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BDS4 Exam Perp > Post and core and re-rct > Flashcards

Post and core and re-rct Flashcards

1
Q

5 possible problems after Rct/reRCT

A
  • inadequate tooth structure left
  • Lack or no ferrule
  • Fractured instruments
  • Perforations
  • Inadequate root fillings
  • Wide post holes
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2
Q

Are teeth more brittle after RCT?

A

no

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3
Q

What is one of the most important causes of RCT failure?

A
  • Coronal micro-leakage
  • more problematic in multi-rooted teeth
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4
Q

When should an unrestored root filled teeth be reroot treated?

A

if unrestored for 3 months

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5
Q

Ideal restoration for anterior teeth with intact marginal ridges? (root treated)

A

Composite veneer

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6
Q

Ideal restoration for discoloured anterior teeth with intact marginal ridges?

A

Bleaching / composite veneer

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7
Q

Ideal restoration for anterior teeth with marginal ridges destroyed?

A
  • Post crown
  • Core build up with crown
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8
Q

What is the function of a post/core?

A
  • Gains intraradicular support for a definitive restoration
  • Core provides retention for crown
  • Post retain core
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9
Q

Where is a post placed?

A

in the root canal

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10
Q

When would you not place a post in incisors and canines?

A

When there is sufficient coronal dentine

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11
Q

Why would you avoid post placement in mandibular incisors?

A

due to thin/tapering and narrow mesiodistal roots

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12
Q

Why would you avoid post placement in premolars, and where should you place the post if indicated?

A
  • due to small pulp chambers and tapering roots
  • Place in widest root canal
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13
Q

Why would you avoid placing a post in curved canals?

A

To avoid perforations

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14
Q

What is the root filling length that should be left when placing a post?

A

4-5mm root filling apically

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15
Q

How should the post width be?

A
  • no more than 1/3 of root width at narrowest point
  • 1mm of remaining circumferential coronal dentine
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16
Q

How much of the post should go into the root?

A

At least half of the root length

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17
Q

What is the minimum post/crown length ratio?

A

1:1

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18
Q

What is ferrule?

A

Dentine collar
* which is an encirclement of 1-2mm of vertical axial tooth structure within the walls of a crown

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19
Q

What is the function of the ferrule?

A

Prevent tooth fracture when placing a post

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20
Q

What is the dimensions of the ferrule ?

A

At least 1.5mm height and width of remaing coronal dentine

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21
Q

2 methods of making a ferrule if there is lack of it?

A
  • Orthodontic extrusion
  • Crown lengthening
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22
Q

3 features of an ideal post?

A
  • Parallel
  • non threaded (passive)
  • Cement retained
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23
Q

Why is parallel sided post better than tapered?

A
  • more retentive than tapered
  • avoids wedging
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24
Q

Why is non threaded post better than threaded?

A

less stress on tooth - less risk of fracture

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25
Q

Which post is more retentive , threaded or cement retained (parallel) ?

A
  • Threaded
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26
Q

Why is cement retained better than threaded although threaded is more retentive?

A

because cement act as a buffer between masticatory forces and post/tooth

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27
Q

Name A - F

A
  • Tapered smooth
  • Tapered serrated
  • Tapered threaded
  • Parallel smooth
  • Parallel serrated
  • Parallel threaded
28
Q

3 advantages of prefabricated posts ?

A
  • only 1 visit required
  • no impression and laboratory visit required
  • large selection of designs and materials
29
Q

What are 3 materials of posts?

A
  • Metal - gold, SS , brass, titanium
  • Ceramics - alumina and zirconia
  • Fibre - glass, quartz and carbon
30
Q

advantages of metal posts?

A

Radiopaque on radiographs

31
Q

4 disadvantages of metal posts?

A
  • poor aesthetics
  • root fracture
  • corrosion
  • nickel sensitivity
32
Q

3 advantages of ceramic posts?

A
  • good aesthetics
  • high flexural strength
  • Good fracture toughness
33
Q

2 disadvantages of ceramic posts

A
  • difficult to retrieve
  • root fracture
34
Q

4 advantages of fibre posts?

A
  • retrievable
  • flexible
  • similar properties to dentine
  • bond to dentine with DBA
35
Q

What is a core buildup?

