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BDS4 Restorative Dentistry > Restoration of the Endodontically Tx Tooth > Flashcards

Restoration of the Endodontically Tx Tooth Flashcards

1
Q

Before restoring a tooth what must we assess?

A

If tooth is restorable - can we isolate tooth with rubber dam?

how much tooth structure remains? ferrule

coronal seal?

any sign of infection? TTP?

Mobility?

Probe for pocketing - perio disease, root fracture

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2
Q

What is the tx aims when restoring an endo tx tooth?

A

To retain tooth as functional unit in arch

To maintain the coronal seal of root canal system

to protect and preserve tooth structure

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3
Q

What is a post made of?

A

dk?

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4
Q

What do we assess in radiograph of an endodontically tx tooth?

A

Quality of obturation - length (1-2 of radiographic apex, well condensed? coronal GP at level of ACJ?)

Any unfilled or missed root canals (MB2 in 6s)

Shape of canal - if we are going to do a post

Patency of canal - fractured instruments?

Sclerosis of canals?

Crown root ratio

Pathology

Bone levels

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5
Q

What is sclerosis of the canals?

A

This is where pulp become obliterated by deposition of peritubular dentine (either due to edge or defence against trauma)

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6
Q

What do we want to known about prev endo tx?

A

How it was carried out - rubber dam used? sodium hypochlorite used? if not then re-RCT as not done under gold standards

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7
Q

Why do we need cusp coverage on posterior teeth?

A

To prevent coronal micro leakage and ingress of bacteria into tooth

to prevent catastrophic fracture - if tooth splits through furcation and buccal wall comes off then unrestorable

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8
Q

What is coronal micro leakage?

A

This is where there is ingress of Microorganisms into the root canal space and is a cause of root canal failure

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9
Q

If RCT tooth has GP exposed what is the rule?

A

If >3 months then tooth needs re-RCT due to risk of ingress of MOs into root canal space leading to infection

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10
Q

Where do we trim GP back to after obdurating?

A

ACJ - so we can see canal orifice openings

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11
Q

What do we do after obdurating with GP and trimming GP back to ACJ?

A

We then seal over with vitrebond/RMGIC over the pulp floor and root canal opening

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12
Q

Why do we ensure liner of GI over pulp isn’t too thick?

A

so we can utilise retainer of pulp chamber for retention and restoration

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13
Q

Why is coronal seal so important?

A

the technical quality of the coronal sal if more important than technical quality of RCT

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14
Q

How do we assess the quality of RCT?

A

Condensed - well or poorly?
Voids presence?
GP at level of ACJ
1-2mm of radiographic apex
voids around master and accessory points?

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15
Q

What is a ferrule?

A

Collar of dentine that encircles tooth (360 degrees) and prevents tooth fracture

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16
Q

Why does a ferrule prevent tooth fracture?

A

As it means the coronal restoration will be on tooth structure (dentine) rather than filling material (core)

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17
Q

What increases the risk of root fracture in restored teeth?

A

If there is no ferrule and restoration lies on restorative material rather than dentine so decreased longevity of crown

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18
Q

Does RCT make teeth more brittle?

A

No

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19
Q

Does RCT make tooth more likely to fracture?

A

No if minimal loss of dentine

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20
Q

Does endo make tooth become weaker?

A

Actual endodontic tx itself doesn’t alter dentine harness but access cavity weakness tooth

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21
Q

How can we restore a tooth post endo tx?

A

Direct restoration (composite, GIC)

Indirect restoration (crown, post crown, veneer)

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22
Q

What is a marginal ridge?

A

Enamel that forms M+D of anterior and posterior tooth

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23
Q

In anterior teeth if marginal ridge is intact what do we do for post endo restoration?

A

Direct restoration (we dont want to do crown/post crown which would affect integrity of marginal ridge)

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24
Q

If anterior teeth have loss or compromised marginal ridge what do we do for post endo restoration?

