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Endo > endo third year. - restoration of endo treated tooth > Flashcards

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
Q

does length of post increase retention?

A

yes

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26
Q

guidelines for post placement - ferrule

A

at least 1.5mm height and width of remaining coronal dentine from the gingival margin

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27
Q

what is a ferrule?

A

1.5-2mm collar of dentine extending supragingivally 360 degrees round circumference

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28
Q

advantage of a ferrule

A

reduces fracture risk of tooth, and also root when crown placed

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29
Q

what does the post length below the crown need to at least equal?

A

crown length

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30
Q

ideal post features

A

parallel sided
non-threaded (passive)
cement-retained

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31
Q

ideal post features - parallel sided

A

avoids wedging

more retentive than tapered

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32
Q

ideal post features - non-threaded

A

smooth surface incorporates less stress to remaining tooth than threaded

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33
Q

ideal post features - cement retained

A

less retentive than threaded posts but cement acts as a buffer between masticatory forces and post/tooth

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34
Q

3 classifications of posts

A

manufacture - prefabricated or custom made
material - cast metal, steel, zirconia, carbon/glass fibre
shape - parallel sided or tapered

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35
Q

advantage of prefabricated posts

A

only one visit required - no impressions/lab visit

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36
Q

disadvantage of prefabricated posts

A

posts and core are different materials

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37
Q

advantage of custom made posts

A

unified post and core - preferred for non-vital teeth as avoids material interfaces

38
Q

disadvantage of custom made posts

A

2 visits required - temporisation between risks contamination of RC

39
Q

what do cast custom posts tend to be made from?

A

type 4 heat hardened gold

40
Q

what materials can posts be made from?

A

metal
ceramics
fibre

41
Q

metal posts materials

A

cast gold, SS, brass, titanium

42
Q

disadvantages of metal posts

A

poor aesthetics
root fracture
corrosion
nickel sensitivity

43
Q

advantages of metal posts

A

radiopaque

44
Q

ceramic post materials

A

alumina, zirconia

45
Q

advantages of ceramic posts

A

high flexural strength and fracture toughness

good aesthetics

46
Q

disadvantages of ceramic posts

A

difficult retrievability

root fracture common

47
Q

fibre post materials

A

glass, quartz, carbon

48
Q

advantages of fibre posts

A 
flexible
similar properties to dentine
aesthetic
retrievable
bond to dentine with DBAs
49
Q

are fibre posts radiolucent or radiopaque?

A

radiolucent

50
Q

post shapes

A

tapered

parallel

51
Q

describe a core build up

A

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
Q

do all cores need a post?

A

no

53
Q

core materials

A

composite
amalgam
GI

54
Q

composite as a core material

A 
most commonly used
good aesthetics 
bonds to tooth structure
technique sensitive - moisture control required
used with fibre posts
55
Q

amalgam as a core material

A

tend to avoid as retention is required
poor aesthetics
core can’t be prepared straight away - need 24hrs to set
avoid pinned amalgams

56
Q

GI as a core material

A

not really used as it absorbs water and core expands in size

57
Q

Nayyar core

A

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
Q

problems with posts

A

perforation
core fracture - v common
root fracture
post fracture

59
Q

post perforation management

A

repair - internal or external (PR surgery)

extraction

60
Q

post removal

A 
US
Masseran Kit (trephan)
Moskito forceps (screw retained)
Eggler device
sliding hammer
anthogyr (safe relax)
61
Q

why do most posts fail?

A

restorative reasons>PD reasons>endo reasons

62
Q

what material is usually used for a direct post?

A

fibre

63
Q

for a direct fibre post what is required?

A

ferrule

64
Q

bonding a direct fibre post

A

resin cement under dam

65
Q

which type of post can be done (not ideal) without a ferrule?

A

cast post

66
Q

why should you avoid posts where possible?

A

it is a last resort to save the tooth

67
Q

stages in cast post prep (11)

A 
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
Q

why is it so important to be confident in the quality of RCT before placing a post?

A

posts are difficult to dismantle and there is a risk of root fracture

69
Q

what is the risk with tapered posts?

A

act as wedges - root fracture

70
Q

how much GP should remain apically with a post?

A

3-5mm

71
Q

where should crown margins be placed and why?

A

on the ferrule - solid tooth tissue

gives resistance to rotational forces and micro leakage, reduces fracture risk

72
Q

core design

A

6 degree taper

length required - to allow 2mm clearance incisally for MCC

73
Q

what options do you have for a provisional restoration?

A

provisional post core crown e.g. tempbond
immediate denture
dressing e.g. ZOE
Essix retainer with some teeth on

74
Q

what size GG do you need to get to when removing GP In straight part of canal for a post?

A

min size 3

75
Q

how do you ensure you leave 3-5 mm of GP apically?

A

use WL and rubber stopper on GG

76
Q

what can you use to ensure a GP plug remains?

A

loupes
microscope
PA

77
Q

how can you soften GP?

A

heat or solvent

78
Q

why is it sensible to leave once obturated for 24 hours before post prep?

A

to allow resin sealer to set

- ideally post prep at same time as obturation but risk disrupting that

79
Q

ParaPost XP

A 
indirect casting technique post system
different drill sizes
brushing motion
Ti provisional post
imp post
parapost drill
80
Q

what should you do before post space prep?

A

impression

81
Q

ParaPost XP - preparing provisional post

A

cut it from apical end 2-3mm short of incisal edge

82
Q

ParaPost XP - post space prep

A

heat source remove GP
GGs and irrigate
Parapost drill. irrigate
pro temp into putty matrix - parapost retained in pro temp

83
Q

ParaPost XP - definitive master impression

A

putty wash technique

  • light body
  • putty impression over top
  • post retained in imp (imp post)
84
Q

antirotation groove

A

some cut this into prep to prevent rotational displacement

in bulkiest area of root, usually lingual

85
Q

lab prescription for cast post

A

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
Q

cast post try in

A 
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
Q

cast post fit

A

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
Q

post removal problems

A 
unable to remove
root fracture (immediate/delayed)
render tooth unrestorable
post space too wide
you break post
89
Q

posts in molars

A

-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
Q

which roots do posts usually involve in molars and why?

A

distal L molars
palatal U molars
they provide a large and usually straighter canal for post-insertion

91
Q

cuspal protection

A

prevent catastrophic fracture
prevent microbial ingress
maintain coronal seal

92
Q

posts in premolars

A

only if roots are adequately bulky, long and straight

only one canal should be used

Endo (5 decks)

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