should only be used if roots are adequately long, bulky and straight
-only one canal should be used

BDS3 Endo (9 decks)

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