ENDO Retreatment procedures

Question 1

According to the European Society of Endodontology’s Quality Guidelines, when should RCT’s be followed up?

Answer 1

clinical and radiographic follow-up at least 1 year after tx

Question 2

When following up RCTs what are we looking for?

Answer 2

complete bony healing

if this does not happen, follow up for 4 years

Question 3

When is root canal retreatment indicated?

Answer 3

1. persistent PA pathology following RCT
2. new PA pathology associated with a root-filled tooth
3. a new restoration is planned for tooth and radiographic assessment shows an inadequate root canal filling and/or PA radiolucency

Question 4

What is a radiographic sign of persistent PA pathology?

Answer 4

no radiographic signs of bony healing after 4 years

Question 5

what is a sign of new PA pathology associated with root-filled tooth?

Answer 5

initial healing but a new radiolucency develops some time later

root canal system has become infected subsequent to previous treatment

Question 6

does periradicular periodontitis affect endodontic tx?

Answer 6

yes

Question 7

what are the prognostic factors for the success rate of root canal retreatment?

Answer 7

1. pre-op PA lesion
2. apical extent of root canal filling
3. quality of coronal restoration

Question 8

what are the terms to describe the outcome of root canal retreatment?

Answer 8

healed
healing
asymptomatic function
persistent/ recurrent/ emerged disease

Question 9

described a ‘healing’ retreated root canal?

Answer 9

clinical - no signs or symptoms
radiological - reduced radiolucency in follow up <4 years

Question 9

described a ‘healed’ retreated root canal?

Answer 9

clinically - no signs/ symptoms
radiological - no residual radiolucency, or scarring after surgery

Question 10

describe a ‘asymptomatic function’ retreated root canal?

Answer 10

clinical - no signs or symptoms combined with no or persistent radiolucency, reduced in size or unchanged.

Question 11

describe a ‘persistent/ recurrent/ emerged disease’ retreated root canal?

Answer 11

clinical - with or without symptoms
radiological - new, increased, unchanged or reduced after > 4 years

Question 12

what are the guidelines for prevention of post treatment disease?

Answer 12

1. rubber dam isolation
2. proximity of preparation to apical constriction
3. sufficient taper of preparation
4. adequate irrigation and placement of interappointment medicament
5. correct extension of root canal obturation without extrusion
6. adequate coronal seal to prevent re-infection

Question 13

what are indications for root canal retreatment?

Answer 13

1. previous treatment has failed (signs of inflammation or infection)
2. persistent symptoms, sinus tract, swelling, pain
3. failure of previous treatment because of technical reasons
4. existing pathology and new restoration planned for tooth

Question 14

what is a sinus tract a sign of?

Answer 14

chronic abscess

Question 15

list the causes of post-treatment disease?

Answer 15

1. intraradicular microbes
2. extraradicular infection
3. foreign body reaction
4. true cyst

Question 16

where do you find intraradicular microbes and why?

Answer 16

apical parts of root canal often where inaccessible by instrumentation (difficult to disinfect)

Question 17

explain extraradicular infection?

Answer 17

microbes have evaded host defense mechanisms and have established themselves in the PA tissues

Question 18

what is a foreign body reaction?

Answer 18

reaction to extrusion of RCT filling material

Question 19

specifically, what are the microbial causes of post-treatment disease?

Answer 19

1. intraradicular microbes
2. extraradicular microbes
3. radicular cyst
4. cracked teeth, vertical root fracture
5. coronal leakage

Question 20

what is the major cause of endodontic treatment failure?

Answer 20

intraradicular infection, persistent or secondary

Question 21

what is the difference between persistent infection and secondary infection?

Answer 21

persistent - microbes not removed in initial treatment, they remain in the root canal system after disinfection and interappointment dressing
secondary - microbes enter root canal system by a coronal leakage

Question 22

specifically, what are the non-microbial causes of post treatment disease?

Answer 22

1. cholesterol crystals
2. foreign body reactions in periapical tissues

Question 23

what bacteria have been found to be persistent?

Answer 23

gram positive

Question 24

how may you still find bacteria in well treated canals?

Answer 24

they do not always maintain an infectious process they may be located in areas where they have no access to periapical tissues

Question 25

what are common microbes found in retreatment cases?

Answer 25

E faecalis strep lactobacillus actinomyces propionibacterium candida albicans

Question 26

where are the possible origins of microbes found in retreatment cases?

Answer 26

contamination during initial treatment leaving a tooth on open drainage coronal leakage post-treatment

Question 27

in most cases, what prevents microorganisms from invading the periapical tissues?

Answer 27

apical periodontitis

Question 28

when microbes overcome the defense barrier of apical periodontitis what happens?

Answer 28

they establish an extraradicular infection e.g., acute apical abscess

Question 29

what is the most common odontogenic cyst of inflammatory origin?

Answer 29

radicular cyst

Question 30

where do radicular cysts arise from?

Answer 30

epithelial cell rests in periodontal ligament

Question 31

what is the difference between a true cyst and a pocket cyst?

Answer 31

a pocket cyst will heal following endodontic treatment whereas a true cyst wont

Question 32

what is a true cyst?

