Retreatment (Archer)

Question 1

What is the problem with a tooth that is previously endodontically treated that requires retreatment?

Answer 1

Bacteria

Question 2

What can cause problems with an existing root canal?

Answer 2

Pre-existing or introduction of new bacteria into the canal

Question 3

What is the only way to know if a previously endo treated tooth requires retreatment?

Answer 3

Accurate diagnostic testing

Question 4

Is the radiograph enough to determine if a previously endo treated tooth requires retreatment?

Answer 4

No

Question 5

Can a patient be sensitive to percussion without the presence of a periapical radiolucency (PARL)?

Answer 5

Yes

Question 6

What is indicated for a tooth that has no periapical radiolucency, but is sensitive to percussion and it has not had recent restorative work done on it?

Answer 6

Evaluate for NSRCT

Question 7

What 4 factors can lead to retreatment?

Answer 7

1. Leaking coronal restoration
2. Leaking apical seal
3. Remaining bacterial irritants from initial therapy
4. Missed or untreated canals

Question 8

If a PARL stays the same size or gets smaller on a previously NSRCT tooth, is retreatment (RETX) indicated?

Answer 8

No

Question 9

If the PARL gets larger after NSRCT, should RETX be done, even if the patient does not have symptoms?

Answer 9

Yes

Question 10

What are 3 times RETX is indicated in the absence of symptom?

Answer 10

1. Caries extending into pulp chamber
2. Lack of permanent restorations for months after initial NSRCT
3. Existing NSRCT is short, thread, or canal is missed

Question 11

What are 4 obstacles that complicate RETX?

Answer 11

1. Siilver points
2. Thermafill
3. Posts
4. Separated instruments

Question 12

What corrode rapidly from the apical and coronal aspects of the tooth to form toxic silver amine sulfate amide hydrate?

Answer 12

Silver points

Question 13

Why are Thermafills poor for NSRCT and why do they make RETX difficult?

Answer 13

Stiff plastic carrier allows the obturators to be seated to length in poorly instrumented canals

Question 14

These can trap bacteria in canal if separate early in cleaning and shaping, and also obscure entry into apical portion of root?

Answer 14

Separated instruments

Question 15

What must be done to a post in an endo treated tooth before it is loosened and removed?

Answer 15

All core material around post above and below orifice must be removed

Question 16

What is used to loosen and remove a post and how long will the post normally take to come loose during this process?

Answer 16

1. Ultrasonic in circumferential rotation w/ continuous irrigation
2. 10 minutes

Question 17

What can be used to remove a separated instrument in a canal?

Answer 17

1. Long thin ultrasonic tip

2. Instrument retrieval system to engage and remove

Question 18

What is done during RETX if unable to remove a separated instrument?

Answer 18

Attempt to bypass segment with a smaller file

Question 19

What are 3 instances when the RETX of a tooth is not indicated?

Answer 19

1. Clinically unrestorable
2. Extensive resorption
3. Vertical root fracture

Question 20

Working around existing materials in the canals requires what 2 things?

Answer 20

1. Light

2. Magnification

Question 21

Why is magnification and light needed to remove NSRCT materials in a RETX?

Answer 21

Must be able to see fine detail

Question 22

Ultrasonics used for RETX can do what?

Answer 22

1. Discreet dentin removal
2. Remove core material
3. Remove cements
4. Vibrate out posts
5. Vibrate out instruments
6. Vibrate out silver points

Question 23

What is a small beaked forceps that can be used to remove materials during RETX?

Answer 23

Stieglitz

Question 24

What is a threaded tube system used to engage the visible part of a separated instrument?

Answer 24

Instrument removal system

Question 25

What consists of trephine burs and taps used to extract tight posts?

Answer 25

Post removal system

Question 26

What is a Trephine?

Answer 26

Cylindrical or crown saw for the removal of a disk of bone or other firm tissues

Question 27

A small amount of this chemical can be used to initiate the softening of hard gutta percha during a RETX?

Answer 27

Chloroform (solvent)

Question 28

Why are the past concerns about chloroform not relevant?

Answer 28

Amount of chloroform found past apex is several orders of magnitude less than permissible dose

Question 29

How does Dr. Perry Jones retreat previous endodontically treated teeth?

Answer 29

Invisalign

Question 30

What can be used to irrigate?

Answer 30

1. NaOCl 2. EDTA(ethylenediamine tetraacetic acid) 3. CHX

Question 31

What is a medicament for RETX?

Answer 31

Ca(OH)2

Question 32

What are 2 good things about 2.5% and 5.25% NaOCl?

Answer 32

1. Dissolves vital and necrotic tissue | 2. Antimicrobial

Question 33

What does using EDTA do for irrigation?

Answer 33

17% EDTA for 1 minute removes inorganic smear layer and leaves organic tissue components

Question 34

What must be used after irrigating for 1 minute with EDTA and why?

Answer 34

Irrigate w/ NaOCl to get rid of organic debris

Question 35

What is a use of Chlorhexidine as an irrigant?

Answer 35

1. Broad spectrum antimicrobial 2. Substantive 3. 2% CHX has approximately the same properties as 5.25% NaOCl, but 2% CHX is more effective against Enterococcus faecalis

Question 36

Can Chlorhexidine dissolve necrotic tissue or remove the smear layer?

Answer 36

No

Question 37

Why is Calcium Hydroxide a medicament?

Answer 37

1. Antimicrobial due to alkaline pH | 2. May aide in dissolving necrotic tissue remnants, bacteria, and their byproducts

Question 38

What % of root canals done by general dentists and endodontists that fail?

Answer 38

10%

Question 39

RETX is an option that should always be evaluated by whom?

Answer 39

Endodontist (don't EXT until consult)

Question 40

What is the healed rate of endodontic retreatment cases when the cause of failure is identified and corrected?

Answer 40

81%