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endo third year. - restoration of endo treated tooth Flashcards

1
Q

what do you clinically assess in a RCT tooth?

A 
coronal seal
remaining tooth structure - ferrule
restorable? - can you isolate with dam
swelling
sinus
TTP
buccal sulcus TTP
mobility
increased pocketing - PDD and root fracture
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2
Q

what do you radiographically assess in an RCT tooth?

A

root filling - length, quality, voids
unfilled/missed RCs
shape of canal
patency - fractured instruments, posts, sclerosis
bone support
crown to root ratio (1:1.5)
pathology - PA radiolucency, resorption, perforations

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3
Q

which is the most commonly missed RC?

A

2MB canal 16/26

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4
Q

if the root filling is inadequate what should you do?

A

re-treat before pros

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5
Q

problems with restoring a tooth after RCT

A

amount of remaining tooth structure internally and externally
lack/no ferrule
wide post holes
endo complications - fractured instruments. perforations, short/long root fillings

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6
Q

are RCT teeth more brittle?

A

no

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7
Q

what is coronal leakage?

A

ingress of oral microorganisms into the RC system

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8
Q

what is the most important cause of RCT failure?

A

coronal microleakage

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9
Q

generally if root filled teeth are unrestored for how long should they be re-RCT?

A

3m or longer

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10
Q

how do you create an ideal coronal seal?

A

trim the GP to ACJ and place RMGI over pulp floor and RC openings (lateral canals)
not too thick - allow remainder of pulp chamber for retention and restoration

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11
Q

Rx options for anterior teeth - intact marginal ridges

A

composite

veneer

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12
Q

Rx options for anterior teeth - intact marginal ridges and discoloured crown

A

bleaching or veneer

crown

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13
Q

Rx options for anterior teeth - marginal ridges destroyed

A

core build up with crown

post crown

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14
Q

function of a post-core

A

gain intraradicular support for a definitive restoration

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15
Q

function of core

A

provides retention for crown

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16
Q

function of post

A

retains core

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17
Q

do posts strengthen or weaken teeth?

A

weaken - removing more tooth structure

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18
Q

6 guidelines for post placement

A 
try to avoid
1 - tooth type 
2 - root filling length 
3 - post width
4 - sufficient alveolar bone support
5 - crown length/post length ratio
6 - ferrule
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19
Q

guidelines for post placement - tooth type

A

avoid L incisors- thin/tapering MD roots, 30% have 2 RCs
avoid in curved canals - avoid perforations
premolars - small pulp chambers and tapering roots, place in widest RC

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20
Q

guidelines for post placement - root filling length

A

4-5mm GP apically

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21
Q

guidelines for post placement - post width

A

no more than 1/3 of root width at narrowest point and 1mm of remaining circumferential coronal dentine

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22
Q

does diameter of post increase retention?

