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

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2
Q

How can you reduce risk of perforation?

A

carefully assess pre-tx radiograph

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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

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4
Q

What process is used to remove a crown?

A

Sectioning

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5
Q

What bur would be used to remove a porcelain crown?

A

Diamond

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6
Q

What bur would be used to remove a metal crown?

A

Tungsten carbide

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7
Q

Name 2 crown removers

A

Crown tapper
Kavo Coronaflex

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7
Q

Name 2 crown removers

A

Crown tapper
Kavo Coronaflex

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8
Q

What are the 2 main techniques of post removal?

A

ultrasonic energy
post pulling devices

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9
Q

What should you always warn pts before post removal?

A

Risk of root fracture

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10
Q

What frequency of ultrasonic is used for post removal?

A

pizoelectric 30-40 Hz

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11
Q

Do US tips for removal have a sharp or blunt end?

A

Blunt

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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
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13
Q

How would you remove a cast post & core?

A
  • remove coronal restoration
  • cut back core w/ tungsten carbide
  • use ultrasonic
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14
Q

Which canals are hardest to remove cast post & core from?

A

oval shaped canals

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15
Q

Name 4 types of post pulling devices

A

Egglers post pulling device
Ivory miniature post puller
Ruddle post pulling kit
Massarann kit

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16
Q

Which types of cements make retrievability of posts difficult?

A

adhesive resin cements

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17
Q

What would you use to remove a quartz fibre post?

A

RTD fibre post removal

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18
Q

Name 4 root filling materials that could require removal

A

Gutta Percha
Carrier based systems (thermafill & guttacore)
Silver points
Endodontic pastes

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19
Q

Name 4 methods of removing gutta percha

A

Rotary files
Ultrasonic
Heat
Solvents

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20
Q

What speed & torque would you use rotary protaper retreatment files?

A

600 rpm, 4 Ncm

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21
Q

What material are Hedstrom files made of?

A

Stainless steel

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22
Q

When would you use Hedstrom?

A

Poorly compacted GP
Single core obturation

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23
Q

Name 5 solvents for GP

A

Chloroform
Turpentine
DMS W (eugenol)
Endosolv R (resin)
Endosolv E (eugenol)

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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