Answer 32

lesion enclosed by epithelial lining

Question 33

what is a pocket cyst?

Answer 33

epithelial sac communicates with root canal system

Question 34

what are the non-microbial causes of post-treatment disease?

Answer 34

cholesterol crystals foreign body reaction

Question 35

what are cholesterol crystals?

Answer 35

from dying cells during chronic inflammation

Question 36

what materials can cause a foreign body reaction?

Answer 36

gutta percha sealers paper points cotton pellets

Question 37

why may people gave a foreign body reaction to paper points/ cotton pellets?

Answer 37

they contain cellulose in which the body cannot breakdown

Question 38

what are the treatment options you would give to a pt for root canal retreatment?

Answer 38

do nothing xLA retreatment surgical retreatment

Question 39

during retreatment, what do you remove the pulp chamber with?

Answer 39

ultrasonic

Question 40

what is the risk of access through existing crowns?

Answer 40

higher risk of perforation due to reduced visibility and tooth alignment may be altered by the crown

Question 41

explain sectioning crowns?

Answer 41

section imp taken crown sectioned into 2 halves removed with excavator

Question 42

when removing crowns what burs are used?

Answer 42

diamond for porcelain crowns tungsten carbide for metal crowns

Question 43

in what situations can you not use a wamkey to remove a crown?

Answer 43

if an adhesive cement has been used

Question 44

name types of crown removers?

Answer 44

crown tapper KaVo Coronaflex

Question 45

when would you use a crown remover?

Answer 45

crown margins not intact

Question 46

what is a risk when removing a post?

Answer 46

root fracture

Question 47

what are the 2 main techniques for post removal?

Answer 47

ultrasonic energy post pulling devices

Question 48

describe the ultrasonics for post removal?

Answer 48

peizoelectric ultrasonics vibrations 30-40kHz tips have a blunt end

Question 49

what must the nurse do when you are using a piezoelectric ultrasonic to remove a post?

Answer 49

blow air/ water coolent at the tip if not, the heat can cause bony necrosis

Question 50

what are the types of post pulling devices?

Answer 50

egglers post pulling device ivory minatiure post puller ruddle post pulling kit massarann kit

Question 51

when removing a post, what technique must be tried first?

Answer 51

ultrasonic then use post pullers if you need

Question 52

what material, used for posts, does not always show up on a radiograph?

Answer 52

quartz fibre

Question 53

how may quartz fibre posts fail?

Answer 53

fibres become contaminated by moisture and then frey

Question 54

what does the RTD fibre post removal kit contain?

Answer 54

pin drill: creates a pilot hole through post channel hole piezo size 2: removes remaining fibres

Question 55

why are thermafil obturators not used any more?

Answer 55

they have a central plastic sprue covered in GP which is very hard to remove

Question 56

what has thermafil been replaced with?

Answer 56

guttacore - the sprue is made from cross linking GP so it is easier to remove

Question 57

what is resorcinol?

Answer 57

an endodontic paste used in eastern european countries containing formaldehyde

Question 58

what are the techniques used to remove gutta percha?

Answer 58

rotary endo files ultrasonics heat solvents

Question 59

what rotary endodontic files are used for retreatment?

Answer 59

dentsply protaper D files PTG endo instruments

Question 60

what rpm and torque are rotary protaper retreatment files used at?

Answer 60

600rpm 4Ncm

Question 61

why are rotary protaper retreatment files not flexible?

Answer 61

made from NiTi

Question 62

what are the sizes of protaper retreatment files?

Answer 62

D1 - 16mm 30 D2 - 18mm 25 D3 - 22mm 20

Question 63

why may D1 Protaper retreatment file cause ledges and perforations

Answer 63

it has a partially cutting tip

Question 64

what files are used when using PTG to remove GP (PTG sequence)?

Answer 64

F2 or F3, length 21 depending on canal diameter set to 600rpm work from 3-1 work in 1mm increments checking EAL until WL and patency have been achieved

Question 65

when using PTG to remove GP, what would you do if the apical part of the canal is underprepared/ not obturated?

Answer 65

negotiate with size 10 file establish WL/ patency complete prep using PTG sequence at 300rpm

Question 66

what technique may you use to remove GP if a single cone obturation or it is poorly compacted?

Answer 66

hedstrom files and solvent

Question 67

why is the hedstrom file and solvent technique not suitable when removing GP from narrow, curved canals?

Answer 67

files made from stainless steel so less flexible

Question 68

what are types of solvents for GP?

Answer 68

chloroform turpentine DMS IV (eugenol) Endosolv R (resin) Endosolv E (eugenol)

Question 69

when should you never use solvents?

Answer 69

when preparing a post space - it can compromise seal

Question 70

what technique would you use to remove carrier-based GP?

Answer 70

hedstrom file and solvent protaper D files

Question 71

how do you remove silver points?

Answer 71

do not cut coronal end remove with stieglitz forceps or gently trough around with fine ultrasonic tip

Question 72

why are endodontic pastes no longer recommended in most countries?

Answer 72

shrinkage and poor seal made from toxic materials: often contain paraformaldehyde

Question 73

what happens if endo pastes are over extended?

Answer 73

nerve paraesthesia