A

no

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23
Q

guidelines for post placement - sufficient alveolar bone support

A

at least half of the post length into the root

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24
Q

guidelines for post placement - post length/crown length ratio

A

min 1:1

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25
does length of post increase retention?
yes
26
guidelines for post placement - ferrule
at least 1.5mm height and width of remaining coronal dentine from the gingival margin
27
what is a ferrule?
1.5-2mm collar of dentine extending supragingivally 360 degrees round circumference
28
advantage of a ferrule
reduces fracture risk of tooth, and also root when crown placed
29
what does the post length below the crown need to at least equal?
crown length
30
ideal post features
parallel sided non-threaded (passive) cement-retained
31
ideal post features - parallel sided
avoids wedging | more retentive than tapered
32
ideal post features - non-threaded
smooth surface incorporates less stress to remaining tooth than threaded
33
ideal post features - cement retained
less retentive than threaded posts but cement acts as a buffer between masticatory forces and post/tooth
34
3 classifications of posts
manufacture - prefabricated or custom made material - cast metal, steel, zirconia, carbon/glass fibre shape - parallel sided or tapered
35
advantage of prefabricated posts
only one visit required - no impressions/lab visit
36
disadvantage of prefabricated posts
posts and core are different materials
37
advantage of custom made posts
unified post and core - preferred for non-vital teeth as avoids material interfaces
38
disadvantage of custom made posts
2 visits required - temporisation between risks contamination of RC
39
what do cast custom posts tend to be made from?
type 4 heat hardened gold
40
what materials can posts be made from?
metal ceramics fibre
41
metal posts materials
cast gold, SS, brass, titanium
42
disadvantages of metal posts
poor aesthetics root fracture corrosion nickel sensitivity
43
advantages of metal posts
radiopaque
44
ceramic post materials
alumina, zirconia
45
advantages of ceramic posts
high flexural strength and fracture toughness | good aesthetics
46
disadvantages of ceramic posts
difficult retrievability | root fracture common
47
fibre post materials
glass, quartz, carbon
48
advantages of fibre posts
``` flexible similar properties to dentine aesthetic retrievable bond to dentine with DBAs ```
49
are fibre posts radiolucent or radiopaque?
radiolucent
50
post shapes
tapered | parallel
51
describe a core build up
internal part of tooth is built up with restorative material to replace the lost tooth tissue core is prepared - provides retention and resistance for permanent restorations
52
do all cores need a post?
no
53
core materials
composite amalgam GI
54
composite as a core material
``` most commonly used good aesthetics bonds to tooth structure technique sensitive - moisture control required used with fibre posts ```
55
amalgam as a core material
tend to avoid as retention is required poor aesthetics core can't be prepared straight away - need 24hrs to set avoid pinned amalgams
56
GI as a core material
not really used as it absorbs water and core expands in size
57
Nayyar core
root treatment is removed from the RCs amalgam is packed into the RCs and tooth built up - provides retention for the amalgam cannot be prepared for 24hrs until amalgam sets
58
problems with posts
perforation core fracture - v common root fracture post fracture
59
post perforation management
repair - internal or external (PR surgery) | extraction
60
post removal
``` US Masseran Kit (trephan) Moskito forceps (screw retained) Eggler device sliding hammer anthogyr (safe relax) ```
61
why do most posts fail?
restorative reasons>PD reasons>endo reasons
62
what material is usually used for a direct post?
fibre
63
for a direct fibre post what is required?
ferrule
64
bonding a direct fibre post
resin cement under dam
65
which type of post can be done (not ideal) without a ferrule?
cast post
66
why should you avoid posts where possible?
it is a last resort to save the tooth
67
stages in cast post prep (11)
``` assessment design of new restoration provisional restoration GP removal post space prep and anti-rotation features provisional construction impression lab prescription provisional placement try in fit ```
68
why is it so important to be confident in the quality of RCT before placing a post?
posts are difficult to dismantle and there is a risk of root fracture
69
what is the risk with tapered posts?
act as wedges - root fracture
70
how much GP should remain apically with a post?
3-5mm
71
where should crown margins be placed and why?
on the ferrule - solid tooth tissue | gives resistance to rotational forces and micro leakage, reduces fracture risk
72
core design
6 degree taper | length required - to allow 2mm clearance incisally for MCC
73
what options do you have for a provisional restoration?
provisional post core crown e.g. tempbond immediate denture dressing e.g. ZOE Essix retainer with some teeth on
74
what size GG do you need to get to when removing GP In straight part of canal for a post?
min size 3
75
how do you ensure you leave 3-5 mm of GP apically?
use WL and rubber stopper on GG
76
what can you use to ensure a GP plug remains?
loupes microscope PA
77
how can you soften GP?
heat or solvent
78
why is it sensible to leave once obturated for 24 hours before post prep?
to allow resin sealer to set | - ideally post prep at same time as obturation but risk disrupting that
79
ParaPost XP
``` indirect casting technique post system different drill sizes brushing motion Ti provisional post imp post parapost drill ```
80
what should you do before post space prep?
impression
81
ParaPost XP - preparing provisional post
cut it from apical end 2-3mm short of incisal edge
82
ParaPost XP - post space prep
heat source remove GP GGs and irrigate Parapost drill. irrigate pro temp into putty matrix - parapost retained in pro temp
83
ParaPost XP - definitive master impression
putty wash technique - light body - putty impression over top - post retained in imp (imp post)
84
antirotation groove
some cut this into prep to prevent rotational displacement | in bulkiest area of root, usually lingual
85
lab prescription for cast post
please construct cast post and core para post (colour) core 6 degree taper please leave 2mm space in occlusion for crown enclosed registration/opposing impression/(shade) for crown
86
cast post try in
``` check post space for any remaining temp bond or debris - US to clean out irrigate CHX 0.2% - dam? dry PP ensure fits around prep - protect airway do you have enough occlusal clearance? ```
87
cast post fit
don't fill post space with cement - may prevent it seating, hard to remove it again firm apical pressure get rid of excess can ask lab for provisional acrylic crown make sure no excess around or gingival bleeding when taking crown imp/fitting MCC
88
post removal problems
``` unable to remove root fracture (immediate/delayed) render tooth unrestorable post space too wide you break post ```
89
posts in molars
-s outweigh +s if absolutely have to in most cases sufficient natural retention for a core if no coronal tissue - posts may be inserted for short distance into largest straightest root canal at least 1mm ferrule of definitive coronal restoration required unless all-porcelain Rx
90
which roots do posts usually involve in molars and why?
distal L molars palatal U molars they provide a large and usually straighter canal for post-insertion
91
cuspal protection
prevent catastrophic fracture prevent microbial ingress maintain coronal seal
92
posts in premolars
only if roots are adequately bulky, long and straight | only one canal should be used

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