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Pre-BDS3 Endodontics > Restoration of the endodontically treated tooth > Flashcards

Restoration of the endodontically treated tooth Flashcards

1
Q

When we clinically assess the tooth what do we want to look at

A

• Look at the coronal seal of the restoration or crown, is there any leakage or caries?
• Look at the amount of remaining tooth structure, how much ferrule is there?
Is the tooth restorable and can it be isolated with a rubber dam?

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2
Q

When doing the clinical assessment what things do we look at that indicate infection

A

• Is there any swellings
• Are there any sinuses
• Is there tenderness to percussion
• Is the buccal sulcus tender to palpation
• Is the tooth mobile
Is there increased pocketing due to periodontal disease and root fracture

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3
Q

What do we look at in a radiographic assessment in relation to the tooth

A
  • What is the shape of the canal?
    • Is bone support mild, moderate or severe
    • What is the crown to root ratio?
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4
Q

What is the ideal crown to root ratio

A

○ Want height of the crown from the ACJ to the incisal edge/cusp
Want the root to be 1.5 times the length of the crown

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5
Q

When doing the radiographic assessment, what do we look at when critiquing the root treatment

A

○ Are there unfilled or missing root canals?
○ Are there any voids?
○ Is there fractured instruments?
○ Is there posts?
○ Is there root canal sclerosis?
○ Is there any pathologies such as periapical radiolucency
○ Is there any healing or resorption?

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6
Q

What should be done to inadequate root fillings

A

should be retreated before prosthodontics commences

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7
Q

What are other considerations in assessment

A

When was the RCT done? Is it healing or has it failed
• Was the treatment done under rubber dam and was hypochlorite irrigant used
Is the root filling short or long

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8
Q

What is coronal micro leakage

A
  • This is the ingress of oral micro-organisms into the root canal system
    • It is an importance cause of root canal treatment failure
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9
Q

When should a tooth be retreated after exposure

A

• If filled teeth is unrestored for 3 months or longer it should generally be re-rot treated as the GP is exposed to the mouth and so the root canal will be contaminated with bacteria as they have entered coronally

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10
Q

How important is coronal seal

A

• Technical quality of the coronal restoration is significantly more important for periodontal health than the technical quality of the RCT

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11
Q

What are problems after RCT/re-RCT

A
  • Amount of remaining tooth structure both externally and internally
    • The restoration type
    • Lac or no ferrule
    • Wide post holes
    • Endodontic complications such as fractured instruments, perforations, short/long fillings
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12
Q

Are endodontic teeth more brittle

A

• Teeth do not become more brittle after endodontic treatment

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13
Q

Is an endodontic tooth more likely to fracture

A

• A root filled tooth with minimal loss of dentine is not more likely to fracture than a vital tooth

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14
Q

Is dentine hardness altered after endo tx

A

• Dentine hardness is not altered after endodontic treatment

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15
Q

Does dehydration of the tooth weaken dentine

A

• Dehydration does not appear to weaken dentine structure in terms of strength or toughness

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16
Q

What are the clinical choices

A 
• Direct restoration - composite (glass ionomer) - class III or IV (glass ionomer tends to be used in class V cervical restorations)
Indirect restoration - crown or post crown (veneer
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17
Q

What is the significance of marginal ridges

A
  • If these are intact then you do a restoration, not crowns and post crowns
    • When you lose a lot of the marginal ridge then you may need to go down the road of replacing them with crowns
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18
Q

What is the restoration for an anterior tooth with intact marginal ridge

A

can be given a direct restoration using composite

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19
Q

What is the restoration of anterior teeth with intact marginal ridges with our without a discoloured crown

A

direct restoration with composite, bleaching (think of bleaching both internally and externally before going down the route of indirect restorations)and or a veneer or a crown

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20
Q

What is the restoration for anterior teeth with marginal ridges destroyed

A

can opt for a core build up with a crown or a post crown

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21
Q

What is the function of a post/core

A

Gains intraradicular support for a definitive restoration

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22
Q

What does the core do

A

Core provides retention for crown

is what the prosthesis is cemented to e.g crown or bride abutment

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23
Q

What does the post do

A
  • Post retains the core
    • Posts DO NOT strength or reinforce teeth

placed in the root canal

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24
Q

Why can posts weaken teeth

A

• Prep of the root canal for a post weakens the tooth because you have to remove tooth structure in the inside to create space

