Instrumentation of Root Canal System

Question 1

What is the aim of instrumentation of the root canal system?

Answer 1

Remove canal contents- infected soft and hard tissues

Give disinfecting irritants apace to gain access to the canal space

Create space for delivery of intra-canal medicaments

Retain integrity of radicular structures

Question 2

What is recapitulation and patency filing?

Answer 2

Recapitulation- using a small file to ensure latency and dislodge debris before introducing a larger file.

Patency filing- placing the file into the apical constriction to contact apical tissues.

Question 3

What is the modified double flare technique?

Answer 3

Involves development of an initial coronal flare, followed by apical flare.

Then step back technique allows you to create a continuous taper.
- uses GG and stainless steel K files.

Question 4

What are the different file movements that can be utilised?

Answer 4

Balanced force- for smaller K files

Watch winding- for larger k files

Question 5

What is corrected working length?

Answer 5

Distance in mm from a known coronal reference point to the position of in the apical region of the tooth, where endodotnic preparation and obturation terminates.

Question 6

What are the design objectives of endo treatment?

Answer 6

Continuously tapered funnel shaped canal

Maintain apical foramen in original position

Keep apical opening as small as possible

Question 7

How can you get your corrected working length?

Answer 7

File into canal at EWL and take a PA
Electronic apex locator

Question 8

What is estimated working length?

Answer 8

Estimated length at which instrumentation should be limited.

Measure distance between coronal reference point and radiographic apex and subtract 1mm- based off a pre-op radiograph.

Question 9

What is a master apical file?

Answer 9

Largest diameter file that is taken to WL- therefore represents the final preparation size of the apical portion of the canal at WL.

Question 10

What type of file can be used to extirpate the pulp?

Answer 10

Barbed broach

Must not engage the canal- only to remove th pulp contents.

Question 11

What are the advantages of NiTi vs SS?

Answer 11

More flexible

Less lateral pressure required

Increased cutting efficiency

Good safety

Question 12

What are the disadvantages of NiTi preparation?

Answer 12

Prone to fracture

Expensive

Access can be difficult in posterior teeth

Unsuitable for complex canal anatomy

Question 13

What is chemomechanical disinfection?

Answer 13

Chemo- using chemicals to disrupt biofilm and smear layer

Mechanical- shaping the root canal space and debriding canal.

Question 14

When analysing a tooth on a radiograph for root treatment, what are we looking for?

Answer 14

Number of roots
Number of canals
Anatomy of roots- curved, splayed.
Length of roots
Angulation of roots
Proximity to vital structures
Canal calcifications- pulp space narrow or wide?
How far does the PA pathology extend?
Any posts or large coronal restorations already in situ
Separated instruments
Ledges or perforations

Question 15

What methods can be used to determine corrected working length?

Answer 15

Electronic Apex locator
WL radiograph using paralleling technique
Paper points

Question 16

Describe, in simple terms, the stages of modified double flare technique.

Answer 16

Access
Coronal preparation at 2/3 of EWL
Work out CWL
Apical preparation
Apical gauging
Apical flare

Question 17

What sealer is used to obturate?

Answer 17

AH plus- epoxy resin sealer

Slow setting- 8 hours
Good selling ability
Initial toxicity declining after 24 hours

Question 18

What are the components of GP?

Answer 18

20% gutta percha
65% zinc oxide
10% radio pacifiers
5% plasticisers

Question 19

What methods of obturation exist?

Answer 19

Cold lateral compaction
- Master cone as same size as your master apical file and then use a finger spreader to create space for accessory cones to fill the voids.

Question 20

What is a cone fit radiograph?

Answer 20

After doing final rinse with EDTA and sodium hypochlorite
- Place master apical cone into canal, while it is still wet.

Take radiograph and see if the MAC is at the CWL.

Also can check clinically if you mark the CWL on the cone with the tweezers and check it goes to WL.

Question 21

What is the final rinse?

Answer 21

10 mins sodium hypochlorite- 30ml.
1 min EDTA 17%
1 min sodium hypochlorite
Then do cone fit
Then dry with paper points

Question 22

Describe the process of apical gauging.

Answer 22

First stage of obturation.

Take the equivalent K file to the reciprocal file that you used at CWL.

Put it to CWL and then place apex locator on it.
- gentle apical pressure and it should not reach 0.

This tells us we have apical control- can now obturate with the equivalent master apical cone.

Question 23

Describe, in simple terms, the procedure for reciproc.

Answer 23

Coronal flare with R25 at 2/3 EWL.
Determine CWL
Create glide path with size 15 file
Then take R25 to CWL.
Apical gauging with equivalent K file
Final rinse with sodium hypochlorite and EDTA
Master cone fit
Dry the canal
Obturate

Question 24

If someone is pregnant, is it okay for them to have endo treatment?

