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BDS4 Exam Prep > 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
Which post is more retentive , threaded or cement retained (parallel) ?
* Threaded
26
Why is cement retained better than threaded although threaded is more retentive?
because cement act as a buffer between masticatory forces and post/tooth
27
Name A - F
* Tapered smooth * Tapered serrated * Tapered threaded * Parallel smooth * Parallel serrated * Parallel threaded
28
3 advantages of prefabricated posts ?
* only 1 visit required * no impression and laboratory visit required * large selection of designs and materials
29
What are 3 materials of posts?
* Metal - gold, SS , brass, titanium * Ceramics - alumina and zirconia * Fibre - glass, quartz and carbon
30
advantages of metal posts?
Radiopaque on radiographs
31
4 disadvantages of metal posts?
* poor aesthetics * root fracture * corrosion * nickel sensitivity
32
3 advantages of ceramic posts?
* good aesthetics * high flexural strength * Good fracture toughness
33
2 disadvantages of ceramic posts
* difficult to retrieve * root fracture
34
4 advantages of fibre posts?
* retrievable * flexible * similar properties to dentine * bond to dentine with DBA
35
What is a core buildup?
Internal part of tooth is built up with restorative material to provide retention and resistance for definitive restorations
36
2 reasons why posts is not a good idea in posterior teeth?
* high occlusal forces * have multiple roots
37
3 core materials ?
* composite * amalgam * glass ionomer
38
2 reasons why composite is the most commonly used material for cores?
* Good aesthetics * Bonds to tooth structure
39
What core material is used with fibre posts?
Composite
40
1 disadvantage of composite as a core material?
Technique sensitive and requires good moisture control
41
3 disadvantages of using amalgam as a core material?
* not aesthetic * need 24h to set * needs retention
42
What is the disadvantage with using GI as a core material?
* absorbs water and expands
43
What is a Nayyar core ?
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
5 methods to remove a post?
* Ultrasonic * Masseran kit - Trephan * Eggler device * Moskito forceps * Sliding hammer * Anthogyr - safe relax
45
4 problems you would encounter when removing a post?
* Post fracture * Root fracture * Tooth becomes unrestorable * Post space becomes too wide
46
4 problems with posts ?
* Perforation * Core fracture * Root fracture * Post fracture
47
2 management options for post perforation?
* Repair - internal or external (periradicular surgery) * Extraction
48
Post failure rate due to restorative reasons?
60%
49
What is the ideal taper of a core?
6 degrees
50
Why is length of core important ?
Important to allow clearance for definitive restoration 2mm for MCC
51
What material would you use for a provisional post core and crown?
Temp bond
52
3 provisional restorations for post and core ?
* provisional post core crown * immediate denture * Essex retainer * Dressing
53
4 Steps to remove gutta percha?
* 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
Write a prescription for a post and core to the lab
* 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
4 treatment options when RCT fails?
* Monitor if asymptomatic * Orthograde treatment * Periradicular surgery * Extract ± implant
56
3 indication of non surgical root canal retreatment?
* intra-radicular infection * New restoration with poor RCT * Loss of coronal seal
57
6 principles of retreatment?
* remove restoration * assess restorability * remove all root filling * assess anatomy * refine and modify preparation * complete treatment as de novo case
58
How would you remove insoluble resins from the root canal?
Ultrasonics
59
How would you remove gutta percha and soluble paste from the canal ? (generally)
* Handfiles and solvents * then reciproc
60
Which files will you use to remove poorly condensed GP?
Hedstroem files
61
What is the problem with removing well condensed GP?
* Harder as need to create space
62
What reciproc files GP for reroot treatment? and why?
Reciproc (r25, R40, R50) , to avoid loss of tooth substance as these files are regressively tapered
63
What solvent would you use
* chloroform * eucalyptus
64
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 ?
Using solvents lead to more gutta percha and sealer remnants on root canal wall and inside dentinal tubules
65
What are the 4 steps in retreatment using GP?
* 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
2 advantages of using reciproc for retreatment?
very efficient removes bulk of GP

BDS4 Exam Prep (72 decks)

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