A

Internal part of tooth is built up with restorative material to provide retention and resistance for definitive restorations

36
Q

2 reasons why posts is not a good idea in posterior teeth?

A
  • high occlusal forces
  • have multiple roots
37
Q

3 core materials ?

A
  • composite
  • amalgam
  • glass ionomer
38
Q

2 reasons why composite is the most commonly used material for cores?

A
  • Good aesthetics
  • Bonds to tooth structure
39
Q

What core material is used with fibre posts?

A

Composite

40
Q

1 disadvantage of composite as a core material?

A

Technique sensitive and requires good moisture control

41
Q

3 disadvantages of using amalgam as a core material?

A
  • not aesthetic
  • need 24h to set
  • needs retention
42
Q

What is the disadvantage with using GI as a core material?

A
  • absorbs water and expands
43
Q

What is a Nayyar core ?

A

A core of amalgam where root filling is removed from coronal part and amalgam is packed into the root canals and tooth built up which provides retention

44
Q

5 methods to remove a post?

A
  • Ultrasonic
  • Masseran kit - Trephan
  • Eggler device
  • Moskito forceps
  • Sliding hammer
  • Anthogyr - safe relax
45
Q

4 problems you would encounter when removing a post?

A
  • Post fracture
  • Root fracture
  • Tooth becomes unrestorable
  • Post space becomes too wide
46
Q

4 problems with posts ?

A
  • Perforation
  • Core fracture
  • Root fracture
  • Post fracture
47
Q

2 management options for post perforation?

A
  • Repair - internal or external (periradicular surgery)
  • Extraction
48
Q

Post failure rate due to restorative reasons?

A

60%

49
Q

What is the ideal taper of a core?

A

6 degrees

50
Q

Why is length of core important ?

A

Important to allow clearance for definitive restoration
2mm for MCC

51
Q

What material would you use for a provisional post core and crown?

A

Temp bond

52
Q

3 provisional restorations for post and core ?

A
  • provisional post core crown
  • immediate denture
  • Essex retainer
  • Dressing
53
Q

4 Steps to remove gutta percha?

A
  • Dental dam
  • soften using heat or solvent
  • Use gates glidden to minimum size 3 ( straight part of canal only)
  • Use working length and rubber stopper on gates glidden
54
Q

Write a prescription for a post and core to the lab

A
  • Please construct post and core
  • Para post (colour)
  • Core 6 degree taper
  • Please leave 2mm space in occlusion for crown
    Provide the lab with registration and impressions with shade
55
Q

4 treatment options when RCT fails?

A
  • Monitor if asymptomatic
  • Orthograde treatment
  • Periradicular surgery
  • Extract ± implant
56
Q

3 indication of non surgical root canal retreatment?

A
  • intra-radicular infection
  • New restoration with poor RCT
  • Loss of coronal seal
57
Q

6 principles of retreatment?

A
  • remove restoration
  • assess restorability
  • remove all root filling
  • assess anatomy
  • refine and modify preparation
  • complete treatment as de novo case
58
Q

How would you remove insoluble resins from the root canal?

A

Ultrasonics

59
Q

How would you remove gutta percha and soluble paste from the canal ? (generally)

A
  • Handfiles and solvents
  • then reciproc
60
Q

Which files will you use to remove poorly condensed GP?

A

Hedstroem files

61
Q

What is the problem with removing well condensed GP?

A
  • Harder as need to create space
62
Q

What reciproc files GP for reroot treatment? and why?

A

Reciproc (r25, R40, R50) , to avoid loss of tooth substance as these files are regressively tapered

63
Q

What solvent would you use

A
  • chloroform
  • eucalyptus
64
Q

What is the difference between using a solvent and not using a solvent on the on root canal walls according to Horvath et el 2009 ?

A

Using solvents lead to more gutta percha and sealer remnants on root canal wall and inside dentinal tubules

65
Q

What are the 4 steps in retreatment using GP?

A
  • Remove GP from coronal third using Ultrasonics, GG or heat carrier
  • Remove GP from Mid third using Reciproc 25 (set stopper to 2/3 of EWL) in slow pecking motions , can use eucalyptus to soften GP
  • Determine working length with K files size 10/15
  • Complete apical third using R25/R25 blue to CWL
66
Q

2 advantages of using reciproc for retreatment?

A

very efficient
removes bulk of GP

BDS4 Exam Perp (72 decks)

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