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25
What is the guidelines for posts in incisors and canines
§ the post is unnecessary if there is sufficient coronal dentine present § if there is extensive loss of coronal tooth tissue then the tooth will require a post as the pulp chamber and a single root canal are not adequate to retain a core avoid in mandibular incisors
26
Why should posts be avoided in mandibular incisors
avoid in mandibular incisors due to thin/tapering/narrow mesiodistal roots
27
What are features of premolars
hey have small pulp chambers and tapering roots § They are thin in mesiodistal cross section and have proximal invaginations e.g the canine eminence region where there is a concavity
28
If a post is placed in a premolar where should it be placed
§ If a post is to be placed then it should be placed in the widest root canal § Avoid in curved canals to avoid perforations as the posts are straight
29
What should the length of the root filling be for a post
4-5mm root filling apically
30
What should the post width be
○ No more than 1/3 of root width at the narrowest point and 1mm of remaining circumferential coronal dentine
31
How much of the post length should be in the root
• Sufficient alveolar bone support is required and at least half of the post length should be into the root
32
What ratio of post length:crown length do we want
Want a minimum of 1:1 post length/crown length ratio
33
What is a ferrule
A ferrule is a dentine collar - it is an encirclement of 1-2mm of vertical axial tooth structure within walls of a crown
34
What is the benefit of a ferrule
It prevents tooth fracture
35
What is the risk of a crown margin is not placed on solid tooth
risk of root fracture is significantly increased
36
What may have to be done to achieve a ferrule
Orthodontic extrusion or crown lengthening may be necessary to achieve this
37
What is the ideal post
parallel sided non threaded cement retained
38
Why do we want a parallel sided post
○ Avoids 'wedging' | More retentive than tapered
39
Why do we want a non threaded post
○ Passive ○ Smooth surface incorporates less stress to remaining tooth than threaded (active) as if it has grooves for example then it can transmit forces to the tooth
40
Why do we want a cement retained post
○ Less retentive than threaded posts but cement acts as a buffer between the masticatory forces and post/tooth
41
How can we classify posts
manufacture material shape
42
What is the manufacturer classifications
preformed/prefabricated or custom made
43
What are the material classifications
cast metal, steel, zirconia, carbon/glass fibre
44
What are the shape classifications
parallel sided or tapered
45
What are the benefits of prefabricated posts
* Only 1 visit is required * No impressions and no fit visit required * Chairside core build up * Post and core are different materials * Immediate preparation of core * Large selection of designs and materials
46
What are custom posts
* Cast from direct pattern fabricated in patients mouth e.g duralay * The indirect pattern can be fabricated in the lab by getting an impression of the post hole and waxing up the post and core in the lab * Unified post and core e.g made one piece, the same material
47
What are the disadvantages of custom posts
• 2 visits are required - impression and fit • Temporisation between visits and lab stage is required • There is risk of contamination of the root canal between visits The cast post is made in type IV heat hardened gold
48
What materials can posts be made of
cast gold, stainless steel, brass, titanium
49
What are the disadvantages of metal posts
○ Poor aesthetics as the metal could shine through the crown but now opaquer are put in the crown to try and stop this ○ Root fracture ○ Corrosion ○ Nickel sensitivity, radiopaque on radiographs
50
What are the ceramic posts made of
alumina, zirconia
51
What are the advantages of ceramic posts
○ High flexural strength and fracture toughness | ○ Favourable aesthetics
52
What are the disadvantages of ceramic posts
○ Difficult retrievability and root fracture is common
53
What are the fibre posts made of
glass, quartz, carbon
54
What are the advantages of fibre posts
○ Flexible (more than ceramic), similar properties to dentine ○ Aesthetic ○ Retrievable - there are burs to drill them out in the event of fracture Bond to dentine with dentine bonding agents
55
What are the disadvantages of fibre posts
○ Flexible (more than ceramic), similar properties to dentine ○ Aesthetic ○ Retrievable - there are burs to drill them out in the event of fracture Bond to dentine with dentine bonding agents
56
What are the advantages of tapered prefab posts
conservative high strength high stiffness
57
What are the disadvantages of tapered prefab posts
less retentive than parallel or threaded
58
What are the advantages of parallel prefab posts
high strength good retention comprehensive system
59
What are the disadvantages of parallel prefab posts
precious metal post expensive corrosion of SS less conservative
60
What are the advantages of threaded posts
high retention
61
What are the disadvantages of threaded posts
stresses generated in canal may cause fracture
62
What are the advantages of custom cast post and core
high strength better than prefab
63
Wha are the disadvantages of custom cast post and core
less stiff than wrought | multiple appointments complex
64
What is a core build up
• The internal part of the tooth is built up with restorative material to replace the lost tooth tissue so that the restoration can go on top of it and is held by the core
65
What are core build ups used more for
* Especially for molar access for RCT, may have not much tooth tissue left * The core is prepared and it provides retention and resistance for permanent restorations
66
What are the core materials
composite amalgam glass ionomer
67
What are the features of composite as a core material
``` ○ Most commonly used core material ○ Tooth coloured so good aesthetics ○ Bonds to the tooth structure ○ Technique sensitive so moisture control is required Used with fibre posts ```
68
What are the features of amalgam as a core material
○ Tends to be used for posterior teeth ○ Tend to avoid as retention is required (undercuts) ○ Poor aesthetics ○ Core cannot be prepared straight away - needs 24h to set ○ Avoid pinned amalgams
69
What are the features of glass ionomer as a core material
○ Not really used as it absorbs water and core expands in size meaning when it comes time to cement the restoration on, you cant get it on as it has expanded in size
70
Are there differences in the core materials
There are no significant differences in fracture and failure characteristics of composite, amalgam and cast gold as core material under a crown provided a 2mm ferrule exists on the margin of healthy tooth
71
What is a nayyar core
* After the tooth is root treated and its set, you go into the root canal and take out some GP and you pack down some amalgam into the root canal and this is built up in to the pulp chamber * This provides retention for the amalgam as it is packed into the little nooks and crannies under the pulp chamber * It cannot be crown prepared for 24h until the amalgam has set
72
What is the management for a post perforation
○ Repair § Can repair internally or externally (periradicular surgery) ○ Extraction
73
What should posts be avoided in
narrow root canals
74
What are common teeth that get post perforation
Common teeth that get perforated are premolars because they have particularly buccal root canals and they are very narrow
75
What is a core fracture
• If there is no ferrule then the core may break off from the root and you will see the crown with the core in it
76
What is root fracture
• This is when the post and core survive but the tooth doesn’t Patient can complain of pain and you may see a deep pocket
77
What is post fracture
Sometimes the post is too short and sometimes its too narrow and if there are lots of lateral forces then the post will fracture off
78
How can posts be removed
• Ultra sonics • Masseran kit • Eggler Moskito forceps (screw retained)
79
What is post crown failures due to
• 60% is due to restorative reasons such as caries around the crown margins • 32% is due to periodontal problems such as a pre existing perio condition or a perio-endo lesion 8% is due to endodontic reasons

Pre-BDS3 Endodontics (13 decks)

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