Endo Flashcards
1
Q
What is the risk of accessing through existing crowns?
A
Higher risk of perforation as tooth alignment may be altered by the crown
2
Q
How can you reduce risk of perforation?
A
carefully assess pre-tx radiograph
3
Q
Why would you remove a crown for RCT treatment?
A
defective/caries
assessment of remaining tooth
visibility & accessed improved
avoid risk of perforation
4
Q
What process is used to remove a crown?
A
Sectioning
5
Q
What bur would be used to remove a porcelain crown?
A
Diamond
6
Q
What bur would be used to remove a metal crown?
A
Tungsten carbide
7
Q
Name 2 crown removers
A
Crown tapper
Kavo Coronaflex
7
Q
Name 2 crown removers
A
Crown tapper
Kavo Coronaflex
8
Q
What are the 2 main techniques of post removal?
A
ultrasonic energy
post pulling devices
9
Q
What should you always warn pts before post removal?
A
Risk of root fracture
10
Q
What frequency of ultrasonic is used for post removal?
A
pizoelectric 30-40 Hz
11
Q
Do US tips for removal have a sharp or blunt end?
A
Blunt
12
Q
How would you remove a screw type active post?
A
- remove core material w/ high speed & ultrasconic
- use wrench supplied by manufacturer for insertion
- ultrasonic can aid to break cement
13
Q
How would you remove a cast post & core?
A
- remove coronal restoration
- cut back core w/ tungsten carbide
- use ultrasonic
14
Q
Which canals are hardest to remove cast post & core from?
A
oval shaped canals
15
Q
Name 4 types of post pulling devices
A
Egglers post pulling device
Ivory miniature post puller
Ruddle post pulling kit
Massarann kit
16
Q
Which types of cements make retrievability of posts difficult?
A
adhesive resin cements
17
Q
What would you use to remove a quartz fibre post?
A
RTD fibre post removal
18
Q
Name 4 root filling materials that could require removal
A
Gutta Percha
Carrier based systems (thermafill & guttacore)
Silver points
Endodontic pastes
19
Q
Name 4 methods of removing gutta percha
A
Rotary files
Ultrasonic
Heat
Solvents
20
Q
What speed & torque would you use rotary protaper retreatment files?
A
600 rpm, 4 Ncm
21
Q
What material are Hedstrom files made of?
A
Stainless steel
22
Q
When would you use Hedstrom?
A
Poorly compacted GP
Single core obturation
23
Q
Name 5 solvents for GP
A
Chloroform
Turpentine
DMS W (eugenol)
Endosolv R (resin)
Endosolv E (eugenol)
24
What is thermafil?
Plastic carrier covered in alpha phase GP
25
What is guttacore?
Carrier made from cross-linked GP
26
How would you remove silver points from root canal?
Stieglitz forceps
Trough around w/ fine ultrasonic tip
27
Why are endodontic pastes no longer recommended?
Contain paraformaldehyde
Mutogenic & carcinogenic
28
What can overextension of endodontic pastes cause?
Nerve paraesthesia
29
What are the 4 aims of endodontic tx?
- assess, clean & disinfect RCS
- reduce number of microorganisms
- remove necrotic tissue
- seal the system to prevent reinfection
30
What are the 2 types of periradicular cysts?
True or Pocket (bay)
31
What is a true cyst?
Cavities completely enclosed in epithelium
32
What is a pocket (bay) cyst?
Epithelium-lined cavity that is open to the root canal
33
What are the European Society of Endodontic guidelines for RCT follow-up?
Clinical & radiographic follow-up at least 1 year post tx
Further follow up for 4 years
34
When is RCT retreatment indicated? (3)
- Persistent periapical pathology following RCT
- New periapical pathology associated with a root-filled tooth
- A new restoration is planned for a tooth & xray shows inadequate RCT
35
What are the signs of persistent PA pathology following RCT?
No radiographic signs of bony healing after 4 years
36
What are the prognostic factors of endo re-treatment?
- Pre-periapical lesion
- Apical extent of root canal filling
- Quality of coronal restoration
37
How to prevent post-RCT disease?
- rubber dam isolation
- proximity of prep to apical constriction
- sufficient taper of prep
- adequate irrigation & medicament
- correct extension of obturation
- adequate coronal seal
38
what are the microbial causes of post RCT disease?
- intradicular microbes
- radicular cysts
- extraradicular microbes
- cracked teeth
- coronal leakage
39
What are the non-microbial causes of post RCT disease?