Answer 24

In the first trimester, it should be emergency intervention only.

Question 25

How long should you wait after to do endo treatment after someone has had an MI?

Answer 25

6 months. Emergency treatment should be provided in consultation with patient's cardiologist.

Question 26

How would you get consent for a procedure?

Answer 26

Explain the diagnoses and clinical findings to the patient. Treatment options available for those diagnoses Why you think a particular treatment is necessary Consequences, risks and benefits of treatment Likely prognosis after treatment Your recommended treatment Cost of proposed treatment What might happen if the proposed treatment is not carried out Whether the treatment is guaranteed, how long it is guaranteed for and any exclusions that apply. Ask if the patient has any questions. Record all of this in the patient's notes.

Question 27

What are the potential risks of endo treatment?

Answer 27

Failure Perforation Instrument separation Post-op pain Hypochlorite accident Damage to exiting restorations Caries

Question 28

Why is sodium hypochlorite a good irritant?

Answer 28

Antimicrobial Dissolves pulp remnants and collagen Only root canal irrigation that dissolves necrotic and vital tissue Helps disrupt sear layer

Question 29

What factors are important for sodium hypochlorite function?

Answer 29

Volume Concentration Contact Mechanical agitation Exchange

Question 30

What concentration is used for sodium hypochlorite?

Answer 30

Between 0.5 and 6%. We use Parcan in GDH- 3%.

Question 31

What is manual dynamic irrigation?

Answer 31

Using sodium hypochlorite within the canal plus using your MAC to manually disrupt the biofilm as well.

Question 32

What is used to remove the smear layer?

Answer 32

17% EDTA for 1 minute.

Question 33

Why is it important to dry the canal in between the terminal rinses with EDTA and NAOH?

Answer 33

Reduces the therapeutic benefits of sodium hypochlorite.

Question 34

What are some of the complications of sodium hypochlorite?

Answer 34

Discolouration of fabrics Ophthalmic injuries due to eye contact Apical extrusion lidding to tissue encores Allergic reaction

Question 35

What are the common symptoms of sodium hypochlorite extrusion?

Answer 35

Ecchymosis along the superficial vasculature on the same side Pain Swelling Haemorrhage Neurological complications Airway obstruction

Question 36

What are the guidelines for use of sodium hypochlorite?

Answer 36

Give patient PPE Dam placement Ensure all syringes labelled accordingly Side vented needle for irrigation 27G luer lock syringe Never fill the syringe more than 2/3 full Never bind the needle into the root canal at any time Depress the plunger with the index finger and never the thumb.

Question 37

What is the purpose of an intra-canal medicament?

Answer 37

Placed in between appointments in an attempt to destroy the micro-organisms and prevent reinfection. Control of root resorption Reduce inflammation and exudate

Question 38

What is the gold standard intra-canal medicament?

Answer 38

Non-setting calcium hydroxide for 7 days - Ultracal or Optident. Must come into direct contact with bacterial cell wall to be effective.

Question 39

What is Ledermix and when would you use it?

Answer 39

Anti-microbial and anti-inflammatory paste. - Contains corticosteroid and tetracycline. Used in cases of hot pulp.

Question 40

What is the goal of obturation?

Answer 40

Prevent passage of micro-organisms and fluid along the root canal Fill the whole root canal system Block apical foramina and dentinal tubules and accessory canals.

Question 41

What techniques are available for obturation?

Answer 41

Cold lateral compaction Warm compaction- vertical or lateral Continuous wave obturation Carrier based obturation

Question 42

If the tooth had an open apex, what would you need to do?

Answer 42

Create an apical plug- use either MTA or biodentine.

Question 43

How does MTA act as an apical plug?

Answer 43

Biocompatible but is also osseo-inductibe- we see bone and cementum growing alongside it.

Question 44

What is the function of a root canal sealer?

Answer 44

Seals space between dentinal wall and core Fills voids and irregularities in canal, lateral canals and between GP points Lubricates during obturation

Question 45

After obturation, what must you do?

Answer 45

Obtain adequate coronal seal to prevent bacterial recontamination of the root canal system or fracture of the tooth. We want both a good coronal seal and a good apical seal.

Question 46

What is the 5 and 10 year survival rate for Endodontically treated teeth?

Answer 46

Lots of varying factors- indirect vs direct restorations, ferrule present, quality of endo tx, type of tooth. 5 year- 85-90% 10 years- 75-80%

Question 47

What is the survival rate of endodontically treated teeth with indirect and direct restorations post-endo treatment?

Answer 47

Indirect at 3 years- 92% Direct with amalgam or composite at 3 years- 83% But Indirects have much better long term prognosis- 5-10 years, 6 times more likely to fail without an indirect restoration. - indirect- 81%, direct- 62% Study showing teeth that had to be extracted following endo treatment- 85% did not have an indirect restoration.