A

Indirect restration - crown/post Crown

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25
What is average survival rate for well done crown?
8-10 years
26
Does a post and core strengthen a tooth?
No - just increases longevity of tooth in the mouth
27
What is the purpose of a post and core?
Provides intra-radicular support for a definitive restoration and is used when not enough tooth structure present so we can attach/cement a crown
28
What does a post do?
It retains the core
29
What does a core do?
Provides retention for the crown
30
What does prep for a post do?
Weakens the tooth - as to create space for post we need to remove tooth structure
31
Where is the post placed?
In the root canal system to retain the core
32
What is the core?
This is what the prosthesis is cemented onto (crown)
33
Do we use posts in incisors and canines
No if we have enough ferrule present if extensive loss of coronal tooth tissue = need post as single root canal is not adequate at retaining a core
34
When do we avoid posts?
Lower incisors - due to thin, tapering, narrow mesiodistal roots
35
If we have multi-rooted tooth where do we place post?
Widest canal and in straight canals to avoid risk of perforation
36
What are the 4 criteria for post placement?
4-5mm Apical GP remaining (so apex is sealed and majority of lateral canals occur in apical 5mm) width <1/3rd post length: 1:1 crown root ratio or 2?3rd root length 2mm ferrule circumferentially
37
What does a ferrule allow us to do?
Build up a core so that when we place a coronal restoration the crown margins will be on dentine (reduces chance of root fracture)
38
Where should crown margins finish?
On tooth structure or else inc likelihood of fracture
39
If here is no ferrule what options do we have?
ortho extrusion surgical crown lengthening
40
What are the 3 features of an ideal post?
PARALLEL SIDED NON THREADED PASSIVE POST CEMENT RETAINED
41
What is a non threaded post?
This is where post is passive and doesn't cause transmission of force inside root reducing risk of root fracture
42
What are the types of posts?
Pre-formed Custom Made (direct or indirect)
43
What material can posts be made of?
Cast metal Steel Zirconia Carbon Glass fibre
44
What are the shapes of posts?
Parallel sided Tapered (less retentive than parallel) Smooth Serrated Threaded (screw) - most retentive but most likely to fracture root
45
What are pre-fabricated posts?
These are posts that are ready made in diff shapes - can be smooth or threaded they only require 1 visit - no impression required and can do chair side core build up
46
What are custom made posts?
These are posts that are made in the lab we create post hole, take impression, cover it in adhesive, place silicone in imp tray, pour up in ab and lab make post and core requires two visits - imps and then fit
47
Difference between tapered and parallel posts?
Tapered posts follow the root and ensure stress is concentrated coronally but they are retained by cement parallel place stress along length of root and concentrate stress apically
48
Difference between threaded and non threaded posts?
Threaded - inc retention due to self threading into dentine but inc risk of fracture as it cuts into canal Non-threaded - retained by cement which helps to distribute forces evenly but less retention
49
What types of metal can be used for a post?
Cast gold, stainless steel, brass poor aesthetiucs risk of shine through risk of root fracture corrosion risk radiopaque
50
What are benefits of ceramic posts?
high flexural strength and fracture toughness (post wont fracture but tooth may) good aesthetics - tooth coloured, no shine through issue if they break difficult to retrieve and risk of root fracture
51
What are benefits of fibre posts such as carbon and glass fibre?
flexible, similar properties to dentine, aesthetic, retrievable, bonds to dentine with DBA but hard to etch into post hole
52
What cement can be used for posts?
Adhesive resin GIC RMGIC
53
What cement provides highest retention for posts?
Adhesive resin - however bonding can be impaired by endo material remnants in canal
54
Describe GI as a cement for posts
Weak chemical bond to dentine easier to retrieve fluoride release several days to reach max strength
55
What is a core build up?
This is where we buildup internal part of tooth with restorative material to replace lost tooth tissue and then we can put a crown on
56
What does core do?
Provides retention and resistance for permeant restorations
57
What can we use as a core?
Composite Amalgam nagar core
58
What is a composite core?
this is where we use composite to build up core and it bonds to tooth structure with DBA and has good aesthetics and is tooth coloured
59
What is a nyaar core?
2-3mm coronal GP removed amalgam packed into coronal aspect of canal - locks in undercuts and used to retain core takes 24 hours to set - cant be prepd straight away poor aesthetics doesn't bond to tooth uses pulp space and orifice to retain amalgam
60
What are some risks of post crowns?
Perforations Core fracture Root fractyure Post fracture
61
Describe post perforation
This is where post perforates the tooth (common in curved, narrow canals)
62
If post perforates the tooth what may we see?
Lateral radiolucency
63
What is management of post perforation?
Xla Peri-radigular surgery
64
How does core fracture happen?
This is where theres not enough tooth structure or lack of ferrule and core fractures off
65
Why can post fracture?
If too short or narrow
66
How do we remove posts?
Ultrasonic Masseran KIt Mosquito forceps Eggler Anthogyr
67
What are some problems during removal of post?
Fracture of post fracture of root unable to remove post tooth becomes unrestiroable
68
What is deemed as endodontic failure?
presence of clinical signs and symptoms of infection enlargement of existing peri-radicular lesion new peri-radicular lesion Persistnce of peri-radicular lesion of tooth RCT 4 years previously
69
What can we do once we identify failed RCT?
Monitor Orthograde Re-RCT Peri-radicular surgery Extract
70
Before re-RCT a tooth what must we consider?
Can we improve? cost? risks ans benefits
71
What are indications for orthograde Re-RCT?
Intra- radicular infection (RC short of apex, loss of coronal system) if pt needs new complex restoration and we are unsure of standard of prev RCT loss of corneal seal - exposed GP >3 months
72
What are the principles of re-RCT?
Remove restoration Assess tooth - caries removal, assess for fractures removal all of root filling assess anatomy refine/modify prep obturate
73
How do we remove GP?
Eucalyptus oil Ultrasonic removal Hand files Reciproc R25

BDS4 Restorative Dentistry (10 decks)

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