- cholestrol crystals
- foreign body reaction in PA tissues
40
What causes intraradicular infections in root treated teeth?
- persisting infection
- new secondary infection through leakage
41
Which type of bacteria are most resistant to antimicrobial tx?
Gram positive
42
What number of species remain in well treated canals?
1-5 species
43
What number of species remain in inadequately treated canals?
10 - 20 species
44
What are the common microbes in RCT retreatment cases?
E faecalis
Streptococcus
Lactobacillus
Actinomyces
Propionibacterium
Candida Albicans
45
What are the possible origins of microbes post RCT?
Contamination during intial tx
Leaving tooth on open drainage
Coronal leakage
46
Where does a radicular cyst form from?
Epithelial cells rests in periodontal ligament
47
What is a true cyst?
Lesion enclosed by epithelial lining
48
What is a pocket cyst?
Epithelial sac communicated with root canal system
49
Which type of cyst will heal following RCT?
Pocket cyst
50
Where do cholestrol crystals arise from?
from dying cells during chronic inflammation
51
Which foreign bodies can cause post RCT disease?
Gutta-percha
Sealers
Paper points
Cotton pellets
52
What do you have to do before re RCTing teeth with direct restoration?
- remove existing caries
- reduce unsupported cusps
- ensure sufficient structure left
- ensure rubber dam if possible
53
What are the indication for endodontic surgery?
- failure of previous RCT
- anatomical deviations
- procedural errors
- exploratory surgery
54
What anatomical deviations would require endo surgery?
Tortuous, curved roots
Canal calcification
55
What procedural errors could need endo surgery?
ledges
blocks
perforation
file breakage
overfills
56
What are the condtaindications of endo surgery?
anatomical factors
inadequate perio support
non-restorable tooth
medical history
skill & ability of surgeon
57
What anatomical factors would contraindicate perio surgery?
- proximity to neurovascular bundles
- thick cortical bone
- difficult access (palatal roots of upper molars)
58
What is the triad of endodontic microsurgery?
Magnification
Illumination
Instruments
59
What is magnification determined by?
- power of the eyepiece
- focal length of binoculars
- magnification changer factor
- focal length of objective loss
60
What is low 3x - 8x magnification used for?
orientation & alignment of instruments
61
What is midrange x10 - x16 magnification used for?
Working magnifications
62
What is high x20 - x30 magnification used for?
inspection of fine detail
63
What preoperative anti-inflammatory would you give and why before endo resurgery?
Ibuprofen 600mg immediately before
Inhibits cyclo-oxygenase, preventing the formation of inflammatory mediators
64
What antibacterial rinse would you give pre-endo surgery & when would it be taken?
0.2% Chlorohexidine
Night before, morning of & 30 mins before appt
65
If pt was very nervous, what premedication could be given?
5mg diazepam
66
what are the rules for flap design?
must never cross a bony defect
releasing incisions should be over concave bone surface
incision meet free gingival margin at 90 degrees
67
what are the issues with a semilunar flap?
disruption of blood supply
poor wound healing
limited surgical access
scarring
68
what is osteotomy?
removal of cortical plate to expose root end
69
what can be used intraopertatively for haemostasis?
epinephrine pellets
ferric sulphate
calcium sulphate
70
what is the advantages of root end resection?
decreases dentine tubules peripheral microfiltration
removes majority of lateral canals
avoids endo-perio communications
71
what is the aim of ultrasonic retrocavity preparation?
create a clean, well conformed type 1 cavity into the sectioned root
72
what is best to use as a root end filling matieral?
MTA mineral trioxide aggregate
73
what are the good properties of MTA?
high pH
good sealing ability
hydrophillic
radiopaque
good biocompatibility
regeneration of cementum
74
what are the post op complications of endo surgery?
pain
swelling
ecchymosis
paraesthesia
infection
lacerations
sinus perforation
75
what is the definition of resoprtion?
a physiological or pathological event mainly occurring due to the action of activated clast cells
76
what is required for resorption to occur?
injury and stimulation
77
what types of injury cause resorption?
mechanical - trauma, surgery, excessive pressure
infections of root canal or PDL
chemical - hydrogen peroxide
78
what stimulation causes resorption?
infection
pressure
79
what are the systemic causes of resorption?
hypo and hyperthyroidism
calcinosis
gauchers syndrome
turner syndrome
pagets disease
herpes zoster
80
what is the mechanism of resoprtion?
damage causes chemotactic process which attracts activated cells
these colonise the damaged surfaces and initiate resorptive process
81
what is the most common cause of resorption?
pulp infection
82
what usually causes external inflammatory root resorption?
trauma (intrusion, lateral luxation, avulsion)
83
what is the tx for external inflammatory root resorption?
remove necrotic pulp as soon as signs of EIR
calcium hydroxide as interappointment dressing
many cases too advanced to treat
84
what is invasive cervical resoprtion?
originates on external root surface but can invade root dentine in any direction
occurs when loss of protective non-mineralized layer at CEJ
85
what are the predisposing factors of invasive cervical resoprtion?
ortho, trauma, surgery, intracoronal bleeding
86
what are the clinical features of invasive cervical resorption?
asymptomatic
tooth may look pink
+ve sensibility test
87
what are the clinical classifications of invasive cervical resorption?
class 1 - small with shallow penetration
class 2 - close to coronal pulp, no radicular extension
class 3 - deeper but not beyond coronal third
class 4 - extensive beyond coronal third
88
what is the tx for invasive cervical resorption?
remove granulation tissue from defect w/ 90% trichloracetic acid
restore with GI, composite or biodentine
rct if communication with pulp canal
89
what is internal root resoprtion?
originates in and affects root canal wall
follows damage to odontoblastic layer and predentine
pulp will become necrtoic and resorption will stop
90
how does internal root resorption present clinically?
extensive resorption resulting in pink discolouration of the crown
91
what is the treatment for internal root resorption?
rct if tooth can be saved
lesion difficult to clean and obturate
92
how does orthodontic pressure root resorption appear radiographically?
shortened roots with no sign of radiolucency in bone
93
what is ankylotic root resorption?
replacement resorption
lack of physiological mobility and sound metallic to percussion
94
what are the types of rotary file fractures?
torsional stress - tip bends against a canal wall and the coronal part of the file rotates
cyclic fatigue - repeated cycles of tension and compression happened during bending
95
what factors contribute to file fracture?
file size and taper
type of alloy
experience of operator
inadequate access and glide path
high speed
repeated use
96
what factors influence successful removal of fractured files?
position of the file in relation to root curvature
depth within canal
whether file is visible using microscope
97
what is the risk of removal of fractured instruments?
excessive removal of radicular dentine which may predispose root to fracture
ledging
perforation
limited application in narrow and curved canals
possibility of extrusion of the fractured file
98
what are the techniques for removing fractured instruments?
1. mechanical
2. ultrasonic
3. tube techniques
4. other
99
what are the mechanical techniques for file removal?
H files
gripping devices
excavators
100
what happens if instrument cannot be removed?
favourable prognosis if pulp vital and not infected
and
if instrument fractures during advanced stages of preparation
101
what is ledge formaton
an iatrogenically created irregularity in the canal that impedes access of the instruments to the apex
102
where are ledges most common?
outer side of curved canals
103
what are the causes of ledge formation?
inadequate access cavity
incorrect assessment of canal curvature
failure to pre bend ss files
negotiation of calcified canal
failure to use files in sequential manner
104
how would you manage a ledge formation?
establish depth ledge is at
coronal flaring up to f2-f3 working 1-2mm shorter than ledge
PUI with chelator and NaOCl
probe with pre-bent 08 ss file and use a gentle picking motion
repeat with size 10, 15 and 20 files until ledge removed
use pre-bent hand protaper files to complete preparation
105
what happens if the ledge is not possible to by-pass?
copious irrigation
dress with ns caoh2
obturate with thermoplastic technique
106
how can ledge formation be prevented?
create a reproducible glide path
copious irrigation w 30 needle
107
what may a blocked canal contain?
compacted dentinal mud
residual pulp tissue
remnants of filling materials
108
what are the causes of canal blockage?
apical patency not confirmed
during instrumentation pulpal tissue is packed and solidified in apical constriction
instrumentation not accompanied by irrigation and recapitulation
instruments not cleaned before insertion into canal
109
how do you recognise canal blockage?
instruments or gp no longer reaches full WL
110
does blockage affect prognosis?
not if recognised and corrected
111
how do you prevent blockage?
copious irrigation as soon as pulp chamber roof removed
coronal pre-flaring
recapitulation
112
what is canal transportation?
removal of canal wall structure on the outside curve in apical half
may lead to ledge formation and possible perforation
113
what are the causes of canal transportation?
insufficiently designed access cavity
canal curvature
instrumentation using ss files
leaving rotary files in same position
forcing a file into canal
